WO2009094691A1 - Methods and apparatuses for operating heat pumps in hot water systems - Google Patents
Methods and apparatuses for operating heat pumps in hot water systems Download PDFInfo
- Publication number
- WO2009094691A1 WO2009094691A1 PCT/AU2008/001884 AU2008001884W WO2009094691A1 WO 2009094691 A1 WO2009094691 A1 WO 2009094691A1 AU 2008001884 W AU2008001884 W AU 2008001884W WO 2009094691 A1 WO2009094691 A1 WO 2009094691A1
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- Prior art keywords
- evaporator
- fan
- compressor
- heat pump
- ambient air
- Prior art date
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- 238000000034 method Methods 0.000 title claims abstract description 39
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 109
- 239000012080 ambient air Substances 0.000 claims abstract description 51
- 239000003507 refrigerant Substances 0.000 claims abstract description 46
- 239000003570 air Substances 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 abstract description 10
- 239000008235 industrial water Substances 0.000 abstract description 3
- 238000004891 communication Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 238000005485 electric heating Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000008450 motivation Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Classifications
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- 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
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D11/00—Central heating systems using heat accumulated in storage masses
- F24D11/02—Central heating systems using heat accumulated in storage masses using heat pumps
- F24D11/0214—Central heating systems using heat accumulated in storage masses using heat pumps water heating system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/136—Defrosting or de-icing; Preventing freezing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/212—Temperature of the water
- F24H15/223—Temperature of the water in the water storage tank
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/258—Outdoor temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/375—Control of heat pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/375—Control of heat pumps
- F24H15/38—Control of compressors of heat pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/414—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/414—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based
- F24H15/45—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based remotely accessible
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
- F24D19/1009—Arrangement or mounting of control or safety devices for water heating systems for central heating
- F24D19/1039—Arrangement or mounting of control or safety devices for water heating systems for central heating the system uses a heat pump
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- 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
- F25B2339/00—Details of evaporators; Details of condensers
- F25B2339/04—Details of condensers
- F25B2339/047—Water-cooled condensers
-
- 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
- F25B2500/00—Problems to be solved
- F25B2500/31—Low ambient temperatures
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- 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
- F25B2600/00—Control issues
- F25B2600/02—Compressor control
- F25B2600/025—Compressor control by controlling speed
- F25B2600/0251—Compressor control by controlling speed with on-off operation
-
- 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
- F25B2600/00—Control issues
- F25B2600/11—Fan speed control
- F25B2600/112—Fan speed control of evaporator fans
-
- 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
- F25B2600/00—Control issues
- F25B2600/23—Time delays
-
- 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
- F25B2700/2106—Temperatures of fresh outdoor air
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- 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
- F25D21/06—Removing frost
- F25D21/12—Removing frost by hot-fluid circulating system separate from the refrigerant system
- F25D21/125—Removing frost by hot-fluid circulating system separate from the refrigerant system the hot fluid being ambient air
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
Definitions
- the present invention relates to the operation of heat pumps that may be used in hot water systems and more particularly to the operation of such heat pumps under low ambient temperature conditions.
- Heat pumps are devices or systems that move heat from a 'source' location to a 'sink' location using work. Heat pumps operate by exploiting the physical properties of an evaporating and condensing fluid known as a refrigerant.
- the refrigerant in a 0 pressurised gaseous state, is circulated through the heat pump circuit by a compressor.
- hot and highly pressurised gas is cooled in a heat exchanger known as a condenser until the gas condenses into a high pressure liquid at a relatively more moderate temperature.
- the condensed refrigerant then passes through a pressure-lowering device such as a thermostatic expansion valve or capillary tube, which 5 passes the low pressure, barely liquid, refrigerant to another heat exchanger, known as an evaporator, where the refrigerant evaporates into a gas via heat absorption.
- a pressure-lowering device such as a thermostatic expansion valve or capillary tube
- the refrigerant evaporates into a gas via heat absorption.
- the refrigerant is then returned to the compressor and the cycle is repeated.
