U.S. patent application number 13/060119 was filed with the patent office on 2011-06-30 for refrigerant system with adaptive hot gas reheat.
Invention is credited to Michael F. Taras.
Application Number | 20110154837 13/060119 |
Document ID | / |
Family ID | 42074089 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110154837 |
Kind Code |
A1 |
Taras; Michael F. |
June 30, 2011 |
REFRIGERANT SYSTEM WITH ADAPTIVE HOT GAS REHEAT
Abstract
A refrigerant system incorporates a hot gas reheat circuit. The
hot gas reheat circuit includes a reheat valve for selectively
tapping at least a portion of refrigerant from a location
downstream of a compressor and upstream of a condenser, and through
a reheat heat exchanger. At least one refrigerant flow control
device controls the amount of refrigerant passing through the
reheat heat exchanger. A control for the refrigerant system is
operable to receive inputs from an indoor environment, and to
control the amount of refrigerant passing through the reheat heat
exchanger to achieve desired temperature and humidity in the
conditioned environment.
Inventors: |
Taras; Michael F.;
(Fayetteville, NY) |
Family ID: |
42074089 |
Appl. No.: |
13/060119 |
Filed: |
September 2, 2009 |
PCT Filed: |
September 2, 2009 |
PCT NO: |
PCT/US09/55707 |
371 Date: |
February 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61102021 |
Oct 2, 2008 |
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Current U.S.
Class: |
62/79 ;
62/150 |
Current CPC
Class: |
F25B 2700/2104 20130101;
F25B 2600/2501 20130101; F25B 2400/0419 20130101; F24F 3/153
20130101; F25B 40/00 20130101; F25B 2600/2509 20130101 |
Class at
Publication: |
62/79 ;
62/150 |
International
Class: |
F25B 29/00 20060101
F25B029/00; F25D 21/04 20060101 F25D021/04 |
Claims
1. A refrigerant system comprising: a compressor for compressing
and delivering refrigerant to a heat rejection heat exchanger,
refrigerant from the heat rejection heat exchanger passing through
an expansion device, and then to a heat accepting heat exchanger; a
reheat circuit including a reheat valve for selectively tapping at
least a portion of refrigerant from a location downstream of the
compressor and upstream of the heat rejection heat exchanger, and
through a reheat heat exchanger, the reheat heat exchanger being
positioned to be in a path of air having passed over the heat
accepting heat exchanger, and to be delivered into an indoor
environment to be conditioned, a refrigerant flow control device to
selectively control the amount of refrigerant passing through said
reheat heat exchanger; and a control for the refrigerant system,
the control being operable to receive inputs from the conditioned
environment, and to control said refrigerant flow control device to
achieve desired temperature and humidity in the conditioned
environment.
2. The refrigerant system as set forth in claim 1, wherein the
refrigerant flow control device is a second valve that controls the
amount of refrigerant passing through the reheat heat
exchanger.
3. The refrigerant system as set forth in claim 2, wherein the
second valve is provided within the reheat circuit downstream of
said reheat valve.
4. The refrigerant system as set forth in claim 2, wherein the
second valve is provided on a bypass line bypassing said reheat
circuit.
5. The refrigerant system as set forth in claim 2, wherein the
second valve is positioned on a bypass line bypassing said reheat
heat exchanger.
6. The refrigerant system as set forth in claim 2, wherein the
second valve is controlled by at least one of pulsation or
modulation technique to achieve precise control over the amount of
refrigerant passing through the reheat heat exchanger.
7. The refrigerant system as set forth in claim 2, wherein there
are two of said second valves, with one valve positioned on a
bypass line bypassing said reheat circuit, and another valve
positioned within the reheat circuit downstream of said reheat
valve.
8. The refrigerant system as set forth in claim 1, wherein said
refrigerant flow control device is said reheat valve precisely
controlling the amount of refrigerant passing through said reheat
heat exchanger.
9. A method of operating a refrigerant system including the steps
of: providing a reheat circuit of a refrigerant system including a
reheat valve for selectively tapping at least a portion of
refrigerant from a location downstream of a compressor and upstream
of a heat rejection heat exchanger, and controlling the amount of
refrigerant passing through said reheat heat exchanger based upon
inputs from an indoor environment to be conditioned to provide
precise control over temperature and humidity within the
conditioned environment.
10. The method as set forth in claim 9, wherein a second valve
controls the amount of refrigerant passing through the reheat heat
exchanger.
11. The method as set forth in claim 10, wherein the second valve
is provided within the reheat circuit downstream of said reheat
valve.
