EP2588819B1 - Evaporator refrigerant saturation demand defrost - Google Patents
Evaporator refrigerant saturation demand defrost Download PDFInfo
- Publication number
- EP2588819B1 EP2588819B1 EP11730522.7A EP11730522A EP2588819B1 EP 2588819 B1 EP2588819 B1 EP 2588819B1 EP 11730522 A EP11730522 A EP 11730522A EP 2588819 B1 EP2588819 B1 EP 2588819B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- refrigerant
- temperature
- defrost
- evaporator
- heat exchanger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000003507 refrigerant Substances 0.000 title claims description 150
- 238000000034 method Methods 0.000 claims description 34
- 230000006835 compression Effects 0.000 claims description 33
- 238000007906 compression Methods 0.000 claims description 33
- 238000005057 refrigeration Methods 0.000 claims description 26
- 230000000977 initiatory effect Effects 0.000 claims description 22
- 230000001143 conditioned effect Effects 0.000 claims description 4
- 238000010257 thawing Methods 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims 1
- 238000001816 cooling Methods 0.000 description 21
- 238000012546 transfer Methods 0.000 description 12
- 230000001276 controlling effect Effects 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000035508 accumulation Effects 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000004320 controlled atmosphere Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000078 germane Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
- F25D21/002—Defroster control
- F25D21/006—Defroster control with electronic control circuits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2117—Temperatures of an evaporator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2117—Temperatures of an evaporator
- F25B2700/21171—Temperatures of an evaporator of the fluid cooled by the evaporator
- F25B2700/21172—Temperatures of an evaporator of the fluid cooled by the evaporator at the inlet
Definitions
- This invention relates generally to refrigeration systems and, more particularly, to refrigerant vapor compression system evaporator coil defrost control and, more specifically, to the on demand initiation of a defrost cycle for the evaporator coil in response to a differential between return air temperature and evaporator refrigerant saturation temperature.
- Refrigerant vapor compression systems are well known in the art and commonly used for conditioning air to be supplied to a climate controlled comfort zone within a residence, office building, hospital, school, restaurant or other facility.
- Refrigerant vapor compression systems are also commonly used in refrigerating air supplied to display cases, merchandisers, freezer cabinets, cold rooms or other perishable/frozen product storage area in commercial establishments.
- Refrigerant vapor compression systems are also commonly used in transport refrigeration systems for refrigerating air supplied to a temperature controlled cargo space of a truck, trailer, container or the like for transporting perishable/frozen items by truck, rail, ship or intermodal.
- Refrigerant vapor compression systems typically include a compressor, a condenser, an evaporator, and an expansion device. These basic components are interconnected by refrigerant lines in a closed refrigerant circuit, arranged in accord with known refrigerant vapor compression cycles.
- the expansion device is disposed upstream, with respect to refrigerant flow, of the evaporator and downstream of the condenser.
- the evaporator includes a heat exchanger, typically a heat exchange tube coil, finned or un-finned, through which refrigerant flowing through the refrigerant circuit passes in heat exchange relationship with air drawn from and circulated back to a temperature controlled space.
- the air within the temperature controlled space will contain moisture, to varying degrees, whether the climate controlled be an air conditioned room, a refrigerated display case, or a temperature controlled transport cargo box, and because the temperature of the refrigerant flowing through the evaporator heat exchange tube coil may drop below the freezing point of water, in some applications and under certain operating conditions, moisture in the air flowing over the heat exchange tube coil will condense on the heat exchange surface of the tube coil and form frost. As the frost accumulates over time of system operation in a cooling mode, the frost builds up on heat exchange surface of the tube coil, adversely impacting heat transfer performance and restricting air flow over the tube coil.
- a defrost cycle can be accomplished by reversing the flow of refrigerant through the refrigerant circuit so as to circulate a heated refrigerant, typically hot refrigerant vapor, through the evaporator heat exchanger.
- Defrost may also be accomplished through the activation of one or more electrical resistance heater operatively associated with the evaporator heat exchange tube coil for heating the tube coil.
- 6,205,800 discloses a method for defrosting on demand by initiating a defrost routine for removing condensate from an evaporator of a refrigerated device if the difference between the sensed air temperature within the refrigerated enclosure of the refrigerated device and the refrigerant temperature sensed by a refrigerant temperature sensor mounted on or disposed within the evaporator tube coil is greater or equal to a defrost threshold.
- U.S. Pat. No. 6,318,095 discloses controlling an outdoor coil defrost cycle on a reversible heat pump by continuously monitoring the difference between the outdoor coil temperature and the outdoor air temperature and initiating a defrost cycle when that difference exceeds a target value.
- Refrigerant vapor compression systems used in connection with transport refrigeration systems are generally subject to more stringent operating conditions due to the wide range of refrigeration load conditions and the wide range of outdoor ambient conditions over which the refrigerant vapor compression system must operate to maintain product within the cargo space at a desired temperature.
- the refrigerant vapor compression system must not only have sufficient capacity to rapidly pull down the temperature of product loaded into the cargo space at ambient temperature, but also should operate energy efficiently over the entire load range, including at low load when maintaining a stable product temperature during transport.
- the air within the transport cargo box may have a particularly high moisture level after product is first loaded, therefore frost formation can be particularly troublesome during pull down when maximum cooling capacity is needed to draw down the product temperature as quickly as possible. Excessive accumulation of frost on the evaporator tube coil results in reduced heat transfer, which prolongs the time required for pull down.
- a common method currently in use in truck trailer applications for controlling initiation of a defrost cycle relies on a differential pressure switch that triggers a defrost cycle whenever the airside pressure drop across the evaporator tube coil exceeds a preset threshold.
- frost formation can also impact the airside pressure drop.
- field installed air chutes can significantly alter the air flow patterns and low airside air flows through the evaporator may not be sufficient to cause the pressure differential switch to trigger despite excessive frost formation of the heat exchange surface of the evaporator tube coil.
- the airside air flow through the evaporator may again be too low to cause the differential pressure switch to rigger despite excessive frost accumulation on the evaporator tube coil.
- frost/ice buildup is not an uncommon problem with respect to evaporators associated with refrigerant vapor compression systems in transport refrigeration applications.
- frost/ice buildup may be heavy on some sections of the evaporator heat exchange surface and nearly non-existent on other sections of the evaporator heat exchange surface.
- the air flow over the heat transfer surface becomes restricted and may not generate enough pressure drop to trigger an air pressure defrost switch to defrost the sections of the evaporator that have heavy frost/ice accumulations.
- the refrigeration unit is provided with a safety defrost which is automatically triggered whenever the temperature differential between the sensed return air temperature and a sensed evaporator heat exchanger surface temperature exceeds a preselected threshold, which is indicative of insufficient heated being absorbed by the refrigerant due to frost build-up on the evaporator heat exchange surface.
- the sensed surface temperature is typically taken by a thermister mounted to the heat exchanger tube sheet or a tube fin, but could also be mounted on the surface of a tube.
- Cooling capacity may roll-off by 75% or more over as little as two or three hours of operation in the cooling mode with an excessively frosted coil.
- Continued cooling operation with an excessively frosted coil also results in increased diesel fuel consumption to power the refrigeration unit. Therefore, an active and more direct method for initiating a defrost cycle that is directly influenced by the build-up of frost on the heat exchange surface of the evaporator tube coil is needed.
- EP 0501387 and DE 3441921 disclose methods of the type defined in the preamble of claim 1.
- the invention provides a method for controlling initiation of a defrost cycle of an evaporator heat exchanger of a refrigerant vapor compression system for supplying conditioned air to a temperature controlled space, the method comprising the steps of: establishing a return air-saturation temperature differential equal to the difference of a sensed air temperature of an air flow returning from the temperature controlled space to pass over the evaporator heat exchanger minus a refrigerant saturation temperature of a flow of refrigerant passing through the evaporator heat exchanger; comparing the return air-saturation temperature differential to a set point threshold defrost temperature differential; and if the return air-saturation temperature differential exceeds the set point threshold defrost temperature differential, initiating a defrost cycle for defrosting the evaporator heat exchanger and characterized by sensing a refrigerant pressure of and generating a signal indicative of the sensed refrigerant pressure of a flow of refrigerant passing through the evapor
- the step of calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures may include calculating the adjusted refrigerant saturation temperature as an arithmetic mean of the plurality of refrigerant saturation temperatures.
