U.S. patent application number 11/175847 was filed with the patent office on 2007-01-11 for system and method for controlling air temperature in an appliance.
This patent application is currently assigned to General Electric Company. Invention is credited to Warren Frank Bessler, Darren Lee Hallman, Philip Alexander Shoemaker, Ramasamy Thiyagarajan, Olga Kotsyuba Zhushma.
Application Number | 20070006601 11/175847 |
Document ID | / |
Family ID | 37617068 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006601 |
Kind Code |
A1 |
Thiyagarajan; Ramasamy ; et
al. |
January 11, 2007 |
System and method for controlling air temperature in an
appliance
Abstract
An apparatus and method for controlling air temperature in an
appliance. The apparatus includes an air cooling unit disposed in
an airflow path and an air heating unit disposed in the airflow
path and fluidically coupled to the air cooling unit by a
refrigerant. The apparatus also includes a de-heater fluidically
coupled to the air cooling unit and the air heating unit by the
refrigerant to controllably dissipate heat from the
refrigerant.
Inventors: |
Thiyagarajan; Ramasamy;
(Bangalore, IN) ; Hallman; Darren Lee; (Clifton
Park, NY) ; Shoemaker; Philip Alexander; (Scotia,
NY) ; Zhushma; Olga Kotsyuba; (Indian Trail, NC)
; Bessler; Warren Frank; (Amsterdam, NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY;GLOBAL RESEARCH
PATENT DOCKET RM. BLDG. K1-4A59
NISKAYUNA
NY
12309
US
|
Assignee: |
General Electric Company
|
Family ID: |
37617068 |
Appl. No.: |
11/175847 |
Filed: |
July 6, 2005 |
Current U.S.
Class: |
62/173 ;
62/176.6; 62/178 |
Current CPC
Class: |
D06F 2103/50 20200201;
D06F 2103/32 20200201; D06F 43/02 20130101; D06F 2105/26 20200201;
D06F 2105/30 20200201; F26B 21/086 20130101; D06F 2105/24 20200201;
D06F 58/34 20200201; D06F 58/30 20200201; D06F 2103/36 20200201;
D06F 34/08 20200201; D06F 25/00 20130101; D06F 58/26 20130101 |
Class at
Publication: |
062/173 ;
062/176.6; 062/178 |
International
Class: |
F25B 29/00 20060101
F25B029/00; F25B 49/00 20060101 F25B049/00; F25D 17/00 20060101
F25D017/00 |
Claims
1. An apparatus comprising: an air cooling unit disposed in an
airflow path; an air heating unit disposed in the airflow path and
fluidically coupled to the air cooling unit by a refrigerant; and a
de-heater fluidically coupled to the air cooling unit and the air
heating unit by the refrigerant to controllably dissipate heat from
the refrigerant.
2. The apparatus of claim 1, wherein the heat is controllably
dissipated from the refrigerant such that an airflow following the
airflow path is prevented from exceeding a determined
temperature.
3. The apparatus of claim 1, wherein the apparatus further
comprises: a blower to generate an airflow along the airflow path;
and a drum to contain at least one article for drying, the drum
positioned to receive the airflow.
4. The apparatus of claim 3 further comprising a controller coupled
to the air cooling unit, the air heating unit and the de-heater to
control an exchange of heat between the airflow and the
refrigerant.
5. The apparatus of claim 4, wherein the apparatus further
comprises a first air sensor positioned at an inlet of the drum to
sense air temperature at the inlet of the drum and configured to
send a signal indicative of the air temperature at the inlet of the
drum to the controller.
6. The apparatus of claim 4 further comprising a bypass valve to
cause at least a portion of the airflow to controllably bypass the
air cooling unit.
7. The apparatus of claim 4, wherein the apparatus further
comprises a second air sensor positioned at an outlet of the air
cooling unit to sense air temperature at the outlet of the air
cooling unit and configured to send a signal indicative of the air
temperature at the outlet of the air cooling unit to the
controller.
