U.S. patent application number 16/837593 was filed with the patent office on 2020-10-08 for air conditioning system and control method thereof.
The applicant listed for this patent is Carrier Corporation. Invention is credited to Yinshan Feng, Parmesh Verma.
Application Number | 20200318881 16/837593 |
Document ID | / |
Family ID | 1000004810265 |
Filed Date | 2020-10-08 |
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United States Patent
Application |
20200318881 |
Kind Code |
A1 |
Verma; Parmesh ; et
al. |
October 8, 2020 |
AIR CONDITIONING SYSTEM AND CONTROL METHOD THEREOF
Abstract
An air conditioning system and a startup control method. The air
conditioning system includes: a compressor, a condenser, a thermal
expansion valve and an evaporator connected via a pipeline; and a
thermal temperature sensing bulb disposed on an outlet pipeline of
the evaporator and associated with the thermal expansion valve; the
air conditioning system further includes a thermal power source
which is thermally coupled to the thermal temperature sensing bulb
and controlledly cools or heats the thermal temperature sensing
bulb. The thermal temperature sensing bulb is cooled or heated, as
needed, by a thermal power source thermally coupled to the thermal
temperature sensing bulb, thereby enabling the thermal expansion
valve associated with the thermal temperature sensing bulb to be
opened and closed more smoothly.
Inventors: |
Verma; Parmesh; (South
Windsor, CT) ; Feng; Yinshan; (Manchester,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carrier Corporation |
Palm Beach Gardens |
FL |
US |
|
|
Family ID: |
1000004810265 |
Appl. No.: |
16/837593 |
Filed: |
April 1, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 41/062 20130101;
F25B 2341/064 20130101; F25B 49/02 20130101; F25B 2341/06 20130101;
F25B 2400/077 20130101 |
International
Class: |
F25B 49/02 20060101
F25B049/02; F25B 41/06 20060101 F25B041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2019 |
CN |
201910261297.X |
Claims
1. An air conditioning system, comprising: a compressor, a
condenser, a thermal expansion valve and an evaporator connected
via a pipeline; and a thermal temperature sensing bulb disposed on
an outlet pipeline of the evaporator and associated with the
thermal expansion valve; the air conditioning system further
comprising a thermal power source which is thermally coupled to the
thermal temperature sensing bulb and controlledly cools or heats
the thermal temperature sensing bulb.
2. The air conditioning system according to claim 1, wherein the
thermal power source controlledly cools the thermal temperature
sensing bulb before the compressor is started.
3. The air conditioning system according to claim 1, wherein during
steady state operation of the air conditioning system, the thermal
power source controlledly cools or heats the thermal temperature
sensing bulb to adjust the degree of superheat of the evaporator
outlet.
4. The air conditioning system according to claim 1, wherein the
thermal power source comprises a thermoelectric sheet disposed on
the thermal temperature sensing bulb, or an energy storage device
disposed on the thermal temperature sensing bulb, and the energy
storage device draws and stores heat from the evaporator or the
condenser during operation of the air conditioning system.
5. A control method of an air conditioning system, the air
conditioning system comprising: a compressor, a condenser, a
thermal expansion valve and an evaporator connected via a pipeline;
and a thermal temperature sensing bulb disposed on an outlet
pipeline of the evaporator and associated with the thermal
expansion valve; and the air conditioning system further comprising
a thermal power source which is thermally coupled to the thermal
temperature sensing bulb; the control method comprising: the
thermal power source controlledly pre-cooling the thermal
temperature sensing bulb before the compressor is started, so that
a range of valve opening degree oscillation of the thermal
expansion valve caused by a temperature change of the thermal
temperature sensing bulb is reduced.
6. The startup control method according to claim 5, wherein the
thermal power source pre-cools the thermal temperature sensing bulb
for a target time of 1-60 seconds.
7. The startup control method according to claim 6, wherein the
thermal power source pre-cools the thermal temperature sensing bulb
for a target time of 10-25 seconds.
