U.S. patent application number 12/785063 was filed with the patent office on 2010-09-16 for method and apparatus for dehumidification.
Invention is credited to Patrick Gordon GAVULA, John Terry KNIGHT, Anthony William LANDERS, Stephen Blake PICKLE.
Application Number | 20100229579 12/785063 |
Document ID | / |
Family ID | 36272485 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100229579 |
Kind Code |
A1 |
KNIGHT; John Terry ; et
al. |
September 16, 2010 |
METHOD AND APPARATUS FOR DEHUMIDIFICATION
Abstract
An HVAC system including a compressor, a condenser and an
evaporator connected in a closed refrigerant loop. The evaporator
includes a plurality of refrigerant circuits. The evaporator also
includes at least one distributor configured to distribute and
deliver refrigerant to each circuit of the plurality of circuits.
The plurality of circuits are arranged into a first and second set
of circuits. The evaporator also includes a valve configured and
disposed to isolate the first set of circuits from refrigerant flow
from the condenser and provide flow of refrigerant from the
compressor in a dehumidification operation of the HVAC system.
Inventors: |
KNIGHT; John Terry; (Moore,
OK) ; LANDERS; Anthony William; (Yukon, OK) ;
GAVULA; Patrick Gordon; (Oklahoma City, OK) ; PICKLE;
Stephen Blake; (Norman, OK) |
Correspondence
Address: |
MCNEES WALLACE & NURICK LLC
100 PINE STREET, P.O. BOX 1166
HARRISBURG
PA
17108-1166
US
|
Family ID: |
36272485 |
Appl. No.: |
12/785063 |
Filed: |
May 21, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11165106 |
Jun 23, 2005 |
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12785063 |
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60640038 |
Dec 29, 2004 |
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Current U.S.
Class: |
62/196.1 ;
62/498 |
Current CPC
Class: |
F24F 3/153 20130101;
F25B 2400/0403 20130101; F25B 5/02 20130101; F25B 2600/2507
20130101 |
Class at
Publication: |
62/196.1 ;
62/498 |
International
Class: |
F25B 41/04 20060101
F25B041/04; F25B 1/00 20060101 F25B001/00 |
Claims
1. An HVAC system comprising: a compressor, a condenser and an
evaporator connected in a closed refrigerant loop, the evaporator
including a plurality of refrigerant circuits; the evaporator
including at least one distributor configured to distribute and
deliver refrigerant to each circuit of the plurality of circuits;
the plurality of circuits being arranged into a first set of
circuits and second set of circuits; and the evaporator including a
valve arrangement configured and disposed to isolate the first set
of circuits from refrigerant flow from the condenser and to permit
flow of refrigerant from the compressor to the first set of
circuits in a dehumidification operation of the HVAC system.
2. The system of claim 1, further comprising: a first control valve
fluidly connected to the first set of circuits, wherein the first
control valve controls flow of refrigerant to the first set of
circuits; and a second control valve fluidly connected to the
second set of circuits, wherein the second control valve controls
flow of refrigerant to the second set of circuits.
3. The system of claim 2, further comprising: a first control valve
sensor for sensing temperature communicating with the first control
valve, the first control valve controlling flow of refrigerant
through the first set of circuits in response to the temperature
sensed by the first control valve sensor; and a second control
valve sensor for sensing temperature communicating with the second
control valve, the second control valve controlling flow of
refrigerant through the second set of circuits in response to the
temperature sensed by the first control valve sensor.
4. The system of claim 3, wherein the second control valve is
capable of permitting a greater amount of refrigerant flow than the
first control valve.
5. The system of claim 3, wherein the first and second control
valves are thermostatic expansion valves.
6. The system of claim 2, further comprising a header for
distributing the flow of refrigerant, the header including a
plurality of fluid connections to each of the circuits of the first
set of circuits and the second set of circuits, wherein each fluid
connection includes a control valve that controls flow of
refrigerant through the fluid connection to the corresponding
circuit.
7. The system of claim 1, further comprising: a fluid connection
between the compressor and the first set of circuits allowing flow
of at least a portion of refrigerant discharged from the compressor
to the first set of circuits, wherein the flow of refrigerant in
the fluid connection bypasses the condenser.
8. The system of claim 7, wherein the fluid connection connects the
discharge of the compressor to the inlet of the first set of
circuits.
9. The system of claim 8, the fluid connection further comprising a
device selected from the group consisting of a bypass valve that
can selectively prevent flow of refrigerant through the fluid
connection, a flow restriction device that controls the amount of
flow through the fluid connection and combinations thereof.
10. The system of claim 1, the valve arrangement further
comprising: a first valve and second valve in a parallel
configuration; the first valve being configurable into a closed
position that prevent flow into or out of the first set of
refrigerant circuits and configurable into an open position that
allows flow into or out of the first set of refrigerant circuits;
and the second valve being capable of preventing flow of
refrigerant into the first set of circuits and allowing flow of
refrigerant out of the first set of refrigerant circuits.
11. The system of claim 10, wherein the fluid connection connects
the discharge of the compressor to the outlet of the first set of
circuits, wherein flow of refrigerant from the compressor through
the first set of circuits flows countercurrent to the flow of
refrigerant in the second set of circuits in response to a
dehumidification operation.
12. The system of claim 10, wherein the fluid connection includes a
3-way valve that selectively connects the outlet of the first set
of circuits to either the discharge of the compressor or the inlet
of the compressor.
13. The system of claim 11, wherein the refrigerant flowing
countercurrent to the flow of refrigerant in the second set of
circuits condenses from a gas to a liquid and combines with the
inlet of the second set of circuits.
14. The system of claim 1, wherein the first set of circuits
includes a plurality of portions, each portion having a
predetermined number of circuits and a corresponding valve
arrangement arranged and disposed to independently isolate each of
the portions from flow of refrigerant from the condenser.
15. An HVAC system comprising: a compressor, a condenser and an
evaporator connected in a closed refrigerant loop, the evaporator
including a plurality of refrigerant circuits; the evaporator
including at least one distribution arrangement configured to
distribute and deliver refrigerant to each circuit of the plurality
of circuits; the plurality of circuits being arranged into a
plurality of sets of circuits; and the evaporator including a valve
arrangement configured and disposed to isolate at least one of the
sets of circuits from refrigerant flow from the condenser and to
permit flow of refrigerant from the compressor to the at least one
of the sets of circuits in a dehumidification operation of the HVAC
system.
16. The system of claim 15, further comprising: a control valve
fluidly connected to each of the sets of circuits, wherein the
control valve controls flow of refrigerant to the corresponding set
of circuits.
17. The system of claim 16, further comprising: a control valve
sensor for sensing temperature communicating with each of the
control valves, each control valve controlling flow of refrigerant
through the corresponding set of circuits in response to the
temperature sensed by the corresponding control valve sensor.
18. The system of claim 15, further comprising: a fluid connection
between the compressor and at least one of the sets of circuits
allowing flow of at least a portion of refrigerant discharged from
the compressor to the corresponding sets of circuits, wherein the
flow of refrigerant in the fluid connection bypasses the
condenser.
19. The system of claim 18, wherein the fluid connection connects
the discharge of the compressor to the inlet of the corresponding
sets of circuits.
20. The system of claim 19, the fluid connection further comprising
a device selected from the group consisting of a bypass valve that
can selectively prevent flow of refrigerant through the fluid
connection, a flow restriction device that controls the amount of
flow through the fluid connection and combinations thereof.
21. The system of claim 19, the valve arrangement further
comprising: a first valve and second valve in a parallel
configuration; the first valve being configurable into a closed
position that prevent flow into or out at least one of the
plurality of sets of refrigerant circuits and configurable into an
open position that allows flow into or out of the corresponding
sets of refrigerant circuits; and the second valve being capable of
preventing flow of refrigerant into the first set of circuits and
allowing flow of refrigerant out of the corresponding sets of
refrigerant circuits.
