U.S. patent application number 12/939563 was filed with the patent office on 2012-05-10 for vapor-compression refrigeration apparatus with backup air-cooled heat sink and auxiliary refrigerant heater.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Levi A. CAMPBELL, Richard C. CHU, Michael J. ELLSWORTH, JR., Madhusudan K. IYENGAR, Robert E. SIMONS.
Application Number | 20120111038 12/939563 |
Document ID | / |
Family ID | 46018351 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120111038 |
Kind Code |
A1 |
CAMPBELL; Levi A. ; et
al. |
May 10, 2012 |
VAPOR-COMPRESSION REFRIGERATION APPARATUS WITH BACKUP AIR-COOLED
HEAT SINK AND AUXILIARY REFRIGERANT HEATER
Abstract
Apparatus and method are provided for cooling an electronic
component. The apparatus includes a refrigerant evaporator in
thermal communication with a component(s) to be cooled, and a
refrigerant loop coupled in fluid communication with the evaporator
for facilitating flow of refrigerant through the evaporator. The
apparatus further includes a compressor in fluid communication with
a refrigerant loop, an air-cooled heat sink coupled to the
refrigerant evaporator, for providing backup cooling to the
electronic component in a backup, air cooling mode, and a
controllable refrigerant heater coupled to the heat sink. The
refrigerant heater is in thermal communication across the heat sink
with refrigerant passing through the refrigerant evaporator, and is
controlled in a primary, refrigeration cooling mode to apply an
auxiliary heat load to refrigerant passing through the refrigerant
evaporator to ensure that refrigerant in the refrigerant loop
entering the compressor is in a superheated thermodynamic
state.
Inventors: |
CAMPBELL; Levi A.;
(Poughkeepsie, NY) ; CHU; Richard C.; (Hopewell
Junction, NY) ; ELLSWORTH, JR.; Michael J.;
(Lagrangeville, NY) ; IYENGAR; Madhusudan K.;
(Woodstock, NY) ; SIMONS; Robert E.;
(Poughkeepsie, NY) |
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
46018351 |
Appl. No.: |
12/939563 |
Filed: |
November 4, 2010 |
Current U.S.
Class: |
62/115 ; 165/185;
62/159; 62/259.2; 62/507 |
Current CPC
Class: |
F25B 2500/06 20130101;
H05K 7/208 20130101; H05K 7/20836 20130101; F25B 49/02 20130101;
F25B 39/02 20130101; H05K 7/20809 20130101; F25B 2400/01 20130101;
Y10T 29/49826 20150115 |
Class at
Publication: |
62/115 ;
62/259.2; 62/507; 62/159; 165/185 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F28F 7/00 20060101 F28F007/00; F25B 29/00 20060101
F25B029/00; F25D 31/00 20060101 F25D031/00; F25B 39/02 20060101
F25B039/02 |
Claims
1. An apparatus for facilitating cooling of an electronic
component, the apparatus comprising: a refrigerant evaporator in
thermal communication with the electronic component, the
refrigerant evaporator comprising at least one channel therein for
accommodating flow of refrigerant therethrough; a refrigerant loop
coupled in fluid communication with the at least one channel of the
refrigerant evaporator for facilitating flow of refrigerant
therethrough; a compressor coupled in fluid communication with the
refrigerant loop; an air-cooled heat sink coupled to the
refrigerant evaporator and providing backup cooling to the
electronic component in a backup, air cooling mode; and a
controllable refrigerant heater coupled to the air-cooled heat sink
and in thermal communication across the air-cooled heat sink with
refrigerant passing through the refrigerant evaporator, the
controllable refrigerant heater being controlled in a primary,
refrigeration cooling mode to apply an auxiliary heat load to
refrigerant passing through the refrigerant evaporator to ensure
that refrigerant in the refrigerant loop entering the compressor is
in a superheated thermodynamic state.
2. The apparatus of claim 1, wherein the refrigerant evaporator
comprises a first main surface and a second main surface, the first
main surface and the second main surface extending substantially
parallel, and wherein the electronic component is in thermal
communication with the refrigerant evaporator across the first main
surface thereof and the air-cooled heat sink is in thermal
communication with the refrigerant evaporator across the second
main surface thereof.
3. The apparatus of claim 2, wherein the refrigerant evaporator
further comprises a plurality of heat conduction structures
facilitating conducting heat from the electronic component to the
air-cooled heat sink in the backup, air cooling mode, the plurality
of heat conduction structures further facilitating conduction of
the auxiliary heat load to refrigerant passing through the
refrigerant evaporator in the primary, refrigeration cooling
mode.
4. The apparatus of claim 2, wherein the air-cooled heat sink
comprises a heat sink base coupled to the second main surface of
the refrigerant evaporator and a plurality of thermally conductive
heat sink fins extending from the heat sink base.
5. The apparatus of claim 4, wherein the controllable refrigerant
heater couples at least partially to at least one thermally
conductive heat sink fin of the plurality of thermally conductive
heat sink fins of the air-cooled heat sink, and is in thermal
communication with refrigerant passing through the refrigerant
evaporator across, at least in part, the at least one thermally
conductive heat sink fin.
6. The apparatus of claim 5, wherein the controllable refrigerant
heater comprises a heater block and a plurality of thermally
conductive heater fins extending therefrom, and wherein the
controllable refrigerant heater is coupled to the air-cooled heat
sink with the plurality of thermally conductive heater fins
interdigitated with the plurality of thermally conductive heat sink
fins.
7. The apparatus of claim 6, further comprising a thermal interface
material disposed between at least two opposing surfaces of the
interdigitated plurality of thermally conductive heater fins and
plurality of thermally conductive heat sink fins.
8. The apparatus of claim 6, wherein the plurality of thermally
conductive heat sink fins extend in a first direction and the
plurality of thermally conductive heater fins extend in a second
direction, the first direction and the second direction being
perpendicular directions.
9. The apparatus of claim 5, wherein the controllable refrigerant
heater comprises a heater block including multiple grooves sized
and positioned to partially accommodate therein multiple thermally
conductive heat sink fins of the plurality of thermally conductive
heat sink fins of the air-cooled heat sink, and wherein the
controllable refrigerant heater is in thermal communication with
refrigerant passing through the refrigerant evaporator across, at
least in part, the multiple thermally conductive heat sink
fins.
10. The apparatus of claim 5, wherein the controllable refrigerant
heater comprises at least one heater slat coupled in thermal
communication with at least one thermally conductive heat sink fin
of the air-cooled heat sink, the at least one heater slat
comprising a flat heater disposed within a thermally conductive
housing.
11. The apparatus of claim 4, wherein the controllable refrigerant
heater comprises a plurality of heater slats, each heater slat
comprising a flat heater disposed within a thermally conductive
housing, and at least one heater slat of the plurality of heater
slats being disposed between two adjacent thermally conductive heat
sink fins of the plurality of thermally conductive heat sink fins
of the air-cooled heat sink.
12. The apparatus of claim 1, further comprising a controller
coupled to the controllable refrigerant heater for automatically
controlling the auxiliary heat load applied by the controllable
refrigerant heater to refrigerant passing through the refrigerant
evaporator, wherein the controller periodically monitors a current
heat load of the electronic component and, responsive thereto,
automatically determines whether the current heat load of the
electronic component is above a specified heat load, and responsive
to the current heat load of the electronic component being above
the specified heat load, automatically sets the auxiliary heat load
applied by the controllable refrigerant heater to zero, and
responsive to the current heat load of the electronic component
being below the specified heat load, automatically sets the
auxiliary heat load applied by the controllable refrigerant heater
to the refrigerant passing through the refrigerant evaporator to
the specified heat load less the current heat load of the
electronic component.
13. The apparatus of claim 1, further comprising a controller
coupled to the controllable refrigerant heater for automatically
controlling the auxiliary heat load applied by the controllable
refrigerant heater to refrigerant in the refrigerant loop, and a
refrigerant temperature sensor and a refrigerant pressure sensor
for monitoring a temperature and a pressure of refrigerant,
respectively, within the refrigerant loop, and wherein the
controller automatically adjusts auxiliary heat load applied by the
controllable refrigerant heater with reference to the monitored
temperature of refrigerant and pressure of refrigerant within the
refrigerant loop, and wherein the auxiliary heat load applied by
the controllable refrigerant heater is automatically incrementally
increased responsive to refrigerant entering the compressor being
superheated by less than a specified delta temperature threshold,
and is automatically incrementally decreased responsive to
refrigerant entering the compressor being superheated by greater
than the specified delta temperature threshold.
