U.S. patent application number 12/228808 was filed with the patent office on 2010-02-18 for high performance compact heat exchanger.
Invention is credited to David H. Altman, Anthony J. Burdi, Scott R. Cheyne, Joseph R. Ellsworth, Michael P. Martinez, Michael E. Null.
Application Number | 20100038056 12/228808 |
Document ID | / |
Family ID | 41680460 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100038056 |
Kind Code |
A1 |
Ellsworth; Joseph R. ; et
al. |
February 18, 2010 |
High performance compact heat exchanger
Abstract
A high performance compact heat exchanger includes a base plate
with evaporator channels for cooling a heat source adjacent to the
base plate. A condenser is connected to the base plate and includes
fins with channels therein for the coolant. A pump delivers the
coolant to the evaporator channels of the base plate after passing
through the fins of the condenser.
Inventors: |
Ellsworth; Joseph R.;
(Worcester, MA) ; Cheyne; Scott R.; (Brookline,
NH) ; Null; Michael E.; (Marlborough, MA) ;
Martinez; Michael P.; (Worcester, MA) ; Altman; David
H.; (Framingham, MA) ; Burdi; Anthony J.;
(Waltham, MA) |
Correspondence
Address: |
Iandiorio Teska & Coleman
260 Bear Hill Road
Waltham
MA
02451
US
|
Family ID: |
41680460 |
Appl. No.: |
12/228808 |
Filed: |
August 15, 2008 |
Current U.S.
Class: |
165/80.3 ;
165/121 |
Current CPC
Class: |
F28D 15/0266 20130101;
F24H 3/022 20130101; H01L 2924/0002 20130101; F28F 3/12 20130101;
H01L 2924/0002 20130101; H01L 23/467 20130101; F28D 1/0473
20130101; F28F 2215/06 20130101; F28D 7/04 20130101; F28D 1/0472
20130101; H01L 2924/00 20130101; H01L 23/427 20130101 |
Class at
Publication: |
165/80.3 ;
165/121 |
International
Class: |
F28F 7/00 20060101
F28F007/00; F24H 3/02 20060101 F24H003/02 |
Claims
1. A high performance compact heat exchanger comprising: a base
plate including evaporator channels for cooling a heat source
adjacent the base plate; a condenser connected to the base plate
and including fins with channels therein for the coolant; and a
pump for delivering the coolant to the evaporator channels of the
base plate after passing through the fins of the condenser.
2. The heat exchanger of claim 1 further including a fan for moving
air over the fins of the condenser.
3. The heat exchanger of claim 2 in which the condenser is disposed
between the fan and the base plate.
4. The heat exchanger of claim 1 in which the fins of the condenser
are in a spiral configuration.
5. The heat exchanger of claim 4 in which the fins comprise a
continuous body with an orifice therein for the coolant.
6. The heat exchanger of claim 4 in which the fins comprise an
array of individual conduits in a spiral configuration.
7. The heat exchanger of claim 1 in which the evaporator channels
comprise a continuous groove formed in the base plate.
8. The heat exchanger of claim 7 in which the groove is formed in a
spiral configuration.
9. The heat exchanger of claim 1 in which the evaporator channels
in the base plate are micro-channels within the base plate.
10. The heat exchanger of claim 1 further including a synthetic jet
ejector micro-array subsystem between the base plate and the
condenser and configured to move air over the fins of the
condenser.
11. A high performance compact heat exchanger comprising: a base
plate including coolant evaporator channel for cooling a heat
source adjacent the base plate; a condenser with fins carrying the
coolant therein for condensing the same; and means for moving air
over the fins.
12. The heat exchanger of claim 11 in which the means for moving
air over the fins includes a synthetic jet ejector micro-array
subsystem between the base plate and the condenser.
13. The heat exchanger of claim 11 in which the means for moving
air over the fins includes a fan disposed on the condenser.
14. The heat exchanger of claim 11 in which the means for moving
air over the fans includes a synthetic jet ejector micro-array
subsystem between the base plate and the condenser and a fan
disposed on the condenser.
15. The heat exchanger of claim 11 in which the fins of the
condenser are in a spiral configuration.
16. The heat exchanger of claim 11 in which the fins comprise a
continuous body with an orifice therein.
17. The heat exchanger of claim 11 in which the fins comprise an
array of individual conduits in a spiral configuration.
18. The heat exchanger of claim 11 in which the evaporator channel
comprises a continuous groove formed in the base plate.