8. The apparatus of claim 4, further comprising: a compressor
fluidically coupled to the air cooling unit, the air heating unit,
and the de-heater to compress the refrigerant; and an expansion
chamber fluidically coupled to the air heating unit to receive the
refrigerant from the air heating unit to provide expansion and
cooling of the refrigerant.
9. The apparatus of claim 8, wherein the air heating unit comprises
a condenser fluidically coupled to the de-heater to receive the
refrigerant exiting from the de-heater, the condenser further in
thermal connection with the airflow to transfer heat from the
refrigerant to the airflow; and wherein the air cooling unit is an
evaporator fluidically coupled between the compressor and the
expansion chamber to receive the refrigerant exiting from the
expansion chamber, the evaporator further in thermal connection
with the airflow to transfer the heat from the airflow to the
refrigerant, wherein the refrigerant exiting from the evaporator is
circulated back to the compressor.
10. The apparatus of claim 9 further comprising a fan coupled to
the de-heater to provide a second airflow to cool refrigerant
passing through the de-heater.
11. The apparatus of claim 10, wherein operation of the fan is
controlled by the controller such that the compressor can operate
continuously during heat dissipation from the refrigerant.
12. The apparatus of claim 11, further comprising a thermocouple
positioned at an outlet of the de-heater to sense temperature of
the refrigerant at the outlet of the de-heater and configured to
send a signal indicative of the temperature of the refrigerant at
the outlet to the controller.
13. A method for controlling air temperature in an appliance, the
method comprising: disposing an air cooling unit in an airflow path
designed to carry an airflow; disposing an air heating unit in the
airflow path and fluidically coupling the air heating unit to the
air cooling unit by a refrigerant; and disposing a de-heater and
fluidically coupling the de-heater to the air cooling unit and the
air heating unit by the refrigerant to controllably dissipate heat
from the refrigerant.
14. The method of claim 13, wherein the heat is controllably
dissipated based at least in part upon a temperature of the
refrigerant.
15. The method of claim 13 further comprising: in the air heating
unit, transferring heat from the refrigerant to the airflow to heat
the airflow; and in the air cooling unit, transferring heat from
the airflow to the refrigerant to cool the airflow, wherein the
refrigerant exiting from the air cooling unit is compressed to
further heat the refrigerant.
16. In an appliance, a method comprising: defining an airflow path
to carry an airflow for drying articles within the appliance;
defining a refrigerant flow path to circulate a refrigerant in a
closed loop such that the refrigerant acts at least in part to both
heat and cool the airflow; and controlling temperature of the
refrigerant such that the airflow does not exceed a determined
temperature.
17. The method of claim 16 further comprising: generating the
airflow; removing heat from the airflow to create a cooled airflow
by exposing the airflow to the refrigerant having a first state;
adding a controlled amount of heat to the cooled airflow to create
a heated airflow by exposing the cooled airflow to the refrigerant
in a second state; and providing the heated airflow to the articles
in the appliance.
18. The method of claim 17 further comprising: cooling the
refrigerant to a first temperature; flowing the refrigerant through
an evaporator positioned in the airflow path to cool the airflow;
heating the refrigerant to a temperature that does not exceed the
determined temperature; and flowing the heated refrigerant through
a condenser to heat the airflow.
19. The method of claim 18, wherein heating the refrigerant to a
temperature that does not to exceed the determined temperature
comprises: compressing the refrigerant; flowing the heated
refrigerant through a second condenser; determining whether the
temperature of the heated refrigerant is equal to or exceeds the
determined temperature; and controllably generating a secondary
airflow and directing the secondary airflow toward the second
condenser to remove heat from the refrigerant when the temperature
of the heated refrigerant is equal to or exceeds the determined
temperature.
20. The method of claim 19, wherein cooling the refrigerant
comprises allowing the compressed refrigerant to expand in
volume.
21. The method of claim 19, wherein the second condenser operates
to remove super heat from the refrigerant.
Description
BACKGROUND
[0001] Embodiments of the present invention relate to a system and
method for controlling air temperature in an appliance.