- the selected time period may range from at least about three minutes up to about five minutes.
- the method may include the further step of adjusting the set point threshold defrost temperature differential as a function of refrigerant mass flow rate of the refrigerant flowing through the evaporator heat exchanger prior to comparing the return air- saturation temperature differential to the set point threshold defrost temperature differential.
- the method may include the further steps of: calculating a clean coil temperature differential equal to the difference of the sensed return air temperature minus the refrigerant saturation temperature following termination of the defrost cycle; resetting the set point threshold defrost temperature to be the clean coil temperature differential plus a predetermined temperature delta; and initiating the next defrost cycle when the return air-saturation temperature differential exceeds the reset set point temperature differential.
- FIG. 1 there is shown a truck trailer 100 having a refrigerated cargo box 110 having access doors 112 that open to the interior space 114 of the cargo box from the exterior of the truck trailer to facilitate loading of product into the cargo box 110 for transport.
- the truck trailer 100 is equipped with a transport refrigeration unit 10 for regulating and maintaining a temperature controlled atmosphere within the cargo box during transport within a desired storage temperature range selected for the perishable product being shipped therein.
- the demand defrost method disclosed herein will be described herein with reference to the refrigerated cargo box of the depicted truck trailer, it is to be understood that the invention may also be used in connection with other refrigerated cargo transport boxes, including for example a refrigerated box of a truck, or a refrigerated cargo container for transporting perishable product by ship, by rail, by road or intermodal transport.
- the disclosed demand defrost method may also be applied to controlling evaporator defrost cycle initiation on demand in refrigerant vapor compression systems for supplying conditioned air to a temperature controlled space, such as use in connection with air conditioning systems and commercial refrigeration systems.
- the transport refrigeration unit 10 includes a refrigerant vapor compression system 12 and an associated power source.
- the refrigerant vapor compression system 12 includes a compression device 20, a condenser 30 having a heat exchanger and associated condenser fan(s) 34, an evaporator 40 having a heat exchanger 42 and associated evaporator fan(s) 44, and an evaporator expansion device 46, all arranged in a conventional refrigeration cycle and connected in a refrigerant circulation circuit including refrigerant lines 22, 24, 26 and the condenser tubular heat exchanger 32 and the evaporator tubular heat exchanger 42.
- the transport refrigeration system 10 is mounted as in conventional practice to an exterior wall of the truck trailer 100, for example the front wall 116 thereof, with the compressor 20 and the condenser 30 with its associated condenser fan(s) 34 and power source 50 disposed externally of the refrigerated cargo box 110 in a housing 118.
- the evaporator 40 extends through an opening in the front wall 116 into the refrigerated cargo box 110.
- the expansion device 46 which in the depicted embodiment is an electronic expansion valve, but could be a thermostatic expansion valve, is disposed in refrigerant line 24 downstream with respect to refrigerant flow of the condenser heat exchanger 32 and upstream with respect to refrigerant flow of the evaporator heat exchanger 42 for metering the flow of refrigerant through the evaporator in response to the degree of superheat in the refrigerant at the outlet of the evaporator 40, as in conventional practice.
- a refrigerant pressure sensor 48 is mounted on the tubular heat exchanger 42 of the evaporator 40 for monitoring the sensing the refrigerant flowing through the evaporator heat exchanger 42 at or near the outlet thereof.
- the evaporator heat exchanger 42 may, for example, comprise one or more heat exchange tube coils, as depicted in the drawing, or one or more tube banks formed of a plurality of tubes extending between respective inlet and outlet manifolds.
- the tubes may be round tubes or flat tubes and may be finned or un-finned.
- the compressor 20 may comprise a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor, although the particular type of compressor used is not germane to or limiting of the invention.
- the compressor is a reciprocating compressor, such as for example, an 06D model reciprocating compressor manufactured by Carrier Corporation or a variant thereof, having a compressing mechanism, an internal electric compressor motor and an interconnecting drive shaft that are all sealed within a common housing of the compressor 20.
- the power source 50 powers the internal electric motor of the compressor. In an embodiment, the power source 50 generates sufficient electrical power for fully driving the electrical motor of the compressor 20 and also for providing all other electrical power required by the fans 34, 44 and other parts of the refrigeration unit 10.
- the power source 50 comprises a single on-board engine driven synchronous generator configured to selectively produce at least one AC voltage at one or more frequencies.
- An electrically powered transport refrigeration system suitable for use on truck trailer transport vehicles are shown in U.S. Pat. No. 6,223,546 , assigned to the assignee of the present application.
- the transport refrigeration unit 10 also includes an electronic controller 60 that is configured to operate the transport refrigeration unit 10 to maintain a predetermined thermal environment within the interior space 114 defined within the cargo box 110 wherein the product is stored during transport.
- the electronic controller 60 maintains the predetermined thermal environment by selectively powering and controlling the operation of various components of the refrigerant vapor compression system, including the compressor 20, the condenser fan(s) 34 associated with the condenser 30, the evaporator fan(s) 44 associated with the evaporator 40, and various valves in the refrigerant circuit, including but not limited to the electronic expansion valve 46 (if present) and the suction modulation valve 62 (if present).
- the electronic controller 60 activates the compressor 20, the condenser fan(s) 34 and the evaporator fan(s) 44, as appropriate, and adjusts the position of the electronic expansion valve 46 to meter the flow of refrigerant through the evaporator heat exchanger 42 to provide a desired degree of superheat in the refrigerant vapor at the evaporator outlet, and adjusts the position of the suction modulation valve 62 to increase or decrease the flow of refrigerant supplied to the compressor 20 as appropriate to control and stabilize the temperatures within the interior space 114 within the cargo box 110 at the respective set point threshold defrost temperature, which corresponds to the desired product storage temperatures for the particular products stored within cargo box 110.
- the electronic controller 60 includes a microprocessor and an associated memory.
- the memory of the controller 60 may be programmed to contain preselected operator or owner desired values for various operating parameters within the system, including, but not limited to, a temperature set point for the air within the interior space 114 of the cargo box 110, refrigerant pressure limits, current limits, engine speed limits, and any variety of other desired operating parameters or limits within the system.
- the programming of the controller is within the ordinary skill in the art.
- the controller 60 may include a microprocessor board that includes the microprocessor, an associated memory, and an input/output board that contains an analog-to-digital converter which receives temperature inputs and pressure inputs from a plurality of sensors located at various points throughout the refrigerant circuit and the refrigerated cargo box, current inputs, voltage inputs, and humidity levels.
- the input/output board may also include drive circuits or field effect transistors and relays which receive signals or current from the controller 60 and in turn control various external or peripheral devices associated with the transport refrigeration system.
- the controller 60 may comprise the MicroLinkTM controller available from Carrier Corporation, the assignee of this application. However, the particular type and design of the controller 60 is within the discretion of one of ordinary skill in the art to select and is not limiting of the invention.
- the refrigerant circulates through the refrigerant circuit via refrigerant line 22 to and through the heat exchange tube coil or tube bank of the condenser heat exchanger 32, wherein the refrigerant vapor condenses to a liquid, and the subcooler 32, thence through refrigerant line 24 through a first refrigerant pass of the refrigerant-to-refrigerant heat exchanger 35, and thence traversing the evaporator expansion device 46 before passing through the evaporator heat exchanger 42 and thence through refrigerant line 26, passing a second refrigerant pass of the refrigerant-to-refrigerant heat exchanger 35 before passing to the suction inlet of the compression device 20.
- the refrigerant evaporates, and is typically superheated, as it passes in heat exchange relationship the air passing through the airside of the evaporator 40.
- the air is drawn from within the cargo box 110 by the evaporator fan(s) 44, passed over the external heat transfer surface of the heat exchange tube coil or tube bank of the evaporator heat exchanger 42 and circulated back into the interior space 114 of the cargo box 110.
- the air drawn from the cargo box 110 is referred to as "return air” and the air circulated back to the cargo box 110 is referred to as "supply air".
- air as used herein includes mixtures of air and other gases, such as for example, but not limited to nitrogen or carbon dioxide, sometimes introduced into a refrigerated cargo transport box.
- a temperature sensor 45 is provided to sense the actual temperature of the return air drawn from the temperature controlled interior space 114 of the cargo box 110 before passing over the evaporator heat exchanger 42.
- an electrical resistance heater 70 is provided in operative association with the evaporator heat exchanger 42 to melt the accumulated frost/ice deposited on the heat transfer surface of the evaporator heat exchanger 42.