14. A cooled electronic system comprising: an electronic component;
and an apparatus for cooling the electronic component, the
apparatus comprising: a refrigerant evaporator in thermal
communication with the electronic component, the refrigerant
evaporator comprising at least one channel therein for
accommodating flow of refrigerant therethrough; a refrigerant loop
coupled in fluid communication with the at least one channel of the
refrigerant evaporator for facilitating flow of refrigerant
therethrough; a compressor coupled in fluid communication with the
refrigerant loop; an air-cooled heat sink coupled to the
refrigerant evaporator and providing backup cooling to the
electronic component in a backup, air cooling mode; and a
controllable refrigerant heater coupled to the air-cooled heat sink
and in thermal communication across the air-cooled heat sink with
refrigerant passing through the refrigerant evaporator, the
controllable refrigerant heater being controlled in a primary,
refrigeration cooling mode to apply an auxiliary heat load to
refrigerant passing through the refrigerant evaporator to ensure
that refrigerant in the refrigerant loop entering the compressor is
in a superheated thermodynamic state.
15. The cooled electronic system of claim 14, wherein the
refrigerant evaporator comprises a first main surface and a second
main surface, the first main surface and the second main surface
extending substantially parallel, and wherein the electronic
component is in thermal communication with the refrigerant
evaporator across the first main surface thereof and the air-cooled
heat sink is in thermal communication with the refrigerant
evaporator across the second main surface thereof.
16. The cooled electronic system of claim 15, wherein the
refrigerant evaporator further comprises a plurality of heat
conduction structures facilitating conducting heat from the
electronic component to the air-cooled heat sink in the backup, air
cooling mode, the plurality of heat conduction structures further
facilitating conduction of the auxiliary heat load to refrigerant
passing through the refrigerant evaporator in the primary,
refrigeration cooling mode.
17. The cooled electronic system of claim 15, wherein the
air-cooled heat sink comprises a heat sink base coupled to the
second main surface of the refrigerant evaporator and a plurality
of thermally conductive heat sink fins extending from the heat sink
base, and wherein the controllable refrigerant heater couples at
least partially to at least one thermally conductive heat sink fin
of the plurality of thermally conductive heat sink fins of the
air-cooled heat sink, and is in thermal communication with
refrigerant passing through the refrigerant evaporator across, at
least in part, the at least one thermally conductive heat sink
fin.
18. The cooled electronic system of claim 17, wherein the
controllable refrigerant heater comprises a heater block and a
plurality of thermally conductive heater fins extending therefrom,
and wherein the controllable refrigerant heater is coupled to the
air-cooled heat sink with the plurality of thermally conductive
heater fins interdigitated with the plurality of thermally
conductive heat sink fins.
19. The cooled electronic system of claim 18, wherein the plurality
of thermally conductive heat sink fins extend in a first direction
and the plurality of thermally conductive heater fins extend in a
second direction, the first direction and the second direction
being perpendicular directions.
20. The cooled electronic system of claim 17, wherein the
controllable refrigerant heater comprises a heater block including
multiple grooves sized and positioned to partially accommodate
therein multiple thermally conductive heat sink fins of the
plurality of thermally conductive heat sink fins of the air-cooled
heat sink, and wherein the controllable refrigerant heater is in
thermal communication with refrigerant passing through the
refrigerant evaporator across, at least in part, the multiple
thermally conductive heat sink fins.
21. The cooled electronic system of claim 17, wherein the
controllable refrigerant heater comprises at least one heater slat
coupled in thermal communication with at least one thermally
conductive heat sink fin of the air-cooled heat sink, the at least
one heater slat comprising a flat heater disposed within a
thermally conductive housing.
22. A method of facilitating cooling of an electronic component,
the method comprising: coupling in thermal communication a
refrigerant evaporator to the electronic component, the refrigerant
evaporator comprising at least one channel therein for
accommodating flow of refrigerant therethrough; providing a
refrigerant loop in fluid communication with the at least one
channel of the refrigerant evaporator for facilitating flow of
refrigerant therethrough; coupling a compressor in fluid
communication with the refrigerant loop; coupling an air-cooled
heat sink to the refrigerant evaporator for providing backup
cooling to the electronic component in a backup, air cooling mode;
and coupling a controllable refrigerant heater to the air-cooled
heat sink, the controllable refrigerant heater being in thermal
communication across the air-cooled heat sink with refrigerant
passing through the refrigerant evaporator, and being controlled in
a primary, refrigeration cooling mode, to apply an auxiliary heat
load to refrigerant passing through the refrigerant evaporator to
ensure that refrigerant in the refrigerant loop entering the
compressor is in a superheated thermodynamic state.
23. The method of claim 22, wherein the refrigerant evaporator
comprises a first main surface and a second main surface, the first
main surface and the second main surface extending substantially
parallel, and wherein coupling in thermal communication the
refrigerant evaporator to the electronic component comprises
coupling the electronic component in thermal communication with the
refrigerant evaporator across the first main surface thereof, and
coupling the air-cooled heat sink to the refrigerant evaporator
comprises coupling the air-cooled heat sink in thermal
communication with the refrigerant evaporator across the second
main surface thereof.
24. The method of claim 23, wherein the air-cooled heat sink
comprises a heat sink base coupled to the second main surface of
the refrigerant evaporator and a plurality of thermally conductive
heat sink fins extending from the heat sink base, and wherein
coupling the controllable refrigerant heater to the air-cooled heat
sink comprises coupling the controllable refrigerant heater at
least partially to at least one thermally conductive heat sink fin
of the plurality of thermally conductive heat sink fins of the
air-cooled heat sink, wherein the controllable refrigerant heater
is in thermal communication with refrigerant passing through the
refrigerant evaporator across, at least in part, the at least one
thermally conductive heat sink fin.
Description
BACKGROUND
[0001] The present invention relates to heat transfer mechanisms,
and more particularly, to cooling apparatuses, liquid-cooled
electronics racks and methods of fabrication thereof for removing
heat generated by one or more electronic components of the
electronics rack.
[0002] The power dissipation of integrated circuit chips, and the
modules containing the chips, continues to increase in order to
achieve increases in processor performance. This trend poses a
cooling challenge at both the module and system levels. Increased
airflow rates are needed to effectively cool higher power modules
and to limit the temperature of the air that is exhausted into the
computer center.
[0003] In many large server applications, processors along with
their associated electronics (e.g., memory, disk drives, power
supplies, etc.) are packaged in removable drawer configurations
stacked within a rack or frame. In other cases, the electronics may
be in fixed locations within the rack or frame. Typically, the
components are cooled by air moving in parallel airflow paths,
usually front-to-back, impelled by one or more air moving devices
(e.g., fans or blowers). In some cases it may be possible to handle
increased power dissipation within a single drawer by providing
greater airflow, through the use of a more powerful air moving
device(s) or by increasing the rotational speed (i.e., RPMs) of an
existing air moving device. However, this approach is becoming
problematic at the rack level in the context of a data center.
BRIEF SUMMARY
[0004] In one aspect, the shortcomings of the prior art are
overcome and additional advantages are provided through the
provision of an apparatus for facilitating cooling of an electronic
component. The apparatus includes: a refrigerant evaporator, a
refrigerant loop, a compressor, an air-cooled heat sink, and a
controllable refrigerant heater. The refrigerant evaporator is in
thermal communication with the electronic component, and includes
at least one channel therein for accommodating flow of refrigerant
therethrough. The refrigerant loop is coupled in fluid
communication with the at least one channel of the refrigerant
evaporator to facilitate flow of refrigerant through the
evaporator, and the compressor is coupled in fluid communication
with the refrigerant loop. The air-cooled heat sink is coupled to
the refrigerant evaporator, and provides backup cooling to the
electronic component in a backup, air cooling mode. The
controllable refrigerant heater is coupled to the air-cooled heat
sink, and is in thermal communication across the air-cooled heat
sink with refrigerant passing through the refrigerant evaporator.
