U.S. patent application number 13/690676 was filed with the patent office on 2013-06-27 for refrigeration apparatus and method.
This patent application is currently assigned to Welbilt Walk-Ins, LP. The applicant listed for this patent is Welbilt Walk-Ins, LP. Invention is credited to Michael S. Chandler, Adam Franklin McCranie, David L. Schardt, STEVEN TERENCE WORLEY.
Application Number | 20130160471 13/690676 |
Document ID | / |
Family ID | 48536092 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130160471 |
Kind Code |
A1 |
WORLEY; STEVEN TERENCE ; et
al. |
June 27, 2013 |
REFRIGERATION APPARATUS AND METHOD
Abstract
Methods and apparatus for an energy efficient freezer or cooler
defrost, which are particularly suited for an automated system,
include procedures utilized for this purpose. The procedures are
included in the firmware of an embedded controller and operate the
cooler or freezer defrost cycle when required for increased energy
efficiency.
Inventors: |
WORLEY; STEVEN TERENCE;
(Kokomo, IN) ; Chandler; Michael S.; (Barth
Spring, TN) ; Schardt; David L.; (Brentwood, TN)
; McCranie; Adam Franklin; (Safety Harbor, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Welbilt Walk-Ins, LP; |
Fort Worth |
TX |
US |
|
|
Assignee: |
Welbilt Walk-Ins, LP
Fort Worth
TX
|
Family ID: |
48536092 |
Appl. No.: |
13/690676 |
Filed: |
November 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61566555 |
Dec 2, 2011 |
|
|
|
Current U.S.
Class: |
62/81 ;
62/156 |
Current CPC
Class: |
F25D 2700/10 20130101;
F25D 21/006 20130101; F25D 2700/123 20130101; F25D 21/06 20130101;
F25D 21/08 20130101 |
Class at
Publication: |
62/81 ;
62/156 |
International
Class: |
F25D 21/06 20060101
F25D021/06 |
Claims
1. A refrigeration apparatus comprising: a fan that provides an
airflow; an evaporator assembly that comprises an evaporator coil
disposed in said airflow; a refrigerant assembly disposed in fluid
communication with said evaporator coil to supply refrigerant to
said evaporator coil; a first sensor that senses a temperature of
said airflow at an airflow input side of said evaporator coil; a
second sensor that senses a temperature of said airflow at an
airflow output side of said evaporator coil; a third sensor that
senses a temperature on a suction line near the outlet side of said
evaporator coil; a fourth sensor that senses a temperature in a
location that is representative of an evaporator coil temperature;
a fifth sensor that senses pressure of said refrigerant leaving
said evaporator coil, wherein said pressure of said refrigerant
corresponds to an output saturated suction refrigerant temperature;
and a controller that is connected to said first, second, third,
fourth and fifth sensors, that controls said evaporator assembly
and said refrigerant assembly in a cooling mode and in a defrost
mode, and that controls an initiation of said defrost mode based on
comparison of a reference dynamic efficiency with a dynamic
efficiency that is a function of current values of said temperature
of said airflow at said airflow input side of said evaporator coil,
said temperature of said airflow at said airflow output side of
said evaporator coil and said output saturated suction refrigerant
temperature of said refrigerant leaving said evaporator coil.
2. The refrigeration apparatus of claim 1, wherein said evaporator
assembly is disposed in an enclosed space that requires
refrigeration and/or air conditioning.
3. The refrigeration application of claim 2, wherein said
refrigerant assembly and said controller are located outside said
enclosed space.
4. The refrigeration apparatus of claim 1, wherein said dynamic
efficiency is determined by a difference between the current
temperature values sensed by said first and second sensors divided
by a difference between the temperature value sensed by said first
sensor and said output saturated suction refrigerant temperature
value sensed by said fifth sensor.
5. The refrigeration apparatus of claim 1, wherein said first
sensor is an input air temperature sensor.
6. The refrigeration apparatus of claim 1, wherein said second
sensor is an output air temperature sensor.
7. The refrigeration apparatus of claim 1, wherein said third
sensor is an evaporator output refrigerant temperature sensor.
8. The refrigeration apparatus of claim 1, wherein said fourth
sensor is a defrost termination sensor.
9. The refrigeration apparatus of claim 1, wherein said fifth
sensor is a refrigerant suction pressure transducer.
10. The refrigeration apparatus of claim 1, further comprising a
heater safety termination switch.