- the controller 60 will deactivate the compression device 20, the condenser fan(s) 34 and the evaporator fan(s) 44 for the duration of the defrost cycle and activate the electrical resistance heater 70 for the duration of the defrost cycle by selectively switching on the supply of electrical power from power source 50.
- the controller 60 will terminate the defrost cycle by deactivating, i.e. switching off the supply of electrical power to, the electrical resistance heater 70.
- the controller 60 may terminate the defrost cycle after a predetermined period of time in operation in the defrost cycle elapses or may terminate the defrost cycle based on a temperature signal from a coil defrost termination sensor indicative of a sensed surface temperature indicative of an external tube surface temperature of the evaporator heat exchanger 42.
- the controller 60 will return the refrigerant vapor compression system to operation in the cooling mode, by restarting the compression device 20, the condenser fan(s) 34 and the evaporator fan(s) 44.
- the controller 60 will initiate a defrost cycle based on an return air-saturation temperature differential (RASTD), which is defined as the actual return air temperature (RAT), which is sensed by the return air temperature sensor 45 at step 202, minus the refrigerant saturation temperature (ERST) within the evaporator heat exchanger 42.
- RASTD return air-saturation temperature differential
- RAT actual return air temperature
- ERST refrigerant saturation temperature
- the controller 60 uses the signal indicative of the sensed return air temperature generated by and received from the return air temperature sensor 45 in controlling operation of the refrigeration unit in the cooling mode and also uses the signal indicative of the sensed evaporator refrigerant pressure (ERP) generated by and received from the pressure sensor 48 at step 204 to calculate the evaporator refrigerant saturation temperature (ERST) for controlling the electronic expansion valve 46 to control superheat.
- ERP evaporator refrigerant pressure
- the controller 60 will, at step 206, determine the evaporator refrigerant saturation temperature (ERST) based upon the sensed evaporator refrigerant pressure (ERP) sensed by pressure sensor 48 at step 204, and at step 208 calculate the return air- saturation temperature differential (RASTD) by subtracting the evaporator refrigerant saturation temperature (ERST) from the actual return air temperature (RAT) sensed by the return air temperature sensor 45 at step 202.
- ERP evaporator refrigerant pressure
- RASTD return air- saturation temperature differential
- the controller 60 compares the calculated return air-saturation temperature differential (RASTD) to a defrost threshold defrost temperature differential (TDTD). If the calculated return air- saturation temperature differential does not exceed the defrost threshold approach temperature differential at block 212, the controller 60 continues operation of the refrigerant vapor compression system in the refrigeration (cooling) mode and repeats steps 202 through 210.
- RASTD calculated return air-saturation temperature differential
- TDTD defrost threshold defrost temperature differential
- the controller 60 interrupts operation of the refrigerant vapor compression system in the refrigeration (cooling) mode and initiates a defrost cycle to remove frost/ice accumulated on the heat transfer surface of the evaporator heat exchanger 42 in the manner discussed hereinbefore.
- the controller 60 continues operation of the refrigerant vapor compression system 10 in the defrost cycle until all or at least substantially all of the frost/ice accumulated on the heat transfer surface of the evaporator heat exchanger 42 has been removed.
- the controller 60 may calculate an adjusted evaporator refrigerant saturation temperature as a function of a plurality of instantaneous evaporator refrigeration saturation temperatures (ERSi) sensed at spaced time intervals (step 206) to filter out evaporator superheat control related noise and any influence on control logic.
- the controller 60 calculates the adjusted evaporator refrigerant saturation temperature as a running average of a plurality of instantaneous evaporator refrigerant saturation temperatures over a selected period of time.
- the controller 60 may calculate the adjusted evaporator refrigerant saturation temperature as an arithmetic mean of a plurality of instantaneous evaporator refrigerant saturation temperatures over a selected period of time.
- the adjusted evaporator refrigerant saturation temperature may be calculated as the arithmetic average or arithmetic mean of those instantaneous evaporator refrigerant saturation temperatures calculated over the immediately past three to five minutes.
- the controller 60 may compensate for variation in refrigerant mass flow rate through the evaporator heat exchanger 42 by adjusting the threshold defrost temperature differential (TDTD) as a function of the refrigerant mass flow rate.
- the controller 60 may select the threshold defrost return air-saturation temperature differential from an initiation curve of threshold defrost return air-saturation temperature differential versus refrigerant mass flow rate through the evaporator heat exchanger 42.
- the initiation curve may be empirically developed based on testing of the actual refrigerant vapor compression system in use.
- the controller 60 will compare the calculated return air-saturation temperature differential to a adjusted threshold defrost temperature differential selected from the aforementioned initiation curve based on the actual refrigerant mass flow rate through the evaporator heat exchanger 42 associated with the evaporator refrigerant saturation temperature used in calculating the return air-saturation temperature differential.
- the calculated return air-saturation temperature differential comprises an adjusted return air-saturation temperature differential based on a plurality of instantaneous return air-saturation temperature differentials
- the evaporator refrigerant mass flow rate associated therewith for purposes of selection of the adjusted threshold defrost temperature differential would be the corresponding average or mean evaporator refrigerant mass flow rate.
- the threshold defrost temperature differential may be selected based on a sensed "clean coil” return air-saturation temperature differential, For example, in implementing this aspect of the method, at the termination of each defrost cycle when the heat exchange surface of the evaporator heat exchanger 42 is substantially frost/ice free, the controller 60 will calculate a "clean coil” return air-saturation temperature differential based upon the then current sensed return air temperature and evaporator refrigerant saturation temperature. The controller 60 would then set the defrost threshold approach temperature differential for triggering the next defrost cycle to be a pre-determined temperature delta from that "clean coil” return air-saturation temperature differential.
- the return air-saturation temperature differential would need to exceed the actual "clean coil” return air-saturation temperature differential at termination of the last previous defrost cycle by a pre-determined temperature delta.
- the initiation of defrost cycles is automatically adapted in response to operating conditions associated with the particular product being shipped, local ambient conditions, loading, air flow variations, and other operational factors that may potentially influence frost/ice formation.
- the method for initiating a defrost cycle as discloses relies on information available from conventional sensors that are customarily provided on conventional refrigerant vapor compression systems and therefore does not require the installation of new hardware. Additionally, the method disclosed herein eliminates the need for an air pressure switch for initiating defrost, thereby reducing cost and improving overall reliability. Further, triggering defrost based on return air-saturation temperature differential in accord with the method disclosed herein, allows for more effective and more efficient cooling operation by reducing unnecessary run time in the cooling with a highly frosted evaporator while waiting for a safety type defrost to initiate because the air pressure switch failed to trigger a defrost cycle when needed..
- the expansion valve 46 throttles the refrigerant flow passing through the tubes of the evaporator heat exchanger 42 in an attempt to maintain the desired refrigerant superheat, which results in a drop in evaporator refrigerant pressure.
- the refrigerant saturation temperature also decreases.
- the controller 60 at step 216, will monitor the position of the expansion valve 46 and the degree of superheat in the refrigerant leaving the evaporator heat exchanger 42 as a feedback to detect whether the one demand defrost indication is the result of a low refrigerant flow condition through the evaporator heat exchanger 42 rather than the result of excessive frost build-up.
- the controller 60 will determine whether both the position of the expansion valve 46 and the superheat are within normal operating range. If so, the controller 60 will terminate operation in the cooling mode and initiate a defrost cycle. If not, the controller will continue operation in the cooling mode.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Defrosting Systems (AREA)
- Devices That Are Associated With Refrigeration Equipment (AREA)
Description
- This invention relates generally to refrigeration systems and, more particularly, to refrigerant vapor compression system evaporator coil defrost control and, more specifically, to the on demand initiation of a defrost cycle for the evaporator coil in response to a differential between return air temperature and evaporator refrigerant saturation temperature.
- Refrigerant vapor compression systems are well known in the art and commonly used for conditioning air to be supplied to a climate controlled comfort zone within a residence, office building, hospital, school, restaurant or other facility. Refrigerant vapor compression systems are also commonly used in refrigerating air supplied to display cases, merchandisers, freezer cabinets, cold rooms or other perishable/frozen product storage area in commercial establishments. Refrigerant vapor compression systems are also commonly used in transport refrigeration systems for refrigerating air supplied to a temperature controlled cargo space of a truck, trailer, container or the like for transporting perishable/frozen items by truck, rail, ship or intermodal.