19. The heat exchanger of claim 11 in which the groove is formed in
a spiral configuration.
20. The heat exchanger of claim 11 in which the base plate
evaporator channels are micro-channels formed inside the base
plate.
Description
FIELD OF THE INVENTION
[0001] The subject invention relates to methods for cooling heat
sources such as radar arrays.
BACKGROUND OF THE INVENTION
[0002] A variety of heat sinks with different fin configurations
are used to cool heat sources such as electronic chips. See U.S.
Pat. Nos. 6,508,301 and 6,519,955 incorporated herein by this
reference. The technique used for many decades to air cool one or
more heat dissipating components was to place an extruded aluminum
heat sink containing straight fins onto the device. In the prior
art, the heat fluxes were low enough that natural convection along
with the increase in surface area due to the fins sufficiently
cooled the components. As the thermal challenges increased, active
cooling using a fan in conjunction with the fin heat sink was
needed. Additional optimizations included changing the shape of the
fins to maximize the effective thermal conductance (a product of
surface area and heat transfer coefficient) from the fins to the
surrounding air. Fin shapes and styles such as wavy fins,
convoluted fins, lanced and offset fins, and serrated fins were
engineered. Although these specialized fins typically resulted in
an increase air side pressure drop, the corresponding thermal
conductance also increased. One of the challenges is determining
the optimum fin configuration (e.g., spacing, thickness, height,
and the like).
[0003] The next generation of heat sinks used high thermal
conductivity inserts such as copper in the base of the heat sink.
The insert more efficiently spread the heat load over the entire
base and therefore lowered the effective heat flux at the fins. The
current state of the art in cooling uses a combination of these
techniques to maximize the effective thermal conductants at an air
flow and pressure drop suitable for today's state of the art
fans.
[0004] In radar arrays, cooling of the numerous transmit/receive
integrated microwave modules (TRIMMs) is usually effected by
mounting the side rails of the TRIMM module to a cooling manifold
rib carrying a coolant in the equipment rack housing the TRIMM
modules. See U.S. patent application Ser. No. 11/716,864 filed Mar.
12, 2007 incorporated herein by this reference.
[0005] In an active electronically scanned array (AESA) radar, high
power, high density electronics are packed into tight arrays with
extremely limited space for thermal management. For such a radar
system and other new radar systems, thermal management remains a
concern.
BRIEF SUMMARY OF THE INVENTION
[0006] It is therefore an object of this invention to provide a new
heat exchanger.
[0007] It is a further object of this invention to provide such a
heat exchanger which is compact.
[0008] It is a further object of this invention to provide a high
performance heat exchanger.
[0009] It is a further object of this invention to provide a heat
exchanger with improved thermal performance.
[0010] It is a further object of this invention to provide such a
heat exchanger with a lower power draw.
[0011] It is a further object of this invention to provide such a
heat exchanger with a greater thermal conductance.
[0012] It is a further object of this invention to provide such a
heat exchanger which can be manufactured at a reasonable cost.
[0013] The subject invention results from the realization that a
compact, high performance heat exchanger is effected in a design
where a pumped refrigerant flows in both the base and the fins of
the heat sink.
[0014] This invention features a novel high performance compact
heat exchanger. A base plate includes evaporator channels for
cooling a heat source adjacent the base plate. A condenser is
connected to the base plate and includes fins with channels therein
for the coolant. A pump delivers the coolant to the evaporator
channels of the base plate after passing through the fins of the
condenser.
[0015] A fan may be included for moving air over the fins of the
condenser. Typically, the condenser is disposed between the fan and
the base plate. In one preferred embodiment, the fins of the
condenser are in a spiral configuration and comprise a continuous
body with an orifice therein for the coolant. In another example,
the fins comprise an array of individual conduits in a spiral
configuration. The evaporator channels may comprise a continuous
spiral groove formed inside the base plate. The evaporator channels
in the base plate may be micro-channels within the base plate.
[0016] The heat exchanger may further include a synthetic jet
ejector micro-array subsystem between the base plate and the
condenser and configured to move air over the fins of the
condenser.
[0017] A high performance compact heat exchanger in accordance with
the subject invention includes a base plate with coolant evaporator
channels cooling a heat source adjacent the base plate, a condenser
with fins carrying the coolant therein for condensing the same; and
means for moving air over the fins. The means for moving air over
the fans may include a synthetic jet ejector micro-array subsystem
between the base plate and the condenser and/or a fan disposed on
the condenser.