22. The system of claim 21, wherein the fluid connection connects a
discharge of the compressor to the outlet of the corresponding sets
of circuits, wherein flow of refrigerant from the compressor
through the corresponding sets of circuits flows countercurrent to
the flow of refrigerant in the remaining sets of circuits in
response to a dehumidification operation.
23. The system of claim 21, wherein the fluid connection includes a
3-way valve that selectively connects the outlet of the
corresponding sets of circuits to either a discharge of the
compressor or an inlet of the compressor.
24. The system of claim 22, wherein the refrigerant flowing
countercurrent to the flow of refrigerant in the second set of
circuits condenses from a gas to a liquid and combines with the
inlet of the second set of circuits.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/165,106, filed Jun. 23, 2005, which claims the benefit of
U.S. Provisional Application No. 60/640,038, filed Dec. 29, 2004,
both of which are hereby incorporated by reference.
BACKGROUND
[0002] The present application is directed to providing
dehumidification in heating, ventilation and air conditioner (HVAC)
systems. In particular, the present application is directed to an
arrangement for HVAC systems that can dehumidify air.
[0003] Dehumidification of air in HVAC systems typically takes
place through the use of the evaporator in cooling mode. One
drawback to using an evaporator, alone, for dehumidification, is
the excess reduction in air temperature that results, which is
commonly referred to as overcooling. Overcooling occurs when air
that is subject to dehumidification is cooled to a temperature that
is below the desired temperature of the air. Overcooling is a
particular problem when the dehumidification is required in a room
that is already relatively cool. Overcooling generally involves air
temperatures of approximately 50.degree. F. to 55.degree. F. or
lower.
[0004] Overcooling has been addressed by utilization of a reheat
coil, as disclosed in U.S. Pat. No. 5,752,389 (the '389 patent).
Air that is overcooled by the evaporator is passed over the reheat
coil in order to increase the temperature of the overcooled,
dehumidified air to a desired temperature. In the '389 patent, the
reheat coil is heated by diverting hot refrigerant gas through the
reheat coil when dehumidification is required. Reheat may also be
provided by alternate heat sources, such as electric heat or gas
heat. The reheat coil system for providing heat to the
dehumidified, overcooled air has several drawbacks including the
requirement of additional equipment and/or piping and/or additional
energy input. The presence of an additional coil in the indoor air
stream results in losses that must be overcome by the indoor
blower. These losses are present any time the indoor blower is
running, regardless of the operational mode of the unit. The result
is higher relative energy usage to circulate air with an additional
coil present.
[0005] Another dehumidification method known in the art is
disclosed in U.S. Pat. No. 4,182,133 (the '133 patent). The '133
patent is directed to a dehumidification method that controls
refrigerant flow through circuits within the indoor coil of an air
conditioning/heat pump unit. The '133 patent system, when providing
dehumidification, has a liquid header that distributes the
refrigerant across several circuits within the indoor coil. At the
opposite end of the indoor coil, the outlets of the various
circuits of the coil are allowed to flow into a single common vapor
header. The liquid header at the inlet of the indoor coil contains
a solenoid valve that may be closed to prevent refrigerant flow to
one or more of the circuits within the coil. The '133 patent system
operates such that when humidity reaches a certain level, the valve
in the liquid header is closed in order to limit the number of
available circuits for refrigerant flow. The area of the indoor
coil that remains in the active circuit and receives refrigerant
flow, experiences an increase in refrigerant flow through a given
heat transfer area. The increased flow of refrigerant results in a
greater amount of moisture being removed from the air in that
portion of the indoor coil. The distribution to the parts of the
indoor coil is achieved through a single liquid header. The
operation of the '133 patent system is only concerned with removal
of humidity. One drawback of the '133 system is that the
dehumidified air is not reheated and may be overcooled. Another
drawback of the '133 system is that the inlet header does not
distribute flow across the circuits of the evaporator, leading to
uneven phase distribution of refrigerant across the evaporator heat
exchanger.
[0006] Therefore, what is needed is a method and system for
dehumidification that dehumidifies air without overcooling and
provides a system that can be retrofitted into existing
systems.
SUMMARY
[0007] The present application is directed to an HVAC system
including a compressor, a condenser and an evaporator arrangement
connected in a closed refrigerant loop. The evaporator arrangement
includes a plurality of refrigerant circuits. The evaporator
arrangement also includes at least one distributor configured to
distribute and deliver refrigerant to each circuit of the plurality
of circuits. The plurality of circuits are arranged into a first
and second set of circuits. The evaporator arrangement also
includes an isolation means configured and disposed to isolate the
first set of circuits from refrigerant flow from the condenser and
to permit flow of refrigerant from the compressor during a
dehumidification operation of the HVAC system.
[0008] Another embodiment of the present application includes an
HVAC system having a compressor, a condenser and an evaporator
arrangement connected in a closed refrigerant loop. The evaporator
arrangement includes a plurality of refrigerant circuits. The
evaporator arrangement also includes at least one distribution
arrangement configured to distribute and deliver refrigerant to
each circuit of the plurality of circuits. The plurality of
circuits is arranged into a plurality of sets of circuits. The
evaporator arrangement also includes a valve arrangement configured
and disposed to isolate at least one of the sets of circuits from
refrigerant flow from the condenser and to permit flow of
refrigerant from the compressor during a dehumidification operation
of the HVAC system.
[0009] Still another embodiment of the present application includes
a method for dehumidification. The method comprises providing a
compressor, a condenser and an evaporator arrangement connected in
a closed refrigerant loop. The evaporator arrangement including a
plurality of refrigerant circuits. The evaporator arrangement also
includes at least one distributor configured to distribute and
deliver refrigerant to each circuit of the plurality of circuits.
The plurality of circuits are arranged into a first and second set
of circuits. The evaporator arrangement also includes a valve
configured and disposed to prevent refrigerant flow from the
condenser to the first set of circuits upon being in a closed
position. The method further includes determining an operational
mode for the refrigeration cycle. The operational mode being a
selected from the group consisting of cooling and dehumidification.
The first set of refrigerant circuits are isolated from flow of
refrigerant from the condenser and provided with flow of
refrigerant from the compressor when the operational mode is
dehumidification. Flow of refrigerant is permitted from the
condenser to both the first and second set of refrigerant circuits
when the operational mode is cooling. Heat transfer fluid is flowed
over the evaporator, the heat transfer fluid being in a heat
exchange relationship with the evaporator.
[0010] One advantage of the present application is that it may
easily be retrofitted into existing systems.
[0011] Another advantage of the present application is that the
system and method distributes refrigerant substantially uniformly
across the evaporator to provide substantially uniform refrigerant
phase distribution and heat exchange across the evaporator.
[0012] Another advantage of the present application is that the
system can reheat air without the need for a separate airflow
system.
[0013] Another advantage of the present application is that the
system does not require a discrete reheat coil.
[0014] Another advantage of this system is that enhanced
dehumidification features are made available without increasing
energy usage associated with circulating indoor air.
[0015] Other features and advantages of the present application
will be apparent from the following more detailed description of
the exemplary embodiments, taken in conjunction with the
accompanying drawings which illustrate, by way of example, the
principles of the application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates schematically a refrigeration or HVAC
system.
[0017] FIG. 2 illustrates one embodiment of an evaporator and
piping arrangement of the present application.
[0018] FIG. 3 illustrates another embodiment of an evaporator and
piping arrangement of the present application.
[0019] FIG. 4 illustrates further embodiment of an evaporator and
piping arrangement of the present application.
[0020] FIG. 5 illustrates schematically one embodiment of a
refrigeration or HVAC system according to the present
application.
[0021] FIG. 6 illustrates schematically a refrigeration or HVAC
system of another embodiment of the present application.
