Experimental And Thearetical Study Of Heat Transfer Performance Optimisation Of Phase Change Thermal Storage Heat Exchagner Tubes

The energy consumption of air conditioning system can be reduced byusing high-temperature cooling system combiened with cold storagetechnology. However, the application of this technology is limited due to thepoor thermal conductivity of the current phase change heat exchangers. Inthis paper, an experimental and theoretical study are conducted based on anhigh efficient phase change thermal storage tubes, the main work issummarized as follows:(1) Combined with the current domestic and overseas researches ofthe colde storage air conditioning system, some commonly used phasechage materials, sturctures of the PCM heat exchangers are summarized.Finned tube heat exchangers as well as the lauric acid-based organic phasechange materials are selected for the research, in order to improve the phase-change heat storage system performance.(2) A new type of fined tube phase change thermal storage heatexchanger is developed.which the heat transfer properties of phase changematerials is improved by adding a certain amount of nanomaterials.Experiemnts of both cold storage and release are conducted in the typicaloperating conditions of high temperature cooling system. The result showsthat the heat exchanger rate of the new fined tube phase change heatexchangers is40%higher than that of the heat exchanger balls.(3) Constructed a mathematical model of the finned phase changeheat exchanger tube by using enthalpy-porosity method. Solve the modeland analysis the heat transfer phenomenon by using thesolidification/melting model of Fluent on the secondary boundary condition.The numerical simulation results and experimental results fit wellwith the relative error which is8.3%.(4) In order to improve the efficiency of heat exchange tubes, aseries of theoretical researchs are conducted over the following two aspects:the structure and the operating conditions. Studied the heat transferenhancement performance of straight fins and round fins, the results shows:when the distance between round fins is40mm, straight fin density is9, finthickness is1mm, straight fin width is37.5mm, the fined phase change heatexchanger tube achive the higest heat transfer performance. Compared withthe original version, the heat exchange speed of optimized tube is30.5%higher. Research over the implication of the heat exchanger performation ofvarious heat transfer flow’s(HTF) temperature and flow rate are conducted.(5) Phase change heat exchangers of various storage capacity can beconstructed by parallely combining the phase change heat exchanger tubes.The phase change thermal storage system can improve heat transferperformance while can meet different cooling capacity requirements.