The controllable refrigerant heater is controlled in a primary,
refrigeration cooling mode to apply an auxiliary heat load to
refrigerant passing through the refrigerant evaporator to ensure
that the refrigerant in the refrigerant loop entering the
compressor is in a superheated thermodynamic state.
[0005] In another aspect, a cooled electronic system is provided
which includes an electronic component, and an apparatus for
cooling the electronic component. The apparatus includes: a
refrigerant evaporator, a refrigerant loop, a compressor, an
air-cooled heat sink, and a controllable refrigerant heater. The
refrigerant evaporator is in thermal communication with the
electronic component, and includes at least one channel therein for
accommodating flow of refrigerant therethrough. The refrigerant
loop is coupled in fluid communication with the at least one
channel of the refrigerant evaporator to facilitate flow of
refrigerant through the evaporator, and the compressor is coupled
in fluid communication with the refrigerant loop. The air-cooled
heat sink is coupled to the refrigerant evaporator, and provides
backup cooling to the electronic component in a backup, air cooling
mode. The controllable refrigerant heater is coupled to the
air-cooled heat sink, and is in thermal communication across the
air-cooled heat sink with refrigerant passing through the
refrigerant evaporator. The controllable refrigerant heater is
controlled in a primary, refrigeration cooling mode to apply an
auxiliary heat load to refrigerant passing through the refrigerant
evaporator to ensure that the refrigerant in the refrigerant loop
entering the compressor is in a superheated thermodynamic
state.
[0006] In a further aspect, a method of facilitating cooling of an
electronic component is provided. The method includes: coupling in
thermal communication a refrigerant evaporator to the electronic
component, the refrigerant evaporator comprising at least one
channel therein for accommodating flow of refrigerant therethrough;
providing a refrigerant loop in fluid communication with the at
least one channel of the refrigerant evaporator to facilitating
flow of refrigerant therethrough; coupling a compressor in fluid
communication with the refrigerant loop; coupling an air-cooled
heat sink to the refrigerant evaporator for providing backup
cooling to the electronic component in a backup, air cooling mode;
and coupling a controllable refrigerant heater to the air-cooled
heat sink, the controllable refrigerant heater being in thermal
communication across the air-cooled heat sink with refrigerant
passing through the refrigerant evaporator, and being controlled in
a primary, refrigeration cooling mode to apply an auxiliary heat
load to refrigerant passing through the refrigerant evaporator to
ensure that refrigerant in the refrigerant loop entering the
compressor is in a superheated thermodynamic state.
[0007] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects
of the invention are described in detail herein and are considered
a part of the claimed invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] One or more aspects of the present invention are
particularly pointed out and distinctly claimed as examples in the
claims at the conclusion of the specification. The foregoing and
other objects, features, and advantages of the invention are
apparent from the following detailed description taken in
conjunction with the accompanying drawings in which:
[0009] FIG. 1 depicts one embodiment of a conventional raised floor
layout of an air-cooled data center;
[0010] FIG. 2A is an isometric view of one embodiment of a modular
refrigeration unit (MRU) and its quick connects for attachment to a
cold plate and/or evaporator disposed within an electronics rack to
cool one or more electronic components (e.g., modules) thereof, in
accordance with an aspect of the present invention;
[0011] FIG. 2B is a schematic of one embodiment of a
vapor-compression refrigeration system for cooling an evaporator
(or cold plate) coupled to a high heat flux electronic component
(e.g., module) to be cooled, in accordance with an aspect of the
present invention;
[0012] FIG. 3 is an schematic of an alternate embodiment of a
vapor-compression refrigeration system for cooling multiple
evaporators coupled to respective electronic components to be
cooled, in accordance with an aspect of the present invention;
[0013] FIGS. 4A & 4B depict one embodiment of a portion of a
cooled electronic system comprising a vapor-compression
refrigeration apparatus coupled to an electronic component to be
cooled, and including an air-cooled heat sink providing backup air
cooling to the electronic component across the refrigerant
evaporator, wherein a primary, refrigeration cooling mode is
illustrated in FIG. 4A, and a backup, air cooling mode is
illustrated in FIG. 4B, in accordance with an aspect of the present
invention;
[0014] FIG. 5 is a schematic of one embodiment of a cooled
electronic system comprising a vapor-compression refrigeration
apparatus cooling one or more electronic components, in accordance
with an aspect of the present invention;
[0015] FIG. 6A is an isometric view of one embodiment of a
controllable refrigerant heater configured to couple to an
air-cooled heat sink of a vapor-compression refrigeration apparatus
such as depicted in FIGS. 4A-5, in accordance with an aspect of the
present invention;
[0016] FIG. 6B depicts a plan view of the controllable refrigerant
heater of FIG. 6A, in accordance with an aspect of the present
invention;
[0017] FIG. 6C depicts an end elevational view of the controllable
refrigerant heater of FIGS. 6A & 6B, in accordance with an
aspect of the present invention;
[0018] FIG. 6D is an isometric view of an interdigitated assembly
comprising the controllable refrigerant heater of FIGS. 6A-6C
coupled to an air-cooled heat sink comprising a plurality of
thermally conductive heat sink fins such as depicted in the
vapor-compression refrigeration apparatus illustrated in FIGS.
4A-5, in accordance with an aspect of the present invention;
[0019] FIG. 6E is an elevational view of the interdigitated
assembly of FIG. 6D coupled to a refrigerant evaporator of a
vapor-compression refrigeration apparatus such as depicted in FIGS.
4A-5, in accordance with an aspect of the present invention;
[0020] FIG. 7A is an isometric view of another embodiment of a
controllable refrigerant heater configured to couple to an
air-cooled heat sink of a vapor-compression refrigeration apparatus
such as depicted in FIGS. 4A-5, in accordance with an aspect of the
present invention;
[0021] FIG. 7B is a plan view of the controllable refrigerant
heater of FIG. 7A, in accordance with an aspect of the present
invention;
[0022] FIG. 7C is an elevational view of the controllable
refrigerant heater of FIGS. 7A & 7B, viewed from line 7C-7C in
FIG. 7B, in accordance with an aspect of the present invention;
[0023] FIG. 7D is a further elevational view of the controllable
refrigerant heater of FIGS. 7A-7C, view from line 7D-7D in FIG. 7B,
in accordance with an aspect of the present invention;
[0024] FIG. 7E is an integrated assembly comprising the
controllable refrigerant heater of FIGS. 7A-7D coupled to an
air-cooled heat sink comprising a plurality of thermally conductive
heat sink fins such as depicted in the vapor-compression
refrigeration apparatus illustrated in FIGS. 4A-5, in accordance
with an aspect of the present invention;
[0025] FIG. 7F is a cross-sectional elevational view of the
integrated assembly of FIG. 7E coupled to a refrigerant evaporator
of a vapor-compression refrigeration apparatus, shown cooling an
electronic component such as depicted in FIGS. 4A-5, in accordance
with an aspect of the present invention;
[0026] FIG. 8A is an isometric view of another embodiment of a
controllable refrigerant heater configured to couple to an
air-cooled heat sink of a vapor-compression refrigeration apparatus
such as depicted in FIGS. 4A-5, in accordance with an aspect of the
present invention;
[0027] FIG. 8B is an isometric view of an integrated assembly
comprising several controllable refrigerant heaters, such as
depicted in FIG. 8A, integrated with an air-cooled heat sink
comprising a plurality of thermally conductive heat sink fins, such
as depicted with the vapor-compression refrigeration apparatuses of
FIGS. 4A-5, in accordance with an aspect of the present
invention;
[0028] FIG. 8C is a cross-sectional elevational view of the
integrated assembly of FIG. 8B coupled to a refrigerant evaporator
of a vapor-compression refrigeration apparatus shown cooling an
electronic component such as depicted in FIGS. 4A-5, in accordance
with an aspect of the present invention
[0029] FIG. 9A is a flowchart of one embodiment of a process for
ensuring that a specified heat load is dissipated to refrigerant
passing through the refrigerant evaporator of the vapor-compression
refrigeration apparatus of FIG. 5, in accordance with an aspect of
the present invention;
[0030] FIG. 9B is a flowchart of one embodiment of a process for
maintaining refrigerant entering the compressor of the
vapor-compression refrigerant apparatus of FIG. 5 in a superheated
thermodynamic state, in accordance with an aspect of the present
invention; and
[0031] FIG. 10 depicts one embodiment of a computer program product
incorporating one or more aspects of the present invention.