- Coefficient of Performance is a measure used to describe energy efficiency, that is, the amount of heat moved per unit of work. COP values are thus relatively higher when the ambient air temperature is much less or much greater than the water temperature in a hot water system. When the ambient air temperature is substantially lower or substantially higher than the actual or demanded water temperature (i.e., at relatively higher COP values), the heat pump becomes subject to excessive strain.
- One conventional method of operating under such temperature conditions is to turn off the heat pump and employ a booster (e.g., an auxiliary electric heating element) to heat the water.
- a method for operating a heat pump in low ambient air temperatures comprises the steps of: periodically or temporarily halting flow of refrigerant through an evaporator of the heat pump; and providing forced airflow across the evaporator while the refrigerant flow is halted.
- the step of periodically or temporarily halting flow of refrigerant through an evaporator may comprise the step of repeatedly turning a compressor of the heat pump off for a first predetermined time period and on for a second predetermined time period. The second predetermined time period is greater than the first predetermined time period.
- the heat pump circuit is adapted to hold a charge of refrigerant.
- the electronic controller is adapted to: obtain ambient air temperature values from the temperature sensor; repeatedly turn the compressor on and off while the ambient air temperature values are lower than a first predetermined temperature value; and operate the fan to provide forced airflow across the evaporator while the compressor is turned off.
- the electronic controller may be adapted to cyclically operate the compressor by repeatedly turning the compressor off for a first predetermined time duration and on for a second predetermined time duration.
- the second predetermined time duration is greater than the first predetermined time duration.
- a hot water system comprising: a water tank for storing water; a heat pump circuit comprising a compressor, a pressure- lowering device, an evaporator, and a condenser in a heat exchanging relationship with the water in the water tank; a fan adapted to generate airflow across the evaporator; a first temperature sensor adapted to determine ambient air temperature; and an electronic controller coupled to the compressor, the fan and the first temperature sensor.
- the electronic controller is adapted to: obtain ambient air temperature values from the temperature sensor; repeatedly turn the compressor on and off while the ambient air temperature values are lower than a first predetermined temperature value; and operate the fan to provide forced airflow across the evaporator while the compressor is turned off.
- the hot water system may further comprise a second temperature sensor coupled to the electronic controller and adapted to determine temperature of water in the water tank.
- the electronic controller is further adapted to: obtain water temperature values from the second temperature sensor; and turn off the compressor and the fan when the water temperature exceeds a third predetermined temperature.
- the electronic controller may be adapted to cyclically operate the compressor by repeatedly turning the compressor off for a first predetermined time duration and on for a second predetermined time duration.
- the second predetermined time duration is greater than the first predetermined time duration.
- the step of temporarily halting flow of refrigerant through the evaporator and reversing the direction of the forced airflow across the evaporator may be performed periodically while the heat pump is operational to heat water in the tank of the hot water system and ambient air temperature is lower than a predetermined temperature value.
- the flow of refrigerant through the evaporator may be halted and the direction of the fan reversed for a period of approximately 30 minutes every 2 hours.
- the direction of the fan may be reversed to provide forced airflow onto a side of the evaporator that is less susceptible to icing.
- a hot water system comprising: a water tank for storing water; a heat pump circuit comprising a compressor, a pressure- lowering device, an evaporator, and a condenser in a heat exchanging relationship with said water in the water tank; a fan adapted to provide forced airflow across the evaporator; a temperature sensor adapted to determine ambient air temperature; and an electronic controller coupled to the compressor, the fan and the temperature sensor.
- the electronic controller is adapted to: obtain ambient air temperature values from the temperature sensor; operate the fan to provide forced airflow across the evaporator while the heat pump is operational to heat water in the water tank; and temporarily halt flow of refrigerant through the evaporator and reverse the direction of the forced airflow across the evaporator while ambient air temperature is lower than a predetermined temperature value.
- Fig. 1 is a schematic block diagram of an embodiment of a heat pump
- Fig. 2 is a flow diagram of a method for operating a heat pump, such as the heat pump of Fig. 1, in a hot water system;
- Fig. 3 is a schematic block diagram of an electronic controller for operating a heat pump, such as the heat pump of Fig. 1; and Fig. 4 is a schematic block diagram of another embodiment of a heat pump.