[0002] Traditionally, hot air has been used in one form or another
in clothes dryers to dry articles placed in a drying compartment
such as a drum. In one conventional arrangement, air is heated via
a heating element and fed by a fan into the drum where it
interfaces with the articles to be dried. Moisture contained by the
wet articles is then evaporated by the hot dry air, which in turn
is vented out of the dryer. Although such drying systems may well
dry the articles, they are very inefficient and provide little
control over the air temperature to which the articles are
exposed.
[0003] Another arrangement for drying includes the use of a heat
pump, whereby heating and cooling units are connected at various
points in an airflow path to facilitate article drying. However, in
conventional heat pump arrangements, operation of a compressor is
modulated on and off to control heating and cooling of the airflow.
This also tends to be inefficient and provides little control over
the air temperature to which the articles are exposed.
[0004] As it is common for a wide variety of cleaning solutions,
solvents and materials to be used when drying articles, it is often
desirable to keep the air temperatures within a drum of the drying
apparatus either within a particular temperature range or below a
particular maximum threshold temperature. Unfortunately, current
drying systems either do not provide this capability or attempt do
so at the cost of efficiency.
BRIEF DESCRIPTION
[0005] Briefly, in accordance with one embodiment of the invention,
there is provided an apparatus including an air cooling unit
disposed in an airflow path and an air heating unit disposed in the
airflow path and fluidically coupled to the air cooling unit by a
refrigerant. The apparatus also includes a de-heater fluidically
coupled to the air cooling unit and the air heating unit by the
refrigerant to controllably dissipate heat from the
refrigerant.
[0006] In accordance with another embodiment of the invention,
there is provided a method for controlling air temperature in an
appliance. The method includes disposing an air cooling unit in an
airflow path designed to carry an airflow, disposing an air heating
unit in the airflow path and fluidically coupling the air heating
unit to the air cooling unit by a refrigerant. The method also
includes fluidically coupling a de-heater and the de-heater to the
air cooling unit and the air heating unit by the refrigerant to
controllably dissipate heat from the refrigerant.
DRAWINGS
[0007] FIG. 1 is a block diagram of a thermal management system for
controlling air temperature in an appliance in accordance with one
embodiment of the invention.
[0008] FIG. 2 is a block diagram of a thermal management system
equipped with a controller for controlling air temperature in an
appliance in accordance with a further embodiment of the
invention.
[0009] FIG. 3 is a block diagram illustrating operational aspects
of the thermal management system of FIG. 2 equipped with a
controller for controlling air temperature in an appliance in
accordance with an example embodiment.
[0010] FIG. 4 is a graphical representation illustrating an example
functional relationship between air temperature and refrigerant
temperature in an appliance incorporated with one or more
embodiments of the invention;
[0011] FIG. 5 is a flow chart illustrating a methodology for
monitoring temperature within an appliance in accordance with one
embodiment of the invention; and
[0012] FIG. 6 illustrates an operational flow of a thermal
management system for controlling air temperature in an appliance
in accordance with one embodiment of the invention.
DETAILED DESCRIPTION
[0013] As will be described in further detail herein, embodiments
of the present invention include a system and method for thermal
management of an airflow within an appliance. In certain
embodiments, the thermal management system described herein may be
incorporated within a variety of appliances such as article
cleaning apparatuses including but not limited to a washing
machine, a dryer, and a combination washer/dryer system
(hereinafter referred to as "cleaning apparatuses"). The term
"article" as used herein is intended to refer to a broad class of
items such as fabrics, textiles, garments, linens, and any other
items or material that may be cleaned or dried in a home or
commercial based washing, drying and/or dry-cleaning machine.
[0014] FIG. 1 illustrates one embodiment of a system incorporating
teachings of the present invention. In the illustrated embodiment,
the components of the thermal management system 10 are arranged in
such a manner so as to limit or otherwise control the temperature
of an airflow to which articles within an article holding drum
(hereinafter "drum") 24 may be exposed. As shown in FIG. 1, the
illustrated thermal management system 10 includes an air-heating
unit 16, an air-cooling unit 18, a compressor 12 and a de-heater 14
fluidically coupled by a refrigerant along a refrigerant flow path
4.