- Refrigerant vapor compression systems typically include a compressor, a condenser, an evaporator, and an expansion device. These basic components are interconnected by refrigerant lines in a closed refrigerant circuit, arranged in accord with known refrigerant vapor compression cycles. The expansion device is disposed upstream, with respect to refrigerant flow, of the evaporator and downstream of the condenser. The evaporator includes a heat exchanger, typically a heat exchange tube coil, finned or un-finned, through which refrigerant flowing through the refrigerant circuit passes in heat exchange relationship with air drawn from and circulated back to a temperature controlled space. Because the air within the temperature controlled space will contain moisture, to varying degrees, whether the climate controlled be an air conditioned room, a refrigerated display case, or a temperature controlled transport cargo box, and because the temperature of the refrigerant flowing through the evaporator heat exchange tube coil may drop below the freezing point of water, in some applications and under certain operating conditions, moisture in the air flowing over the heat exchange tube coil will condense on the heat exchange surface of the tube coil and form frost. As the frost accumulates over time of system operation in a cooling mode, the frost builds up on heat exchange surface of the tube coil, adversely impacting heat transfer performance and restricting air flow over the tube coil.
- Consequently, it is customary practice to periodically interrupt system operation in a cooling mode and enter a defrost mode wherein the accumulated frost is melted off the evaporator tube coil. A defrost cycle can be accomplished by reversing the flow of refrigerant through the refrigerant circuit so as to circulate a heated refrigerant, typically hot refrigerant vapor, through the evaporator heat exchanger. Defrost may also be accomplished through the activation of one or more electrical resistance heater operatively associated with the evaporator heat exchange tube coil for heating the tube coil.
- In operating refrigerant vapor compression systems, knowing when to interrupt a cooling cycle to initiate a defrost cycle is important to operating the refrigerant vapor compression system in a most efficient manner. Initiating a defrost cycle at the expiration of specified time intervals of operation in the cooling mode is a simple, but inefficient, control method.
U.S. Pat. No. 6,205,800 discloses a method for defrosting on demand by initiating a defrost routine for removing condensate from an evaporator of a refrigerated device if the difference between the sensed air temperature within the refrigerated enclosure of the refrigerated device and the refrigerant temperature sensed by a refrigerant temperature sensor mounted on or disposed within the evaporator tube coil is greater or equal to a defrost threshold.U.S. Pat. No. 6,318,095 discloses controlling an outdoor coil defrost cycle on a reversible heat pump by continuously monitoring the difference between the outdoor coil temperature and the outdoor air temperature and initiating a defrost cycle when that difference exceeds a target value. - Refrigerant vapor compression systems used in connection with transport refrigeration systems are generally subject to more stringent operating conditions due to the wide range of refrigeration load conditions and the wide range of outdoor ambient conditions over which the refrigerant vapor compression system must operate to maintain product within the cargo space at a desired temperature. The refrigerant vapor compression system must not only have sufficient capacity to rapidly pull down the temperature of product loaded into the cargo space at ambient temperature, but also should operate energy efficiently over the entire load range, including at low load when maintaining a stable product temperature during transport.
- The air within the transport cargo box may have a particularly high moisture level after product is first loaded, therefore frost formation can be particularly troublesome during pull down when maximum cooling capacity is needed to draw down the product temperature as quickly as possible. Excessive accumulation of frost on the evaporator tube coil results in reduced heat transfer, which prolongs the time required for pull down. A common method currently in use in truck trailer applications for controlling initiation of a defrost cycle relies on a differential pressure switch that triggers a defrost cycle whenever the airside pressure drop across the evaporator tube coil exceeds a preset threshold.
- However, other factors that are not related to frost formation can also impact the airside pressure drop. For example, field installed air chutes can significantly alter the air flow patterns and low airside air flows through the evaporator may not be sufficient to cause the pressure differential switch to trigger despite excessive frost formation of the heat exchange surface of the evaporator tube coil. Further, when the system is operating at low fan speeds, for example such as during a stable temperature maintenance cooling mode or a low noise operational mode, the airside air flow through the evaporator may again be too low to cause the differential pressure switch to rigger despite excessive frost accumulation on the evaporator tube coil.
- Additionally, non-uniform frost/ice buildup is not an uncommon problem with respect to evaporators associated with refrigerant vapor compression systems in transport refrigeration applications. As a result of air flow maldistribution through the evaporator heat exchanger, frost/ice buildup may be heavy on some sections of the evaporator heat exchange surface and nearly non-existent on other sections of the evaporator heat exchange surface. The air flow over the heat transfer surface becomes restricted and may not generate enough pressure drop to trigger an air pressure defrost switch to defrost the sections of the evaporator that have heavy frost/ice accumulations. Typically, in transport refrigeration applications, the refrigeration unit is provided with a safety defrost which is automatically triggered whenever the temperature differential between the sensed return air temperature and a sensed evaporator heat exchanger surface temperature exceeds a preselected threshold, which is indicative of insufficient heated being absorbed by the refrigerant due to frost build-up on the evaporator heat exchange surface. The sensed surface temperature is typically taken by a thermister mounted to the heat exchanger tube sheet or a tube fin, but could also be mounted on the surface of a tube.
- Continued cooling operation with an excessively frosted coil is inefficient. Cooling capacity may roll-off by 75% or more over as little as two or three hours of operation in the cooling mode with an excessively frosted coil. Continued cooling operation with an excessively frosted coil also results in increased diesel fuel consumption to power the refrigeration unit. Therefore, an active and more direct method for initiating a defrost cycle that is directly influenced by the build-up of frost on the heat exchange surface of the evaporator tube coil is needed.
-
EP 0501387 andDE 3441921 disclose methods of the type defined in the preamble of claim 1. - Viewed from one aspect, the invention provides a method for controlling initiation of a defrost cycle of an evaporator heat exchanger of a refrigerant vapor compression system for supplying conditioned air to a temperature controlled space, the method comprising the steps of: establishing a return air-saturation temperature differential equal to the difference of a sensed air temperature of an air flow returning from the temperature controlled space to pass over the evaporator heat exchanger minus a refrigerant saturation temperature of a flow of refrigerant passing through the evaporator heat exchanger; comparing the return air-saturation temperature differential to a set point threshold defrost temperature differential; and if the return air-saturation temperature differential exceeds the set point threshold defrost temperature differential, initiating a defrost cycle for defrosting the evaporator heat exchanger and characterized by sensing a refrigerant pressure of and generating a signal indicative of the sensed refrigerant pressure of a flow of refrigerant passing through the evaporator heat exchanger at a plurality of spaced time intervals over a selected time period; calculating a plurality of refrigerant saturation temperatures, one per each one of the plurality of refrigerant pressures sensed over the selected time period; calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures; and establishing the return air- saturation temperature differential as the difference of the sensed air temperature minus the adjusted refrigerant saturation temperature. The step of calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures may include calculating the adjusted refrigerant saturation temperature as an arithmetic average of the plurality of refrigerant saturation temperatures.
- The step of calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures may include calculating the adjusted refrigerant saturation temperature as an arithmetic mean of the plurality of refrigerant saturation temperatures. In an aspect, the selected time period may range from at least about three minutes up to about five minutes.
- The method may include the further step of adjusting the set point threshold defrost temperature differential as a function of refrigerant mass flow rate of the refrigerant flowing through the evaporator heat exchanger prior to comparing the return air- saturation temperature differential to the set point threshold defrost temperature differential. In an aspect, the method may include the further steps of: calculating a clean coil temperature differential equal to the difference of the sensed return air temperature minus the refrigerant saturation temperature following termination of the defrost cycle; resetting the set point threshold defrost temperature to be the clean coil temperature differential plus a predetermined temperature delta; and initiating the next defrost cycle when the return air-saturation temperature differential exceeds the reset set point temperature differential.