11. The refrigeration apparatus of claim 1, wherein said heater
safety termination switch is a safety switch which opens or closes
based on said evaporator coil temperatures sensed by said heater
safety termination switch and is located on said evaporator
coil.
12. A method for efficient defrosting of an evaporator assembly,
said method comprising: a. Initiating start up of a refrigeration
assembly, fan motor and fan if Tair, in is greater than a
temperature set point; b. Cooling Tair, in to within a
predetermined temperature setting relevant to a thermostat set
point; c. Initiating a defrost program if Tair, in is within a
predetermined range of said thermostat set point; d. Calculating
reference dynamic efficiency (RE) and dynamic efficiency (DE)
values; e. Determining if RE minus DE divided by RE is equal to a
predetermined threshold (DET) and if yes, then initiating an
electric defrost by deactivating said refrigeration assembly,
deactivating said fans and activating at least one defrost heater
or initiating an air defrost by deactivating said refrigeration
assembly and maintaining continued operation of said evaporator
fans; f. Determining if (a) a temperature sensed by a defrost
termination sensor is equal to or greater than preset defrost
termination temperature, (b) a defrost time is equal to or greater
than a preset defrost termination time, or (c) a evaporator coil
temperature is equal to or greater than a heater safety termination
temperature; and g. If any one of (a)-(c) in step (f) occur,
deactivating said defrost heater, activating said refrigeration
assembly and activating said fans.
Description
CROSS-REFERENCED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 61/566,555, filed on Dec. 2, 2011, which is
incorporated herein in its entirety by reference thereto.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] This disclosure generally relates to a refrigeration
apparatus and method and, in particular, to a refrigeration
apparatus and method for efficient defrost of an evaporator
assembly.
[0004] 2. Discussion of the Background Art
[0005] In the current economic climate and legislative arena there
is a necessity to reduce the energy consumption of HVAC and
refrigeration equipment. To reduce the overall energy consumption
of this equipment, electronic controllers are being applied to
optimize the energy consumption of such equipment. One function
that requires optimization is evaporator defrost.
[0006] Prior art defrost strategies have used a timer to initiate a
defrost process based on a predetermined schedule, whether or not
needed. For the case of not needed, there is an unnecessary
consumption of energy. The process of defrosting introduces heat
into the conditioned air space, making energy saving important (i)
to reduce the amount of energy used to defrost, and (ii) to reduce
the additional energy required to remove the defrost heat from the
conditioned air space.
[0007] Thus, there is a need for a refrigeration apparatus and
method that initiates a defrost only when needed.
SUMMARY OF THE DISCLOSURE
[0008] A refrigeration apparatus according to the present
disclosure comprises a fan that provides an airflow, an evaporator
assembly that comprises an evaporator coil disposed in the airflow,
and a refrigerant assembly disposed in fluid communication with the
evaporator coil to supply refrigerant to the evaporator coil. A
first sensor that senses a temperature of the airflow at an airflow
input side of the evaporator coil and a second sensor that senses a
temperature of the airflow at an airflow output side of the
evaporator coil. A third sensor that senses the temperature on the
suction line near the outlet of the evaporator coil. A fourth
sensor that senses the temperature in a location that is
representative of the evaporator coil surface temperature. A fifth
sensor (pressure transducer) that senses the pressure of the
refrigerant leaving the evaporator coil. A controller is connected
to the first, second, third, fourth and fifth sensors to control
the evaporator assembly and the refrigerant assembly in a cooling
mode and in a defrost mode. The controller controls an initiation
of the defrost mode based on comparison of a reference dynamic
efficiency with a dynamic efficiency that is a function of current
values of the input airflow temperature, the output airflow
temperature and an output saturated refrigerant temperature of the
refrigerant leaving the evaporator coil. The controller controls
the termination of the defrost mode based on the temperature value
sensed by the fourth sensor satisfying a temperature setting value
within the defrost program or by time based on satisfying a time
setting within the defrost program. The defrost mode terminates
when the temperature setting or time setting has been satisfied
(first achieved).
