Study On The Method Based On Thermal Balance Of Compressor To Measure Field Performance Of Room Air Conditioner

As the typical product type of direct-expansion air source heat pump,the field performance of room air-conditioner has attracted widespread attention from users,enterprises,industry and the whole country.However,there is no instrument with reasonable price、simple operation and high precision to measure the field performance of room air conditioner,leading to difficulty to monitor and assess the operation situation of room air conditioner installed in situ.By combining experimental study with theoretical analysis,this paper f ocus on the implementation of the development of instrument to measure the field performance of room air conditioner,which is beneficial to improve the level of energy-saving control and fault diagnose of room air conditioner.Thus,the research of this paper has academic significance and practical worthiness,the main work of this paper are carried out as follows:First of all,the method based on the thermal balance of compressor is introduced and the feasibility of this method is demonstrated through th e principle and technically demanding of field measurement;then type of the sensors needed in this method is analyzed and according to the analysis results,the sensor solution is divided into three levels including: " poWer sensor + Temperature sensor + Pressure sensor +Optical sensor(WTPO)"," poWer sensor + Temperature sensor + Pressure sensor(WTP)" and " poWer sensor + Temperature sensor(WT)",based on the sensor solution,the third-party instrument to measure the room air conditioner installed on si te and room air conditioner integrated with real-time performance measurement can be developed;Secondly,the required accuracy and cost of sensors in WTPO,WTP and WT solution are determined by sensitivity analysis.Based on this,the estimation of circulation oil rate,the feasibility of replacing the pressure sensor with temperature sensor are put more emphasis on under cooling and heating condition,as well as different frequencies.The effect to the accuracy of the measuring result with different number of the temperature sensors and the way to improve the accuracy of the measuring result are also discussed.Thirdly,the method based on thermal balance of compressor is applied in measurement of the cooling(heating)capacity of a single-stage room air conditioner under the steady and dynamic conditions in enthalpy-difference laboratory.The accuracy of both WTPO,WTP and WT solution is verified.Meanwhile,the reason of error in the measurement is analyzed in detail;the influence on the accuracy when reducing the number of temperature sensors on the development of room air conditioners integrated with the technique of realtime performance measurement is also calculated based on this experiment.Finally,based on the principle of compressor thermal balance measurement,the air conditioner field performance detector software is developed and a third-party performance measuring instrument which can measure single-stage and(quasi)two-stage compression cycle room air conditioner with two power sensors and thirteen temperature sensors is also developed cooperating with the enterprise.By measuring the performance of a single-stage wall-mounted air conditioner with variable speed compressor under forty different cooling and heating conditions at different frequencies in the enthalpy-difference laboratory,indicates that the relative error of this instrument is within 11% in almost 95 percent cases.