- For a further understanding of the disclosure, reference will be made to the following detailed description which is to be read in connection with the accompanying drawing, wherein:
-
FIG. 1 is a perspective view of a truck trailer equipped with a refrigeration unit operatively associated with a temperature controlled cargo box; -
FIG. 2 is a schematic diagram of an exemplary embodiment of a refrigerant vapor compression system associated with the refrigeration unit of the truck trailer ofFIG. 1 ; -
FIG. 3 is a schematic illustration of an exemplary embodiment of the evaporator heat exchanger of the refrigerant vapor compression system ofFIG. 2 ; and -
FIG. 4 is a block diagram illustrating an exemplary embodiment of the method disclosed herein. -
FIG. 5 is a block diagram illustrating an alternate embodiment of the method illustrated inFIG. 4 ; and -
FIG. 6 is a block diagram illustrating an additional step to the method illustrated inFIG. 4 . - Referring initially to
FIG. 1 , there is shown atruck trailer 100 having a refrigerated cargo box 110 havingaccess doors 112 that open to theinterior space 114 of the cargo box from the exterior of the truck trailer to facilitate loading of product into the cargo box 110 for transport. Thetruck trailer 100 is equipped with a transport refrigeration unit 10 for regulating and maintaining a temperature controlled atmosphere within the cargo box during transport within a desired storage temperature range selected for the perishable product being shipped therein. Although the demand defrost method disclosed herein will be described herein with reference to the refrigerated cargo box of the depicted truck trailer, it is to be understood that the invention may also be used in connection with other refrigerated cargo transport boxes, including for example a refrigerated box of a truck, or a refrigerated cargo container for transporting perishable product by ship, by rail, by road or intermodal transport. The disclosed demand defrost method may also be applied to controlling evaporator defrost cycle initiation on demand in refrigerant vapor compression systems for supplying conditioned air to a temperature controlled space, such as use in connection with air conditioning systems and commercial refrigeration systems. - Referring now also to
FIG. 2 , the transport refrigeration unit 10 includes a refrigerantvapor compression system 12 and an associated power source. The refrigerantvapor compression system 12 includes acompression device 20, acondenser 30 having a heat exchanger and associated condenser fan(s) 34, anevaporator 40 having aheat exchanger 42 and associated evaporator fan(s) 44, and anevaporator expansion device 46, all arranged in a conventional refrigeration cycle and connected in a refrigerant circulation circuit includingrefrigerant lines tubular heat exchanger 32 and the evaporatortubular heat exchanger 42. The transport refrigeration system 10 is mounted as in conventional practice to an exterior wall of thetruck trailer 100, for example thefront wall 116 thereof, with thecompressor 20 and thecondenser 30 with its associated condenser fan(s) 34 andpower source 50 disposed externally of the refrigerated cargo box 110 in ahousing 118. - The
evaporator 40 extends through an opening in thefront wall 116 into the refrigerated cargo box 110. Theexpansion device 46, which in the depicted embodiment is an electronic expansion valve, but could be a thermostatic expansion valve, is disposed inrefrigerant line 24 downstream with respect to refrigerant flow of thecondenser heat exchanger 32 and upstream with respect to refrigerant flow of theevaporator heat exchanger 42 for metering the flow of refrigerant through the evaporator in response to the degree of superheat in the refrigerant at the outlet of theevaporator 40, as in conventional practice. A refrigerant pressure sensor 48 is mounted on thetubular heat exchanger 42 of theevaporator 40 for monitoring the sensing the refrigerant flowing through theevaporator heat exchanger 42 at or near the outlet thereof. Although the particular type ofevaporator heat exchanger 42 used is not limiting of the invention, theevaporator heat exchanger 42 may, for example, comprise one or more heat exchange tube coils, as depicted in the drawing, or one or more tube banks formed of a plurality of tubes extending between respective inlet and outlet manifolds. The tubes may be round tubes or flat tubes and may be finned or un-finned. - The
compressor 20 may comprise a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor, although the particular type of compressor used is not germane to or limiting of the invention. In the exemplary embodiment depicted inFig. 2 , the compressor is a reciprocating compressor, such as for example, an 06D model reciprocating compressor manufactured by Carrier Corporation or a variant thereof, having a compressing mechanism, an internal electric compressor motor and an interconnecting drive shaft that are all sealed within a common housing of thecompressor 20. Thepower source 50 powers the internal electric motor of the compressor. In an embodiment, thepower source 50 generates sufficient electrical power for fully driving the electrical motor of thecompressor 20 and also for providing all other electrical power required by thefans 34, 44 and other parts of the refrigeration unit 10. In an electrically powered embodiment of the transport refrigeration unit 10, thepower source 50 comprises a single on-board engine driven synchronous generator configured to selectively produce at least one AC voltage at one or more frequencies. An electrically powered transport refrigeration system suitable for use on truck trailer transport vehicles are shown inU.S. Pat. No. 6,223,546 , assigned to the assignee of the present application. - The transport refrigeration unit 10 also includes an
electronic controller 60 that is configured to operate the transport refrigeration unit 10 to maintain a predetermined thermal environment within theinterior space 114 defined within the cargo box 110 wherein the product is stored during transport. Theelectronic controller 60 maintains the predetermined thermal environment by selectively powering and controlling the operation of various components of the refrigerant vapor compression system, including thecompressor 20, the condenser fan(s) 34 associated with thecondenser 30, the evaporator fan(s) 44 associated with theevaporator 40, and various valves in the refrigerant circuit, including but not limited to the electronic expansion valve 46 (if present) and the suction modulation valve 62 (if present). When cooling of the environment withininterior space 114 of the cargo box 110 is required, theelectronic controller 60 activates thecompressor 20, the condenser fan(s) 34 and the evaporator fan(s) 44, as appropriate, and adjusts the position of theelectronic expansion valve 46 to meter the flow of refrigerant through theevaporator heat exchanger 42 to provide a desired degree of superheat in the refrigerant vapor at the evaporator outlet, and adjusts the position of thesuction modulation valve 62 to increase or decrease the flow of refrigerant supplied to thecompressor 20 as appropriate to control and stabilize the temperatures within theinterior space 114 within the cargo box 110 at the respective set point threshold defrost temperature, which corresponds to the desired product storage temperatures for the particular products stored within cargo box 110. - In one embodiment, the
electronic controller 60 includes a microprocessor and an associated memory. The memory of thecontroller 60 may be programmed to contain preselected operator or owner desired values for various operating parameters within the system, including, but not limited to, a temperature set point for the air within theinterior space 114 of the cargo box 110, refrigerant pressure limits, current limits, engine speed limits, and any variety of other desired operating parameters or limits within the system. The programming of the controller is within the ordinary skill in the art. Thecontroller 60 may include a microprocessor board that includes the microprocessor, an associated memory, and an input/output board that contains an analog-to-digital converter which receives temperature inputs and pressure inputs from a plurality of sensors located at various points throughout the refrigerant circuit and the refrigerated cargo box, current inputs, voltage inputs, and humidity levels. The input/output board may also include drive circuits or field effect transistors and relays which receive signals or current from thecontroller 60 and in turn control various external or peripheral devices associated with the transport refrigeration system. In an embodiment, thecontroller 60 may comprise the MicroLink™ controller available from Carrier Corporation, the assignee of this application. However, the particular type and design of thecontroller 60 is within the discretion of one of ordinary skill in the art to select and is not limiting of the invention. - As in conventional practice, when the refrigerant vapor compression system is in operation, low temperature, low pressure refrigerant vapor is compressed by the
compressor 20 to a high pressure, high temperature refrigerant vapor and passed from the discharge outlet of thecompressor 20 intorefrigerant line 22. The refrigerant circulates through the refrigerant circuit viarefrigerant line 22 to and through the heat exchange tube coil or tube bank of thecondenser heat exchanger 32, wherein the refrigerant vapor condenses to a liquid, and thesubcooler 32, thence throughrefrigerant line 24 through a first refrigerant pass of the refrigerant-to-refrigerant heat exchanger 35, and thence traversing theevaporator expansion device 46 before passing through theevaporator heat exchanger 42 and thence throughrefrigerant line 26, passing a second refrigerant pass of the refrigerant-to-refrigerant heat exchanger 35 before passing to the suction inlet of thecompression device 20. - In flowing through the heat exchange tube coil or tube bank of the