- Embodiments of methods and apparatuses are described hereinafter for operating a heat pump under low ambient temperature conditions.
- the embodiments are described with reference to a heat pump used to heat water in a hot water system, it is not intended to limit the present invention in this manner.
- the embodiments described hereinafter may have application for operating heat pumps used for other purposes such as heating systems for buildings (e.g., reverse cycle air conditioning).
- references to hot water systems in this specification are intended to include both domestic and industrial water heating systems.
- Fig. 1 shows an embodiment of a heat pump 100.
- the heat pump 100 has a heat pump circuit comprising an evaporator 170, a compressor 150, a condenser 140 and a pressure reducing device 130 such as a thermostatic expansion valve (TX valve).
- the heat pump circuit is configured such that the outlet of the compressor 150 is coupled to an inlet of the condenser 140, an outlet of the condenser 140 is coupled to the inlet of the pressure reducing device 130, the outlet of the pressure reducing device 130 is coupled to an inlet of the evaporator 170, and an outlet of the evaporator 170 is coupled to an inlet of the compressor 150.
- TX valve thermostatic expansion valve
- the heat pump circuit is adapted to hold a charge of refrigerant that is circulated through the heat pump circuit by the compressor 150 in a direction shown by the arrows 190.
- the foregoing components of the heat pump 100 operate to produce a refrigeration cycle, as is well known to persons skilled in the art.
- a fan 160 is used to generate airflow 180 across the evaporator 170.
- the fan 160 may comprise a single, multi or variable speed fan. Operation of the compressor 150 and the fan 160 is controlled by an electronic controller 120, which is coupled to a source of electricity (not shown), typically mains power.
- a temperature sensor 110 is also coupled to the electronic controller 120, for determining and providing the electronic controller 120 with ambient temperature values.
- the condenser 140 is typically positioned in a heat exchanging relationship with a body of water contained in a tank 145 of the hot water system.
- the heat pump 100 may become subject to excessive strain when the ambient air temperature is substantially lower or substantially higher than the actual or demanded water temperature. Furthermore, when the ambient air temperature is substantially lower than the water temperature, moisture in the air condenses and forms ice on the evaporator and other refrigerant bearing components used to couple the evaporator to the heat pump circuit.
- An embodiment of the present invention provides a method for operating the heat pump 100 in low ambient air temperatures.
- the method comprises temporarily or periodically halting the flow of refrigerant through the evaporator 170 of the heat pump 100 and providing forced airflow from the fan 160 across the evaporator 170 while the refrigerant flow is halted.
- Forced airflow from the fan 160 is preferably provided for the entire duration the refrigerant flow is halted. However, this is not essential as the forced airflow may only need to be maintained for a substantial portion of the time the refrigerant flow is halted.
- the refrigerant flow through the evaporator 170 may be halted by switching off the compressor 150.
- An effect of halting the flow of refrigerant is that the forced airflow from the fan 160 causes the static refrigerant in the evaporator 170 to heat up. This causes the difference in temperature between the refrigerant and the ambient air to reduce significantly, which in turn causes any ice build-up on the evaporator 170 and associated coupling components to melt. De-icing is assisted by the use of a single wall evaporator structure.
- the fan 160 is adapted to draw air to heat the refrigerant in the evaporator 170.
- the direction of forced airflow as indicated by arrow 180 in Fig. 1 is across the evaporator 170 towards the fan 160.
- the forced airflow first strikes the side of the evaporator 170 that is most susceptible to icing as a consequence of low ambient temperature conditions.
- the inventor has discovered that operating the fan 160 in the reverse direction to cause forced airflow from the fan 160 towards the side of the evaporator 170 less susceptible to icing (i.e., forced airflow in a direction opposite to that indicated by the arrow 180 in Fig.
- the fan 160 is adapted to provide forced air flow in the direction of arrow 180 during normal (i.e., non-de-icing) operation and is reversed during de-icing operation to provide forced air flow in the direction opposite to arrow 180.