12. The method as set forth in claim 10, wherein the second valve
provides bypass around said reheat circuit.
13. The method as set forth in claim 10, wherein the second valve
provides bypass around said reheat heat exchanger.
14. The method as set forth in claim 10, wherein the second valve
is controlled by at least one of pulsation or modulation technique
to achieve precise control over the amount of refrigerant passing
through the reheat heat exchanger.
15. The method as set forth in claim 9, wherein said reheat valve
is a regulating valve that precisely controls the amount of
refrigerant passing through said reheat heat exchanger.
Description
BACKGROUND OF THE INVENTION
[0001] Refrigerant systems are known and utilized to condition a
secondary fluid, such as air, to be delivered into a
climate-controlled environment. Typically, a compressor compresses
a refrigerant and delivers that refrigerant to an outdoor heat
exchanger, known as a condenser for subcritical applications and as
a gas cooler for transcritical applications. From the outdoor heat
exchanger, the refrigerant passes through an expansion device, and
then to an indoor heat exchanger, known as an evaporator.
[0002] An optional refrigerant system feature is a reheat circuit.
In a reheat circuit, a refrigerant is passed through a heat
exchanger located downstream in the path of air having passed over
an evaporator. A control for the refrigerant system may then
control the evaporator operation such that it will initially cool
the air below a temperature that is desired by an occupant of the
environment to be conditioned. This allows the removal of extra
moisture from the air. The air then passes downstream over the
reheat heat exchanger, and is warmed back to the desired
temperature. The refrigerant system incorporating a reheat circuit
provides the ability to remove additional moisture from the air
stream, when dehumidification is desired and no or little cooling
is required.
[0003] One known reheat option is a "hot gas" reheat system. In a
hot gas reheat system, the refrigerant passed through the reheat
heat exchanger is tapped from a location intermediate the
compressor and the condenser or a gas cooler (the outdoor heat
exchanger will be referred to as a condenser throughout the text).
In such systems, at times the refrigerant system may be called on
to provide dehumidification without any cooling being provided for
the air. Air conditioning systems are generally designed to provide
cooling, or sensible capacity, as the primary function. They are
not typically designed to provide latent capacity, and
dehumidification is typically a by-product of the cooling process.
Thus, when a system is called upon to provide only
dehumidification, there are some challenges present for a
refrigerant system designer.
[0004] Refrigerant systems having hot gas reheat circuits have been
somewhat inflexible in providing strictly latent capacity, or
dehumidification into an air stream supplied into a conditioned
environment. The refrigerant systems have easily provided neutral
air temperature only at a single design point, while providing
sensible (cooling or heating) at all other off-design conditions.
Thus, these refrigerant systems have been somewhat lacking design
flexibility in satisfying comfort requirements in a
climate-controlled environment and causing discomfort to an
occupant of a conditioned space. Therefore, there is a need for
adaptive reheat systems, and hot gas reheat systems in particular,
which would meet both temperature and humidity demands at a variety
of environmental conditions and internal/external thermal
loads.
SUMMARY OF THE INVENTION
[0005] A refrigerant system has a compressor for compressing and
delivering refrigerant to a condenser. Refrigerant from the
condenser passes through an expansion device, and then to an
evaporator. A reheat circuit includes a reheat valve for
selectively tapping at least a potion of refrigerant from a
location downstream of the compressor and upstream of the
condenser. The reheat refrigerant passes through a reheat heat
exchanger positioned to be in a path of air having passed over the
evaporator, and to be delivered into an indoor environment to be
conditioned. At least one refrigerant flow control device such as
valve is included to control the amount of refrigerant passing
through the reheat heat exchanger. A control for the refrigerant
system is operable to receive inputs regarding conditions of the
indoor environment, and to control the at least one valve to
achieve a desired amount of dehumidification in the indoor
environment.
[0006] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows a first circuit schematic.
[0008] FIG. 2 shows a second circuit schematic.
[0009] FIG. 3 shows a third circuit schematic.
[0010] FIG. 4 shows a fourth circuit schematic.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] FIG. 1 shows a typical refrigerant system 20 having a
compressor 22 delivering a compressed refrigerant to an outdoor
heat exchanger, or a condenser, 24. Refrigerant from the condenser
24 passes through an expansion device 28, and through an indoor
heat exchanger, or evaporator, 26. Refrigerant from the evaporator
26 returns to the compressor 22. A hot gas reheat circuit is
incorporated into the refrigerant system 20, and includes a
refrigerant flow control device such as three-way valve 30 for
selectively diverting refrigerant through a reheat heat exchanger
32. It has to be noted that the three-way valve may be replaced by
a pair of conventional valves. A fan 34 pulls air over the
evaporator 26, and then over the reheat heat exchanger 32, into an
indoor environment to be conditioned X. An occupant of the indoor
environment X may request temperature adjustment or/and
dehumidification by a control such as thermostat T and humidistat
H.