[0018] The subject invention, however, in other embodiments, need
not achieve all these objectives and the claims hereof should not
be limited to structures or methods capable of achieving these
objectives.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] Other objects, features and advantages will occur to those
skilled in the art from the following description of a preferred
embodiment and the accompanying drawings, in which:
[0020] FIG. 1 is a schematic three-dimensional top view of a
typical prior art heat sink;
[0021] FIG. 2 is a schematic three-dimensional front view showing
the primary components associated with an example of a more compact
high performance heat exchanger in accordance with the subject
invention;
[0022] FIG. 3 is a schematic three-dimensional view showing a
portion of the base plate evaporator shown in FIG. 2;
[0023] FIG. 4 is a schematic three-dimensional front view showing
the base plate evaporator and condenser components of the heat
exchanger shown in FIG. 2;
[0024] FIG. 5 is a schematic three-dimensional front view showing
the fan and pump components of the heat exchanger shown in FIG.
2;
[0025] FIG. 6 is a schematic three-dimensional cut away view
showing again the primary components associated with an example of
a compact, high performance heat exchanger in accordance with the
subject invention;
[0026] FIG. 7 is a schematic three-dimensional front cutaway view
showing the primary components associated with another example of a
compact, high performance heat exchanger in accordance with the
subject invention;
[0027] FIG. 8 is a schematic three-dimensional front view showing
the primary components associated with another example of a
compact, high performance heat exchanger in accordance with the
subject invention; and
[0028] FIG. 9 is a schematic block diagram showing the flow of a
refrigerant through the heat exchanger of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Aside from the preferred embodiment or embodiments disclosed
below, this invention is capable of other embodiments and of being
practiced or being carried out in various ways. Thus, it is to be
understood that the invention is not limited in its application to
the details of construction and the arrangements of components set
forth in the following description or illustrated in the drawings.
If only one embodiment is described herein, the claims hereof are
not to be limited to that embodiment. Moreover, the claims hereof
are not to be read restrictively unless there is clear and
convincing evidence manifesting a certain exclusion, restriction,
or disclaimer.
[0030] FIG. 1 shows an example of a prior art heat sink 10 with
fins 12. A heat source such as electronic chip 14 on heat spreader
16 is cooled by heat sink 10. An active heat sink may include a fan
to blow air over fins 12.
[0031] FIG. 2 shows an example of a high performance compact heat
exchanger in accordance with the subject invention. Base plate 20
(made of aluminum for example) serves as an evaporator and includes
channels 22, FIG. 3 for a coolant (e.g., a refrigerant such as
R-134a, HFC-236FA, Genetron 245FA, and the like) typically in a
spiral configuration as shown where a continuous groove is formed
inside the body of the base plate. A heat source is mounted to base
plate opposite face 23.
[0032] Condenser 30, FIG. 2 is attached to base plate 20 (and may
be used to seal the channels thereof). Condenser 30, FIG. 4
includes fins 32 with channels therein for the coolant. Pump 40,
FIGS. 2 and 5 (e.g., a mini-refrigerant pump or a single-phase
pump) delivers the liquid coolant to inlet 24, FIG. 3 of base plate
evaporator 20. The coolant proceeds in channels 22 picking up heat
from a heat source disposed on an opposite side of base plate 20
and then changes to a liquid-vapor phase. At outlet 26, the coolant
proceeds to the interior of fins 32, FIG. 4 of condenser 30 where
the coolant condenses via the action of air passing over fins 32.
The coolant then proceeds to the pump in a continuous loop.
Optional fan 50, FIGS. 2 and 5 may be employed to move air over
fins 32, FIG. 4 of condenser 30.