DETAILED DESCRIPTION
[0032] As used herein, the terms "electronics rack", "rack-mounted
electronic equipment", and "rack unit" are used interchangeably,
and unless otherwise specified include any housing, frame, rack,
compartment, blade server system, etc., having one or more heat
generating components of a computer system or electronics system,
and may be, for example, a stand alone computer processor having
high, mid or low end processing capability. In one embodiment, an
electronics rack may comprise multiple electronic subsystems, each
having one or more heat generating components disposed therein
requiring cooling. "Electronic subsystem" refers to any
sub-housing, blade, book, drawer, node, compartment, etc., having
one or more heat generating electronic components disposed therein.
Each electronic subsystem of an electronics rack may be movable or
fixed relative to the electronics rack, with rack-mounted
electronics drawers of a multi-drawer rack unit and blades of a
blade center system being two examples of subsystems of an
electronics rack to be cooled.
[0033] "Electronic component" refers to any heat generating
electronic component or module of, for example, a computer system
or other electronic unit requiring cooling. By way of example, an
electronic component may comprise one or more integrated circuit
dies and/or other electronic devices to be cooled, including one or
more processor dies, memory dies and memory support dies. As a
further example, the electronic component may comprise one or more
bare dies or one or more packaged dies disposed on a common
carrier.
[0034] As used herein, "refrigerant-to-air heat exchanger" means
any heat exchange mechanism characterized as described herein
through which refrigerant coolant can circulate; and includes, one
or more discrete refrigerant-to-air heat exchangers coupled either
in series or in parallel. A refrigerant-to-air heat exchanger may
comprise, for example, one or more coolant flow paths, formed of
thermally conductive tubing (such as copper or other tubing) in
thermal or mechanical contact with a plurality of air-cooled
cooling or condensing fins. Size, configuration and construction of
the refrigerant-to-air heat exchanger can vary without departing
from the scope of the invention disclosed herein.
[0035] Unless otherwise specified, "refrigerant evaporator" refers
to a heat-absorbing mechanism or structure within a refrigeration
loop. The refrigerant evaporator is alternatively referred to as a
"sub-ambient evaporator" when temperature of the refrigerant
passing through the refrigerant evaporator is below the temperature
of ambient air entering the electronics rack. Within the
refrigerant evaporator, heat is absorbed by evaporating the
refrigerant of the refrigerant loop. Still further, "data center"
refers to a computer installation containing one or more
electronics racks to be cooled. As a specific example, a data
center may include one or more rows of rack-mounted computing
units, such as server units.
[0036] As used herein, the phrase "controllable refrigerant heater"
refers to an adjustable heater which allows active control of an
auxiliary heat load applied to refrigerant passing through the
refrigerant loop of a cooling apparatus, such as described herein.
In one example, the controllable refrigerant heater comprises one
or more electrical resistance elements coupled in thermal
communication with the refrigerant passing through the refrigerant
evaporator and powered by an electrical power source.
[0037] One example of the refrigerant employed in the examples
below is R134a refrigerant. However, the concepts disclosed herein
are readily adapted to use with other types of refrigerant. For
example, the refrigerant may alternatively comprise R245fa, R404,
R12, or R22 refrigerant.
[0038] Reference is made below to the drawings, which are not drawn
to scale for ease of understanding, wherein the same reference
numbers used throughout different figures designate the same or
similar components.
[0039] FIG. 1 depicts a raised floor layout of an air cooled data
center 100 typical in the prior art, wherein multiple electronics
racks 110 are disposed in one or more rows. A data center such as
depicted in FIG. 1 may house several hundred, or even several
thousand microprocessors. In the arrangement illustrated, chilled
air enters the computer room via perforated floor tiles 160 from a
supply air plenum 145 defined between the raised floor 140 and a
base or sub-floor 165 of the room. Cooled air is taken in through
louvered or screened doors at air inlet sides 120 of the
electronics racks and expelled through the back (i.e., air outlet
sides 130) of the electronics racks. Each electronics rack 110 may
have one or more air moving devices (e.g., fans or blowers) to
provide forced inlet-to-outlet airflow to cool the electronic
components within the drawer(s) of the rack. The supply air plenum
145 provides conditioned and cooled air to the air-inlet sides of
the electronics racks via perforated floor tiles 160 disposed in a
"cold" aisle of the computer installation. The conditioned and
cooled air is supplied to plenum 145 by one or more air
conditioning units 150, also disposed within the data center 100.
Room air is taken into each air conditioning unit 150 near an upper
portion thereof. This room air comprises in part exhausted air from
the "hot" aisles of the computer installation defined by opposing
air outlet sides 130 of the electronics racks 110.
[0040] In high performance server systems, it has become desirable
to supplement air-cooling of selected high heat flux electronic
components, such as the processor modules, within the electronics
rack. For example, the System z.RTM. server marketed by
International Business Machines Corporation, of Armonk, N.Y.,
employs a vapor-compression refrigeration cooling system to
facilitate cooling of the processor modules within the electronics
rack. This refrigeration system employs R134a refrigerant as the
coolant, which is supplied to a refrigerant evaporator coupled to
one or more processor modules to be cooled. The refrigerant is
provided by a modular refrigeration unit (MRU), which supplies the
refrigerant at an appropriate temperature.
[0041] FIG. 2A depicts one embodiment of a modular refrigeration
unit 200, which may be employed within an electronic rack, in
accordance with an aspect of the present invention. As illustrated,
modular refrigeration unit 200 includes refrigerant supply and
exhaust hoses 201 for coupling to a refrigerant evaporator or cold
plate (not shown), as well as quick connect couplings 202, which
respectively connect to corresponding quick connect couplings on
either side of the refrigerant evaporator, that is coupled to the
electronic component(s) or module(s) (e.g., server module(s)) to be
cooled. Further details of a modular refrigeration unit such as
depicted in FIG. 2A are provided in commonly assigned U.S. Pat. No.
5,970,731.
[0042] FIG. 2B is a schematic of one embodiment of modular
refrigeration unit 200 of FIG. 2A, coupled to a refrigerant
evaporator for cooling, for example, an electronic component within
an electronic subsystem of an electronics rack. The electronic
component may comprise, for example, a multichip module, a
processor module, or any other high heat flux electronic component
(not shown) within the electronics rack. As illustrated in FIG. 2B,
a refrigerant evaporator 260 is shown that is coupled to the
electronic component (not shown) to be cooled and is connected to
modular refrigeration unit 200 via respective quick connect
couplings 202. Within modular refrigeration unit 200, a motor 221
drives a compressor 220, which is connected to a condenser 230 by
means of a supply line 222. Likewise, condenser 230 is connected to
evaporator 260 by means of a supply line which passes through a
filter/dryer 240, which functions to trap particulate matter
present in the refrigerant stream and also to remove any water
which may have become entrained in the refrigerant flow. Subsequent
to filter/dryer 240, refrigerant flow passes through an expansion
device 250. Expansion device 250 may be an expansion valve.
However, it may also comprise a capillary tube or thermostatic
valve. Thus, expanded and cooled refrigerant is supplied to
evaporator 260. Subsequent to the refrigerant picking up heat from
the electronic component coupled to evaporator 260, the refrigerant
is returned via an accumulator 210 which operates to prevent liquid
from entering compressor 220. Accumulator 210 is also aided in this
function by the inclusion of a smaller capacity accumulator 211,
which is included to provide an extra degree of protection against
the entry of liquid-phase refrigerant into compressor 220.
Subsequent to accumulator 210, vapor-phase refrigerant is returned
to compressor 220, where the cycle repeats. In addition, the
modular refrigeration unit is provided with a hot gas bypass valve
225 in a bypass line 223 selectively passing hot refrigerant gasses
from compressor 220 directly to evaporator 260. The hot gas bypass
valve is controllable in response to the temperature of evaporator
260, which is provided by a module temperature sensor (not shown),
such as a thermistor device affixed to the evaporator/cold plate in
any convenient location. In one embodiment, the hot gas bypass
valve is electronically controlled to shunt hot gas directly to the
evaporator when temperature is already sufficiently low. In
particular, under low temperature conditions, motor 221 runs at a
lower speed in response to the reduced thermal load. At these lower
speeds and loads, there is a risk of motor 221 stalling. Upon
detection of such a condition, the hot gas bypass valve is opened
in response to a signal supplied to it from a controller of the
modular refrigeration unit.