8. The startup control method according to claim 5, wherein the
thermal power source pre-cools the thermal temperature sensing bulb
to a target temperature in a range of .+-.10.degree. C. from a
final stable temperature of the thermal temperature sensing
bulb.
9. The startup control method according to claim 6, wherein the
thermal power source pre-cools the thermal temperature sensing bulb
to a target temperature which corresponds to a final stable
temperature of the thermal temperature sensing bulb.
10. A control method of an air conditioning system, the air
conditioning system comprising: a compressor, a condenser, a
thermal expansion valve and an evaporator connected via a pipeline;
and a thermal temperature sensing bulb disposed on an outlet
pipeline of the evaporator and associated with the thermal
expansion valve; and the air conditioning system further comprising
a thermal power source which is thermally coupled to the thermal
temperature sensing bulb; the control method comprising: the
thermal power source controlledly cooling or heating the thermal
temperature sensing bulb to adjust the degree of superheat of the
evaporator outlet, during steady state operation of the air
conditioning system.
Description
FOREIGN PRIORITY
[0001] This application claims priority to Chinese Patent
Application No. 201910261297.X, filed Apr. 2, 2019, and all the
benefits accruing therefrom under 35 U.S.C. .sctn. 119, the
contents of which in its entirety are herein incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to the field of heat
exchange, and in particular to a startup control of an air
conditioning system.
BACKGROUND OF THE INVENTION
[0003] For refrigeration systems that do not have a variable
frequency device, they typically control the cooling load in the
form of frequent switching between on and off modes. For such
systems, a cyclic degradation coefficient is often used as one of
the indicators for evaluating system performance. That is, it is a
parameter indicating a comparison between the dynamic performance
(such as cooling capacity and power consumption) provided by the
refrigeration system and the steady-state performance of the same
system during the cycle of starting and stopping a compressor. When
the coefficient is smaller, it indicates that the performance of
the corresponding system is better, and when it is larger, the
performance is not as good.
[0004] In practical applications, a non-variable frequency
refrigeration system in which a thermal expansion valve is used as
a throttling element may have a cyclic degradation coefficient of
0.2 or higher. One of the reasons is that an opening degree of the
thermal expansion valve will suddenly rise and fall during the
re-starting phase after the compressor is stopped, which will be
reflected as a violent oscillation of the cooling capacity, that
is, an excessive power consumption of the compressor will be
caused.
[0005] Specifically, as a mature component in the field of
refrigeration, the opening degree of the thermal expansion valve is
determined by a resultant force of three forces. In an equilibrium
state, the resultant force of a spring preload force P3 in the
thermal expansion valve and an evaporator outlet pressure P2 is
canceled out with a pressure P1 caused by temperature change of a
thermal temperature sensing bulb. After the compressor has been
shut down for a period of time, the thermal expansion valve remains
closed due to the force balance. At this point, if the compressor
is directly started, referring to FIG. 1, under the suction of the
compressor, the evaporator outlet pressure P2 drops rapidly, and
the force balance of the three forces disappears. Since the
pressure P1 is much larger than the spring preload force P3, the
thermal expansion valve is quickly opened to a very large opening
degree. As the thermal expansion valve opens, the refrigerant
compressed by the compressor quickly flows through the evaporator
and back to the compressor via the thermal expansion valve. On one
hand, this will lead to excessive refrigerant flow and liquid
slugging on the compressor; on the other hand, the evaporator
outlet pressure P2 is quickly restored at this point, and the
opening degree of the thermal expansion valve is greatly reduced in
cooperation with the spring preload force P3, resulting in a rapid
decrease in the cooling capacity. As a result, the aforementioned
problems of the opening degree of thermal expansion valve and
corresponding sudden increase and sudden drop of the cooling
capacity are caused, which will further affect the system cyclic
degradation coefficient and system performance.
[0006] In addition, when the air conditioning system is in
steady-state operation, generally, the thermal expansion valve can
only be passively adjusted based on system operating conditions.
