Experimental Study on the Control Optimization of Compressor Frequency and Electronic Expansion Valve With CO2 Heat Pump Water Heater
Transcritical carbon dioxide heat pumps are used in water heaters because of their high heating efficiency and ability to produce hot water at high temperatures.The discharge pressure is one of the most important parameters in determining the operating efficiency of a heat pump system.In order to achieve the optimal discharge pressure and quickly reach the target temperature under operating conditions,several optimizations were made for the original control strategy.Experimental results showed that increasing the discharge temperature to 105℃ can increase the average discharge pressure by 0.2 MPa.The lower limit of the discharge pressure is increased by 0.45 MPa by weakening the electronic expansion valve control based on the discharge temperature.In addition,increasing the frequency of the compressor results in higher heat production and shorter heating time.
heat pump water heatercarbon dioxidetranscritical cycleoptimizationcontrol strategy
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