[0022] FIG. 7 illustrates schematically a refrigeration or HVAC
system of a further embodiment of the present application.
[0023] FIG. 8 schematically illustrates a suction header
arrangement for an evaporator of the present application.
[0024] FIG. 9 illustrates a control method of the present
application.
[0025] FIG. 10 illustrates a control method of another embodiment
of the present application.
[0026] FIG. 11 illustrates a control method of a further embodiment
of the present application.
[0027] FIG. 12 illustrates a control method of a further embodiment
of the present application.
[0028] FIG. 13 illustrates a control method of a further embodiment
of the present application.
[0029] Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0030] FIG. 1 illustrates a HVAC, refrigeration, or chiller
refrigeration system 100. Refrigeration system 100 includes a
compressor 130, a condenser 120, and an evaporator 110. Refrigerant
is circulated through the refrigeration system 100. The compressor
130 compresses a refrigerant vapor and delivers it to the condenser
120 through compressor discharge line 135. The compressor 130 is
preferably a reciprocating or scroll compressor, however, any other
suitable type of compressor can be used, for example, screw
compressor, rotary compressor, and centrifugal compressor. The
refrigerant vapor delivered by the compressor 130 to the condenser
120 enters into a heat exchange relationship with a first heat
transfer fluid 150 heating the fluid while undergoing a phase
change to a refrigerant liquid as a result of the heat exchange
relationship with the fluid 150. The first heat transfer fluid 150
is moved by use of a fan 170 (see FIG. 5), which moves the first
heat transfer fluid 150 through condenser 120 in a direction
perpendicular the cross section of the condenser 120. The second
heat transfer fluid 155 is moved by use of a blower 160 (see FIG.
5), which moves the second heat transfer fluid 155 through
evaporator 110 in a direction perpendicular the cross section of
the evaporator 110. Although FIG. 5 depicts the use of a blower 160
and fan 170, any fluid moving means may be used to move fluid
through the evaporator and condenser. Suitable fluids for use as
the first heat transfer fluid 150 include, but are not limited to,
air and water. In an exemplary embodiment, the refrigerant vapor
delivered to the condenser 120 enters into a heat exchange
relationship with air as the first heat transfer fluid 150. The
refrigerant leaves the condenser through the evaporator inlet line
140 and is delivered to an evaporator 110. The evaporator 110
includes a heat-exchanger coil. The liquid refrigerant in the
evaporator 110 enters into a heat exchange relationship with the
second heat transfer fluid 155 and undergoes a phase change to a
refrigerant vapor as a result of the heat exchange relationship
with the second fluid 155, which lowers the temperature of the
second heat transfer fluid 155. Suitable fluids for use as the
second heat transfer fluid 155 include, but are not limited to, air
and water. In an exemplary embodiment, the refrigerant vapor
delivered to the evaporator 110 enters into a heat exchange
relationship with air as the second heat transfer fluid 155. The
vapor refrigerant in the evaporator 110 exits the evaporator 110
and returns to the compressor 130 through a compressor suction line
145 to complete the cycle. It is to be understood that any suitable
configuration of condenser 120 can be used in the system 100,
provided that the appropriate phase change of the refrigerant in
the condenser 120 is obtained. The conventional refrigerant system
includes many other features that are not shown in FIG. 1. These
features have been purposely omitted to simplify the figure for
ease of illustration.
[0031] FIG. 2 illustrates a partitioned evaporator 200 according to
one embodiment of the present application. The inlet of the
partitioned evaporator 200 includes an inlet line 140 from the
condenser 120, a first and second expansion device 260 and 265, an
isolation valve 250 and a first and second distributor 240 and 245.
The expansion device may be any suitable refrigerant expanding
device, including a thermostatic expansion valve, a
thermal-electric expansion valve, or an orifice. The first
expansion device 260 is positioned between inlet line 140 and the
first distributor 240. The second expansion device 265 is
positioned between the inlet line 140 and the second distributor
245. The partitioned evaporator 200 includes a plurality of
refrigerant circuits 210. The number of circuits 210 may be any
number of circuits 210 that provide sufficient heat transfer to
maintain operation of the partitioned evaporator within the
refrigerant system 100. The partitioned evaporator 200 is
preferably partitioned into a first and second portion 220 and 230.
Although FIG. 2 shows the evaporator 200 as only including two
portions, any number of portions may be used in the present
application. The first and second evaporator portion 220 and 230
may be sized in any proportion. For example, the first evaporator
portion 220 may be 60% of the size of the partitioned evaporator
200 and the second evaporator portion 230 may be 40% of the size of
the partitioned evaporator 200 or the first evaporator portion 220
may be 40% of the size of the partitioned evaporator 200 and the
second evaporator portion 230 may be 60% of the size of the
partitioned evaporator 200 or the first and second evaporator
portions 220 and 230 may each represent 50% of the size of the
partitioned evaporator 200. Although FIG. 2 shows the partitioned
evaporator 200 as only including two portions, any number of
portions may be used in the present application. Where more than
two evaporator portions are present, the flow may be regulated to
each of the portions. For example, in the embodiment where the
evaporator is split into three portions, two of the three portions
include valve arrangements that allow independent isolation of each
of these portions. One or both of the two portions with valve
arrangements may be isolated, dependent on a signal from a
controller and/or sensor.
[0032] The outlet of the partitioned evaporator 200 includes a
first and second suction header 270 and 275, a first and second
sensing devices 264 and 269, and a suction line 145 to the
compressor 130. The first suction header 270 receives refrigerant
from the circuits 210 in the first evaporator portion 220. The
second suction header 275 receives refrigerant from the circuits
210 present in the second evaporator portion 230. The first sensing
device 264 is positioned between the first suction header 270 and
the suction line 145. The first sensing device 264 senses the
temperature of the refrigerant leaving the first suction header 270
and compares the temperature of the refrigerant to the temperature
of the refrigerant at the first expansion device 260 through line
262. The flow of refrigerant through the first expansion device 260
is increased as the temperature difference at the first sensing
device 264 and the first expansion device 260 increases. The flow
of refrigerant through the first expansion device 260 is decreased
as the temperature difference at the first sensing device 264 and
the first expansion device 260 decreases. The second expansion
device 265 operates in the same manner with respect to the
refrigerant discharge from the second suction header 275, which
senses temperature at second sensing device 269, and communicates
the temperature measurement to the second expansion device 265
through line 267. In an alternate embodiment of the application,
sensing devices 264 and 269 may communicate temperature to a
thermostat or other control device, which provides control to the
system. In yet another embodiment of the application, the
partitioned evaporator according to the application may use a first
and second expansion device 260 and 265, such as orifice plates,
that do not require sensing devices 264 and 269. The isolation
valve 250 allows the first portion 220 of the partitioned
evaporator to be isolated from flow of refrigerant. In one
embodiment, to accommodate an increased flow of refrigerant to the
second evaporator portion 230, as discussed in detail below, the
size of the second expansion device 265 (i.e., the amount of flow
permitted through the valve) is greater than the size of the first
expansion device 260.
[0033] During operation of the HVAC system 100 in cooling mode,
refrigerant flows from the condenser 120 to the partitioned
evaporator 200 through line 140. The flow is split into two
refrigerant flow paths prior to entering the partitioned evaporator
200. Although FIG. 2 shows two paths leading to the distributors
240 and 245, the refrigerant flow may be split into two or more
paths. If the system is in a cooling only mode, isolation valve 250
is open and refrigerant is permitted to flow into both the first
and second portions 220 and 230 of the partitioned evaporator 200.