This leads to reaction lag of such systems in responding to the
need to adjust the operating conditions, and the lack of adjustment
ability to actively respond.
SUMMARY OF THE INVENTION
[0007] In view of this, the present disclosure provides an air
conditioning system and various control methods thereof, thereby
effectively solving or at least alleviating one or more of the
above problems in the prior art and in other aspects.
[0008] In order to achieve at least one object of the present
disclosure, according to a first aspect of the present disclosure,
an air conditioning system is provided, which includes: a
compressor, a condenser, a thermal expansion valve and an
evaporator connected via a pipeline; and a thermal temperature
sensing bulb disposed on an outlet pipeline of the evaporator and
associated with the thermal expansion valve; the air conditioning
system further including a thermal power source which is thermally
coupled to the thermal temperature sensing bulb and controlledly
cools or heats the thermal temperature sensing bulb.
[0009] Optionally, the thermal power source controlledly cools the
thermal temperature sensing bulb before the compressor is
started.
[0010] Optionally, during steady state operation of the air
conditioning system, the thermal power source controlledly cools or
heats the thermal temperature sensing bulb to adjust the degree of
superheat of the evaporator outlet.
[0011] Optionally, the thermal power source is thermally coupled to
the thermal temperature sensing bulb by means of thermal radiation,
thermal convection or thermal conduction.
[0012] Optionally, the thermal power source includes a
thermoelectric sheet disposed on the thermal temperature sensing
bulb.
[0013] Optionally, the thermal power source includes an energy
storage device disposed on the thermal temperature sensing bulb,
and the energy storage device draws and stores heat from the
evaporator or the condenser during operation of the air
conditioning system.
[0014] Optionally, the air conditioning system is a refrigeration
system or a heat pump system.
[0015] According to another aspect of the present disclosure, a
startup control method of an air conditioning system is also
provided, wherein the air conditioning system includes: a
compressor, a condenser, a thermal expansion valve and an
evaporator connected via a pipeline; and a thermal temperature
sensing bulb disposed on an outlet pipeline of the evaporator and
associated with the thermal expansion valve; and the air
conditioning system further includes a thermal power source which
is thermally coupled to the thermal temperature sensing bulb;
wherein the startup control method includes: the thermal power
source controlledly pre-cooling the thermal temperature sensing
bulb before the compressor is started, so that a range of valve
opening degree oscillation of the thermal expansion valve caused by
a temperature change of the thermal temperature sensing bulb is
reduced.
[0016] Optionally, the thermal power source pre-cools the thermal
temperature sensing bulb for a target time of 1-60 seconds.
[0017] Optionally, the thermal power source pre-cools the thermal
temperature sensing bulb for a target time of 10-25 seconds.
[0018] Optionally, the thermal power source pre-cools the thermal
temperature sensing bulb to a target temperature in a range of
.+-.10.degree. C. from a final stable temperature of the thermal
temperature sensing bulb.
[0019] Optionally, the thermal power source pre-cools the thermal
temperature sensing bulb to a target temperature which corresponds
to a final stable temperature of the thermal temperature sensing
bulb.
[0020] Optionally, the thermal power source pre-cools the thermal
temperature sensing bulb by means of thermal radiation, thermal
convection, or thermal conduction.
[0021] Optionally, the thermal power source includes a
thermoelectric sheet disposed on the thermal temperature sensing
bulb.
[0022] Optionally, the thermal power source includes an energy
storage device disposed on the thermal temperature sensing bulb,
and the energy storage device draws and stores cooling capacity
from the evaporator during operation of the air conditioning
system.
[0023] Optionally, the air conditioning system is a refrigeration
system or a heat pump system.