[0012] As typically incorporated in prior art systems, the
three-way valve 30 is operable to either send the entire
refrigerant flow through the reheat heat exchanger 32, or bypass
it. It is typically not able to modulate or vary the amount of
refrigerant through the reheat circuit. Thus, such refrigerant
systems have to run in a "digital" mode to satisfy thermal load
demands in the conditioned space X and are inflexible in operation
and control, as mentioned above.
[0013] In the refrigerant system 20, a refrigerant bypass line 38
and an associated refrigerant flow control device such as valve 40,
selectively bypass at least some amount of refrigerant around the
reheat circuit, in the reheat mode of operation. A control 100 for
the refrigerant system can achieve precise dehumidification, or
latent conditioning, of air delivered to the indoor environment X,
with or without any appreciable temperature change, by controlling
the exact amount of refrigerant which passes through the reheat
heat exchanger 32, in relation to the amount of refrigerant passing
through the evaporator 26. A worker of ordinary skill in the art
would recognize how the controlled amount of refrigerant that
passes through the reheat heat exchanger 32 would achieve this
desired air conditioning (temperature and humidity). The air would
be overcooled in the evaporator 26 to remove the desired amount of
moisture from the air stream and obtain the required humidity
level, and then would be heated back toward the target temperature
by the refrigerant flowing through the reheat heat exchanger 32.
For instance, by controlling a precise amount of refrigerant
passing through the reheat heat exchanger 32, the designer will be
able to achieve the desired dehumidification with little or no
temperature change. The valve 40 could be, for example, a simple
on/off solenoid valve controlled by one of pulse width modulation
techniques or a regulating valve with an adjustable opening
controlled by a stepper motor.
[0014] A control 100 that operates the valves 30 and 40, and may be
a general control for the refrigerant system 20. Control 100 takes
in signals from thermostat T and humidistat H (or any equivalent
devices) and controls the refrigerant system 20, at least in part
based on these inputs. A worker ordinarily skilled in the art will
be able to provide an appropriate design and control sequence based
upon the disclosure of this invention.
[0015] FIG. 2 shows an alternative embodiment, wherein the
refrigerant bypass line 52 includes a valve 54, and selectively
bypasses just the reheat heat exchanger 32, rather than the entire
reheat circuit. In this arrangement, in the reheat mode of
operation, the entire refrigerant flow will pass through the reheat
circuit, while at least a portion of the refrigerant flow could be
selectively bypassed around the reheat heat exchanger 32. Again,
the valve 54 may be an on/off valve or an adjustable regulating
valve. As above, the amount of refrigerant passing through the
reheat heat exchanger 32 would be varied to achieve precise control
of the refrigerant system 50 to satisfy temperature and humidity
requirements in the conditioned environment X.
[0016] FIG. 3 shows a refrigerant system 60 wherein the three-way
valve 30 is actually a regulating valve. In other words, the
conventional three-way valve of FIGS. 1 and 2 is combined with the
valve 40 or 54 respectively. The amount of refrigerant diverted by
the valve 30 into the reheat heat exchanger 32 can be precisely
controlled by one of modulation or pulsation techniques (depending
on the valve type). Again, the control of the amount of refrigerant
passing through the reheat exchanger 32 will in turn result in
precise control of the temperature and humidity in the indoor
environment X.
[0017] FIG. 4 shows a refrigerant system 70, wherein a regulating
(through pulsation or modulation) valve 72 is incorporated into the
reheat circuit, for instance, on a refrigerant line downstream of
the three-way valve 30 and leading to the reheat heat exchanger 32.
Other locations with the reheat circuit are also feasible. The
reheat circuit bypass line 38 and another regulating valve 40
positioned on the bypass line 38 are also included. This embodiment
would allow even higher degree of operational flexibility for the
refrigerant system 70 and precise control over temperature and
humidity in the conditioned environment X. Furthermore, various
combinations of the FIG. 1-4 embodiments are also feasible and
within the scope of the invention.
[0018] Although an embodiment of this invention has been disclosed,
a worker of ordinary skill in this art would recognize that certain
modifications would come within the scope of this invention. For
that reason, the following claims should be studied to determine
the true scope and content of this invention.
* * * * *