The two refrigerant flow paths are further split by a first and
second distributor 240 and 245 into a plurality of lines,
corresponding to the individual refrigerant circuits 210. The first
and second distributors 240 and 245 may include any number of
refrigerant lines that distribute the flow to the individual
circuits within the partitioned evaporator 200. Refrigerant passing
through an expansion device is typically present as a two-phase
fluid. Distributors provide substantially even distribution of
two-phase flow. The first and second distributors 240 and 245
provide refrigerant to the circuits 210 of the partitioned
evaporator 200. The distributors 240 and 245 distribute the
refrigerant prior to entering the circuits 210 of the evaporator,
providing uniform phase distribution across the circuits 210 of the
partitioned evaporator 200 to provide substantially uniform heat
transfer. The refrigerant flows into the circuits 210 of first and
second evaporator portions 220 and 230. The circuits 210 permit
heat transfer from the refrigerant to a second heat transfer fluid
155 to cool the second heat transfer fluid 155. The refrigerant
then travels from the first and second headers 270 and 275 past the
first and second sensing devices 264 and 269. The first and second
sensing devices 264 and 269 sense the temperature of the
refrigerant leaving the partitioned evaporator 200 and communicates
the temperature to the first and second expansion devices 260 and
265 in order to determine refrigerant flow. After traveling past
the first and second sensing devices 264 and 269, the refrigerant
is delivered to compressor 130 through line 145.
[0034] If the system shown in FIG. 2 is in dehumidification mode,
isolation valve 250 is closed and refrigerant flow to the first
evaporator portion 220 is prevented. The refrigerant flow in the
second evaporator portion 230 occurs substantially as described
above in cooling mode. However, the flow of refrigerant to the
first evaporator portion 220 is prevented. Since flow to the first
evaporator portion 220 is prevented, the flow to the second
evaporator portion is increased. Due to the reduction of evaporator
surface area, overall heat transfer into the evaporator coil is
decreased. This reduction in evaporator surface area results in a
drop on overall system pressures. Accordingly, the refrigerant
present in the evaporator will boil at a lower temperature than it
did previously resulting in greater dehumidification over that
portion of the evaporator coil. Therefore, when the second heat
transfer fluid 155 is passed through the second evaporator portion
230 the second heat transfer fluid 155 is cooled and dehumidified,
and the second heat transfer fluid 155 passing through the first
evaporator portion remains substantially unchanged in temperature
and humidity from inlet to outlet. The second heat transfer fluid
155 passed through the second evaporator portion 230 is generally
overcooled and the second heat transfer fluid 155 passed through
the first evaporator portion 220 is warmer. The warmer second heat
transfer fluid 155 that passes though the first evaporator portion
220 mixes with the second heat transfer fluid 155 passing through
the second evaporator portion 230 and produces an outlet heat
transfer fluid, preferably air, that is dehumidified and not
overcooled. As shown in FIG. 2, the flow of the second heat
transfer fluid 155 is substantially perpendicular to the
cross-section of the evaporator. The direction of the flow is such
that the heat transfer fluid 155 flows simultaneously through first
evaporator portion 220 and second evaporator portion 230. A single
means for moving the second heat transfer fluid 155, such as an air
blower 160, can be used to simultaneously move air through first
evaporator portion 220 and second evaporator portion 230.
[0035] FIG. 3 illustrates a partitioned evaporator 200 according to
another embodiment of the present application. The inlet of the
partitioned evaporator 200 includes substantially the same
arrangement of components as FIG. 2, including an inlet line 140
from the condenser 120, expansion devices 260 and 265, check valve
255 and first and second distributors 240 and 245. Although FIG. 3
shows check valve 255 as a separate device, the check valve may be
integrated into the expansion device. The check valve 255 is any
suitable device capable of blocking flow in one direction, while
permitting flow in the opposite direction. The partitioned
evaporator 200 includes substantially the same arrangement of
refrigerant circuits 210 as FIG. 2. The outlet of the partitioned
evaporator shown in FIG. 3 includes the first and second suction
headers 270 and 275, first and second sensing devices 264 and 269,
a suction line 145 to the compressor 130 and a suction line 310 to
a three-way valve 610 (see FIG. 6). The first suction header 270
receives refrigerant from the circuits 210 present in the first
evaporator portion 220. The second suction header 275 receives
refrigerant from the circuits 210 present in the second evaporator
portion 220. The first sensing device 264 is positioned on
discharge line 310. The first sensing device 264 senses the
temperature of the refrigerant leaving the first suction header 270
and compares the temperature of the refrigerant to the temperature
of the refrigerant at the first expansion device 260 through line
262. The flow of refrigerant through the first expansion device 260
is increased as the temperature difference at the first sensing
device 264 and the first expansion device 260 increases. The flow
of refrigerant through the first expansion device 260 is decreased
as the temperature difference at the first sensing device 264 and
the first expansion device 260 decreases. The second expansion
device 265 operates in the same manner with respect to the
refrigerant discharge from the second header 275 and communicates
the temperature measurement to the second expansion 265 through
line 267. The use of independent expansion devices 260 and 265
allows independent control of the flow through each of the portions
of the evaporator.
[0036] During operation in cooling mode, FIG. 3, like in the system
shown in FIG. 2, refrigerant flows from the condenser 120 into the
partitioned evaporator 200 through line 140, through the valve
arrangement, including the first and second expansion devices 260
and 265, and into the first and second distributors 240 and 245.
The circuits 210 permit heat transfer to the refrigerant from the
second heat transfer fluid 155 that flows through the circuits
perpendicular to the cross-section shown in FIG. 3. Due to the heat
transfer with the second heat transfer fluid 155, the refrigerant
entering the first and second headers 270 and 275 generally has a
higher temperature than the temperature of the refrigerant entering
the partitioned evaporator. The refrigerant flow through line 310
from the first header 270 travels past the first sensing device 264
and travels to a three-way valve 610, discussed in greater detail
below. In cooling mode, the three-way valve 610 diverts flow from
line 310 to suction line 145 and any flow of compressor discharge
gas thru three-way valve 610 is prevented. The refrigerant flow
through line 145 from the second header 275 travels past the second
sensing device 269 to compressor 130. The sensing devices 264 and
269 sense the temperature of the refrigerant leaving the
partitioned the respective flow sections of the evaporator 200 and
communicate with the first and second expansion devices 260 and 265
in order to determine refrigerant flow for each flow section. After
traveling past the first and second sensing devices 264 and 269,
the refrigerant is delivered to the compressor 130 as discussed in
detail below with regard to FIG. 6.
[0037] If the system shown in FIG. 3 is operated in
dehumidification mode some refrigerant flow of compressor discharge
gas is received by the three-way valve 610 and this flow of hot
refrigerant gas is diverted through line 310, as discussed in
greater detail below. Any flow of refrigerant from three-way valve
610 to suction line 145 is prevented. The flow from the three-way
valve 610 travels through line 310 in the direction of the first
suction header 270. From the first suction header 270, the hot
refrigerant gas enters the first evaporator portion 220 and travels
through circuits 210 to the first distributor 240. The refrigerant
in circuit 210 heats second heat transfer fluid 155 as the fluid
passes over circuit 210. The hot refrigerant gas is at least
partially condensed to a liquid in the first evaporator portion
220. The refrigerant, which is at least partially condensed to a
liquid, substantially bypasses expansion device 260 by traveling
through check valve 255. The flow through check valve 255 combines
with the inlet flow 140 and enters the second evaporator portion
230 through the second distributor 245. The junction point where
the two refrigerant streams meet may be a "tee" junction or may be
a liquid receiver. Due to the overall reduction of heat exchanger
area available to the evaporating refrigerant, overall system
pressure decreases resulting in lower evaporation temperatures in
the lower portion of the coil. Dehumidification over this portion
of the coil is increased. Simultaneously, hot gas refrigerant
entering the first evaporator portion 220 of the partitioned
evaporator 200 provides an increase in the temperature of the first
evaporator portion 220 due to the condensing of the hot gas and the
heat transfer from the hot gas. Therefore, the second heat transfer
fluid 155 passing through the second evaporator portion 230 is
cooled and dehumidified, while the second heat transfer fluid 155
passing through the first evaporator portion 220 receives heat
exchanged from the hot gas refrigerant from the compressor
discharge. This second heat transfer fluid 155 simultaneously is
circulated through first and second evaporator portions 220 and 230
by fluid moving means, such as an air blower 160, when the second
heat transfer fluid 155 is air. The warmer second heat transfer
fluid 155 that passes though the first evaporator portion 220 mixes
with the second heat transfer fluid 155 passing through the second
evaporator portion 230 and produces an outlet heat transfer fluid,
preferably air, that is dehumidified and not overcooled.