[0043] FIG. 3 depicts an alternate embodiment of a modular
refrigeration unit 300, which may be employed within an electronics
rack, in accordance with an aspect of the present invention.
Modular refrigeration unit 300 includes (in this example) two
refrigerant loops 305, or i.e., sets of refrigerant supply and
exhaust hoses, coupled to respective refrigerant evaporators (or
cold plates) 360 via quick connect couplings 302. Each refrigerant
evaporator 360 is in thermal communication with a respective
electronic component 301 (e.g., multichip module (MCM)) for
facilitating cooling thereof. Refrigerant loops 305 are
independent, and shown to include a compressor 320, a respective
condenser section of a shared condenser 330 (i.e., a
refrigerant-to-air heat exchanger), and an expansion (and flow
control) valve 350, which is employed by a controller 340 to
maintain temperature of the electronic component at a steady
temperature level, e.g., 29.degree. C. In one embodiment, the
expansion valves 350 are controlled by controller 340 with
reference to temperature of the respective electronic component 301
T.sub.MCM1, T.sub.MCM2. The refrigerant and coolant loops may also
contain further sensors, such as sensors for condenser air
temperature IN T1, condenser air temperature OUT T2, temperature
T3, T3' of high-pressure liquid refrigerant flowing from the
condenser 330 to the respective expansion valve 350, temperature
T4, T4' of high-pressure refrigerant vapor flowing from each
compressor 320 to the respective condenser section 330, temperature
T6, T6' of low-pressure liquid refrigerant flowing from each
expansion valve 350 into the respective evaporator 360, and
temperature T7, T7' of low-pressure vapor refrigerant flowing from
the respective evaporator 360 towards the compressor 320. Note that
in this implementation, the expansion valves 350 operate to
actively throttle the pumped refrigerant flow rate, as well as to
function as expansion orifices to reduce the temperature and
pressure of refrigerant passing through it.
[0044] In situations where electronic component 301 temperature
decreases (i.e., the heat load decreases), the respective expansion
valve 350 is partially closed to reduce the refrigerant flow
passing through the associated evaporator 360 in an attempt to
control temperature of the electronic component. If temperature of
the component increases (i.e., heat load increases), then the
controllable expansion valve 350 is opened further to allow more
refrigerant flow to pass through the associated evaporator, thus
providing increased cooling to the component. In extreme
conditions, there is the possibility of too much refrigerant flow
being allowed to pass through the evaporator, possibly resulting in
partially-evaporated fluid, (i.e., liquid-vapor mixture) being
returned to the respective compressor, which can result in
compressor valve failure due to out-of-specification pressures
being imposed on the compressor valve. There is also the
possibility of particulate and chemical contamination over time
resulting from oil break-down inside the loop accumulating within
the controllable expansion valve. Accumulation of contamination
within the valve can lead to both valve clogging and erratic valve
behavior.
[0045] In accordance with an aspect of the present invention, an
alternate implementation of a vapor-compression refrigeration
apparatus is described below with reference to FIGS. 4A-5. This
alternate implementation does not require a mechanical flow control
and adjustable expansion valve, such as described above in
connection with the modular refrigeration unit of FIG. 3, and
ensures that refrigerant entering the compressor is in a
superheated thermodynamic state. In the alternate implementation of
FIGS. 4A-5, an air-cooled heat sink is advantageously provided
coupled to the refrigerant evaporator to provide backup air-cooling
to the electronic component should, for example, primary
refrigeration cooling of the electronic component fail.
[0046] By way of example, FIG. 4A is a partial depiction of a
cooled electronic system comprising a vapor-compression
refrigeration apparatus coupled to an electronic component to be
cooled, and including an air-cooled heat sink providing backup
air-cooling to the electronic component across the refrigerant
evaporator. In FIG. 4A, air-moving device 433 is OFF, and the
cooling apparatus is in primary, refrigeration cooling mode, and in
FIG. 4B, air-moving device 433 is ON, meaning that the
refrigeration cooling has been suspended or has failed, and the
cooling apparatus is in a backup, air cooling mode.
[0047] In the example of FIGS. 4A & 4B, electronic component
405 to be cooled comprises a multichip module (MCM) with multiple
integrated circuit chips 403 (such as processor chips) disposed on
a substrate 402, shown residing on a printed circuit board 401. In
this example, a thermal interface material 406 facilitates heat
conduction from the multiple integrated circuit chips 403 to a
thermally conductive cap 404 of electronic component 405.
Electronic component 405 is shown coupled to a first main surface
of a refrigerant evaporator 410 of the vapor-compression
refrigeration apparatus. Air-cooled heat sink 430 is shown coupled
to a second main surface of refrigerant evaporator 410, wherein the
first main surface and second main surface are substantially
parallel surfaces of the evaporator. In the embodiment illustrated,
refrigerant evaporator 410 includes a refrigerant inlet 411 and a
refrigerant outlet 412 coupled to a refrigerant loop (not shown)
through which refrigerant circulates within the vapor-compression
refrigeration apparatus. A plurality of heat conduction structures
415 are illustrated, which provide (in one aspect) heat conduction
paths from electronic component 405 to air-cooled heat sink 430 in
the backup, air cooling mode. As shown, heat conduction structures
415 are in contact with refrigerant passing through refrigerant
evaporator 410.
[0048] Air-cooled heat sink 430 comprises a heat sink base 431 and
a plurality of thermally conductive heat sink fins 432 extending
from heat sink base 431. By way of example, the plurality of
thermally conductive heat sink fins 432 extend from heat sink base
431 away from refrigerant evaporator 410. In operation, the solid
material of the air-cooled heat sink is thermally coupled to the
electronic component via the heat conduction structures 415 within
refrigerant evaporator 410. In one embodiment, these heat
conduction structures could pass through the outer housing of
refrigerant evaporator 410 and extend into heat sink base 431 of
the air-cooled heat sink 430. Alternatively, a thermal interface
material could be employed to couple air-cooled heat sink 430 to
the second main surface of refrigerant evaporator 410. In the
primary or normal mode of operation, air-moving device 433 is OFF,
and the heat load of the electronic component is exhausted to the
refrigerant passing through refrigerant evaporator 410. When there
is a loss of cooling in the refrigeration loop (for example, the
vapor-compression refrigeration apparatus has been shut down due to
a refrigerant leak or needed MRU maintenance), air-moving device
433 is turned ON and heat from the electronic component is
conducted to air-cooled heat sink 430 for dissipation to the
airflow 434 passing through the thermally conductive heat sink fins
432.
[0049] FIG. 5 illustrates a cooled electronic system 500, which
includes an electronics rack 501 comprising multiple electronic
components 405 to be cooled. By way of specific example only, one
or more of the electronic components 405 to be cooled by the
cooling apparatus may be a multichip module (MCM), such as the
processor MCM depicted in FIGS. 4A & 4B. Note that in the
embodiment of FIG. 5, a dual-loop, cooled electronic system is
depicted by way of example only. Those skilled in the art should
note that the vapor-compression refrigeration apparatus illustrated
in FIG. 5 and described below can be readily configured for cooling
a single electronic component, or a plurality of electronic
components (either with or without employing a shared condenser, as
in the example of FIG. 5).
[0050] In the implementation of FIG. 5, the cooling apparatus is a
vapor-compression refrigeration apparatus with a controlled
refrigerant heat load. Refrigerant evaporator 410 is associated
with a respective electronic component 405 to be cooled, and a
refrigerant loop 520 is coupled in fluid communication with
refrigerant evaporator 410, to allow for the ingress and egress of
refrigerant through the structure. Quick connect couplings 502 are
provided, which facilitate coupling of refrigerant evaporator 410
to the remainder of the cooling apparatus. Each refrigerant loop
520 is in fluid communication with a respective compressor 540, a
condenser section passing through a shared condenser 550, and a
filter/dryer (not shown). An air-moving device 551 facilitates
airflow across shared condenser 550. Note that, in an alternate
implementation, each refrigerant loop of the vapor-compression
refrigeration apparatus could incorporate its own condenser and
air-moving device. In the embodiment of FIG. 5, each refrigerant
loop 520 also includes a fixed orifice expansion valve 511
associated with the respective refrigerant evaporator 410 and
disposed, for example, at a refrigerant inlet to the refrigerant
evaporator 410.