[0015] Refrigerant flow path 4 represents an arrangement within
which a refrigeration liquid or material (hereinafter
"refrigerant") may be circulated in a closed loop between
components of the thermal management system 10. In one embodiment,
the refrigerant may be fluorocarbon R-22, however in other
embodiments other refrigerants may be used.
[0016] The air-heating unit 16 and the air-cooling unit 18 are
further arranged in an airflow path 2, which carries an airflow
generated by a blower 22. In the illustrated embodiment, the
airflow generated by blower 22 circulates within the system 10 such
that the airflow contacts the air-cooling unit 18 and the
air-heating unit 16 as it flows toward the drum 24. The drum 24 may
be an article drying drum, washing drum or combination
washing/drying drum for example. Moreover, drum 24 may be an
integral part of the thermal management system 10 or part of a
cleaning apparatus to which the thermal management system 10 is
incorporated. In one embodiment, the air-heating unit 16 may be a
condenser and the air-cooling unit 18 may be a evaporator.
[0017] In accordance with one embodiment of the invention, the
system 10 facilitates the exchange of heat between an airflow
(e.g., as indicated by airflow path 2), and the refrigerant (e.g.,
as indicated by refrigerant flow path 4). In operation, the airflow
generated by blower 22 contacts the cooling unit 18 where the
airflow is cooled by relatively colder refrigerant flowing through
the cooling unit 18. As the airflow is cooled, moisture present
within the airflow condenses out of the airflow, which may in turn
be recycled or discarded. After passing the cooling unit 18, the
cooled air contacts the heating unit 16 where the airflow is heated
by relatively warmer refrigerant flowing through the heating unit
16. The heated airflow is then directed to the drum 24, which
contains the articles to be dried. As the relatively hot dry
airflow is mixed with wet articles present within the drum 24, it
absorbs moisture from the wet articles in the drum 24. The
moisture-containing airflow is then returned to the cooling unit 18
where the heating and cooling process repeats. Although a single
blower 22 is illustrated in FIG. 1, additional blowers 22 may be
positioned at more than one point along the airflow path 2 to
facilitate movement of the airflow around the cleaning apparatus.
In one embodiment, blower 22 is a fan, however other air movement
mechanisms may be used.
[0018] As was mentioned above, in order to heat and cool the
airflow as described, refrigerant is circulated along the
refrigerant flow path 4. Since the refrigerant flow path 4
represents a closed loop, the beginning and end of the refrigerant
flow can be considered arbitrary designations for the purpose of
this description. For the purposes of simplicity, the following
description assumes an operational starting point corresponding to
the cooling unit 18.
[0019] At the cooling unit 18, the relatively cool refrigerant
absorbs heat from the relatively warmer airflow causing the airflow
to be cooled and the refrigerant to be converted from a liquid
phase to a gas phase. The refrigerant then proceeds to the
compressor 12 where it is compressed causing the refrigerant to be
heated and become a hot, high-pressure gas. Without any additional
modifications, the relatively hot refrigerant could then be passed
through the heating unit 16 where heat from the refrigerant would
be given off to the relatively cooler airflow causing the airflow
to be heated. The compressed refrigerant could then be provided to
an expansion chamber 28 allowing the compressed refrigerant to
expand and thereby be cooled once again. Control of the air
temperature within such a system, however would be dependent upon
the switching "on" and "off"of the compressor 12. A method of
controlling airflow temperature based on switching on/off of the
compressor 12 however puts operational limits on the efficiency of
the thermal management system. For example, every time a compressor
is switched off, a prescribed delay is required before it can be
switched on again. During this time, the air loses additional heat
and as such, may thereby adversely affect the precision and
efficiency of temperature control. Moreover, the operability and
reliability of the compressor may be affected owing to frequent
on/off cycles.