[0024] According to still another aspect of the present disclosure,
a control method of an air conditioning system is further provided,
wherein the air conditioning system includes: a compressor, a
condenser, a thermal expansion valve and an evaporator connected
via a pipeline; and a thermal temperature sensing bulb disposed on
an outlet pipeline of the evaporator and associated with the
thermal expansion valve; and the air conditioning system further
includes a thermal power source which is thermally coupled to the
thermal temperature sensing bulb; the control method including: the
thermal power source controlledly cooling or heating the thermal
temperature sensing bulb to adjust the degree of superheat of the
evaporator outlet, during steady state operation of the air
conditioning system.
[0025] According to the air conditioning system of the present
disclosure and the control method thereof, the thermal temperature
sensing bulb is cooled or heated, as needed, by a thermal power
source thermally coupled to the thermal temperature sensing bulb,
thereby enabling the thermal expansion valve associated with the
thermal temperature sensing bulb to be opened and closed more
smoothly, greatly reducing the opening degree oscillation caused by
sudden pressure change, or providing a certain degree of adjustment
in the steady state operation of the system, and effectively
improving the performance of the air conditioning system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The technical solutions of the present disclosure will be
further described in detail below with reference to the
accompanying drawings and embodiments, but it should be understood
that the drawings are only provided for the purpose of explanation,
and should not be considered as limiting the scope of the present
disclosure. In addition, unless otherwise specified, the drawings
are only intended to conceptually illustrate the structures and
constructions described herein, and are not necessarily drawn to
scale.
[0027] FIG. 1 is a schematic diagram showing oscillation of a
cooling capacity of a refrigeration system in the prior art when it
is restarted;
[0028] FIG. 2 is a schematic diagram of an embodiment of a
refrigeration system of the present disclosure; and
[0029] FIG. 3 is a schematic diagram showing oscillation of a
cooling capacity of a refrigeration system according to an
embodiment of the present disclosure when it is restarted.
DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION
[0030] The present disclosure will be described more fully with
reference to the accompanying drawings in which exemplary
embodiments of the present disclosure are illustrated. However, it
should be understood that the present disclosure may be embodied in
a variety of different forms and should not be construed as being
limited to the embodiments set forth herein. The embodiments are
provided to make the present disclosure more complete and thorough,
and to fully convey the concept of the present disclosure to those
skilled in the art.
[0031] Although the features of the present disclosure are
disclosed in connection with one or more of the embodiments, such
features can be combined with one or more other features of other
implementations/embodiments, as may be desired and/or advantageous
for any given or identifiable function.
[0032] Referring to FIG. 2, an embodiment of a refrigeration system
is provided herein. The refrigeration system 100 includes a
compressor 110, a condenser 120, a thermal expansion valve 130, and
an evaporator 140 that are connected via a pipeline. The
refrigeration system 100 also includes a thermal temperature
sensing bulb 131 which is disposed on an outlet pipeline of the
evaporator 140 and associated with the thermal expansion valve 130.
More critically, the refrigeration system 100 further includes a
thermoelectric sheet 132 disposed on the thermal temperature
sensing bulb 131, and the thermoelectric sheet 132 controlledly
cools or heats the thermal temperature sensing bulb 131. Under this
arrangement, before the compressor is started, due to the
pre-cooling action of the thermoelectric sheet 132 on the thermal
temperature sensing bulb 131, a pressure P1 associated with the
temperature change of the thermal temperature sensing bulb is
relatively decreased by a certain amount as the temperature is
lowered. At this point, if the compressor is restarted, a resultant
force of the pressure P1 and a spring preload force P3 is
correspondingly reduced, and the amplification of the opening
degree of the thermal expansion valve is correspondingly small,
whereby the oscillation of opening degree subsequently caused by
rebalanced pressure is also reduced. Specifically, reference may be
made to FIG. 3 for performance change during system startup,
wherein the system is started at the time of 1800 s, the
oscillation is eliminated by the compressor power consumption
within about 40 s after the startup, and the steady-state operation
is realized at about 1100 W; as compared to the oscillation
elimination time of about 150 s in FIG. 1, the embodiment in FIG. 3
can achieve a steady-state operation extremely quickly without the
need for excess power consumption of the compressor. With continued
reference to FIG. 3, the oscillation of the cooling capacity
corresponding to the starting state of the compressor is
correspondingly reduced, and the oscillation is eliminated within
40 s to achieve a steady-state output of the cooling capacity of
about 18000 Btu/hr; as compared to the oscillation elimination time
of about 150 s in FIG. 1, the embodiment in FIG. 3 can achieve a
steady-state output extremely quickly, thus effectively improving
the cyclic degradation coefficient and system performance
[0033] Although the present concept is described with a set of
refrigeration systems as an embodiment, it should be understood
that the present concept aims to improve the phenomenon that the
oscillation of cooling capacity of a system in which the thermal
expansion valve is used as a throttling element is too large,
thereby improving the cyclic degradation coefficient and system
performance. Thus, it will be apparent to those skilled in the art,
in the light the teachings of the present concept, that the concept
is equally applicable to a heat pump system, or even various types
of more general air conditioning systems, which should therefore be
included within the scope of the present concept.