[0051] In accordance with an aspect of the present invention, the
vapor-compression refrigeration apparatus further includes a
controllable refrigerant heater 560 associated with air-cooled heat
sink 430. Controllable refrigerant heater 560 is in thermal
communication across the air-cooled heat sink with refrigerant
passing through the refrigerant evaporator for controllably
applying (in the primary, refrigeration cooling mode) an auxiliary
heat load thereto, as described further below. Note that, in one
implementation, electronic component 405 is coupled to a first main
surface of refrigerant evaporator 410, and air-cooled heat sink 430
(with the controllable refrigerant heater coupled or integrated
therewith) is coupled to a second main surface of refrigerant
evaporator 410. Advantageously, by coupling the refrigerant heater
to the heat sink, controllable refrigerant heater 560 is in thermal
communication with refrigerant passing through the refrigerant
evaporator without any redesign of the refrigerant loop with
respect to plumbing or other connections.
[0052] A controller 570 is provided electrically coupled to the
controllable refrigerant heaters, refrigerant temperature and
pressure sensors T.sub.R, P.sub.R, and MCM heat load sensors
Q.sub.MCM for facilitating control of the vapor-compression
refrigeration process within each cooling apparatus, for example,
as described further below with reference to the control processes
of FIGS. 9A & 9B. Each controllable refrigerant heater is
associated with and in thermal communication with a respective
refrigerant loop 520 to (in the primary, refrigeration cooling
mode) selectively apply a desired heat load to refrigerant in the
refrigerant loop to ensure that refrigerant entering the compressor
is in a superheated thermodynamic state.
[0053] In operation, each electronic component 405 applies a heat
load Q.sub.MCM to refrigerant passing through refrigerant
evaporator 410. In addition, each controllable refrigerant heater
560 applies an auxiliary heat load Q.sub.HEATER to refrigerant
passing through refrigerant evaporator 410 which together with the
electronic component heat load (Q.sub.MCM), ensures that
refrigerant entering compressor 540 is in a superheated
thermodynamic state. Heat is rejected from the refrigerant in
refrigerant loop 520 to an air stream via the air-cooled condenser
550, and liquid refrigerant is circulated from condenser 550 back
to refrigerant evaporator 410 to repeat the process.
Advantageously, by ensuring that refrigerant entering the
compressor is in a superheated thermodynamic state, the compressor
540 can work at a fixed speed, and a fixed orifice 511 can be used
within refrigerant loop 520 as the expansion valve for the
vapor-compression refrigeration apparatus. The application of an
adjustable, auxiliary heat load by the controllable refrigerant
heater to the refrigerant passing through the refrigerant
evaporator means that a desired heat load can be maintained within
the refrigerant loop, and by prespecifying this desired, specified
heat load, superheated refrigerant can be guaranteed to enter the
compressor, allowing for reliable operation of the
vapor-compression refrigeration apparatus. The controllable
refrigerant heater can be controlled using a variety of approaches,
with various thermal measurements being employed and transmitted to
the controller to incrementally adjust the heat load being applied
by the controllable refrigerant heater to the circulating
refrigerant.
[0054] Advantageously, the use of a cooling apparatus such as
depicted in FIG. 5 addresses electronic component heat load changes
by, for example, maintaining a specified heat load on the
refrigerant in the refrigerant loop. The controllable refrigerant
heater may be controlled based, for example, on current heat load
provided by (or current temperature of) the electronic component,
or alternatively, based on temperature and pressure of refrigerant
within the refrigerant loop, as respectively depicted in FIGS. 9A
& 9B. Advantageously, within the cooling apparatus described
herein, the refrigerant loop may be hard-plumbed, and a constant
speed compressor may be employed, along with a fixed expansion
orifice. This enables a minimum amount of controls on the
refrigerant loop. The resulting cooling apparatus can be packaged
inside a modular refrigerant unit-like subassembly, such as
depicted above in connection with FIG. 2A.
[0055] FIGS. 6A-8C depict alternate implementations of a
controllable refrigerant heater, in accordance with various aspects
of the present invention. In FIGS. 6A-6E, a comb-type heater
structure is depicted, in FIGS. 7A-7F a grooved heater structure is
illustrated, and in FIGS. 8A-8C a slatted heater structure is
shown.
[0056] Referring first to the comb-type heater of FIGS. 6A-6C,
controllable refrigerant heater 600 is shown to comprise a heater
block 610 and a plurality of thermally conductive heater fins 620
extending from heater block 610. Heater block 610 is a thermally
conductive material and includes one or more openings or chambers
which accommodate, for example, one or more electrically
controllable heaters 615 therein. In one specific example, multiple
cylindrical cavities are provided within heater block 610 for
accommodating cylindrical-shaped or cartridge-type heaters 615
therein.
[0057] FIG. 6D depicts an integrated assembly, or more particularly
in this case, an interdigitated assembly, comprising air-cooled
heat sink 430 and controllable refrigerant heater 600.
Interdigitation is achieved by configuring and sizing the plurality
of thermally conductive heater fins 620 (and/or the plurality of
thermally conductive heat sink fins 432) appropriately such that
the plurality of thermally conductive heater fins 620 can reside
between and interleave with the plurality of thermally conductive
heat sink fins 432 extending from heat sink base 431, as
illustrated. In the interdigitated assembly, the plurality of
thermally conductive heater fins 620 extend from heater block 610
in a first direction that is perpendicular to a second direction
within which the plurality of thermally conductive heat sink fins
432 extend from heat sink base 431 of air-cooled heat sink 430.
[0058] In FIG. 6E, the integrated assembly of FIG. 6D is
substituted for the air-cooled heat sink illustrated in FIGS. 4A
& 4B. As shown, the interdigitated assembly (comprising
air-cooled heat sink 430 and controllable refrigerant heater 600)
is coupled to the second main surface of refrigerant evaporator
410, the first main surface of which is coupled to electronic
component 405 to be cooled. In FIG. 6E, primary, refrigeration
cooling mode of the cooling apparatus is illustrated, with
air-moving device 433 OFF. In this mode, the auxiliary heat load
supplied by controllable refrigerant heater 600 is conducted across
air-cooled heat sink 430 through, for example, one or more
thermally conductive heat sink fins and a heat sink base, to
refrigerant evaporator 410 and subsequently to the refrigerant
passing through refrigerant evaporator 410. Advantageously, by
inserting the controllable refrigerant heater as close to the heat
sink base as possible, the length of the thermal conduction paths
required for the auxiliary heat load to traverse is reduced. If
desired, the length of the thermally conductive heat sink fins may
be extended to account for the interdigitated fin heat transfer
area. Depending upon the configuration of the air-cooled heat sink,
multiple controllable refrigerant heaters may be employed to engage
the heat sink from, for example, opposite sides, so as to reduce
the length of the heat conduction paths from the heater(s) within
the heater block(s) to the refrigerant evaporator 410.
[0059] FIGS. 7A-7D depict an alternate embodiment of a controllable
refrigerant heater 700, in accordance with an aspect of the present
invention. In this embodiment, controllable refrigerant heater 700
is one example of a grooved heater structure that may be integrated
with an air-cooled heat sink using, for example, a thermal
interface material (TIM), as described further below. Controllable
refrigerant heater 700 includes a heater block 710 which, in this
embodiment, is configured with a plurality of openings to
accommodate heaters 715, and a plurality of grooves 720 sized and
positioned to receive respective thermally conductive heat sink
fins, as illustrated in FIGS. 7E & 7F.
[0060] In FIG. 7E, an integrated assembly is depicted wherein
controllable refrigerant heater 700 is coupled to the ends of
thermally conductive heat sink fins 432 extending from heat sink
base 431 of air-cooled heat sink 430. As noted, a thermal interface
material may be employed within grooves 720 to facilitate heat
conduction from controllable refrigerant heater 700 to heat sink
fins 432 and hence, to the refrigerant passing through the
refrigerant evaporator 410 (see FIG. 7F).
