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EP-4265979-B1 - HEAT-PUMP WATER HEATER, AND CONTROL METHOD THEREFOR

EP4265979B1EP 4265979 B1EP4265979 B1EP 4265979B1EP-4265979-B1

Inventors

  • DU, Shunxiang
  • CHEN, BINGQUAN
  • YU, Jinjian
  • HUANG, JUAN
  • ZHAO, Runpeng
  • ZHANG, Xiaoqi
  • HUANG, Junji

Dates

Publication Date
20260506
Application Date
20211015

Claims (14)

  1. A heat-pump water heater comprising: - a water tank (3); - an evaporator (1); - a compressor (2) having a refrigerant outlet; - a heat exchange unit (4) comprising at least one condenser (41) disposed on the water tank (3) and connected to the refrigerant outlet of the compressor (2); - a primary expansion valve (5) arranged between an outlet of the heat exchange unit (4) and an inlet of the evaporator (1); and - a controller in communication with the primary expansion valve (5), the controller being configured, in a rapid heating mode, to control an opening degree of the primary expansion valve (5), characterised in that the water tank (3) is divided into at least three heating areas along a height direction of the water tank (3), each of the heating areas is provided with a separate condenser (41), every two adjacent condensers (41) are connected in series through a communicating pipe such that the heat exchange unit (4) is formed, a refrigerant inlet of a condenser (41) at a first end of the heat exchange unit (4) is connected to the refrigerant outlet of the compressor (2), and a refrigerant outlet of a condenser (41) at a second end of the heat exchange unit (4) is connected to a refrigerant inlet of the evaporator (1); wherein each communicating pipe between every two adjacent condensers (41) is provided with a secondary expansion valve (6), the controller is in communication connection with the secondary expansion valves (6) and is configured, in the rapid heating mode, to control an initial opening degree of the primary expansion valve (5) to be larger than an initial opening degree of the secondary expansion valves (6); and wherein every two adjacent heating areas are connected through a connection pipe, connection pipes between every two adjacent heating areas are provided with flow limiting valves (7), respectively, the flow limiting valves (7) are in communication connection with the controller, and the controller is configured to control at least part of the flow limiting valves (7) to be closed in the rapid heating mode.
  2. The heat-pump water heater according to claim 1, wherein a refrigerant inlet of the compressor (2) is provided with a first temperature sensing device (8) for measuring temperature of a refrigerant, and each of the heating areas is provided with a water temperature detection unit (31) for measuring water temperature, the evaporator (1) is provided with a temperature measurement unit (11) for measuring temperature of the evaporator (1), and the first temperature sensing device (8), the water temperature detection unit (31), and the temperature measurement unit (11) are all in communication connection with the controller; the controller controls the primary expansion valve (5) to adjust its opening degree in response to a first difference between a difference of temperatures measured by the first temperature sensing device (8) and by the temperature measurement unit (11) and a target suction superheat temperature difference; the controller controls each secondary expansion valve (6) between condensers (41) in two adjacent heating areas to adjust its opening degree in response to a second difference between a difference of temperatures detected by water temperature detection units (31) in the two adjacent heating areas and a target temperature difference.
  3. The heat-pump water heater according to claim 1 or 2, wherein the refrigerant outlet of the compressor (2) is provided with a second temperature sensing device (9), and the second temperature sensing device (9) is in communication connection with the controller; the controller controls the primary expansion valve (5) and/or the secondary expansion valve (6) to adjust their opening degrees in response to a temperature measured by the second temperature sensing device (9).
  4. The heat-pump water heater according to claim 3, further comprising a motor and a fan (10), the fan (10) is connected to the motor in a transmission way and provided close to the evaporator (1), the motor is electrically connected to the controller, the controller controls a rotation speed of the motor in response to the temperature measured by the second temperature sensing device (9).
  5. The heat-pump water heater according to any one of claims 1-4, wherein an electric heating element is provided in the water tank (3), and the electric heating element is configured to heat water stored in the water tank (3).
  6. A control method for the heat-pump water heater according to claim 1, comprising: starting the heat-pump water heater; controlling, by a controller, an initial opening degree of a primary expansion valve (5) to be larger than an initial opening degree of a secondary expansion valve (6) according to a rapid-heating-mode instruction received by the controller.