[0034] Similarly, although in the foregoing embodiment, the
technical effects of pre-cooling the thermal temperature sensing
bulb are described in an application scenario of the refrigeration
system after the compressor is shut down and before it is
restarted, it should be understood that the concept is applicable
to any scenario in which the thermal expansion valve needs to be
controlled suddenly. The pre-cooling element is intended to make
the opening and closing of the thermal expansion valve associated
with the thermal temperature sensing bulb smoother, greatly
alleviating the oscillation of opening degree caused by sudden
pressure change, and thereby improving the performance of the air
conditioning system. In addition, a certain degree of active
adjustment function of the thermal expansion valve can also be
achieved by the heating or cooling effect of the heating source on
the thermal temperature sensing bulb, thereby improving system
performance or improving system reliability. For example, during a
steady state operation of the air conditioning system, the thermal
power source can controlledly heat the thermal temperature sensing
bulb to reduce the degree of superheat of the evaporator outlet,
thereby improving the cooling efficiency of the system from a
thermodynamic point of view (e.g., COP=cooling capacity/power
consumption). For another example, during the steady state
operation of the air conditioning system, the thermal power source
can controlledly cool the thermal temperature sensing bulb to
increase the degree of superheat of the evaporator outlet, thereby
preventing liquid-phase refrigerant from entering the compressor
and causing liquid slugging damage, and improving compressor
reliability.
[0035] Further, in the foregoing embodiments, the thermoelectric
sheet is described as an element for cooling or heating the thermal
temperature sensing bulb. In fact, it is not intended to limit the
present concept. In the light of the teachings of present concept,
a corresponding purpose can be achieved by disposing a thermal
power source at the thermal temperature sensing bulb. For example,
an energy storage device can be disposed on the thermal temperature
sensing bulb, wherein the energy storage device draws and stores a
cooling capacity from the evaporator during operation of the air
conditioning system, or draws and stores heat from the condenser,
and when it is required to cool or heat the thermal expansion
valve, the energy storage device releases the heat. It is of course
also possible to use other thermal power sources, which are not
exhaustively listed herein, but they should all be included within
the present concept. Similarly, for the arrangement between the
thermal source and the thermal expansion valve, a contact
arrangement not necessarily required. According to the conduction
mode of heat, the thermal power source can be thermally coupled to
the thermal temperature sensing bulb by means of thermal radiation,
thermal convection or thermal conduction to achieve the purpose of
heat transferring.