[0009] A method for efficient defrosting of an evaporator assembly,
the method comprising: (a) Initiating start up of a refrigeration
assembly, fan motor and fan if Tair, in is greater than a
temperature set point; (b) Cooling Tair, in to within a
predetermined temperature setting relevant to a thermostat set
point; (c) Initiating a defrost program if Tair, in is within a
predetermined range of the thermostat set point; (d) Calculating
reference dynamic efficiency (RE) and dynamic efficiency (DE)
values; (e) Determining if RE minus DE divided by RE is equal to a
predetermined threshold (DET) and if yes, then initiating an
electric defrost by deactivating the refrigeration assembly,
deactivating the fans and activating at least one defrost heater;
(f) Determining if (a) a temperature sensed by a defrost
termination sensor is equal to or greater than preset defrost
termination temperature, (b) a defrost time is equal to or greater
than a preset defrost termination time, or (c) a evaporator coil
temperature is equal to or greater than a heater safety termination
temperature; and (g) If any one of (a)-(c) in step (f) occur,
deactivating the defrost heater, activating the refrigeration
assembly and activating the fans.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Other and further objects, advantages and features of the
present disclosure will be understood by reference to the following
specification in conjunction with the accompanying drawings, in
which like reference characters denote like elements of structure
and:
[0011] FIG. 1 is a block diagram of a refrigeration apparatus
according to the present disclosure;
[0012] FIG. 2 is a block diagram that depicts components of the
refrigeration apparatus of FIGS. 1; and
[0013] FIG. 3 is a flow diagram of the programs of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] Referring to FIG. 1, a refrigeration apparatus 20 of the
present disclosure comprises an evaporator assembly 22, a
refrigerant assembly 24 and a controller 26.
[0015] Evaporator assembly 22 is located in an enclosed space 28
that requires refrigeration or air conditioning. Refrigerant
assembly 24 and controller 26 are located outside enclosed space 28
with connections to one another and to evaporator assembly 22.
Enclosed space 28 may be a room that is being cooled for
refrigeration or air conditioning. For example, in a preferred
embodiment, enclosed space 28 is a walk in refrigeration room.
[0016] Evaporator assembly 22 comprises a cabinet 29 that has
openings 31 and 33 located in opposed sidewalls. Disposed within
cabinet 29 are an evaporator coil 30, one or more defrost heater(s)
32, one or more fan(s) 34 and one or more fan motor(s) 36.
Refrigerant enters cabinet 29 via a liquid line 40 and leaves via a
compressor suction line 42. Lines 40 and 42 are connected to
refrigerant assembly 24. Air flows through cabinet 29 via openings
31 and 33 as indicated by arrows 44 and 46. Defrost heater 32
comprises one or more heating elements (not shown).
[0017] During a cooling mode, controller 26 operates refrigerant
assembly 24 to flow refrigerant through liquid line 40, refrigerant
metering device 48 typically an electric expansion valve or
mechanical expansion valve, evaporator coil 30 and suction line 42.
Controller 26 also operates fan motor 36 to rotate fan 34 to draw
air from enclosed space 28 via opening 31 through evaporator coil
30 by fan 34. As the air passes through evaporator coil 30, heat is
removed from the air and transferred to the colder refrigerant
flowing through evaporator coil 30. That is, air is cooled and
moved by fan 34 into enclosed space 28 via opening 33. The net
effect is that the air in enclosed space 28 is cooled.
[0018] Evaporator coil (heat exchanger) 30 is constructed such that
the refrigerant and airflow pass through the evaporator coil
without the two mediums coming physically into contact. For
example, evaporator coil 30 is constructed with a tube through
which the refrigerant flows, the tube being arranged as evaporator
coil 30. Evaporator coil 30 facilitates heat transfer from the air
to the refrigerant.
[0019] Enclosed space 28 generally requires access by a user that
results in warm moist/humid air being introduced to enclosed space
28. The moisture in the infiltrating air or from the product stored
inside enclosed space 28 will be attracted to the cold surfaces
within the enclosed space. Since the evaporator coil surfaces are
the coldest surfaces in enclosed space 28 and exposed to a higher
airflow rate than any other surfaces in enclosed space 28, when the
fan(s) 34 circulate the air through the evaporator coil 30, the
moisture in the air is deposited on the evaporator coil
surfaces.
[0020] The ice deposits on evaporator coil 30 impede the
performance of evaporator assembly 22 in two ways. First, the ice
on the fins (not shown) of evaporator coil 30 acts as an additional
insulative barrier between the airflow and the refrigerant; thereby
reducing heat transfer from the air to the refrigerant. Second, the
ice constricts the airflow through evaporator coil 30, thereby
causing reduced airflow. To remove the ice deposits and maintain
the design performance efficiency of evaporator assembly 22,
defrosting is required. A defrost mode may be activated by one of
three methods: [0021] Demand Defrost Mode (primary active defrost
mode)--a demand defrost automatically initiated based on operating
efficiency status of evaporator. [0022] Safety Defrost Mode--a
safety defrost automatically initiated (if actively programmed) if
applicable preprogrammed parameters have been satisfied. [0023]
Manual Defrost Mode--a manual defrost can be manually initiated via
the controller interface.
