The Experiment Study On Melting Process Of Phase Change Material In The Rectangle Cavity Of High Aspect Ratio

Latent heat storage technology is used for the absorption or release latent heat by phase change material(phase change material,PCM)for the heat or cold storage in the phase change process,the use of the technology can store large amounts of energy,save space and convenience to transport,and is conducive to improving the energy crisis and the status of environmental pollution.However,the application of phase change energy storage technology has been limited due to the low thermal conductivity of most organic phase change materials.In recent years,the research on energy storage technology mainly focuses on strengthening phase change heat transfer from the point of view of strengthening natural convection.However,due to space constraints in the actual project,energy storage process is often carried out in a limited space,at this time natural convection will be very weak.So the method of enhancing the natural convection heat transfer is not fully applicable.And during the phase change process,the solid phase PCM will settle down due to gravity and contacts with the heating wall.The effect of this phenomenon on phase change heat transfer can not be neglected.Therefore,the study on the phase change heat transfer process in finite space is carried out by using the experimental method.The rectangular storage unit with large aspect ratio is taken as the experimental model,and the octadecane was used as the phase change material.The heat transfer process of phase change materials under different inclination angles,different heat fluxes and thicknesses of different energy storage units were discussed.The economical benefit under different thickness and heat transfer rate were discussed.The main results are as follows:(1)It is verified that the gravity sedimentation effect exists in the non-fixed melting process in finite space;(2)Gravity subsidence effect strengthens the phase change heat transfer in finite space,The heat transfer rate is the maximum when the inclination angle is 90 °;(3)the heat transfer rate is different when the heat flux is 40 W,60W and 80W;(4)Under the different conditions of 15 mm,20mm and 25 mm thickness of the energy storage unit,the heat transfer rate is the highest at 15 mm,and the strengthening effect is the best;(5)The comprehensive evaluation of the heat transfer rate for the metal consumption and heat transfer rate of energy storage units of different thicknesses is benefit for optimizing design scheme in actual application.