[0038] FIG. 4 illustrates a partitioned evaporator 200 according to
a further embodiment of the present application. The inlet of the
partitioned evaporator 200 includes an inlet line 140 from the
condenser 120, a bypass line 410 from the discharge of the
compressor 130 (see FIG. 7), first and second expansion devices 260
and 265, isolation valve 250, and first and second distributors 240
and 245. The first expansion device 260 and the isolation valve 250
are positioned between inlet line 140 and the first distributor
240. Bypass line 410 connects to the line between the first
expansion device 260 and the first distributor 240. Bypass line 410
is from the discharge of the compressor 130 and includes a bypass
valve 440. A means of restricting flow through bypass line 410 is
also present and may take the form of a flow restriction orifice
430 or flow may be restricted by adjusting the diameter and/or
length of bypass line 410. The isolation valve 250 is positioned
between inlet line 140 and the first expansion device 260. The
second expansion device 265 is positioned between the inlet line
140 and the second distributor 245. The partitioned evaporator 200
includes substantially the same arrangement of refrigerant circuits
210 as shown in FIG. 2. The outlet of the partitioned evaporator
200 includes first and second suction headers 270 and 275, first
and second sensing devices 264 and 269, and suction line 145 to the
compressor 130. The first suction header 270 receives refrigerant
from the circuits 210 present in the first evaporator portion 220.
The second suction header 275 receives refrigerant from the
circuits 210 present in the second evaporator portion 220. The
first sensing device 264 is positioned between the first suction
header 270 and the suction line 145. The first sensing device 264
senses the temperature of the refrigerant leaving the first suction
header 270 and compares the temperature of the refrigerant to the
temperature of the refrigerant at the first expansion device 260
through line 262. The flow of refrigerant through the first
expansion device 260 is increased as the temperature difference at
the first sensing device 264 and the first expansion device
increases. The flow of refrigerant through the first expansion
device 260 is decreased as the temperature difference at the first
sensing device 264 and the first expansion device 260 decreases.
The second expansion device 265 operates in the same manner with
respect to the refrigerant discharge from the second header 275 and
communicates the temperature measurement to the second expansion
device 265 through line 267. The variation of the flow through
manual adjustment or through signals from a controller may be
optimized to provide maximum cooling and dehumidification, while
maintaining a desirable temperature for the second heat transfer
fluid. Isolation valve 250 allows the first portion 220 of the
partitioned evaporator 200 to be isolated from flow of refrigerant
from the condenser 120. In one embodiment, to accommodate the
increased flow of refrigerant to the second evaporator portion 230,
the size of the second expansion device 265 (i.e. the amount of
flow permitted through the valve) is greater than the size of the
first expansion device 260.
[0039] During operation in cooling mode, FIG. 4, like in the system
shown in FIG. 2, refrigerant flows from the condenser 120 into the
circuits 210 of the partitioned evaporator 200 through line 140,
through the valve arrangement, including the first and second
expansion devices 260 and 265, and the isolation valve 250, and
into the first and second distributors 240 and 245. In cooling
mode, substantially no flow of refrigerant takes place into or out
of the bypass line 410. The operation of the circuits 210 and the
outlet of the partitioned evaporator 200, including the first and
second headers 270 and 275, the first and second sensing devices
264 and 269 and suction line 145 to the compressor is substantially
similar to the operation described above with respect to FIG.
2.
[0040] However, if the system shown in FIG. 4 is in
dehumidification mode, isolation valve 250 is closed and
refrigerant flow to the first expansion device 260 is prevented. A
portion of the refrigerant flow from the discharge of compressor
130 flows through bypass line 410 into the first distributor 240
and into the first evaporator portion 220. The hot gas refrigerant
entering the first evaporator portion 220 of the partitioned
evaporator 200 provides an increase in the temperature of the first
evaporator portion 220. Due to the overall reduction of heat
exchanger area available to the evaporating refrigerant, evaporator
pressure decreases resulting in lower evaporation temperatures in
the lower portion of the coil. Dehumidification over this portion
of the coil is increased. Therefore, the second heat transfer fluid
155 passing through the second evaporator portion 230 is cooled and
dehumidified, while the second heat transfer fluid 155 passing
through the first evaporator portion 220 receives heat exchanged
from the hot gas refrigerant from the compressor discharge. This
second heat transfer fluid 155 simultaneously is circulated through
first and second evaporator portions 220 and 230 by fluid moving
means, such as an air blower 160, when the second heat transfer
fluid 155 is air. The warmer second heat transfer fluid 155 that
passes though the first evaporator portion 220 mixes with the
second heat transfer fluid 155 passing through the second
evaporator portion 230 and produces an outlet heat transfer fluid,
preferably air, that is dehumidified and not overcooled.
[0041] FIG. 5 shows a refrigeration system 100 incorporating a
partitioned evaporator 200 according to the present application.
FIG. 5 shows the refrigeration system, including compressor suction
line 145, blower 160, compressor 130, compressor discharge line
135, condenser 120, a fan 170, evaporator inlet line 140, and first
heat exchange fluid 150, substantially as described above in the
description of FIG. 1. FIG. 5 also shows the partitioned evaporator
200 including first and second expansion devices 260 and 265,
isolation valve 250, first and second distributors 240 and 245,
first and second suction headers 270 and 275, arranged as discussed
above in the description of FIG. 2. Heat transfer fluid flow 510,
preferably air, flows into the partitioned evaporator 200
substantially evenly across the first and second evaporator
portions 220 and 230. Blower 160 moves heat transfer fluid flow
510. Although, FIG. 5 depicts a blower, any suitable fluid moving
means can be used for moving the fluid across the first and second
evaporator portions 220 and 230. The heat transfer fluid enters
into a heat exchange relationship with the first and second
evaporator portions 220 and 230 and exits the partitioned
evaporator as outlet flow 515. During cooling mode, the refrigerant
is circulated from the condenser 120 to the partitioned evaporator
200, through the first and second evaporator portions 220 and 230
and to the compressor 130 through line 145. The inlet flow 510 of
heat transfer fluid is cooled by both the first and second
evaporator portions 220 and 230, providing outlet flow 515 of heat
transfer fluid that has been cooled. During dehumidification mode,
isolation valve 250 is closed, preventing flow of refrigerant into
the first evaporator portion 220. The inlet flow 510 is cooled and
dehumidified by the second evaporator portion 230 and is
substantially untreated by the isolated first evaporator portion
220. The outlet flow 515 is a mixture of the cooled, dehumidified
air that flowed through the second evaporator portion 230 and the
substantially untreated air that flowed though the first evaporator
portion 220. The resultant outlet flow 515 is dehumidified air that
is not overcooled.
[0042] FIG. 6 shows a refrigeration system 100 incorporating a
partitioned evaporator 200 according to the present application.