[0024] During a defrost mode, controller 26 operates defrost heater
32 to melt the ice. Defrost heater 32 is embedded in, attached to
or in close proximity to evaporator coil 30 and the air heat
transfer surfaces of evaporator coil 30. During defrost the
surfaces of evaporator coil 30 are heated to above the freezing
point of the ice. As a result the ice melts into a liquid that is
removed from enclosed space 28 via an evaporator drain (not
shown).
[0025] Evaporator assembly 22 further comprises an input air
temperature sensor 50, an output air temperature sensor 52, an
evaporator output refrigerant temperature sensor 82, a defrost
termination sensor 84, 92, a heater safety termination (HSTS)
switch 68 and a refrigerant suction pressure transducer (sensor)
86. Input air temperature sensor 50 is disposed in the airflow at
or near an input port of evaporator assembly 22 or of evaporator
coil 30. Output air temperature sensor 52 is disposed in the
airflow at or near an output port of evaporator coil 30 or of
evaporator assembly 22. The output signals of input air and output
air temperature sensors 50 and 52 are labeled, respectively, Tair,
in (50, 56) and Tair, out (52, 58) and are proportional to the
input airflow and output airflow temperatures, respectively.
Refrigerant suction pressure transducer (sensor) 86 is located to
measure the pressure of the refrigerant that exits evaporator coil
30. The output signal of refrigerant suction pressure transducer
(sensor) 86, 88 is labeled Tref, out and can be used to determine
the output saturated refrigerant temperature in evaporator coil
30.
[0026] Evaporator output temperature sensor 82 is located adjacent
to and in contact with suction line 42 at or near its connection to
the output side of evaporator coil 30. Defrost termination sensor
84 is located on the evaporator coil 30. HSTS sensor 68 is a safety
switch which opens or closes based on coil temperature and is
located on evaporator coil 30.
[0027] Referring to FIG. 2, controller 26 comprises a processor 70,
a memory 74 and an input/output (I/O) interface 72 that are
interconnected by a bus 76. Memory 74 comprises programs that are
executed by processor 70 to operate refrigeration apparatus 20.
Germane to the present disclosure are a cooling program 78 and a
defrost program 80. Although shown as separate programs, defrost
program 80 in some embodiments may be incorporated within cooling
program 78.
[0028] Processor 70 may be any suitable processor that executes or
runs the programs stored in memory 74. For example, processor 70
may be a microprocessor.
[0029] Memory 74 may be any suitable memory that stores the
parameters and data required for operation and maintenance of
refrigeration apparatus 20. For example, memory 74 may comprise one
or more of a random access memory, a read only memory, an EPROM, a
plug in memory such as a flash memory or a data key, and the
like.
[0030] I/O (input/output) interface 72 is further connected to
input air temperature sensor 50, output air temperature sensor 52,
fan motor 36, defrost heater 32, refrigerant assembly 24, a
refrigerant pressure transducer 86, an output refrigerant
temperature sensor 82, a defrost termination sensor 84, and an HSTS
switch 68 via connections 56, 58, 62, 64, 66, 88, 90, 92 and 96,
respectively.
[0031] Processor 70 executes cooling program 78 in a cooling mode
to cause refrigerant assembly 24 to flow refrigerant through liquid
line 40, a refrigerant metering device 48 (such as an electric
expansion valve or mechanical expansion valve), evaporator coil 30
and suction line 42. Processor 70 also operates fan motor 36 to
rotate fan 34 to draw air via opening 31 from enclosed space 28
through evaporator coil 30 by fan 34 as indicated by arrow 44. As
the air passes through evaporator coil 30, heat is removed from the
air and transferred to the colder refrigerant flowing through
evaporator coil 30. That is, air is cooled and moved by fan 34 via
opening 33 into enclosed space 28 as indicated by arrow 46. The net
effect is that the air in enclosed space 28 is cooled.
[0032] As noted above, warm moist/humid air introduced to enclosed
space 28 causes a deposit of ice on cold surfaces in the enclosed
space 28. These ice deposits will be most prominent at the surfaces
of evaporator coil 30, which are the coldest surfaces in enclosed
space 28 and exposed to a higher airflow rate than any other
surfaces in enclosed space 28.