[0036] Accordingly, a startup control method of an air conditioning
system is also provided herein according to the present concept,
wherein the air conditioning system includes: a compressor, a
condenser, a thermal expansion valve and an evaporator connected
via a pipeline; and a thermal temperature sensing bulb disposed on
an outlet pipeline of the evaporator and associated with the
thermal expansion valve; and the air conditioning system further
includes a thermal power source which is thermally coupled to the
thermal temperature sensing bulb; wherein the startup control
method includes: the thermal power source controlledly pre-cooling
the thermal temperature sensing bulb before the compressor is
started, so that a range of valve opening degree oscillation of the
thermal expansion valve caused by a temperature change of the
thermal temperature sensing bulb is reduced. According to the
method, the thermal temperature sensing bulb is pre-cooled by the
thermal power source thermally coupled to the thermal temperature
sensing bulb before the compressor is started, thereby enabling the
thermal expansion valve associated with the thermal temperature
sensing bulb to be opened and closed more smoothly, greatly
reducing the opening degree oscillation caused by sudden pressure
change and improving the performance of the air conditioning
system.
[0037] Similarly, the method is also applicable to air conditioning
systems in any of the foregoing embodiments or combinations
thereof, including but not limited to refrigeration systems or heat
pump systems. Of course, when the method is applied to the air
conditioning system in the foregoing embodiment, the structural
form and arrangement of the thermal power source can be modified
accordingly. For example, the thermal power source pre-cools the
thermal temperature sensing bulb by means of thermal radiation,
thermal convection or thermal conduction. For another example, the
thermal power source may include a thermoelectric sheet disposed on
the thermal temperature sensing bulb; or it may include an energy
storage device disposed on the thermal temperature sensing bulb,
and the energy storage device draws and stores a cooling capacity
from the evaporator during operation of the air conditioning
system. The description will not be expanded herein.
[0038] It should be understood that there should be a control
target of pre-cooling when implementing the method of the foregoing
embodiment. The control target may be set by a pre-cooling
duration, for example, 1-60 seconds; for another example, 10-25
seconds; or it may be set according to a pre-cooled temperature,
for example, the final stable temperature of the thermal
temperature sensing bulb is .+-.10.degree. C., and the like.
Therefore, a set of closed-loop control is formed, which works only
when needed and is closed after the purpose is achieved.
[0039] Accordingly, a control method of an air conditioning system
is further provided herein according to the present concept,
wherein the air conditioning system includes: a compressor, a
condenser, a thermal expansion valve and an evaporator connected
via a pipeline; and a thermal temperature sensing bulb disposed on
an outlet pipeline of the evaporator and associated with the
thermal expansion valve; and the air conditioning system further
includes a thermal power source which is thermally coupled to the
thermal temperature sensing bulb. The control method includes: the
thermal power source controlledly cooling or heating the thermal
temperature sensing bulb to adjust the degree of superheat of the
evaporator outlet, during steady state operation of the air
conditioning system. This control method can impart a certain
degree of active adjustment to the air conditioning system to which
the thermal expansion valve is applied, thereby improving system
performance or improving system reliability. For example, during
steady state operation of the air conditioning system, the thermal
power source can controlledly heat the thermal temperature sensing
bulb to reduce the degree of superheat of the evaporator outlet,
thereby improving the cooling efficiency of the system from a
thermodynamic point of view (e.g., COP=cooling capacity/power
consumption). For another example, during the steady state
operation of the air conditioning system, the thermal power source
can controlledly cool the thermal temperature sensing bulb to
increase the degree of superheat of the evaporator outlet, thereby
preventing liquid-phase refrigerant from entering the compressor
and causing liquid slugging damage, and improving compressor
reliability.
[0040] While specific order of steps may have been shown,
disclosed, and claimed in particular embodiments of the present
disclosure, it is understood that the steps can be carried out,
separated or combined in any order unless otherwise indicated,
which will still benefit from the disclosure.
[0041] In the description, examples are used to disclose the
present application, including the best mode, with the purpose of
enabling any person skilled in the art to practice the application,
including making and using any device or system and performing any
of the methods covered. The scope of protection of the present
application is defined by the claims, and may include other
examples that can be conceived by those skilled in the art. If such
other examples have structural elements that do not differ from the
literal language of the claims, or if they include equivalent
structural elements that do not substantively differ from the
literal language of the claims, these examples are also intended to
be included in the scope of the claims.
* * * * *