FIG. 6 shows the refrigeration system including compressor suction
line 145, blower 160, compressor 130, compressor discharge line
135, condenser 120, fan 170, evaporator inlet line 140, and first
heat exchange fluid 150, substantially as described above in the
description of FIG. 1. In addition, FIG. 6 includes a three-way
valve 610 that connects to lines 310, 315 and 320. In cooling mode,
three-way valve 610 provides a refrigerant flow path from line 310
to line 320. There is substantially no flow in line 315 during
cooling mode operation. In reheat mode, three-way valve 610
provides a refrigerant flow path from line 315 to line 310. There
is substantially no refrigerant flow in line 320 during reheat mode
operation. FIG. 6 also shows the partitioned evaporator 200
including first and second expansion devices 260 and 265, check
valve 255, first and second distributors 240 and 245, first and
second suction headers 270 and 275, arranged as discussed above in
the description of FIG. 3. Heat transfer fluid flow 510, preferably
air, flows into the partitioned evaporator 200 substantially evenly
across the first and second portions 220 and 230. A blower 160
moves heat transfer fluid flow 510. Although, FIG. 6 depicts a
blower, any suitable fluid moving means can be used for moving the
fluid across the first and second evaporator portions 220 and 230.
The heat transfer fluid enters into a heat exchange relationship
with the first and second evaporator portions 220 and 230 and exits
the partitioned evaporator as outlet flow 515. During cooling mode,
the refrigerant is circulated from the condenser 120 to the
partitioned evaporator 200, through the first and second evaporator
portions 220 and 230 and to the compressor through line 145. The
inlet flow 510 of heat transfer fluid is cooled by both the first
and second evaporator portions 220 and 230, providing outlet flow
515 of heat transfer fluid that has been cooled. During
reheat/dehumidification mode, some portion of the hot gas
refrigerant from the discharge of the compressor flows into the
three-way valve 610, which is opened to allow flow through the
three-way inlet line 315 and through line 310 to the suction header
270 of the first evaporator portion 220. In one embodiment of the
application, a restrictor valve may be place in compressor
discharge line 135 in order to control the flow of refrigerant
traveling to the condenser 120. In addition to controlling the flow
of refrigerant to the condenser, the addition of a restrictor valve
would allow control of the amount of refrigerant traveling to first
evaporator portion 220. The restrictor valve would also allow
modulation of the amount of refrigerant in order to provide
increased control over the reheating capability of the first
evaporator portion 220. The hot gas refrigerant from the discharge
of the compressor 130 enters the circuits 210 of the first
evaporator portion 220 and at least partially condenses to a
liquid. The condensing refrigerant heats the first evaporator
portion 220 and gives up heat to the heat transfer fluid flow 510
to produce a higher temperature heat transfer fluid outlet flow
515. The refrigerant, which is at least partially condensed,
travels through the check valve 255 and combines with the inlet
flow into the second evaporator portion 230. The inlet flow 510 of
heat transfer fluid is cooled and dehumidified by the second
evaporator portion 230 and is heated by heat exchange with the hot
gas from the discharge of the compressor 130 in the isolated first
evaporator portion 220, as the refrigerant gas is condensed. The
outlet flow 515 is a mixture of the cooled, dehumidified air that
flowed through the second evaporator portion 230 and the heated air
that flowed though the first evaporator portion 220. The thoroughly
mixed resultant outlet flow 515 is dehumidified air that is not
overcooled. In cooling mode, first evaporator portion 220 and
second evaporator portion 230 of partitioned evaporator 200,
operate as evaporators. However, in dehumidification mode, first
evaporator portion 220 operates as a condenser, while second
evaporator portion 230 operates as an evaporator.
[0043] FIG. 7 shows a refrigeration system 100 incorporating a
partitioned evaporator 200 according to the present application.
FIG. 7 shows the refrigeration system 100 including suction line
145, blower 160, compressor 130, compressor discharge line 135,
condenser 120, fan 170, evaporator inlet line 140, and first heat
exchange fluid 150, substantially as described above in the
description of FIG. 1. In addition, FIG. 7 includes one or both of
a bypass shutoff valve 440, and a flow restriction valve 430 on
bypass line 410. Bypass line 410 connects the discharge line 135 of
the compressor to the inlet of the first evaporator portion 220
between the first expansion device 260 and the first distributor
240. FIG. 7 also shows the partitioned evaporator 200 including
first and expansion devices 260 and 265, isolation valve 250, first
and second distributors 240 and 245, and first and second suction
headers 270 and 275, arranged as discussed above in the description
of FIG. 4. Heat transfer fluid flow 510, preferably air, flows into
the partitioned evaporator 200 substantially evenly across the
first and second portions 220 and 230. The heat transfer fluid 510
enters into a heat exchange relationship with the first and second
evaporator portions 220 and 230 and exits the partitioned
evaporator as outlet flow 515. During cooling mode, the refrigerant
is circulated from the condenser 120 to the partitioned evaporator
200, through the first and second evaporator portions 220 and 230
and to the compressor 130 through line 145. The bypass shutoff
valve 440 and the flow restriction valve 430 are set to prevent
flow of refrigerant through the bypass line 410. The inlet flow 510
of heat transfer fluid is cooled by both the first and second
evaporator portions 220 and 230, providing outlet flow 515 of heat
transfer fluid that has been cooled. During dehumidification mode,
isolation valve 250 is closed, preventing flow of condensed
refrigerant into the first evaporator portion 220. The bypass
shutoff valve 440 is opened and the flow restriction valve 430 is
set to allow flow of refrigerant from the compressor 130. Although
FIG. 7 is shown with both a bypass shutoff valve 440 and a flow
restriction valve 430, either the bypass shutoff valve 440 or flow
restriction valve 430 may be removed from the bypass line 410, so
long as the flow of the refrigerant may be stopped during cooling
mode and permitted during dehumidification mode. Hot gas
refrigerant from the discharge of the compressor 130 is then
allowed to flow from the compressor discharge line 135 through the
bypass line 410 into the first distributor 240 and the first
evaporator portion 220. The hot gas refrigerant from the discharge
of the compressor 130 heats the first evaporator portion 220, but
preferably does not condense, and combines with the outlet flow
from the second evaporator portion 230 into the evaporator suction
line 145. The inlet flow 510 of heat transfer fluid is cooled and
dehumidified by the second evaporator portion 230 and is heated by
heat exchange with the hot gas from the discharge of the compressor
in the isolated first evaporator portion 220. The outlet flow 515
is a mixture of the cooled, dehumidified air that flowed through
the second evaporator portion 230 and the heated air that flowed
though the first evaporator portion 220. The resultant outlet flow
515 is dehumidified air that is not overcooled. In an alternate
embodiment, valve 440 is opened when transitioning from cooling
mode to dehumidification/reheat mode. In this embodiment, any
liquid refrigerant present in first evaporator portion 220 is
pushed toward the suction header 270 by the hot gas from the
compressor passing through bypass line 410. The movement of the
refrigerant allows the system to come to steady state
dehumidification/reheat more quickly by not requiring the liquid
refrigerant to evaporate in place. In yet another embodiment, valve
440 is operated to bypass a portion of the hot refrigerant gas from
the compressor 130 around the condenser 120 during conditions of
low ambient temperatures. In this mode of operation, hot gas is
allowed to flow to each of the first and second evaporator portions
220 and 230 to provide some heating of the coils. Bypassing a
portion of the hot gas discharge from the compressor 130 helps
prevents the second evaporator portion 230 from freezing when the
condenser 120 experiences cool outdoor temperatures. In this
embodiment, the bypass line 410 can serve two functions
simultaneously.
[0044] FIG. 8 illustrates an exemplary suction header arrangement
for partitioned evaporator 200 according to a further embodiment of
the present application. The arrangement is suitable for use in the
partitioned evaporator 200 of any of the embodiments shown in FIGS.
