Transcritical CO2 heat pump water heater system optimal exhaust pressure extreme value searching control system and method

Abstract

The invention provides a transcritical CO2 heat pump water heater system optimal exhaust pressure extreme value searching control system and method. In the system, an outlet of a compressor is connected with a refrigerant pipeline inlet of a gas cooler; a refrigerant pipeline outlet of a gas cooler is connected with an inlet of an evaporator through a first pipeline and an electronic expansion valve of a middle heat exchanger; the evaporator is connected with the inlet of a gas-liquid separator; a gas outlet of the gas-liquid separator is connected with an inlet of the compressor through a second pipeline of the middle heat exchanger; system input controlled by an extreme value searching controller is the consumed work measurement value of the compressor; system output is the exhaust pressure set value of the compressor; the water flow and inlet temperature for heat exchange in the gas cooler are kept unchanged, and a first PI controller is used for controlling the rotation speed of the compressor, so that the water-side outlet temperature is not changed; and the exhaust pressure of the compressor is controlled by a second controller by changing the effective circulation area of the electronic expansion valve. The transcritical CO2 heat pump water heater system optimal exhaust pressure extreme value searching control system and method can ensure efficient and stable operation of transcritical CO2 heat pumps.

Description

technical field [0001] The invention belongs to the technical field of heat pumps, in particular to a CO 2 Heat pump control system and method. Background technique [0002] In recent years, as people pay more and more attention to environmental issues, the use of environmentally friendly refrigerants has increasingly become the focus of the government and various research institutions. Among them, the use of natural working fluids as refrigerants is the most important part. CO 2 It has good environmental protection performance and will not have any adverse effects on the environment as a refrigerant. Since G. Lorentzen, former president of the International Institute of Refrigeration, proposed modern transcritical CO 2 cycle since, for transcritical CO 2 The research and application of refrigeration devices has once again become a hot spot that has received worldwide attention. [0003] The thermal efficiency and reliability of ordinary heat pump water heaters decrease...

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Problems solved by technology

However, in engineering practice, due to the differences of the respective systems, the optimal exhaust pressure is also different when the main working conditions considered by the correlation are the same, so it is difficult to popularize in the actual exhaust pressure control

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