[0033] The result is an integrated pumped liquid refrigerant loop
in both the base and the fins of the heat sink. The internal
refrigerant loop enables complete optimization of the assembly as a
whole. With a standard heat sink, the shape of the fins and the
amount of the surface area provided by the fins is driven by the
fin efficiency and the associated pressure loss at a particular
flow rate. With forced convection cooling over the fins, the
efficiency decreases as the air flow rate (and air velocity) over
the fins is increased. Circulating a refrigerant within the heat
sink in accordance with the subject invention takes advantage of
the latent heat of vaporization of the refrigerant and results in
an almost perfect (isothermal) heat sink from the entire base to
the tips of all the fins. The fin efficiency for this design
approaches unity since the temperature variation from the base to
the tip of the fins is negligible. Pump 40 actively circulates the
refrigerant inside the fins and it overcomes the inefficiencies
seen in other heat sinks associated with conduction. The result is
that the fins can be shaped so that they maximize thermal
conductance on the air side of the heat sink using the most surface
area and convection enhancements as possible while maintaining a
fin efficiency approaching 100%. This new design results in a
thermal conductance that is estimated to be approximately four
times higher than that seen in the current state of the art designs
and requires less than half of the power draw as well. The design
includes a tremendous amount of surface area on both the internal
refrigerant side and the external air side while maintaining the
pressure drop on both sides to reasonable levels. One way this is
accomplished is with the spiral-like shape of condenser 30 in
combination with the low profile high efficiency evaporator base
plate 20. This combination of attributes allows for the optimum
design possible for any given set of parameters. The evaporator
base plate 20, condenser 30, and pump 40 as well as optional fan 50
comprise an integral assembly minimizing the required volume,
weight, and power draw, while maximizing the thermal performance
using the standard refrigerant evaporation-condensation cycle. The
power draw can further be reduced by incorporating a feed-back
circuit which senses the internal pressure (which corresponds to
the saturation temperature) and varies the speed of fan 50
accordingly.
[0034] In the embodiment shown in FIG. 6, spiral micro-channels 22
inside base plate 20 are internal to the structural body of the
base plate and the fins of condenser 30 comprise a continuous
spiral body 36, FIGS. 4 and 6 with a single orifice 38 therein.
Coolant at outlet 26 of base plate 20 is delivered to orifice 38 at
location 39 and, after traveling through the length of continuous
body 36, the coolant is again delivered to pump 40. Fasteners 25
secure fan 50 and condenser 30 to base plate evaporator 20.
[0035] In the example shown in FIG. 7, duct 60 is added between fan
50 and condenser 30' which now includes fins made of an array of
individual conduits 39. As shown, each fin includes a plurality of
conduits stacked on top of each other in a spiral configuration.
The input of all the conduits is at plenum 41 which is in fluid
communication with the output of base plate 20.
[0036] In the example shown in FIG. 8, the synthetic jet ejector
micro-array subsystem 70 is located between base plate evaporator
20 and condenser 30' to move air over the fins of condenser 30'. In
this embodiment, fan 50 may not be needed. Other means for moving
air over the fins of the condenser besides subsystem 70 and/or a
fan as discussed above are possible and are within the scope of the
subject invention. The refrigerant pumping system includes pump 40
and reservoir 43.
[0037] FIG. 9 shows the flow of the refrigerant from pump 40 to
base plate evaporator 20 and then to the fins of condenser 30 and
then back to pump 40.
[0038] The result in any embodiment is a novel closed loop
refrigerant cycle where coolant flows in both the base plate and
the fins of the heat sink. Such a heat exchanger can be made very
compact (e.g., 4'' wide by 4'' long by 1'' to 4'' tall depending on
whether a fan is used). The novel heat exchanger of the subject
invention can be used in conjunction with radar arrays and also in
connection with other heat sources including electronic components
and assemblies of any configuration. The result is a high
performance heat exchanger with improved thermal performance and a
lower power draw. The cooling channels in the evaporator base
plate, the cooling channels in the fins of the condenser and the
air side surface of the fins of the condenser might also include
heat transfer enhancement features such as vortex winglets, fins or
other means of disrupting the fluid boundary layer and/or
increasing heat transfer surface area.
[0039] Although specific features of the invention are shown in
some drawings and not in others, however, this is for convenience
only as each feature may be combined with any or all of the other
features in accordance with the invention. The words "including",
"comprising", "having", and "with" as used herein are to be
interpreted broadly and comprehensively and are not limited to any
physical interconnection. Moreover, any embodiments disclosed in
the subject application are not to be taken as the only possible
embodiments.
[0040] In addition, any amendment presented during the prosecution
of the patent application for this patent is not a disclaimer of
any claim element presented in the application as filed: those
skilled in the art cannot reasonably be expected to draft a claim
that would literally encompass all possible equivalents, many
equivalents will be unforeseeable at the time of the amendment and
are beyond a fair interpretation of what is to be surrendered (if
anything), the rationale underlying the amendment may bear no more
than a tangential relation to many equivalents, and/or there are
many other reasons the applicant can not be expected to describe
certain insubstantial substitutes for any claim element
amended.
[0041] Other embodiments will occur to those skilled in the art and
are within the following claims.
* * * * *