2, 4, 5 and 7. In particular, the arrangement shown includes a
first and second expansion device 260 and 265, a first and second
evaporator portion 220 and 230, refrigerant circuits 210, first and
second sensing devices 264 and 269, first and second suction
headers 270 and 275, suction line 145, second heat transfer fluid
155, as shown and described with respect to FIGS. 2, 4, 5 and 7. In
this embodiment, the refrigerant circuits 210 are preferably
arranged such that four refrigerant circuits 210 are present in the
first evaporator portion 220 and three refrigerant circuits 210 are
present in the second refrigerant portion 230. Although FIG. 8 has
been shown with a four isolatable refrigerant circuits 210 to three
refrigerant circuits 210 that remain open to flow in each of the
operational modes, any ratio may be used that provides sufficient
heat transfer surface area to provide dehumidified air that is not
overcooled.
[0045] In the embodiment shown in FIG. 8, first suction header 270
includes a first vertical header tube 810 extending vertically to a
horizontal outlet tube 830. The first vertical header tube 810
provides a space where liquid refrigerant, if any, from the first
evaporator portion 220 falls to the bottom of first vertical header
tube 810. Vaporous refrigerant escapes through horizontal outlet
tube 830. The arrangement of the horizontal outlet tube 830 is such
that the first sensing device 264 operates without interference
form the refrigerant passing through the second evaporator portion
230 and without interference from liquid refrigerant passing
through the first evaporator portion 220. Like the arrangement of
first suction header 270, second suction header 275 includes a
second vertical header tube 820 and a second horizontal outlet tube
840 that operate in substantially the same manner with respect to
the second evaporator portion 230.
[0046] FIG. 9 shows a control method according to one embodiment of
the present application. The method includes a mode determination
step 910 where the operational mode of the system is determined or
selected. The operational mode can be provided by the controller
and/or user, where the mode can either be cooling only or require
dehumidification. Examples of control systems for determination of
the operational mode are described in further detail below in the
discussion of FIGS. 12 and 13. The method then includes a
decisional step 920 wherein it is determined whether
dehumidification mode is required or not. If the determination in
step 920 is "NO" (i.e., no dehumidification mode is required), then
the method proceeds to opening step 930 wherein the valve to the
first evaporator portion 220 is opened or remains open. The opening
of the first evaporator portion 220 to the flow of refrigerant
permits both the first and second evaporator portions 220 and 230
to provide cooling to the heat transfer fluid 510. If the
decisional step 920 is a "YES" (i.e., dehumidification mode is
required), then the valve to the first evaporator portion 220 is
closed or remains closed. The closing of the first evaporator
portion 220 to the flow of refrigerant allows the first evaporator
portion 220 to equilibrate at a temperature substantially equal to
the temperature of the heat transfer fluid entering the partitioned
evaporator 200. After either the opening step 930 or the closing
step 840, the method returns to the determination step 810 and the
method repeats.
[0047] Although FIG. 9 shows that the decisional step provides a
"YES" or "NO" in step 920, the method is not limited to an open or
closed isolation valve 250. A flow restricting valve may also be
used. The use of a flow restricting valve allows the amount of flow
into the first evaporator portion 220 to be varied. For example,
the flow restricting valve may be used in an operational mode that
is open to full flow, partially restricted flow or closed to flow,
depending on the signal from a controller. A controller, using
inputs, such as refrigerant temperature, heat transfer fluid
temperatures, and humidity readings, provides a signal to the
restricting valve to determine the amount of refrigerant flow
permitted through the isolation valve 250.
[0048] FIG. 10 shows another control method according to the
present application. The method includes a mode determination step
1010 where the operational mode of the system is determined. As in
the method shown in FIG. 9, the operational mode can be provided by
the controller and/or user, where the mode can either be cooling
only or require dehumidification mode. Examples of control systems
for determination of the operational mode are described in further
detail below in the discussion of FIGS. 12 and 13. The method then
includes a decisional step 1020 wherein it is determined whether
dehumidification mode is required or not. If the determination in
step 1020 is "NO" (i.e., no dehumidification mode is required),
then the method proceeds to step 1030 wherein the valve to the
first evaporator portion 220 is opened or remains open. After or
concurrently with step 1030, three-way valve 610 is set in a flow
directing step 1040 to provide refrigerant flow from the discharge
line 310 of the partitioned evaporator 200 to the intake of the
compressor 130. The opening of the first evaporator portion 220 and
the setting of the three-way valve 610 allow the flow of
refrigerant to both the first and second evaporator portions 220
and 230 to provide cooling to the heat transfer fluid 510. If the
decisional step 1020 is "YES" (i.e., dehumidification mode is
required), then the valve to the first evaporator portion 220 is
closed or remains closed. After or concurrently with step 1050,
three-way valve 610 is set in a flow directing step 1060 to provide
refrigerant flow from the discharge of the compressor to the
cooling mode suction line 310 of the partitioned evaporator 200.
The hot gas refrigerant from the discharge of the compressor 130
flows into the first evaporator portion 220 and provides heat to
the first evaporator portion 220. The directing of hot gas
refrigerant to the first evaporator portion 220 allows the first
evaporator portion 220 to exchange heat with the heat transfer
fluid 510 entering the partitioned evaporator 200. The inlet flow
510 of heat transfer fluid is cooled and dehumidified by the second
evaporator portion 230 and is heated by heat exchange with the hot
gas from the discharge of the compressor 130 in the isolated first
evaporator portion 220. The outlet flow 515 is a mixture of the
cooled, dehumidified air that flowed through the second evaporator
portion 230 and the heated air that flowed though the first
evaporator portion 220. The resultant outlet flow 515 is
dehumidified air that is not overcooled. After either the three-way
valve 610 directing steps 1040 or 1060, the method returns to the
determination step 1010 and the method repeats.
[0049] Although FIG. 10 shows that the decisional step provides a
"YES" or "NO" in step 1020, the method is not limited to an open or
closed isolation valve 250. A flow restriction valve may also be
used. The use of a flow restriction valve allows the amount of flow
into the first evaporator portion 220 to be varied. For example,
the flow restriction valve may be used in an operational mode that
is open to full flow, partially restricted flow or closed to flow,
depending on the signal from a controller. Alternatively, the flow
into the first evaporator portion 220 from the discharge of the
compressor 130 in dehumidification mode may be varied through use
of the three-way valve 610, depending on the signal from a
controller. The three-way valve 610 may also include flow
restriction abilities that allow the flow of refrigerant to be
varied. A controller, using inputs, such as refrigerant
temperature, heat transfer fluid temperatures, and humidity
readings, provides a signal to the restriction valve or the
three-way valve 610 to determine the amount of refrigerant flow
permitted through the isolation valve 250 or the amount of hot gas
refrigerant permitted through the first evaporator portion 220.
[0050] FIG. 11 shows another control method according to the
present application. The method includes a mode determination step
1110 where the operational mode of the system is determined. As in
the method shown in FIG. 9, the operational mode can be provided by
the controller and/or user, where the mode can either be cooling
only or require dehumidification mode. The method then includes a
decisional step 1120 wherein it is determined whether
dehumidification mode is required or not. If the determination in
step 1120 is "NO" (i.e., no dehumidification mode required), then
the method proceeds to step 1130 wherein the valve to the first
evaporator portion 220 is opened or remains open. After or
concurrently with step 1130, a bypass 410 is closed from
refrigerant flow in a bypass closing step 1140. The opening of the
first evaporator portion 220 and the closing of the bypass 410
allow the flow of refrigerant to both the first and second
evaporator portions 220 and 230 to provide cooling to the heat
transfer fluid 510. If the decisional step 1120 is a "YES" (i.e.,
dehumidification mode is required), then the valve to the first
evaporator portion 220 is closed or remains closed. After or
concurrently with step 1150, the bypass 410 is opened to flow of
refrigerant in a bypass opening step 1160. Hot gas refrigerant from
the discharge of the compressor 130 flows through the bypass 410
and into the first evaporator portion 220 and provides heat to the
first evaporator portion 220. The closing of the first evaporator
portion 220 to the flow of refrigerant and the directing of hot gas
refrigerant to the first evaporator portion 220 allows the first
evaporator portion 220 to exchange heat with the heat transfer
fluid 510 entering the partitioned evaporator 200. The inlet flow
510 of heat transfer fluid is cooled and dehumidified by the second
evaporator portion 230 and is heated by heat exchange with the hot
gas from the discharge of the compressor in the isolated first
evaporator portion 220. The outlet flow 515 is a mixture of the
cooled, dehumidified air that flowed through the second evaporator
portion 230 and the heated air that flowed though the first
evaporator portion 220. The resultant outlet flow 515 is
dehumidified air that is not overcooled. After either the bypass
closing step 1140 or the bypass opening step 1160, the method
returns to the determination step 1110 and the method repeats.