- the fan 160 may be adapted to always provide forced airflow in the direction opposite to arrow 180 (i.e., during both normal and de-icing operation).
- the effect of the moving refrigerant during normal operation i.e., compressor 150 operating
- the forced airflow may additionally be caused to pass in close proximity to the compressor 150, thereby providing forced airflow at an increased temperature which will assist de-icing.
- Fig. 2 is a flow diagram of a method for operating a heat pump, such as the heat pump 100 of Fig. 1.
- the method of Fig. 2 may be practiced as a computer program executed by the electronic controller 120 of Fig. 1.
- the method begins at step 210, during which hardware and/or software of the electronic controller 120 is initialised.
- a counter may be initialised for time duration measurement purposes.
- the main program loop includes step 270 and is executed approximately once per minute. However, those skilled in the art will appreciate that other main program loop delay intervals may alternatively be practiced.
- step 220 a determination is made at step 226 whether the water temperature at the top of the water tank of the hot water system (T t ) is greater than a predetermined value of 58 0 C. If so (Y), the water in the tank does not require further heating and the compressor, fan and counter are turned off at step 228. Step 228 effectively turns off the heat pump. The method then proceeds to step 270 of the main loop. If the water in the tank does require further heating (Y), at step 226, the method proceeds directly to step 270 of the main loop without turning the heat pump off.
- step 230 a determination is made whether the ambient air temperature is less than a predetermined value of -5 0 C. If so (Y), the heat pump is effectively turned off from step 232 onwards. A determination is made, at step 232, whether the compressor is on. If so (Y), the compressor is turned off at step 234. After waiting for a delay of 30 minutes at step 236, the counter is turned off at step 238 and the fan is turned off at step 240. Thereafter, the method proceeds to step 270 of the main loop. If the compressor is already off (N), at step 232, the method proceeds directly to step 270 of the main loop.
- step 230 de-icing is performed.
- step 258 After waiting for a delay of 30 minutes at step 258, the counter is turned off at step 260 and the compressor is turned on again at step 262. Thereafter, the method proceeds to step 270 of the main loop. As described hereinbefore with reference to Fig. 2, the compressor is turned on for
- De-icing can be accelerated by increasing airflow across the evaporator, which can be implemented by use of a multi-speed fan.
- a multi-speed fan may also be used to assist heat pump performance at high ambient or water temperatures by decreasing airflow and consequently reducing refrigerant pressure. Forced airflow from the fan is preferably maintained for the entire duration the compressor is turned off. However, this is not essential as the forced airflow may only need to be maintained for a substantial portion of the time the compressor is turned off.
- Fig. 3 is a schematic block diagram of an embodiment of the electronic controller 120 in Fig. 1. Control of the heat pump 100 is performed by a software control program resident in the memory of the microcontroller 310.
- the microcontroller 310 comprises a Microchip PIC16F676 CMOS 8-bit microcontroller.
- the PIC16F676 has 1,792 bytes of flash-based program memory, 64 bytes of RAM and 128 bytes of EEPROM and also includes an on-board 10-bit analog-to-digital (A/D) converter.
- A/D analog-to-digital
- other microcontrollers or microprocessors may alternatively be practiced in the controller 310.
- Various memory and peripheral configurations may also be practiced, such as a combination of on-board and off-board memory.
- the microcontroller 310 controls components of the heat pump 100 via output ports that are interfaced to the devices by means of input/output interface circuitry 320.
- the compressor 150 and the fan 160 are controlled via relays, which form part of the input/output interface circuitry 320.
- alternative control elements may also be practiced, including solid state switches such as thyristors and triacs.
- the relays or control elements for the fan enable reversing of the direction of the fan.
- the microcontroller 310 obtains data from components of the heat pump 100 and/or hot water system via input ports that are interfaced to the devices by means of input/output interface circuitry 320. For example, ambient air temperature data is obtained from the temperature sensor 110 of Fig. 1. Furthermore, the microcontroller 310 may also obtain data relating to the temperature of the water at the top and/or bottom of the hot water tank 145 (T t and Tb, respectively) from temperature sensors (not shown in Fig. 1) coupled via the input/output interface circuitry to input ports of the microcontroller 310. Thus, the microcontroller 310 is able to control the compressor 150 and the fan 160 in accordance with external variables such as water temperature, ambient air temperature, etc.
