Experimental Study Of Multi-split Air-souce Heat Pump With Phase Change Energy Storage Defrost System

Multi-split system is one of the main development direction of air source heatpump(ASHP) in the future, but the serious problem of defrosting has restricted thefurther development of it. In order to solve this difficult problem, multi-split ASHPwith phase change energy storage defrost system is designed on the basis of theoperating principle of the multi-split ASHP. The experimental processes of newsystem, such as space heating, heat accumulation and thermal-storge defrosting areprovided respectively.According to melting point and heat latent, the PCM was selected a mixture of35%mollauric acid and65%molcapric acid. A new computing method of defrostingenergy comsuption that based on the melting frosting mass was provided toguarantee PCM saving. A rectangular PCM-HE is designed independently and itsheat exchange capability is preliminarily calculated to promise the operation of heatstorage-release going well.A multi-split ASHP with phase change energy storage defrost experimentalapparatus basing on the demand of processes designed and experimental verificationis built. Both data collection system and measuring tool are chosen. The calculationresults of the experimental apparatus error show that the test bed is reliable.On all this basis, the experiments of multi-split ASHP space heating/defrostingand heat accumulation/hermal-storge defrosting are completed. The parematers ofspace heating, heat accumulation and defrosting are measured, includingtemperature, pressure, relative humidity and power. These parematers show thecharacteristics and disadvantages of normal space heating and defrosting ofmulti-split air source heat pump. The dynamic parameters, such as defrostingduration, compressor suction pressure/temperature, indoor coil temperature andresuming heating duration of the new system thermal-storge defrosting experimentwith double spiral coils and rectangular PCM-HE are respectively analyzed..Theperformance of different PCM-HE during defrosting are compared with each otherand compared to the normal defrosting to embody its superiority. Experiments showthat the new system has a great deal of ascension on defrosting time, compressorworking environment, indoor environment and energy saving during defrsoting..Theoretical support and technical reserves are given for the phase-changeenergy storage defrosting technology application on multi-split ASHP.