[0033] While cooling program 78 is being executed, processor 70
frequently checks the temperature values of Tair, in, Tair, out and
Tref, out for a predetermined temperature condition based on at
least one and, preferably more of these temperatures, that requires
an initiation of a defrost mode. For example, the checking
operation is an initial step of defrost program 80. If the
temperature condition does not require defrost, processor 70
continues to execute cooling program 78.
[0034] If the temperature condition requires defrost, processor 70
initiates defrost program 80. Processor 70 then, if refrigeration
apparatus 20 is configured in an electric defrost mode, causes fan
motor 36 to be turned off, defrost heater 32 to be turned on and
refrigerant assembly 24 to discontinue supplying refrigerant to
evaporator coil 30. If refrigeration apparatus 20 is configured in
an air defrost mode, processor 70 causes refrigerant assembly 24 to
discontinue supplying refrigerant to evaporator coil 30 for a
predetermined period of time and also causes the fan(s) 34 to
continue operating and circulating air through the evaporator coil
surfaces.
[0035] Defrost program 80 in a preferred embodiment determines the
temperature condition based on a dynamic effectiveness (DE) of the
performance of a heat exchanger (evaporator coil 30). DE is defined
as the actual heat transfer of a heat exchanger divided by the
maximum amount of heat that could be transferred for the same inlet
temperature and flow rates in both cases. For the evaporator where
the refrigerant flow has a greater "heat capacity" than the air
flow the effectiveness (E) can be expressed as the ratio:
E=(Tair,in-Tair,out)/(Tair,in-Tref,out), (1)
where Tair, in is the temperature of the air entering evaporator
coil 30, Tair, out is the temperature of the air exiting evaporator
coil 30, and Tref, out is the saturated refrigerant temperature
exiting evaporator coil 30.
[0036] Processor 70 executes defrost program 80 to monitor Tair,
in, Tair, out and Tref, out to determine dynamic effectiveness DE.
Tref, out is determined by looking up the saturation temperature
that corresponds to a measured refrigerant pressure. A pressure
transducer 86 measures the refrigerant pressure.
[0037] Each time processor 80 monitors Tair, in, Tair, out and
Tref, out during execution of defrost program 80, the value of E is
calculated by processor 70.
[0038] In the following description of defrost program 80 and FIG.
3, the following acronyms are used: [0039] DE Dynamic Effectiveness
[0040] RE Reference Effectiveness [0041] DET Defrost Effectiveness
Threshold [0042] DTT Defrost Termination Temperature [0043] DTS
Defrost Termination Sensor Temperature [0044] DT Defrost Time
[0045] DETT Defrost Termination Time [0046] HSTS Heater Safety
Termination Switch [0047] HSTT Heater Safety Termination
Temperature
[0048] DET is a temperature value determined by design and user
requirements. In one embodiment, DET is 35%. DTT is the
predetermined defrost termination temperature that is found through
testing, for example, typically 40-55.degree. F. DETT is the amount
of time that the defrost cycle operates if the defrost cycle is
terminated by time.--HSTT is the coil temperature that cannot be
exceeded, for example, 70.degree. F. in one embodiment.
[0049] Referring to FIG. 3, processor 70 executes instructions of
cooling program 78 to control start up of refrigeration apparatus
20 at box 100 by determining if Tair, in is greater than a
temperature set point. If not, refrigerant assembly 24 is not
started.
[0050] If yes, processor 70 initiates start up of refrigerant
assembly 24, fan motor 36 and fan 34. Once start up begins, there
is a delay at box 102 while processor 70 waits until Tair, in is
cooled to within a predetermined programmed temperature setting (in
one embodiment 15.degree. F.) relevant to the thermostat set point
before initiating defrost program 80. The temperature set point and
thermostat set point are identical and are determined by the end
user for the product that is being placed in enclosed space 28.
[0051] Once Tair, in is within 15.degree. F. of the thermostat set
point, processor 70 executes instructions of defrost program 80. At
box 104 processor 70 executes instructions to start collecting data
and calculations are initiated to establish RE and DE values. In
one embodiment, the RE and DE values are initially both set to
equal 0. Initially, DE will equal RE and DE will continue to equal
RE until a peak RE value has been established. The peak RE value
may change based on system operation as the system continues to
operate and DE will also change accordingly. Once the final peak RE
value is established (DE will equal RE) then the efficiency of the
evaporator coil starts to deteriorate, the DE value will start to
drop below the RE value.