[0061] Note that in the example of FIGS. 7A-7F, heater block 710
includes cylindrical cavities positioned and sized to accommodate
insertion of cartridge-type heater rods, which are (by way of
example only) the source of the auxiliary heat load. In the
depicted implementation, the controllable refrigerant heater is
positioned such that the tips of the thermally conductive heat sink
fins engage respective grooves in the heater block, and pressure
may be applied using a suitable mechanical attachment mechanism
(not shown) to improve the contact resistance between the
structures. This particular integrated assembly may be employed,
for example, where the thermally conductive heat sink fins 432 are
relatively short, that is, compared with the length of the
thermally conductive heat sink fins described above in connection
with FIGS. 6A-6E. If desired, the overall heat sink fin length may
be made longer to account for the length of the heat sink fins
mating into the grooved, controllable refrigerant heater 700. The
use of a flat heater, such as a foil heater for the auxiliary heat
load source in lieu of the illustrated heater rods could
alternatively be employed to yield a more compact design.
[0062] FIG. 8A illustrates a further embodiment of a controllable
refrigerant heater 800, in accordance with an aspect of the present
invention. In this embodiment, the controllable refrigerant heater
is a slat heater structure which comprises a flat or foil heater
820 attached to a thermally conductive housing (or shell) 810. As
illustrated in FIG. 8A, in one embodiment, foil heater 820 resides
within a U-shaped outer housing or shell 810.
[0063] FIG. 8B depicts an integrated assembly comprising air-cooled
heat sink 430 and multiple controllable refrigerant heaters 800,
each comprising a foil heater 820 disposed within a thermally
conductive housing 810. The multiple controllable refrigerant
heaters 800 are illustrated in FIG. 8B attached to the exposed
sides of the plurality of thermally conductive heat sink fins 432,
as well as disposed between two adjacent thermally conductive heat
sink fins near the middle of the air-cooled heat sink 430.
[0064] FIG. 8C depicts the integrated assembly of FIG. 8B coupled
to refrigerant evaporator 410 in place of the air-cooled heat sink
430 only embodiment depicted in FIGS. 4A & 4B.
[0065] Note that the number and positioning of the controllable
refrigerant heaters 800 of FIGS. 8A-8C can be arranged to spread
out the input of the auxiliary heat load along the width of the
heat sink base. The auxiliary heat load provided by the
controllable refrigerant heaters 800 will flow into the heat sink
base through the adjacent thermally conductive heat sink fins, and
subsequently into the refrigerant evaporator. If desired, the
air-cooled heat sink may be designed to specifically accommodate
the controllable refrigerant heater by, for example, providing
slightly larger dimensions where desired.
[0066] As noted, FIGS. 9A & 9B depict control processes which
may be employed in connection with the vapor-compression
refrigeration apparatus of FIG. 5. Referring to FIG. 9A,
substantially constant refrigerant heating can be established by
first setting the heat load applied to the refrigerant by the
controllable refrigerant heater (Q.sub.HEATER) equal to an initial
(or nominal) heat load value (Q.sub.INITIAL) 900. The current
component heat load (e.g., power data) is collected 910. If the MCM
heat load (Q.sub.MCM) is less than a desired, specified heat load
(Q.sub.SPEC) 920, then the controllable refrigerant heater is
adjusted to apply a heat load (Q.sub.HEATER) which matches the
difference 950. Otherwise, the heat load applied by the
controllable refrigerant heater (Q.sub.HEATER) is set to zero 930.
After adjusting the heat load, processing waits a defined time (t)
940 before repeating the process by again collecting current
component heat load data (Q.sub.MCM) 910.
[0067] In operation, heat load input to the refrigerant in the
refrigerant loop by the auxiliary controllable refrigerant heater
will typically be equal to the difference between the specified
electronic component heat load (e.g., the rated or maximum
electronic component power) and the actual current electronic
component heat load (e.g., current component power). Thus, if the
electronic component is fully loaded and is running at full rated
load, then the controllable refrigerant heater is OFF. In the event
that the electronic component is intrinsically running at a lower
power, or if the computational activity of the electronic component
is reduced, thereby reducing the electronic component load, then
the controllable refrigerant heater is ON and supplying power (or
heat load) to the refrigerant loop that is equal to the difference,
as described above. In this manner, the loading on the refrigerant
loop is maintained at a relatively constant, stable value, which
ensures that the compressor always receives superheated vapor by
design.
[0068] FIG. 9B depicts an alternate control process which ensures
that refrigerant entering the compressor is in a superheated
thermodynamic state. In this approach, measurements of refrigerant
temperature and refrigerant pressure at the inlet of the compressor
are used to control the amount of heat load (or power) delivered by
the auxiliary, controllable refrigerant heater. This advantageously
allows for a stable electronic component temperature, while
ensuring that superheated vapor is received into the compressor.
This in turn advantageously results in the elimination of the use
of any adjustable expansion valves, which might otherwise be used,
and be susceptible to fouling.
[0069] Referring to FIG. 9B, a superheated thermodynamic state is
ensured by first setting the heat load applied to the refrigerant
by the controllable refrigerant heater (Q.sub.HEATER) equal to an
initial (or nominal) heat load value (Q.sub.INIITAL) 955. The
temperature of refrigerant (T.sub.R) and pressure of refrigerant
(P.sub.R) at the inlet of the compressor are collected to determine
the current thermodynamic state of the refrigerant 960. Processing
then determines whether refrigerant entering the compressor is in a
superheated state by less than or equal to a specified temperature
difference (.delta.T.sub.SPEC) from the absolute value of
refrigerant temperature at superheated condition 965. In one
example, .delta.T.sub.SPEC may be 2.degree. C. This determination
can be performed, by way of example, using a table look-up based on
known thermodynamic properties of the refrigerant. By way of
specific example, pressure (P)-enthalpy (H) diagrams for R134a
refrigerant are available in the literature which indicate the
regions in which the refrigerant is sub-cooled, saturated and
superheated. These diagrams or functions utilize variables such as
pressure and temperature (enthalpy if the quality of a two-phase
mixture needs to be known). Thus, the thermodynamic state of the
refrigerant can be determined using pressure and temperature data
and subsequently controlled using the addition of the auxiliary
heat load, if required. The pressure and temperature values
measured can be input into a refrigerant-dependent algorithm
(defined by the P-H diagram and properties of the refrigerant) that
determines if the refrigerant is superheated (or is saturated or is
in liquid phase). It is desired that the coolant entering the
compressor be slightly superheated, that is, with no liquid
content. The extent of superheat can be characterized using a
.delta.T.sub.SPEC value, which is predetermined. It is undesirable
to have a very high extent of refrigerant superheat, because this
would mean that a substantial heat load has been added to the
refrigerant, even after the refrigerant has completely changed from
liquid to gas phase. This is considered unnecessary for compressor
reliability, and would lead to highly inefficient refrigeration
loop operation. It is desired to add only as much auxiliary heat
load as needed to maintain a small degree of superheat for the
refrigerant entering the compressor to ensure reliable compressor
operation. Therefore, if the refrigerant entering the compressor is
superheated by less than a specified temperature difference
(.delta.T.sub.SPEC), then the heat load applied by the controllable
refrigerant heater is increased by a specified amount (.delta.Q)
970. Alternatively, if the refrigerant entering the compressor is
superheated by greater than the specified temperature difference
(.delta.T.sub.SPEC), then the heat load applied by the controllable
refrigerant heater is decreased by the specified amount (e.g.,
.delta.Q) 980. After adjusting the heater heat load, processing
waits a defined time (t) 975 before repeating the process by again
collecting current thermodynamic state data for the refrigerant,
that is, refrigerant temperature (T.sub.R) and refrigerant pressure
(P.sub.R) at, for example, the inlet to the compressor 960.
[0070] As will be appreciated by one skilled in the art, aspects of
the present invention may be embodied as a system, method or
computer program product. Accordingly, aspects of the present
invention may take the form of an entirely hardware embodiment, an
entirely software embodiment (including firmware, resident
software, micro-code, etc.) or an embodiment combining software and
hardware aspects that may all generally be referred to herein as a
"circuit," "module" or "system". Furthermore, aspects of the
present invention may take the form of a computer program product
embodied in one or more computer readable medium(s) having computer
readable program code embodied thereon.