evaporator heat exchanger 42, the refrigerant evaporates, and is typically superheated, as it passes in heat exchange relationship the air passing through the airside of theevaporator 40. The air is drawn from within the cargo box 110 by the evaporator fan(s) 44, passed over the external heat transfer surface of the heat exchange tube coil or tube bank of theevaporator heat exchanger 42 and circulated back into theinterior space 114 of the cargo box 110. The air drawn from the cargo box 110 is referred to as "return air" and the air circulated back to the cargo box 110 is referred to as "supply air". It is to be understood that the term "air' as used herein includes mixtures of air and other gases, such as for example, but not limited to nitrogen or carbon dioxide, sometimes introduced into a refrigerated cargo transport box. Atemperature sensor 45 is provided to sense the actual temperature of the return air drawn from the temperature controlledinterior space 114 of the cargo box 110 before passing over theevaporator heat exchanger 42. - During operation of the refrigerant vapor compression system in a cooling mode, moisture in the return air will condense onto the heat transfer surface, i.e. surface of the tubes and the fins if finned tubes are present, of the
evaporator heat exchanger 42 as the return air is cooled in passing in heat exchange relationship with the refrigerant flowing through theevaporator heat exchanger 42. The condensate will freeze on the heat transfer surface of theevaporator heat exchanger 42 and tend to accumulate as a layer of frost and/or ice on the heat transfer surface of theevaporator heat exchanger 42. As the frost/ice layer builds-up, heat transfer performance of theevaporator heat exchanger 42 deteriorates and the airside flow area through theevaporator heat exchanger 42 becomes more and more restricted. Therefore, operation of the refrigerant vapor compression system in the cooling mode must be interrupted to conduct an evaporator defrost cycle whenever the accumulated frost/ice layer becomes excessive. - Referring now to
FIG. 3 , anelectrical resistance heater 70 is provided in operative association with theevaporator heat exchanger 42 to melt the accumulated frost/ice deposited on the heat transfer surface of theevaporator heat exchanger 42. Whenever a defrost cycle is to be implemented, thecontroller 60 will deactivate thecompression device 20, the condenser fan(s) 34 and the evaporator fan(s) 44 for the duration of the defrost cycle and activate theelectrical resistance heater 70 for the duration of the defrost cycle by selectively switching on the supply of electrical power frompower source 50. - The
controller 60 will terminate the defrost cycle by deactivating, i.e. switching off the supply of electrical power to, theelectrical resistance heater 70. Thecontroller 60 may terminate the defrost cycle after a predetermined period of time in operation in the defrost cycle elapses or may terminate the defrost cycle based on a temperature signal from a coil defrost termination sensor indicative of a sensed surface temperature indicative of an external tube surface temperature of theevaporator heat exchanger 42. After termination of the defrost cycle, thecontroller 60 will return the refrigerant vapor compression system to operation in the cooling mode, by restarting thecompression device 20, the condenser fan(s) 34 and the evaporator fan(s) 44. Thus, during defrost cycle operation, not only is the air to the controlled space not being cooled, but the heat transfer surface of theevaporator heat exchanger 42 is also being heated. - Referring now to
FIG. 4 , in accord with the method disclosed herein, thecontroller 60 will initiate a defrost cycle based on an return air-saturation temperature differential (RASTD), which is defined as the actual return air temperature (RAT), which is sensed by the returnair temperature sensor 45 atstep 202, minus the refrigerant saturation temperature (ERST) within theevaporator heat exchanger 42. Thecontroller 60 uses the signal indicative of the sensed return air temperature generated by and received from the returnair temperature sensor 45 in controlling operation of the refrigeration unit in the cooling mode and also uses the signal indicative of the sensed evaporator refrigerant pressure (ERP) generated by and received from the pressure sensor 48 atstep 204 to calculate the evaporator refrigerant saturation temperature (ERST) for controlling theelectronic expansion valve 46 to control superheat. Additionally, in accord with an aspect of the method disclosed herein, thecontroller 60 will, atstep 206, determine the evaporator refrigerant saturation temperature (ERST) based upon the sensed evaporator refrigerant pressure (ERP) sensed by pressure sensor 48 atstep 204, and atstep 208 calculate the return air- saturation temperature differential (RASTD) by subtracting the evaporator refrigerant saturation temperature (ERST) from the actual return air temperature (RAT) sensed by the returnair temperature sensor 45 atstep 202. - The
controller 60, atstep 210, compares the calculated return air-saturation temperature differential (RASTD) to a defrost threshold defrost temperature differential (TDTD). If the calculated return air- saturation temperature differential does not exceed the defrost threshold approach temperature differential atblock 212, thecontroller 60 continues operation of the refrigerant vapor compression system in the refrigeration (cooling) mode and repeatssteps 202 through 210. However, if the calculated return air- saturation temperature differential exceeds the defrost threshold defrost temperature differential atblock 214, thecontroller 60, interrupts operation of the refrigerant vapor compression system in the refrigeration (cooling) mode and initiates a defrost cycle to remove frost/ice accumulated on the heat transfer surface of theevaporator heat exchanger 42 in the manner discussed hereinbefore. Thecontroller 60 continues operation of the refrigerant vapor compression system 10 in the defrost cycle until all or at least substantially all of the frost/ice accumulated on the heat transfer surface of theevaporator heat exchanger 42 has been removed. - Referring now to
FIG. 5 , in an aspect of the method depicted therein, atstep 207, thecontroller 60 may calculate an adjusted evaporator refrigerant saturation temperature as a function of a plurality of instantaneous evaporator refrigeration saturation temperatures (ERSi) sensed at spaced time intervals (step 206) to filter out evaporator superheat control related noise and any influence on control logic. In an embodiment, thecontroller 60 calculates the adjusted evaporator refrigerant saturation temperature as a running average of a plurality of instantaneous evaporator refrigerant saturation temperatures over a selected period of time. In an embodiment, thecontroller 60 may calculate the adjusted evaporator refrigerant saturation temperature as an arithmetic mean of a plurality of instantaneous evaporator refrigerant saturation temperatures over a selected period of time. For example, the adjusted evaporator refrigerant saturation temperature may be calculated as the arithmetic average or arithmetic mean of those instantaneous evaporator refrigerant saturation temperatures calculated over the immediately past three to five minutes. - In an aspect of the method disclosed herein, the
controller 60 may compensate for variation in refrigerant mass flow rate through theevaporator heat exchanger 42 by adjusting the threshold defrost temperature differential (TDTD) as a function of the refrigerant mass flow rate. For example, thecontroller 60 may select the threshold defrost return air-saturation temperature differential from an initiation curve of threshold defrost return air-saturation temperature differential versus refrigerant mass flow rate through theevaporator heat exchanger 42. The initiation curve may be empirically developed based on testing of the actual refrigerant vapor compression system in use. In determining whether or not to initiate a defrost cycle, thecontroller 60 will compare the calculated return air-saturation temperature differential to a adjusted threshold defrost temperature differential selected from the aforementioned initiation curve based on the actual refrigerant mass flow rate through theevaporator heat exchanger 42 associated with the evaporator refrigerant saturation temperature used in calculating the return air-saturation temperature differential. If the calculated return air-saturation temperature differential comprises an adjusted return air-saturation temperature differential based on a plurality of instantaneous return air-saturation temperature differentials, then the evaporator refrigerant mass flow rate associated therewith for purposes of selection of the adjusted threshold defrost temperature differential would be the corresponding average or mean evaporator refrigerant mass flow rate. - In a further aspect of the method disclosed herein, the threshold defrost temperature differential may be selected based on a sensed "clean coil" return air-saturation temperature differential, For example, in implementing this aspect of the method, at the termination of each defrost cycle when the heat exchange surface of the
evaporator heat exchanger 42 is substantially frost/ice free, thecontroller 60 will calculate a "clean coil" return air-saturation temperature differential based upon the then current sensed return air temperature and evaporator refrigerant saturation temperature. Thecontroller 60 would then set the defrost threshold approach temperature differential for triggering the next defrost cycle to be a pre-determined temperature delta from that "clean coil" return air-saturation temperature differential. Thus, to trigger a defrost cycle, the return air-saturation temperature differential would need to exceed the actual "clean coil" return air-saturation temperature differential at termination of the last previous defrost cycle by a pre-determined temperature delta. In this aspect of the method disclosed herein, the initiation of defrost cycles is automatically adapted in response to operating conditions associated with the particular product being shipped, local ambient conditions, loading, air flow variations, and other operational factors that may potentially influence frost/ice formation. - The method for initiating a defrost cycle as discloses relies on information available from conventional sensors that are customarily provided on conventional refrigerant vapor compression systems and therefore does not require the installation of new hardware. Additionally, the method disclosed herein eliminates the need for an air pressure switch for initiating defrost, thereby reducing cost and improving overall reliability. Further, triggering defrost based on return air-saturation temperature differential in accord with the method disclosed herein, allows for more effective and more efficient cooling operation by reducing unnecessary run time in the cooling with a highly frosted evaporator while waiting for a safety type defrost to initiate because the air pressure switch failed to trigger a defrost cycle when needed..