- the microcontroller 310 may also be coupled to an RF transceiver 350 via an RF communications interface 340 for receiving information from and/or transmitting information to a remote entity. Such information may, for example, be used to remotely monitor system performance (e.g., hot water temperature) and/or hot water consumption.
- the RF transceiver 350 may comprise a communications module for cellular telephone type communication (e.g., GSM, GPRS or CDMA). Other types of communications transceivers may alternatively be practiced, which may use communications channels such as the ultra-high frequency (UHF), very-high frequency (VHF) or microwave bands. Still further, a receiver only may be practiced in place of the RF transceiver 350.
- the RF transceiver may be used to communicate with fixed or mobile, hand-held RF communication devices.
- the microcontroller 310 may also be coupled to an RS-232 communications interface 330 to provide a communication link to a computer apparatus (not shown).
- Various other types of communications interfaces may be practiced in place of the RS- 232 interface, such as a RS-485 interface, a parallel interface, an infra-red interface, a Universal Serial Bus (USB) interface, or any other commonly available or proprietary communications interfaces.
- the computer apparatus may comprise a Personal Computer (PC), a Personal Digital Assistant (PDA), a mobile telephone, or any other off-the-shelf or proprietary computer apparatus. Parameters for operation of the controller 310 may be adjusted by, and/or downloaded to, the controller 310 from such a computer apparatus via the RS-232 communications interface 330.
- bootstrap loader software installed in the program memory of the microcontroller 310 enables downloading of new and/or revised control software to the controller 310 via the RS-232 communications interface 330.
- the microcontroller 310, RF communications interface 340, the RF transceiver 350 and the RS-232 communications interface 330 are powered by a power supply 360, which typically receives input power from the mains supply.
- electronic controller described hereinbefore with reference to Fig. 3 is an example of an electronic controller that may be used to practice embodiments of the present invention.
- Various other types of electronic controllers may alternatively be practiced, including an electronic circuit that does not include a microprocessor or microcontroller.
- Fig. 4 shows another embodiment of a heat pump 400.
- the heat pump 400 is similar to the heat pump 100 of Fig. 1 in that components having the same reference designators in Figs. 1 and 4 are similar or substantially identical.
- the evaporator 170, the fan 160, the compressor 150, the condenser 140 and the pressure reducing device 130 in Figs. 1 and 4 are equivalent or similar in functionality.
- the fan 160 in the embodiment of Fig. 4 is adapted to blow air in the direction of the arrow 480 towards the evaporator 170.
- the evaporator 170 comprises two main operational sides or surfaces for heat exchanging, namely sides 172 and 174. One of the sides is generally more susceptible to icing, for example, on account of being exposed to lower ambient temperatures.
- the forced airflow from the fan 160 strikes the side 174 of the evaporator 170 that is less susceptible to icing. That is, the side 172 of the evaporator 170 is more susceptible to icing.
- the fan 1670 is operated to blow air in the direction of the arrow 480 for a 0.5 hour period every 2 hours to perform de-icing.
- other periods and/or values may alternatively be practiced.
- the fan 160 is typically only turned on to provide forced airflow across the evaporator 170 during water heating to heat the refrigerant in the evaporator 170.
- a predetermined temperature value e.g. 8 0 C
- the flow of refrigerant through the evaporator 170 is temporarily halted (e.g., the compressor 150 is turned off) and the direction of the fan 160 is temporarily reversed (e.g., to provide or direct forced airflow in the direction of arrow 480 in Fig. 4).
- Halting the flow of refrigerant through the evaporator 170 and reversing the direction of the fan 160 is typically performed periodically while the heat pump is operational to heat water in the tank of the hot water system and the ambient air temperature is lower than the predetermined temperature value.
- flow of refrigerant through the evaporator 170 is halted and the direction of the fan 160 is reversed for a period of approximately 30 minutes every 2 hours.
