Research On Performance And Reliability Of Household Variable Frequency Air Source Heat Pump (Cool And Hot Water) Unit

Household air source heat pump(cold and hot water)unit is one of the indispensable products in the central air conditioning market.With the continuous improvement of people's living standards,the requirements for air conditioning comfort are getting higher and higher.The household air source heat pump(cold and hot water)unit uses the fan coil as the end,and has the advantages of suitable outlet air temperature and appropriate humidity.The heating can be used for floor heating or radiator heating,and its comfort is much better than air conditioning.In recent years,with the advancement of the North Coal to Power Project,the development momentum is very rapid.With the upgrading of technology,the frequency conversion technology has been widely applied to the household air source heat pump unit,and the frequency conversion technology can greatly improve the IPLV of the whole working condition of the unit.Vapor injection technology has also become the future development trend of the industry.Under the heating condition,the Vapor injection technology can greatly expand the application range of the product,improve the heating capacity and coefficient of performance of the product,and the application of the Vapor injection technology in the cooling condition can greatly improve the cooling capacity and coefficient of performance.The performance of the household air source heat pump(cold and hot water)unit is the main indicator for determining whether the product is energy-saving or not.At present,there are few studies on the performance and reliability of these aspects.This paper focuses on the performance and reliability of household air source heat pump(cold and hot water)units.The study of performance and reliability is a systematic project.From the design concept,it needs careful consideration.It mainly takes design as the source,comprehensively considers various current technologies,optimizes product performance from design point of view,and improves product reliability.Auxiliary use of theoretical calculations and analysis,combined with a large number of experiments to verify.Although this process is time consuming,it is still the most commonly used method in the air conditioning industry,and it is the most effective means.This paper mainly studies from several aspects such as component selection,control logic,performance and reliability testing,as follows:Components selection: including compressors,water side heat exchangers,fin heat exchangers,electronic expansion valves,oil separators,gas-liquid separators,fans,motors,four-way valves,pumps,expansion tanks and other major components.To ensure that the product has excellent performance,it is necessary to perfectly match the various components to achieve the best performance overall.The compressor is the power source of the system and the most important part of the system.To ensure reliable operation of the compressor,it is necessary to ensure that the operating pressure and temperature of the system are within the allowable range of the compressor.Therefore,after the compressor selection is determined,other components of the refrigeration system such as the condenser,evaporator,and electronic expansion valve are selected to match the compressor to achieve the best performance and can operate reliably.Of course,the economy should be taken into account when choosing the components.Control logic is the brain of the entire system,the main purpose is to enable the refrigeration system to run efficiently,stably and reliably.The key to the operation of the refrigeration system is the compressor,so most of the logic is about how the compressor runs stably.Various frequency settings and protection settings are made for it.Another important point is the water side heat exchanger.If the evaporation temperature is too low,the water will freeze and the heat exchanger will freeze.Therefore,setting effective water flow and temperature protection is especially important.Finally,the adjustment of the electronic expansion valve is mainly to accurately control the flow rate of the main circuit refrigerant and the supplementary circuit refrigerant under various operating conditions,thereby ensuring the optimal performance of each component and ensuring the reliability of each component.The performance and reliability tests are mainly for the above-mentioned component selection and control logic,and the prototype and test bench are built for experimental research.The performance test mainly tests the performance of the unit under various working conditions,and studies the effects of different ambient temperatures,different water temperatures,different frequencies and different vapor injection volumes on the performance to ensure the best performance under various working conditions.The reliability test mainly aims at the extreme bad working conditions,temperature-rising of electrical components,structural stress,defrosting,etc.,and tests to ensure the stability and reliability of the system under these conditions and to understand the limits of product application,thereby adjusting the design of the unit or gives guidance to the user to ensure the stability of the unit.