- As frost builds up on the tube coil or tube bank of the
evaporator heat exchanger 42, the air flow through theevaporator 40 goes down the airside pressure drop increases. Consequently, the refrigerant flowing through the heat exchanger tubes absorbs less heat. Therefore, without as much heat going into the refrigerant, theexpansion valve 46 throttles the refrigerant flow passing through the tubes of theevaporator heat exchanger 42 in an attempt to maintain the desired refrigerant superheat, which results in a drop in evaporator refrigerant pressure. Thus, the refrigerant saturation temperature also decreases. As the refrigerant saturation temperature goes lower and lower a s the expansion valve continues to throttle the refrigerant flow, the temperature differential with respect to the sensed return air temperature increases, which will lead to a demand defrost when the threshold defrost temperature differential is exceeded. However, a low refrigerant pressure condition resulting from a low refrigerant flow in the evaporator despite a wide open valve (for example 90% or more open), which could result from a loss of refrigerant charge, could result in an on demand defrost cycle being called for when the frost build-up per se does not warrant a defrost. Referring now toFIG. 6 , to avoid the initiation of an on demand defrost cycle, thecontroller 60, atstep 216, will monitor the position of theexpansion valve 46 and the degree of superheat in the refrigerant leaving theevaporator heat exchanger 42 as a feedback to detect whether the one demand defrost indication is the result of a low refrigerant flow condition through theevaporator heat exchanger 42 rather than the result of excessive frost build-up. Thecontroller 60 will determine whether both the position of theexpansion valve 46 and the superheat are within normal operating range. If so, thecontroller 60 will terminate operation in the cooling mode and initiate a defrost cycle. If not, the controller will continue operation in the cooling mode. - The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as basis for teaching one skilled in the art to employ the present invention. Those skilled in the art will also recognize the equivalents that may be substituted for elements described with reference to the exemplary embodiments disclosed herein without departing from the scope of the present invention.
- While the present invention has been particularly shown and described with reference to the exemplary embodiment as illustrated in the drawing, it will be recognized by those skilled in the art that various modifications may be made without departing from the scope of the invention. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as, but that the disclosure will include all embodiments falling within the scope of the appended claims.
Claims (9)
- A method for controlling initiation of a defrost cycle of an evaporator heat exchanger (42) of a refrigerant vapor compression system (12) for supplying conditioned air to a temperature controlled space, the method comprising the steps of:establishing a return air-saturation temperature differential (202) equal to the difference of a sensed air temperature of an air flow returning from the temperature controlled space to pass over the evaporator heat exchanger (42) minus a refrigerant saturation temperature of a flow of refrigerant passing through the evaporator heat exchanger (42);comparing the return air-saturation temperature differential to a set point threshold defrost temperature differential (210); andif the return air-saturation temperature differential exceeds the set point threshold defrost temperature differential (214), initiating a defrost cycle for defrosting the evaporator heat exchanger (42) and characterized by sensing a refrigerant pressure (204) of and generating a signal indicative of the sensed refrigerant pressure of a flow of refrigerant passing through the evaporator heat exchanger (42) at a plurality of spaced time intervals over a selected time period (206);calculating a plurality of refrigerant saturation temperatures, one per each one of the plurality of refrigerant pressures sensed over the selected time period (206);calculating an adjusted refrigerant saturation temperature (207) based on the plurality of refrigerant saturation temperatures; andestablishing the return air-saturation temperature differential (208) as the difference of the sensed air temperature minus the adjusted refrigerant saturation temperature.
- The method as recited in claim 1 further comprising the step of sensing the air temperature (202) of and generating a signal indicative of the sensed air temperature of an air flow returning from the temperature controlled space to pass over the evaporator heat exchanger (42).
- The method as recited in claim 1 wherein the step of calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures comprises calculating the adjusted refrigerant saturation temperature as an arithmetic average of the plurality of refrigerant saturation temperatures.
- The method as recited in claim 1 wherein the step of calculating an adjusted refrigerant saturation temperature based on the plurality of refrigerant saturation temperatures comprises calculating the adjusted refrigerant saturation temperature as an arithmetic mean of the plurality of refrigerant saturation temperatures.
- The method as recited in claim 1 wherein the selected time period ranges from at least about three minutes up to about five minutes.
- The method as recited in claim 1 further comprising the step of adjusting the set point threshold defrost temperature differential as a function of refrigerant mass flow rate of the refrigerant flowing through the evaporator heat exchanger (42) prior to comparing the return air-saturation temperature differential to the set point threshold defrost temperature differential (210).
- The method as recited in claim 1 further comprising the steps of:calculating a clean coil temperature differential equal to the difference of the sensed return air temperature minus the refrigerant saturated temperature following termination of the defrost cycle;resetting the set point threshold defrost temperature differential to be the clean coil temperature differential plus a predetermined temperature delta; andinitiating the next defrost cycle when the return air-saturation temperature differential exceeds the reset set point threshold defrost temperature differential (214).
- The method as recited in claim 1 further comprising the step of determining that the position of an evaporator expansion valve is within normal operating range prior to initiating a demand defrost.
- A method as recited in any preceding claim being for controlling initiation of a defrost cycle of an evaporator heat exchanger (42) of a refrigeration system operatively associated with a refrigerated transport cargo box (110).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US36065110P | 2010-07-01 | 2010-07-01 | |
PCT/US2011/042311 WO2012003202A2 (en) | 2010-07-01 | 2011-06-29 | Evaporator refrigerant saturation demand defrost |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2588819A2 EP2588819A2 (en) | 2013-05-08 |
EP2588819B1 true EP2588819B1 (en) | 2019-12-11 |
Family
ID=44628120
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP11730522.7A Active EP2588819B1 (en) | 2010-07-01 | 2011-06-29 | Evaporator refrigerant saturation demand defrost |
Country Status (5)
Country | Link |
---|---|
US (1) | US20130086929A1 (en) |
EP (1) | EP2588819B1 (en) |
CN (1) | CN103069230B (en) |
ES (1) | ES2762238T3 (en) |
WO (1) | WO2012003202A2 (en) |
Families Citing this family (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104813119B (en) * | 2012-07-31 | 2017-05-17 | 开利公司 | Frozen evaporator coil detection and defrost initiation |
EP2717002B1 (en) * | 2012-10-08 | 2019-01-02 | Emerson Climate Technologies GmbH | Method for determining thaw times |
WO2014070292A1 (en) * | 2012-10-30 | 2014-05-08 | Carrier Corporation | Drying a refrigerated cargo box following wash out prior to loading |
CN104515255A (en) * | 2013-09-30 | 2015-04-15 | 郑州科林车用空调有限公司 | Method and system of passenger car air conditioner for regulating temperature through intelligent combined control on temperature and humidity |
US10254027B2 (en) * | 2014-05-02 | 2019-04-09 | Thermo King Corporation | Method and system for controlling operation of evaporator fans in a transport refrigeration system |
US20150343881A1 (en) * | 2014-05-27 | 2015-12-03 | Alliance For Sustainable Energy, Llc | Evaporative cooling cycling using water condensate formed in a vapor-compression a/c system evaporator |
US10442272B2 (en) | 2014-08-22 | 2019-10-15 | Thermo King Corporation | Method and system for defrosting a heat exchanger |
US10935329B2 (en) | 2015-01-19 | 2021-03-02 | Hussmann Corporation | Heat exchanger with heater insert |
EP3311085B1 (en) | 2015-06-19 | 2022-02-09 | Carrier Corporation | Transport refrigeration unit and method of operating the same |
US10168067B2 (en) * | 2015-09-22 | 2019-01-01 | Lennox Industries Inc. | Detecting and handling a blocked condition in the coil |
EP3362333B1 (en) | 2015-10-16 | 2020-04-22 | Carrier Corporation | Flexible cooling system for vehicles |
CN108027185B (en) * | 2015-10-27 | 2020-06-05 | 株式会社电装 | Refrigeration cycle device |
CN108603706B (en) * | 2016-02-05 | 2021-03-23 | 三菱电机株式会社 | Air conditioner |
WO2017155965A1 (en) | 2016-03-07 | 2017-09-14 | Carrier Corporation | Return air intake grille de-icing method |