- forced airflow is provided or directed onto a side of the evaporator 170 that is less susceptible to icing (e.g., with reference to Fig. 4, the direction of forced airflow indicated by the arrow 480 onto the side 174 of the evaporator 170 that is less susceptible to icing, compared to the side 172 of the evaporator 170 that is more susceptible to icing).
- Embodiments described hereinbefore advantageously enable operation of a heat pump at low ambient temperatures.
- Embodiments described hereinbefore also provide a means for de-icing components of a heat pump (e.g., an evaporator), when operating at low ambient temperatures.
- a heat pump e.g., an evaporator
- a significant advantage of the embodiments described is that no supplementary de-icing equipment or energy is required.
- the embodiments are particularly applicable to heat pumps having an evaporator located outdoors, such as domestic and industrial water heating systems.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2008349147A AU2008349147B2 (en) | 2008-01-30 | 2008-12-19 | Methods and apparatuses for operating heat pumps in hot water systems |
NZ586966A NZ586966A (en) | 2008-01-30 | 2008-12-19 | Method for operating a heat pump in low air temperatures by modulating refrigerant and air movements |
CN2008801259552A CN101932892B (en) | 2008-01-30 | 2008-12-19 | Methods and apparatuses for operating heat pumps in hot water systems |
US12/811,731 US20110005245A1 (en) | 2008-01-30 | 2008-12-19 | Methods and apparatuses for operating heat pumps in hot water systems |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2008900409 | 2008-01-30 | ||
AU2008900409A AU2008900409A0 (en) | 2008-01-30 | Methods and apparatuses for operating heat pumps in hot water systems | |
AU2008904653A AU2008904653A0 (en) | 2008-09-08 | Methods and apparatuses for opening heat pumps in hot water systems | |
AU2008904653 | 2008-09-08 |
Publications (1)
Publication Number | Publication Date |
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WO2009094691A1 true WO2009094691A1 (en) | 2009-08-06 |
Family
ID=40912151
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU2008/001884 WO2009094691A1 (en) | 2008-01-30 | 2008-12-19 | Methods and apparatuses for operating heat pumps in hot water systems |
Country Status (5)
Country | Link |
---|---|
US (1) | US20110005245A1 (en) |
CN (1) | CN101932892B (en) |
AU (1) | AU2008349147B2 (en) |
NZ (1) | NZ586966A (en) |
WO (1) | WO2009094691A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102052768A (en) * | 2011-02-14 | 2011-05-11 | 广州德能热源设备有限公司 | Digital heat pump hot water unit |
DE102011051285A1 (en) | 2011-06-23 | 2012-12-27 | Visteon Global Technologies, Inc. | Method for freezing prevention control for evaporator of heat pump of air conditioner in vehicle, involves determining dew point of ambient air present before vehicle, and setting flow speed of ambient air |
DE102012102041A1 (en) | 2012-03-09 | 2013-09-12 | Audi Ag | Apparatus and method for anti-icing control for heat pump evaporators |
WO2021231092A1 (en) * | 2020-05-11 | 2021-11-18 | Rheem Manufacturing Company | Systems and methods for reducing frost accumulation on heat pump evaporator coils |
Families Citing this family (8)
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JP5263421B1 (en) * | 2012-03-30 | 2013-08-14 | 三浦工業株式会社 | Water heating system |
CN103884104B (en) * | 2012-12-21 | 2016-08-24 | 珠海格力电器股份有限公司 | A kind of control method based on Teat pump boiler, device, controller and system |
US10782052B2 (en) * | 2014-08-26 | 2020-09-22 | Syracuse University | Micro environmental control system |
US10056807B2 (en) * | 2014-12-23 | 2018-08-21 | Orange Motor Company L.L.C. | Electronically commutated fan motors and systems |
CN112901319B (en) * | 2014-12-31 | 2022-12-16 | 康明斯排放处理公司 | Closely coupled single module aftertreatment system |