[0071] Any combination of one or more computer readable medium(s)
may be utilized. The computer readable medium may be a computer
readable signal medium or a computer readable storage medium. A
computer readable signal medium may include a propagated data
signal with computer readable program code embodied therein, for
example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electro-magnetic, optical or any suitable
combination thereof. A computer readable signal medium may be any
computer readable medium that is not a computer readable storage
medium and that can communicate, propagate, or transport a program
for use by or in connection with an instruction execution system,
apparatus or device.
[0072] A computer readable storage medium may be, for example, but
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared or semiconductor system, apparatus, or device, or any
suitable combination of the foregoing. More specific examples (a
non-exhaustive list) of the computer readable storage medium
include the following: an electrical connection having one or more
wires, a portable computer diskette, a hard disk, a random access
memory (RAM), a read-only memory (ROM), an erasable programmable
read-only memory (EPROM or Flash memory), an optical fiber, a
portable compact disc read-only memory (CD-ROM), an optical storage
device, a magnetic storage device, or any suitable combination of
the foregoing. In the context of this document, a computer readable
storage medium may be any tangible medium that can contain or store
a program for use by or in connection with an instruction execution
system, apparatus, or device.
[0073] Referring now to FIG. 10, in one example, a computer program
product 1000 includes, for instance, one or more computer readable
storage media 1002 to store computer readable program code means or
logic 1004 thereon to provide and facilitate one or more aspects of
the present invention.
[0074] Program code embodied on a computer readable medium may be
transmitted using an appropriate medium, including but not limited
to wireless, wireline, optical fiber cable, RF, etc., or any
suitable combination of the foregoing.
[0075] Computer program code for carrying out operations for
aspects of the present invention may be written in any combination
of one or more programming languages, including an object oriented
programming language, such as Java, Smalltalk, C++ or the like, and
conventional procedural programming languages, such as the "C"
programming language, assembler or similar programming languages.
The program code may execute entirely on the user's computer,
partly on the user's computer, as a stand-alone software package,
partly on the user's computer and partly on a remote computer or
entirely on the remote computer or server. In the latter scenario,
the remote computer may be connected to the user's computer through
any type of network, including a local area network (LAN) or a wide
area network (WAN), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider).
[0076] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems) and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer program
instructions. These computer program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or
blocks.
[0077] These computer program instructions may also be stored in a
computer readable medium that can direct a computer, other
programmable data processing apparatus, or other devices to
function in a particular manner, such that the instructions stored
in the computer readable medium produce an article of manufacture
including instructions which implement the function/act specified
in the flowchart and/or block diagram block or blocks.
[0078] The computer program instructions may also be loaded onto a
computer, other programmable data processing apparatus, or other
devices to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other devices to
produce a computer implemented process such that the instructions
which execute on the computer or other programmable apparatus
provide processes for implementing the functions/acts specified in
the flowchart and/or block diagram block or blocks.
[0079] The flowchart and block diagrams in the figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of code, which comprises one or more
executable instructions for implementing the specified logical
function(s). It should also be noted that, in some alternative
implementations, the functions noted in the block may occur out of
the order noted in the figures. For example, two blocks shown in
succession may, in fact, be executed substantially concurrently, or
the blocks may sometimes be executed in the reverse order,
depending upon the functionality involved. It will also be noted
that each block of the block diagrams and/or flowchart
illustration, and combinations of blocks in the block diagrams
and/or flowchart illustration, can be implemented by special
purpose hardware-based systems that perform the specified functions
or acts, or combinations of special purpose hardware and computer
instructions.
[0080] In addition to the above, one or more aspects of the present
invention may be provided, offered, deployed, managed, serviced,
etc. by a service provider who offers management of customer
environments. For instance, the service provider can create,
maintain, support, etc. computer code and/or a computer
infrastructure that performs one or more aspects of the present
invention for one or more customers. In return, the service
provider may receive payment from the customer under a subscription
and/or fee agreement, as examples. Additionally or alternatively,
the service provider may receive payment from the sale of
advertising content to one or more third parties.
[0081] In one aspect of the present invention, an application may
be deployed for performing one or more aspects of the present
invention. As one example, the deploying of an application
comprises providing computer infrastructure operable to perform one
or more aspects of the present invention.
[0082] As a further aspect of the present invention, a computing
infrastructure may be deployed comprising integrating computer
readable code into a computing system, in which the code in
combination with the computing system is capable of performing one
or more aspects of the present invention.
[0083] As yet a further aspect of the present invention, a process
for integrating computing infrastructure comprising integrating
computer readable code into a computer system may be provided. The
computer system comprises a computer readable medium, in which the
computer medium comprises one or more aspects of the present
invention. The code in combination with the computer system is
capable of performing one or more aspects of the present
invention.
[0084] Although various embodiments are described above, these are
only examples. For example, computing environments of other
architectures can incorporate and use one or more aspects of the
present invention. Additionally, the network of nodes can include
additional nodes, and the nodes can be the same or different from
those described herein. Also, many types of communications
interfaces may be used. Further, other types of programs and/or
other optimization programs may benefit from one or more aspects of
the present invention, and other resource assignment tasks may be
represented. Resource assignment tasks include the assignment of
physical resources. Moreover, although in one example, the
partitioning minimizes communication costs and convergence time, in
other embodiments, the cost and/or convergence time may be
otherwise reduced, lessened, or decreased.
[0085] Further, other types of computing environments can benefit
from one or more aspects of the present invention. As an example,
an environment may include an emulator (e.g., software or other
emulation mechanisms), in which a particular architecture
(including, for instance, instruction execution, architected
functions, such as address translation, and architected registers)
or a subset thereof is emulated (e.g., on a native computer system
having a processor and memory). In such an environment, one or more
emulation functions of the emulator can implement one or more
aspects of the present invention, even though a computer executing
the emulator may have a different architecture than the
capabilities being emulated. As one example, in emulation mode, the
specific instruction or operation being emulated is decoded, and an
appropriate emulation function is built to implement the individual
instruction or operation.
[0086] In an emulation environment, a host computer includes, for
instance, a memory to store instructions and data; an instruction
fetch unit to fetch instructions from memory and to optionally,
provide local buffering for the fetched instruction; an instruction
decode unit to receive the fetched instructions and to determine
the type of instructions that have been fetched; and an instruction
execution unit to execute the instructions. Execution may include
loading data into a register from memory; storing data back to
memory from a register; or performing some type of arithmetic or
logical operation, as determined by the decode unit. In one
example, each unit is implemented in software. For instance, the
operations being performed by the units are implemented as one or
more subroutines within emulator software.
[0087] Further, a data processing system suitable for storing
and/or executing program code is usable that includes at least one
processor coupled directly or indirectly to memory elements through
a system bus. The memory elements include, for instance, local
memory employed during actual execution of the program code, bulk
storage, and cache memory which provide temporary storage of at
least some program code in order to reduce the number of times code
must be retrieved from bulk storage during execution.
[0088] Input/Output or I/O devices (including, but not limited to,
keyboards, displays, pointing devices, DASD, tape, CDs, DVDs, thumb
drives and other memory media, etc.) can be coupled to the system
either directly or through intervening I/O controllers. Network
adapters may also be coupled to the system to enable the data
processing system to become coupled to other data processing
systems or remote printers or storage devices through intervening
private or public networks. Modems, cable modems, and Ethernet
cards are just a few of the available types of network
adapters.
[0089] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising", when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components and/or groups thereof.
[0090] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below, if any, are intended to include any structure,
material, or act for performing the function in combination with
other claimed elements as specifically claimed. The description of
the present invention has been presented for purposes of
illustration and description, but is not intended to be exhaustive
or limited to the invention in the form disclosed. Many
modifications and variations will be apparent to those of ordinary
skill in the art without departing from the scope and spirit of the
invention. The embodiment was chosen and described in order to best
explain the principles of the invention and the practical
application, and to enable others of ordinary skill in the art to
understand the invention for various embodiment with various
modifications as are suited to the particular use contemplated.
* * * * *