[0020] In certain cleaning apparatuses however, it may be important
or otherwise desirable to more precisely and efficiently control
the temperature of the air to which articles in the drum 24 are to
be exposed. For example, in cleaning apparatuses that utilize
certain wash liquors or solvents having known flashpoints, it may
be desirable to keep airflow temperatures within the drum 24 from
reaching or exceeding such flashpoint temperatures. In accordance
with one embodiment of the present invention and as illustrated in
FIG. 1, de-heater 14 is advantageously provided to facilitate
controllable temperature regulation of the refrigerant that in turn
operates to regulate the temperature of the airflow. In particular,
the operation of de-heater 14 facilitates air temperature
regulation within the drum 24. Incorporation of the de-heater 14
into the refrigerant flow path 4 of the thermal management system
10 facilitates continuous operation of the system without having to
switch the compressor 12 "on" and "off", thereby enhancing energy
efficiency associated with operating a cleaning apparatus
incorporating the thermal management system 10. In a further
embodiment of the present invention, the de-heater 14 may be
utilized to assist the heating unit 16 in heating the air stream
prior to its entering the drum 24. In one embodiment of the
invention, the de-heater 14 may be a fin and tube type heat
exchanger. In another embodiment of the invention, the de-heater 14
may be a tube and tube type heat exchanger.
[0021] FIG. 2 is a block diagram of a thermal management system 20
equipped with a controller for controlling air temperature in an
appliance in accordance with a further embodiment of the invention.
The thermal management system 20 is similar in form to the thermal
management system 10 of FIG. 1 but has been further enhanced by the
addition of a bypass airflow path 6, a controller 32 and a number
of sensors to measure the temperatures at different points of the
airflow path 2.
[0022] In one embodiment, the bypass airflow path 6 includes a
bypass valve 36 to bypass at least a portion of the airflow around
the cooling unit 18. In the illustrated embodiment, the sensors in
the system 20 include a de-heater outlet sensor 34 positioned at
the outlet of the de-heater 14 to measure or otherwise sense the
refrigerant temperature, a cooling outlet sensor 38 positioned at
the outlet of the cooling unit 18 to measure or otherwise sense the
air temperature at the outlet of the cooling unit 18, and a drum
inlet sensor 42 positioned at the inlet of the drum 24 to measure
or otherwise sense the air temperature at the inlet of the drum 24.
In one embodiment, one or more of sensors 34, 38 and 42 may be a
thermocouple.
[0023] In general, the controller 32 is employed to control the
exchange of the heat between the airflow following airflow path 2
and the refrigerant following the refrigerant flow path 4. More
specifically, depending on the temperatures at various sensing
points on the airflow path 2 and the refrigerant flow path 4 as
explained above, the controller 32 monitors and controls operation
of the bypass valve 36, the blower 22, and the de-heater 14 such
that a number of operating conditions are typically at preferred
levels during a typical operation cycle of the system 20.
[0024] For example, in one embodiment of the invention the
de-heater 14 is equipped with a blower or air-moving device such as
a fan 26 that is controlled by the controller 32 to remove super
heat from the hot compressed refrigerant passing through the
de-heater 14 along refrigerant flow path 4. As the fan 26 operates
to increases airflow across the de-heater 14 in response to an
indication received from the controller 32, heat exchange between
the refrigerant and the ambient is increased. In one embodiment,
heated air resulting from the heat exchange at de-heater 14 may be
directed to the drum 24 to further increase the air temperature and
drying capability within the drum 24.
[0025] In another example, if the temperature of the airflow within
the drum 24 (e.g., as may be determined by sensor 42) needs to be
increased, the controller 32 may regulate the opening of the bypass
valve 36 so that extra amount of bypass airflow is diverted into
the bypass flow path 6. If the inlet stream is not close to being
saturated then additional thermal capacity can be gained since the
heating unit 16 is not required to reheat that portion of the
airflow that bypasses the cooling unit 18. If necessary, the
controller 32 may also regulate the speed of the blower 22 so that
a varying amount of airflow is taken into airflow path 2 to achieve
a desired air temperature.
[0026] In one embodiment, the controller 32 determines and
interprets aspects of the heat exchange of the thermal management
system 20 in accordance with a determined criterion. For instance,
in one embodiment, the determined criterion may include a binary
comparison of the temperature of the thermal management system 20
with a determined reference value of temperature. In another
embodiment, the determined criterion may comprise a comparison
between a temperature within the thermal management system 20 and a
determined maximum allowable temperature. In yet another
embodiment, the determined criterion may comprise a comparison
between a temperature within the thermal management system 20 and a
determined minimum value for the same temperature.