US20170292770A1 (en) * | 2016-04-07 | 2017-10-12 | Hussmann Corporation | Refrigeration system with fluid defrost |
US10759326B2 (en) | 2016-05-27 | 2020-09-01 | Carrier Corporation | Method for determining reduced airflow in transport refrigeration system |
CN106839258A (en) * | 2016-12-06 | 2017-06-13 | 珠海格力电器股份有限公司 | Air cooler and defrosting control device and method thereof |
CN111936805B (en) | 2018-04-13 | 2022-07-05 | 开利公司 | Method for defrosting a refrigeration system |
US11493260B1 (en) | 2018-05-31 | 2022-11-08 | Thermo Fisher Scientific (Asheville) Llc | Freezers and operating methods using adaptive defrost |
ES2894502T3 (en) | 2018-06-22 | 2022-02-14 | Danfoss As | A procedure to finish defrosting an evaporator |
EP3587962B1 (en) | 2018-06-22 | 2020-12-30 | Danfoss A/S | A method for terminating defrosting of an evaporator by use of air temperature measurements |
US11740004B2 (en) | 2019-06-26 | 2023-08-29 | Carrier Corporation | Transportation refrigeration unit with adaptive defrost |
CN112594983A (en) * | 2020-12-08 | 2021-04-02 | 格力电器(合肥)有限公司 | Refined forward circulating deicing system of air conditioner and control method |
EP4148348A1 (en) * | 2021-09-09 | 2023-03-15 | SHR GmbH | Method and apparatus for controlling the cleaning and cooling process of heat exchangers |
CN116263263A (en) * | 2021-12-13 | 2023-06-16 | 开利公司 | Method for changing defrosting trigger of heat pump |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4142374A (en) * | 1977-09-16 | 1979-03-06 | Wylain, Inc. | Demand defrost time clock control circuit |
DE3333907A1 (en) * | 1983-09-20 | 1985-04-04 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8000 München | METHOD AND DEVICE FOR DEFROSTING HEAT PUMPS |
DE3441912C2 (en) * | 1984-11-16 | 1994-05-05 | Fichtel & Sachs Ag | Defrost control for a heat pump |
DE3539817A1 (en) * | 1985-11-09 | 1987-05-14 | Licentia Gmbh | Method for metrologically determining, displaying and/or evaluating the icing occurring on the cooling plates of an air cooler |
DE4105880A1 (en) * | 1991-02-25 | 1992-08-27 | Kueba Kaeltetechnik Gmbh | METHOD AND DEVICE FOR OPTIMIZING THE PERFORMANCE AND DEFROSTING OF REFRIGERANT EVAPORATORS |
US5381669A (en) * | 1993-07-21 | 1995-01-17 | Copeland Corporation | Overcharge-undercharge diagnostic system for air conditioner controller |
US5440890A (en) * | 1993-12-10 | 1995-08-15 | Copeland Corporation | Blocked fan detection system for heat pump |
US6223546B1 (en) | 1999-04-21 | 2001-05-01 | Robert A. Chopko | Electrically powered transport refrigeration unit |
US6205800B1 (en) * | 1999-05-12 | 2001-03-27 | Carrier Corporation | Microprocessor controlled demand defrost for a cooled enclosure |
US6334321B1 (en) * | 2000-03-15 | 2002-01-01 | Carrier Corporation | Method and system for defrost control on reversible heat pumps |
US6318095B1 (en) | 2000-10-06 | 2001-11-20 | Carrier Corporation | Method and system for demand defrost control on reversible heat pumps |
DE10311343A1 (en) * | 2003-03-14 | 2004-09-23 | Linde Kältetechnik GmbH & Co. KG | Defrosting method for e.g. evaporator, involves initiating defrosting when temperature at middle of evaporator is lower than critical temperature or temperature difference between middle and inlet of evaporator is lower than set value |
US8136363B2 (en) * | 2005-04-15 | 2012-03-20 | Thermo King Corporation | Temperature control system and method of operating the same |
CN100465555C (en) * | 2005-07-26 | 2009-03-04 | 三菱电机株式会社 | Refrigerating air conditioner |
US7752853B2 (en) * | 2005-10-21 | 2010-07-13 | Emerson Retail Services, Inc. | Monitoring refrigerant in a refrigeration system |
US20100107661A1 (en) * | 2007-02-02 | 2010-05-06 | Awwad Nader S | Method for operating transport refrigeration unit with remote evaporator |
JP5528119B2 (en) * | 2008-01-21 | 2014-06-25 | 三菱電機株式会社 | Heat pump device and air conditioner or water heater equipped with the heat pump device |
JP4642100B2 (en) * | 2008-09-01 | 2011-03-02 | 三菱電機株式会社 | Heat pump equipment |
EP2366968B1 (en) * | 2010-03-17 | 2017-05-17 | Wolf GmbH | Method and device for thawing an evaporator of a heat pump device |
-
2011
- 2011-06-29 WO PCT/US2011/042311 patent/WO2012003202A2/en active Application Filing
- 2011-06-29 ES ES11730522T patent/ES2762238T3/en active Active
- 2011-06-29 US US13/704,314 patent/US20130086929A1/en not_active Abandoned
- 2011-06-29 CN CN201180042426.8A patent/CN103069230B/en active Active
- 2011-06-29 EP EP11730522.7A patent/EP2588819B1/en active Active
Non-Patent Citations (1)
Title |
---|
None * |
Also Published As
Publication number | Publication date |
---|---|
ES2762238T3 (en) | 2020-05-22 |
CN103069230B (en) | 2017-08-04 |
WO2012003202A2 (en) | 2012-01-05 |
WO2012003202A3 (en) | 2012-08-16 |
US20130086929A1 (en) | 2013-04-11 |
CN103069230A (en) | 2013-04-24 |
EP2588819A2 (en) | 2013-05-08 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP2588819B1 (en) | Evaporator refrigerant saturation demand defrost | |
US10619902B2 (en) | Controlling chilled state of a cargo | |
EP2880375B1 (en) | Frozen evaporator coil detection and defrost initiation | |
US9869499B2 (en) | Method for detection of loss of refrigerant | |
EP2118590B1 (en) | Method for operating transport refrigeration unit with remote evaporator | |
US8136363B2 (en) | Temperature control system and method of operating the same | |
US4680940A (en) | Adaptive defrost control and method | |
EP2217872B1 (en) | Control method of refrigerator | |
CN107923665B (en) | Multi-compartment transport refrigeration system with economizer | |
US8538585B2 (en) | Control of pull-down in refrigeration systems | |
US9791175B2 (en) | Intelligent compressor flooded start management | |
JP5483995B2 (en) | Control of cargo refrigeration | |
EP3320277B1 (en) | Multi-compartment transport refrigeration system with economizer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20130102 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
DAX | Request for extension of the european patent (deleted) | ||
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: EXAMINATION IS IN PROGRESS |
|
17Q | First examination report despatched |
Effective date: 20180301 |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
INTG | Intention to grant announced |
Effective date: 20190702 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE PATENT HAS BEEN GRANTED |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: REF Ref document number: 1212594 Country of ref document: AT Kind code of ref document: T Effective date: 20191215 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602011063930 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: IE Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: FP |
|
REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG4D |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200311 Ref country code: BG Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200311 Ref country code: FI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200312 Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2762238 Country of ref document: ES Kind code of ref document: T3 Effective date: 20200522 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: RS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: HR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: CZ Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: RO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200506 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20200411 Ref country code: SM Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 602011063930 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: MK05 Ref document number: 1212594 Country of ref document: AT Kind code of ref document: T Effective date: 20191211 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
26N | No opposition filed |
Effective date: 20200914 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: SI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: PL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MC Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200629 |
|
REG | Reference to a national code |
Ref country code: BE Ref legal event code: MM Effective date: 20200630 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200629 Ref country code: LI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200630 Ref country code: CH Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200630 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200630 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: TR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: MT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 Ref country code: CY Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: MK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20191211 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 20220523 Year of fee payment: 12 |
|
P01 | Opt-out of the competence of the unified patent court (upc) registered |
Effective date: 20230527 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: ES Payment date: 20230703 Year of fee payment: 13 |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: MM Effective date: 20230701 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20230701 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20240521 Year of fee payment: 14 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20240521 Year of fee payment: 14 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20240521 Year of fee payment: 14 |