Study On Performance Of Static Heat Pump Water Heater With Wrapped-tank Mini-channel Condenser

As an efficient heat exchanger,mini-channel condenser has been applied in the field of air source heat pump water heater(HPWH)in recent years.In order to explore the influence of the mini-channel condenser application on the performance of the system,this paper firstly builds a test bench to obtain the operating data of the static air source heat pump water heater with wrapped-tank mini-channel condenser,and establishes a coupling model,which is used in simulation of structure optimization after verification.The wrapped-tank variable flat tube spacing mini-channel condenser structure is proposed in this paper,and the simulation of different wrapped-tank minichannel condenser structures and parameters are carried to analyze the system performance.This provides a guidance for the optimization design of HPWH with wrapped-tank mini-channel condenser.This paper set up an experimental facility of the static ASHPWH with wrappedtank mini-channel condenser,to test the coefficient of performance,compressor suction/exhaust pressure in ambient temperature 20 ℃ and initial water temperature 10,15 and 20 ℃.This provides experimental data for the verification of coupling model.In addition,the condition with the initial water temperature of 15 ℃ is set as the standard condition,which is used as the comparison baseline for subsequent simulation of structure optimization.This paper establishes the vapor compression system model and the water tank heat transfer model respectively,and the data interaction between them is realized through the coupling algorithm.After the comparison of the predictions and the measurements,the relative deviations of the coefficient of performance and the compressor suction/exhaust pressure are within 2 %,which verifies the accuracy of the coupling model and can be used for further simulation.When the air temperature is 20 ℃ and the initial water temperature is 15 ℃,the operating performance and the discharge characteristic of system with constant/variable tube spacing mini-channel condenser are compared and analyzed by simulation.The results show that the COP of the system with variable tube spacing mini-channel condenser is increased by 6.44 % compared with that of the system with variable tube spacing mini-channel condenser in the charging process.In the discharging process,the system COP,the discharge efficiency and the energy release efficiency are increased by5.23 %,2.04 % and 3.85%,respectively.In addition,the influences of initial flat tube spacing and channel size on the performance of the system with variable tube spacing mini-channel condenser are also investigated,and the system performances under three different parameters are compared respectively for the initial flat tube spacing and channel size.The results show that after the reduction of initial flat tube spacing the system COP of charging/discharging process and discharge efficiency are increased by 4.41%,2.86%and 1.00%,respectively.After the reduction of the channel size,the system COP of charging and discharging process are increased by 3.20% and 3.04%,respectively.In conclusion,the wrapped-tank variable tube spacing mini-channel condenser structure can improve the coefficient of performance and the discharge efficiency effectively.