  7. The control method according to claim 6, further comprising: controlling, by the controller, the primary expansion valve (5) to adjust its opening degree in response to a first difference between a difference of temperatures detected by a temperature measurement unit (11) on an evaporator (1) and by a first temperature sensing device (8) on a refrigerant inlet of a compressor (2) and a target suction superheat temperature difference; and measuring, by water temperature detection units (31), water temperatures in two adjacent heating areas, respectively, and controlling, by the controller, a secondary expansion valve (6) between condensers (41) in the heating areas to adjust its opening degree according to a second difference between a difference of the temperatures detected by the two water temperature detection units (31) and a target temperature difference.
  8. The control method according to claim 7, wherein the controlling, by the controller, the primary expansion valve (5) to adjust its opening degree in response to the first difference between the difference of the temperatures detected by the temperature measurement unit (11) on the evaporator (1) and by the first temperature sensing device (8) and the target suction superheat temperature difference specifically comprising: when the first difference is larger than 0, controlling the primary expansion valve (5) to increase its opening degree; when the first difference is lower than 0, controlling the primary expansion valve (5) to reduce its opening degree.
  9. The control method according to claim 7 or 8, wherein the measuring, by the water temperature detection units (31), the water temperatures in the two adjacent heating areas respectively, and controlling, by the controller, the secondary expansion valve (6) between the condensers (41) provided in the heating areas to adjust its opening degree according to the second difference between the difference of temperatures detected by the two water temperature detection units (31) and the target temperature difference specifically comprising: when the second difference is larger than 0, controlling the secondary expansion valve (6) to increase its opening degree; when the second difference is lower than 0, controlling the secondary expansion valve (6) to reduce its opening degree.
  10. The control method according to any one of claims 6-9, further comprising: controlling, by the controller, the primary expansion valve (5) and/or the secondary expansion valve (6) to adjust their opening degrees according to a relationship of values between the temperature detected by the second temperature sensing device (9) and a first preset temperature.
  11. The control method according to claim 10, wherein the controlling, by the controller, the primary expansion valve (5) and/or the secondary expansion valve (6) to adjust their opening degrees according to the relationship of values between the temperature detected by the second temperature sensing device (9) and the first preset temperature specifically comprising: when the temperature detected by the second temperature sensing device (9) is not lower than the first preset temperature, the controller controls the primary expansion valve (5) and the secondary expansion valve (6) to increase their opening degrees; when the temperature detected by the second temperature sensing device (9) is lower than the first preset temperature, the controller controls the primary expansion valve (5) and/or the secondary expansion valve (6) to adjust their opening degrees according to the relationship of values between the temperature detected by the second temperature sensing device (9) and a second preset temperature; wherein the second preset temperature is lower than the first preset temperature.
  12. The control method according to claim 11, wherein the controlling, by the controller, the primary expansion valve (5) and/or the secondary expansion valve (6) to adjust their opening degrees according to the relationship of values between the temperature detected by the second temperature sensing device (9) and the second preset temperature specifically comprising: when the temperature detected by the second temperature sensing device (9) is not lower than the second preset temperature, the controller controls the primary expansion valve (5) to increase its opening degree, and controls the second expansion valve to adjust its opening degree in response to the second difference; when the temperature detected by the second temperature sensing device (9) is lower than the second preset temperature, the controller controls the primary expansion valve (5) to adjust its opening degree in response to the first difference, and controls the second expansion valve to adjust its opening degree in response to the second difference.
  13. The control method according to any one of claims 10-12, further comprising: controlling, by the controller, a rotation speed of a motor of the heat-pump water heater according to the relationship of values between the temperature detected by the second temperature sensing device (9) and the first preset temperature.
  14. The control method according to any one of claims 6-13, further comprising: controlling, by the controller, the initial opening degree of the primary expansion valve (5) to be smaller than that of the secondary expansion valve (6) according to a full-tank-heating-mode instruction received by the controller.