[0027] However the criterion for comparison may be selected, if the
sensed heating or cooling requirement of the airflow or the
refrigerant in the thermal management system 20 falls outside of a
determined reference range for example, the controller 32 may
determine that the status of the heat exchange is not acceptable
and additional action may then be identified. In that event, the
controller 32 may perform a variety of operations to achieve a
desired thermal state within the cleaning apparatus.
[0028] Structurally, the controller 32 may comprise a
micro-controller or a solid-state switch configured for
communication with the sensors 34, 38 and 42 and communication with
the fan 26, the blower 22 and the flow control valve 36. The
communication with the controller 32 may take place using the
signal line 56 coupled to the de-heater outlet sensor 34, signal
line 58 coupled to the drum inlet sensor 42 and signal line 62
coupled to the air cooler outlet sensor 38. In a like manner,
communication from the controller 32 may take place using signal
line 52 coupled to the blower 22, signal line 54 coupled to the
de-heater fan 26 and signal line 55 coupled to the bypass flow
control valve 36. In one embodiment, the controller 32 comprises an
analog-to-digital converter accessible through one or more analog
input ports. In another embodiment, the controller 32 may include
read-out displays, read-only memory, random access memory, and a
conventional data bus.
[0029] As will be appreciated, the controller 32 may be embodied in
several other ways. In one embodiment, the controller 32 may
include a logical processor, threshold detection circuitry and/or
an alerting system. Typically, the logical processor is a
processing unit that performs computing tasks. It may be a software
construct made up using software application programs or operating
system resources. In other instances, it may also be simulated by
one or more physical processor(s) performing scheduling of
processing tasks for more than one single thread of execution
thereby simulating more than one physical processing unit. The
controller 32 aids the threshold detection circuitry in estimating
the strength a typical temperature parameter. For instance, the
temperature parameter may include de-heater outlet temperature, or
drum inlet temperature or evaporator outlet temperature. Further,
the controller 32 may determine the strength of the signals from
such temperature parameters. This estimate information may be
reported to a remote control unit or to an alerting system.
EXAMPLE OPERATION
[0030] FIG. 3 is a block diagram of a thermal management system 30
equipped with a controller for controlling air temperature in an
appliance in accordance with an example embodiment. The thermal
management system 30 is similar in form to the thermal management
system 20 of FIG. 2 except for the addition of example operational
parameters associated with operation of the thermal management
system within a cleaning apparatus. Such operational parameters
include specific temperatures or temperature ranges of air at
various inlet and outlet points of various components positioned in
the airflow path 2, as well as flow rates of air in both the main
airflow path 2 and in the bypass airflow path 6. The operational
parameters also include specific temperatures or temperature ranges
of the refrigerant at various inlet and outlet points of various
components positioned on the refrigerant flow path.
[0031] In the example embodiment of FIG. 3, a typical volume flow
rate of air in the main stream (e.g., that airflow which follows
airflow path 2) is 240 cubic feet per minute (cfm) whereas a
typical volume flow rate for air in the bypass stream (e.g., that
airflow which follows bypass airflow path 6) comprises 29% of the
volume flow rate of air in the main stream (e.g., 69.6 cfm).
Moreover as shown, when the inlet air temperature at the evaporator
18 is typically within a range of 124 F to 129 F, the outlet air
temperature at the evaporator 18 is typically at about 68 F. In a
like manner, when the inlet air temperature at the condenser 16 is
typically within a range of 84 F to 86 F, then the outlet air
temperature at the condenser 16 is typically at about 139 F. This
results in an inlet air temperature at the drum 24 that can be
typically at about 139 F. In turn, and the outlet air temperature
at the drum 24 can be typically within a range of 124 F-129 F.