[0051] Although FIG. 11 shows that the decisional step 1120
provides a "YES" or "NO" in decisional step 1120, the method is not
limited to an open or closed isolation valve 250. A flow
restriction valve may also be used. The use of a flow restriction
valve allows the amount of flow into the first evaporator portion
220 to be varied. For example, the flow restriction valve may be
used in an operational mode that is open to full flow, partially
restricted flow or closed to flow, depending on the signal from a
controller. Additionally, the flow through the bypass line 410 may
be varied through use of the bypass shutoff valve 440 and/or flow
restriction valve 430, depending on the signal from a controller. A
controller, using inputs, such as refrigerant temperature, heat
transfer fluid temperatures, and humidity readings, provides a
signal to isolation valve 250, bypass shutoff valve 440 and flow
restriction valve 430 to determine the amount of refrigerant flow
permitted through the restricting valve in place of isolation valve
250 and the amount of hot gas refrigerant permitted through the
first evaporator portion 220.
[0052] FIG. 12 illustrates a control method according to the
present application that determines the operation mode of the
partitioned evaporator 200. The determination of the operational
mode is made through the use of a controller. This determination
may be used in steps 910, 1010 and 1110 of FIGS. 9, 10 and 11,
respectively. The determination takes place by first sensing
temperature and/or humidity in step 1210. The sufficient
temperature and/or humidity measurements are made for a controller
to determine whether the heat transfer fluid requires cooling or
dehumidification. The inputs from temperature sensors and humidity
sensors are provided to the controller in step 1220, where the
controller uses the sensed temperatures and/or humidity to
determine the operational mode. In step 1220, the controller
determines whether cooling is required and whether dehumidification
is required. In a first decisional step 1230, it is determined
whether the controller has determined that cooling is required. If
the first decisional step 1230 determines "YES", cooling is
required, the partitioned evaporator 200 in the refrigeration
system 100 is set to allow flow into all of the circuits 210 in the
partitioned evaporator 200 and cool across both the first and
second evaporator portions 220 and 230 in step 1240. In addition to
cooling, cooling mode also performs dehumidification. However, in a
cooling mode, the temperature is only cooled and is not heated to
increase the temperature of the second heat transfer fluid 155 once
the second heat transfer fluid 155 travels through the evaporator.
If the first decisional step 1230 determines "NO", then a second
decisional step 1250 is made. The second decisional step 1250
determines whether the controller has determined that
dehumidification (i.e., dehumidification without overcooling) is
required. If the second decisional step 1250 determines "YES",
dehumidification is required, the operational mode is set to
dehumidification in step 1260, which corresponds to step 910, 1010
or 1110 in FIGS. 9-11, and the process continues with determination
step 920, 1020 and 1120, as shown in FIGS. 9-11. If the second
decisional step 1250 determines "NO", dehumidification is not
required, the operational mode is set to inactive and the system
runs neither a cooling nor a dehumidification cycle in step
1270.
[0053] FIG. 13 shows an alternate control method according to the
present application that determines the operation mode of a
multiple refrigerant system. In the system controlled in FIG. 13,
multiple refrigerant systems 100 are utilized and one or more of
the refrigerant systems 100 include a partitioned evaporator 200
according to the application. The control method shown in FIG. 13
operates in a similar manner to FIG. 12 in that the controller
receives inputs from temperature and/or humidity sensors in step
1310 and determines the operational mode of the system in step
1320. Likewise, if the first decisional step 1330 determines "NO",
then a second decisional step 1370 is performed. The second
decisional step 1370 determines whether the controller has
determined that dehumidification mode (i.e., dehumidification
without overcooling) is required. If the second decisional step
1370 determines "YES", dehumidification mode is required, the
operational mode is set to dehumidification mode in step 1380. If
multiple refrigerant systems 100 are present, the controller
independently determines which of the refrigerant systems 100 are
active or inactive, based upon the temperature of the air and
amount of dehumidification required. When multiple refrigeration
systems 100 are present, at least one refrigerant system 100
includes a partitioned evaporator 200. The controller independently
determines which partitioned evaporator 200 is subject to isolation
of the first evaporator portion 220, based upon the temperature of
the air and amount of dehumidification required. However, if the
second decisional step 1370 determines "NO", dehumidification mode
is not required, the operational mode is set to inactive and the
system runs neither a cooling nor a dehumidification cycle in step
1390. If the first decisional step 1330 determines "YES", cooling
is required, a third decisional step 1340 is performed. In the
third decisional step 1340, a determination as to the number of
stages are to be activated in order to provide the cooling. Each
stage has an evaporator capable of providing cooling to the second
heat transfer fluid 155. The greater the number of stages
activated, the greater the amount of cooling provided. At least one
of the multiple refrigerant circuits includes a partitioned
evaporator 200. If the controller determines that the cooling
demand only requires one refrigerant system 100 to be active, one
refrigerant system 100 will be used to cool second heat transfer
fluid 155 in step 1350. When the partitioned evaporator 200 is used
to operate in cooling mode, the partitioned evaporator 200 is
configured to allow flow into all of the circuits 210 in the
partition evaporator 200 and cool across both the first and second
evaporator portions 220 and 230 in step 1350. If multiple
partitioned evaporator 200 is present, all of the circuits 210 in
each of the partitioned evaporator 200 allow flow of refrigerant
into both the first and second evaporator portions 220 and 230 and
cool the second heat transfer fluid 155.
[0054] The present application is not limited to the control
methods shown in FIGS. 9-13. The partitioned evaporator 200 may be
used in one or more refrigerant circuits of multiple refrigerant
circuit systems, where the control of the reheating capabilities
within the first evaporator portion 220 of the partitioned
evaporator 200 may be independently controlled to provide the
desired temperature and/or humidity within the conditioned space.
Any combination of cooling, reheating, or modulation of
combinations of cooling and reheating may be used with the present
application.
[0055] Although the partitioned evaporator 200 has been illustrated
as containing two evaporator portions 220 and 230, the partitioned
evaporator 200 is not limited to two portions. Any number of
portions may be used, so long as one or more of the portions
include means to isolate the respective portion from refrigerant
flow.
[0056] In another embodiment, refrigerant circuits 210 may also be
isolated individually within the first and/or second distributor.
The circuits may be isolated with flow blocking means or flow
restriction means. In this embodiment, a controller is used to
determine the number of circuits isolated. The number of circuits
isolated relates to the amount of cooling and/or heating of
dehumidified air required and may be adjusted by the
controller.
[0057] The lack of additional piping also allows retrofitting of
the system of the present application into existing systems.
Because the system utilizes the same components as existing
systems, the system takes up approximately the same volume as
existing HVAC systems. Therefore, the method and system of the
present application may be used in existing systems whose piping
has arranged according to the present application.
[0058] While the application has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the application. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
application without departing from the essential scope thereof.
Therefore, it is intended that the application not be limited to
the particular embodiment disclosed as the best mode contemplated
for carrying out this application, but that the application will
include all embodiments falling within the scope of the appended
claims.
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