Numerical Simulation And Optimization Of Phase Change Thermal Storage Exchanger

With the rapid economic development, the phenomenon of big peak and-peak difference has become progressively worse. And urban pollution problems caused by winter heating has become increasingly severe. In order to improve these problems,increase the electricity load adjustment and adjust the energy structure for winter heating, it’s necessary that we should further study the storage technology, develop the application of the product. Phase change thermal storage heat exchanger device takes full advantage of the phase change materials which are with large heat storage density and small regenerator temperature fluctuations, all that have a positive effect on recovering industrial waste heat and improving the heating environment. Thus,countries of the world today is facing the energy crisis, new and efficient phase change thermal storage device has a very important impact on the rational use of energy.In this paper, the erythritol is used as the phase change heat storage material and the tubes with inner ribs and fins are adopted to design the phase change thermal storage which is suitable for indoors, and then numerical simulation and parameter optimization for the regenerative process was done. According to the indoor winter heating load in some region, the phase change thermal storage unit size structure is initially designed;The physical model of phase change thermal heat exchanger is built, FLUENT software is applied to establish the mathematical model of the heat transfer process and do the numerical simulation of the regenerative processes. To study the effects of different structures on regenerative properties: it analyses the effect for the performance of regenerator caused by the heat transfer tubes with inner circumferential fins structure or not; compare transformation time and storage thermal efficiency of the thermal storage heat exchanger with different pitches to optimize its structure; The optimum operatingconditions of the inlet velocity and inlet temperature of phase change thermal storage heat exchanger is selected by using numerical simulation data.The results show that: adding the inner circumferential fins structure to the thermal fluid passage can effectively improve the overall performance of the phase change thermal storage heat exchanger, and get the better heat storage effect; The structure of finned tubes has a great impact on the phase change thermal storage process, so reasonable choice of the fin structure can improve the performance of the heat storage.The results show that the inner circumferential fins heat exchanger tube length is proportional to the pressure drop of the inner tube, and the pressure drop is 52.8Pa per centimeter.; the regenerative efficiency first increased and then decreased with the increasing of the tube length, the optimum tube length is 400mm; For the heat pipe exchanger with inner circumferential fins structure, and when the inlet temperature is495 K and the inlet flow rate is 12m/s, the performance of the phase change regenerator is the best,and in this case, the heat storage is 668.35 kJ, the regenerative time is 3458 s and the regenerative efficiency is 87.3%, in addition, there is no thermal stress concentration in the regenerative process.