[0032] Continuing to refer to the example embodiment of FIG. 3,
when a typical inlet temperature of the refrigerant at the
compressor 12 is typically at about 42 F, the outlet temperature of
the refrigerant at the compressor 12 is typically within a range of
about 180 F-220 F. In turn, if the inlet temperature of the
refrigerant at the de-heater 14 is typically within a range of
about 180 F-220 F then due at least in part upon the operation of
the de-heater 14 in combination with the fan 26, the outlet
temperature of the refrigerant at the de-heater 14 is typically at
about 140 F. In the example embodiment, the inlet and outlet
temperatures of the refrigerant at the condenser 16 is typically at
the condensing temperature of the particular refrigerant used in
the particular cleaning apparatus. Further, if the inlet
temperature of the refrigerant at the expansion chamber 28 is
typically at about 140 F, the outlet temperature of the refrigerant
at the expansion chamber 28 is typically at about 42 F. The inlet
and outlet temperatures of the refrigerant at the evaporator 18 can
then further be typically at the evaporating temperature of the
particular refrigerant used in the particular cleaning apparatus.
In one embodiment, the refrigerant used is R-22.
[0033] The numerical values of the temperatures, temperature
ranges, the flow rate of the air in the main stream and the flow
rate of the air in the bypassed stream are provided for the purpose
of illustration and these values are specific to one exemplary
design of the apparatus of FIG. 3. As such, the thermal management
system 10 or 20 illustrated in relation to FIG. 1 or FIG. 2 should
not be construed to be limited by the illustrated values in the
thermal management system 30 illustrated in FIG. 3.
[0034] In another embodiment of the invention, the operation of the
cleaning apparatus of FIG. 2 may be enhanced by using a wash liquid
that contains solvents such as cyclic siloxane (scientifically
known as Decca Methyl Cyclo Penta Siloxane) or D5 in a washing
cycle of the cleaning apparatus as the cleaning quality can be
improved with the use of such solvents. However, one of the
challenging constraints associated with use of such solvents is
flammability of the solvents. Federal guidelines for commercial
dry-cleaning systems as listed by National Fire Protection
Association (NFPA) 32 and as recommended in association with the
use cyclic siloxane or D5, classify the solvent as a Class IIIA
solvent based on its flammability point of 170 F. NFPA 32
guidelines for safe operation of D5 based laundry systems requires
that the temperature everywhere in the associated appliance or
system is 30 F below the flash point temperature (e.g., less than
140 F for D5). As illustrated above, in the thermal management
system 20 of FIG. 2, thermocouples and other sensitive sensors are
used in various points in the airflow to monitor and facilitate
control of the air temperature and such that the air temperature is
kept well below 140F. Thus, through the incorporation of
embodiments of the present invention, the apparatus of FIG. 2 is
well equipped to meet the demand of a high quality cleaning
apparatus using cyclic siloxane or D5 solvent based wash
liquid.
[0035] FIG. 4 is a graphical representation 40 of an example
functional relationship between air temperature and refrigerant
temperature in an appliance and time length of operation of the
appliance in accordance with an embodiment of the invention.
Referring to FIG. 4, each curve illustrates an example of dynamic
temperature changes of either the air or of the refrigerant used in
a washing machine for the inlet or outlet conditions common to
washing machine applications. The vertical or the Y-axis 72 of the
temperature-time curves represents temperature values expressed in
degree Fahrenheit and the horizontal or the X-axis 74 represents
time interval values recorded from the start of the cleaning
apparatus as expressed in seconds. Three different temperature
curves 76, 78 and 82 are presented for illustrative purposes. Curve
76 represents the temperature of the refrigerant at the outlet of
the condenser 16, curve 78 represents the temperature of the
refrigerant at the inlet of the condenser 16 and curve 82
represents the temperature of air at the outlet of the condenser
16.