Description

TECHNICAL FIELD The invention relates to the technical field of household appliances, and in particular to a heat-pump water heater and a control method for the heat-pump water heater. BACKGROUND Heat-pump water heater is a device that uses a refrigerant to absorb low-temperature heat energy in air and transfer it to a water tank to prepare hot water, which has advantages of energy saving and high efficiency. Specifically, a heat-pump water heater includes a water tank, an evaporator, a compressor, a primary expansion valve and a condenser. The condenser is disposed in the water tank, and the primary expansion valve is provided between the condenser and the evaporator. When the heat-pump water heater is on service, the evaporator absorbs heat in the surrounding environment, such that the refrigerant at the evaporator is heated up and gasified into a low-temperature and low-pressure gas. Then, the low-temperature and low-pressure refrigerant flows to the compressor to be compressed into a high-temperature and high-pressure gas. The high-temperature and high-pressure gaseous refrigerant enters the condenser of the water tank to be condensed and release heat, such that the water in the water tank is heated up. Meanwhile, the refrigerant after releasing heat turns into a medium-temperature and high-pressure liquid. Then the medium-temperature and high-pressure liquid refrigerant is turned into a low-temperature and low-pressure gas-liquid mixture under an action of the primary expansion valve, and then flows back to the evaporator to absorb heat and be heated up. This process repeats itself to realize the production of hot water. However, when the water amount consumed by a user is small, the user waits for a long time for the water to be heated. CN110986436A discloses a heat pump water heater. The heat pump water heater comprises an inner container and a heat pump unit. The heat pump unit comprises a compressor, a condenser, a first throttling device and an evaporator which are connected together. The condenser comprises a first sub-condenser, a second sub-condenser and a valve assembly, wherein the first sub-condenser is disposed on the inner container; the second sub-condenser is disposed on the inner container and is located below the first sub-condenser; and the valve assembly is connected between the first sub-condenser and the second sub-condenser, and the valve assembly is used for selectively throttling a refrigerant output from the first sub-condenser. CN110500803A discloses a heat pump system. The heat pump system comprises a compressor, a first heat exchanger, a fan, a second heat exchanger, a temperature sensor, a four-way reversing valve and a control module, wherein an outlet of the compressor is connected to the first heat exchanger through the four-way reversing valve; the first heat exchanger comprises at least one coil pipe; the first heat exchanger is connected to the second heat exchanger through a pipeline; the second heat exchanger is connected to an inlet of the compressor through the four-way reversing valve; and the self-cleaning operation of a heat pump is realized through the self-cleaning steps of the control module. CN112033003A discloses a method of controlling a heat pump water heater. The heat pump water heater comprises a first condenser and a second condenser which are disposed up and down along a water tank, a refrigerant outlet of the first condenser is connected with a refrigerant inlet of the second condenser through a first refrigerant branch pipe, and an adjusting valve is disposed on the first refrigerant branch pipe; and a refrigerant inlet of the second condenser is further connected with a refrigerant header pipe through a second refrigerant branch pipe, and a switch valve is disposed on the second refrigerant branch pipe. A controller is in communication connection with the adjusting valve and the switch valve respectively and used for controlling the switch valve to be opened and controlling the opening degree of the adjusting valve to be reduced to 20-30 B in the layered heating mode. CN110906588A discloses a micro-channel heat exchanger, a heat pump water heater and a control method thereof. The micro-channel heat exchanger includes: two collecting tubes; a plurality of first micro-channel tubes disposed side by side and connected between the two collecting tubes to form a first heating flow path; a plurality of second micro-channel tubes disposed side by side and connected between the two collecting tubes to form a second heating flow path, and the second micro-channel tubes are located below the first micro-channel tubes; a valve assembly connected between the first heating flow path and the second heating flow path, and the valve assembly is configured to selectively throttle a refrigerant output from the first heating flow path. SUMMARY The present invention is set out in the appended set of claims. Embodiments of this application provide a heat-pump water he