[0052] At box 106 processor 70 executes instructions using equation
(1) to calculate RE and DE in real time during operation of
refrigeration apparatus 20. This calculation uses the current
values of Tair, in, Tair out and Tref, out provided by input air
temperature sensor 50, output air temperature sensor 52 and
pressure transducer (sensor) 86. The processor 70 processes the
collected real time data calculations and then per defrost program
80 instructions, generates RE and DE values. At box 108 processor
70 determines if the current processed value of DE is equal to RE.
If yes, in box 110 DE is set equal to the current value of RE,
which is used for the next comparison in box 108. Processor 70 then
returns to box 104.
[0053] If no, at box 112 processor 70 determines if RE--DE divided
by RE is equal to the predetermined threshold DET. If no, defrost
program 80 returns to box 106.
[0054] If yes, control program 80 proceeds to either an electric
defrost mode or an air defrost mode dependent on the system
requirements or application, wherein refrigeration assembly is
deactivated 116, evaporator fans are deactivated 116A and defrost
heaters are activated 118 for electric defrost mode or
refrigeration assembly is deactivated 136 and evaporator fans
continue to operate 138 for air defrost mode.
[0055] If refrigeration apparatus 20 is configured for an electric
defrost mode, at box 116 refrigerant assembly 24 is disabled. That
is, refrigerant is not supplied to evaporator coil 30. At box 116A
controller 26 deactivates or turns off fan motor 36 and fan 34. At
box 118 controller 26 activates or turns on defrost heater 32.
[0056] At box 120 processor 70 uses the temperature sensed by DTS
sensor 84 to determine if it is equal to or greater than the
defrost termination temperature DTT. If no, at box 122 processor 70
determines if the defrost time DT is equal to or greater than the
defrost termination time DETT. If no, at box 124 processor 70
determines if the evaporator coil temperature is equal to or
greater than the heater safety termination temperature HSTT. If no,
cooling program 80 returns to box 120. If the determination at any
of boxes 120, 122 or 124 is yes, at box 126 processor 70 causes
controller 26 to deactivate defrost heater 32. At box 128 processor
initiates a time delay to allow a "drip time" for the evaporator
coil 30. When the delay has ended, refrigerant assembly 24 is
activated, box 130. At box 132 a time delay is then initiated. When
the time delay has ended, at box 134 processor 70 causes controller
26 to turn fan motor 36 and fan 34 on. Processor 70 then resumes
execution of defrost program 80 at box 104.
[0057] If refrigeration apparatus 20 is configured for an air
defrost mode, at box 136 refrigerant assembly 24 is deactivated. At
box 138 processor 70 allows continued operation of fan motor 36 and
fan 34. At box 140 processor 70 determines if DT is equal to or
greater than DTT. If no, processor 70 continues to execute the
instructions of box 140 until DT is equal to or greater than DTT.
When this happens, at box 142 processor 70 causes controller 26 to
activate refrigerant assembly 24 in box 142 to provide refrigerant
flow to evaporator assembly 22. Processor 70 then resumes execution
of defrost program 80 at box 104.
[0058] If refrigeration apparatus 20 is configured for a manual
defrost mode 114, the method determined in 114A if a manual defrost
has been requested. If no, then no defrost is initiated 114B. If
yes, then defrost is initiated 115 and electric defrost procedures
are followed in steps 116-142 as discussed above or air defrost
procedures are followed in steps 136-142 as discussed above.
[0059] The method also provides for a safety defrost mode 113,
wherein the system monitors various safety defrost parameters 113A
to determine if the maximum safety defrost parameters are exceeded
113B. If parameters are not exceeded, then the system returns to
113A. If the parameters are exceeded, then the system initiates
defrost 115 and electric defrost procedures are followed in steps
116-142 as discussed above or air defrost procedures are followed
in steps 136-142 as discussed above.
[0060] There are several advantages to the electronic controller of
the present disclosure. There is a cost saving, as energy costs
increase the additional cost of the electronic controller becomes
more justifiable. In a "smart kitchen concept" where all of the
operating parameters are centralized in one microprocessor, the
electronic controller of the present disclosure in refrigeration
equipment is essential to communicate with a central
microprocessor. There is also a legislative advantage as the
electronic controller is able to collect and store temperature
data, allowing a storeowner to prove correct storage temperature
and conditions of food produce. The refrigeration apparatus of the
present disclosure also has the advantage of initiating defrost
when the conditions at the evaporator coil require defrost.
[0061] The present disclosure having been thus described with
particular reference to the preferred forms thereof, it will be
obvious that various changes and modifications may be made therein
without departing from the spirit and scope of the present
disclosure as defined in the appended claims.
* * * * *