[0036] Referring to FIG. 4, it will be noted that by using the
de-heater 14 in tandem with the condenser 16, the temperature of
the refrigerant at the inlet of the condenser 16 is constrained
within a controlled limit. In one embodiment of the invention, the
de-heater 14 operates to maintain the refrigerant at a steady
temperature while the refrigerant condenses in the condenser 16. In
the illustrated example of FIG. 4, the steady temperature may be
130 degrees Fahrenheit, which is the condensation temperature of
the R-22 refrigerant that happens to have been used. The
oscillations in the curves 76 and 78 represent the rise or fall of
the temperature of the refrigerant due to the variation in the
speed of the fan 26 of FIG. 2 as is relates to the operation of the
de-heater 14. This functionality will be described in more details
later in relation to FIG. 6. The heat given up by the refrigerant
during its condensation in the condenser 16 is absorbed by the
airflow and the temperature of the airflow in turn rises from room
temperature up to a steady temperature over a period of time. The
steady temperature of the airflow in the particular example of FIG.
4 may be 110 degree Fahrenheit, depending on the thermal efficiency
of the apparatus and its components, which has been determined to
be a preferred temperature for drying clothes in the drum 24.
[0037] FIG. 5 illustrates a methodology for monitoring and
controlling temperature within an appliance in accordance with one
embodiment of the invention. The method 50 begins with an airflow
path being defined to carry an airflow for drying articles within
the appliance as in functional block 102. At the same time a
refrigerant flow path is defined to circulate a refrigerant in a
closed loop such that the refrigerant acts at least in part to both
heat and cool the airflow as in functional block 104. Lastly, the
temperature of the refrigerant is then controlled such that the
airflow does not exceed a determined temperature as in functional
block 106.
[0038] FIG. 6 illustrates an operational flow of the thermal
management system 30 of FIG. 2 for controlling air temperature in
an appliance in accordance with an exemplary embodiment of the
invention. As illustrated, description of the operational flow
begins at functional block 108. Thereafter, the controller 32
performs a number of operations, which may be performed in parallel
or in a sequential order. However, for the purposes of
illustration, it is assumed that the operations illustrated in FIG.
6 occur in parallel. In particular, the temperature of the
refrigerant in refrigerant flow path 4 is sensed at an outlet end
of the de-heater 14 (functional block 114) and the decision logic
of the controller 32 then determines whether the sensed temperature
of the refrigerant is less than a determined set point (functional
block 122). In one embodiment, the temperature of the refrigerant
is sensed using a thermocouple positioned at the outlet end of the
de-heater 14. If the temperature of the refrigerant is determined
to be lower than the determined set point, the speed of the fan 26
associated with de-heater 14 may then be decreased as shown in
functional block 124. On the other hand, if the temperature of the
refrigerant is determined to be higher than the determined set
point, then the fan speed may be increased as shown in functional
block 126.
[0039] At functional block 116, the controller 32 further
identifies the temperature of the air at the inlet of the drum 24
and the decision logic of the controller 32 determines whether the
temperature of the air at the inlet of the drum 24 is lower than a
determined set point (functional block 132). If the temperature of
the air is determined to be higher than the set point, the speed of
blower 22 may be increased as shown by functional block 134. On the
other hand, if the temperature of the air is determined to be less
than the set point, the blower speed is decreased as shown in
functional block 136.
[0040] At functional block 118, the controller 32 further
determines the temperature of the air at the outlet of the
evaporator 18 (functional block 118) and the decision logic of the
controller 32 determines whether the temperature of the air is less
than a determined set point as shown in functional block 142. If
the temperature of the air is determined to be higher than the set
point, the volume of air that is bypassed around the cooling unit
18 is increased as shown in functional block 144. On the other
hand, if the temperature of the air is determined to be less than
the set point, the volume of bypassed air is decreased as shown in
functional block 146. Finally, in an iterative manner, the decision
logic of the controller 32 determines at functional block 152
whether an end of the drying process is reached. If the end of the
process is reached, the process completes at functional block 154.
Otherwise, the drying process continues to operate accordingly.
[0041] Although the present invention has been described with
reference to particular embodiments, it should be recognized that
these embodiments are merely illustrative of the principles of the
present invention. Those of ordinary skill in the art will
appreciate that the method of the present invention may be
implemented in other ways and embodiments. Accordingly, the
description herein should not be read as limiting the present
invention, as other embodiments also fall within the scope of the
present invention.
[0042] While only certain features of the invention have been
illustrated and described herein, many modifications and changes
will occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention.
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