US20170045238A1 (en) * | 2015-08-12 | 2017-02-16 | General Electric Company | Method for operating a heat pump water heater appliance |
CN107525267A (en) * | 2017-09-15 | 2017-12-29 | 佛山市澳霆环境设备制造有限公司 | A kind of high-efficient compressor system |
US10465935B2 (en) * | 2017-10-20 | 2019-11-05 | Mitsubishi Electric Corporation | Air-conditioning apparatus |
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JP2004116955A (en) * | 2002-09-27 | 2004-04-15 | Mitsubishi Electric Corp | Heat pump type water heater |
US20050189431A1 (en) * | 2002-01-29 | 2005-09-01 | Hiroshi Nakayama | Heat pump type water heater |
GB2434196A (en) * | 2005-12-21 | 2007-07-18 | Martin Hook | Heating module and system controller for increasing the efficiency of heat pumps |
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NZ528678A (en) * | 2003-10-06 | 2006-11-30 | Energy Saving Concepts Ltd | Heat pump with refrigerant from high pressure side passed through heat exchanger to prevent ice formation on evaporator |
CN2767925Y (en) * | 2005-01-10 | 2006-03-29 | 颜世峰 | Heating cycle system for air energy heat pump |
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- 2008-12-19 NZ NZ586966A patent/NZ586966A/en not_active IP Right Cessation
- 2008-12-19 US US12/811,731 patent/US20110005245A1/en not_active Abandoned
- 2008-12-19 CN CN2008801259552A patent/CN101932892B/en not_active Expired - Fee Related
- 2008-12-19 AU AU2008349147A patent/AU2008349147B2/en not_active Ceased
- 2008-12-19 WO PCT/AU2008/001884 patent/WO2009094691A1/en active Application Filing
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US20050189431A1 (en) * | 2002-01-29 | 2005-09-01 | Hiroshi Nakayama | Heat pump type water heater |
JP2004116955A (en) * | 2002-09-27 | 2004-04-15 | Mitsubishi Electric Corp | Heat pump type water heater |
GB2434196A (en) * | 2005-12-21 | 2007-07-18 | Martin Hook | Heating module and system controller for increasing the efficiency of heat pumps |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102052768A (en) * | 2011-02-14 | 2011-05-11 | 广州德能热源设备有限公司 | Digital heat pump hot water unit |
DE102011051285A1 (en) | 2011-06-23 | 2012-12-27 | Visteon Global Technologies, Inc. | Method for freezing prevention control for evaporator of heat pump of air conditioner in vehicle, involves determining dew point of ambient air present before vehicle, and setting flow speed of ambient air |
DE102011051285B4 (en) * | 2011-06-23 | 2015-11-12 | Halla Visteon Climate Control Corporation | Method and device for anti-icing control for evaporators of a heat pump of air conditioning systems in vehicles |
DE102012102041A1 (en) | 2012-03-09 | 2013-09-12 | Audi Ag | Apparatus and method for anti-icing control for heat pump evaporators |
WO2013132046A1 (en) | 2012-03-09 | 2013-09-12 | Visteon Global Technologies, Inc. | Device and method for icing prevention regulation for heat pump evaporators |
DE102012102041B4 (en) * | 2012-03-09 | 2019-04-18 | Audi Ag | Apparatus and method for anti-icing control for heat pump evaporators |
US10914504B2 (en) | 2012-03-09 | 2021-02-09 | Audi Ag | Device and method for icing prevention regulation for heat pump evaporators |
WO2021231092A1 (en) * | 2020-05-11 | 2021-11-18 | Rheem Manufacturing Company | Systems and methods for reducing frost accumulation on heat pump evaporator coils |
US11466910B2 (en) | 2020-05-11 | 2022-10-11 | Rheem Manufacturing Company | Systems and methods for reducing frost accumulation on heat pump evaporator coils |
Also Published As
Publication number | Publication date |
---|---|
CN101932892B (en) | 2012-10-24 |
AU2008349147A1 (en) | 2009-08-06 |
NZ586966A (en) | 2012-01-12 |
CN101932892A (en) | 2010-12-29 |
AU2008349147B2 (en) | 2013-11-28 |
US20110005245A1 (en) | 2011-01-13 |
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