Design And Experimental Study Of Direct Contact Heat Storage Based On PCM Jet Breakup

Heat storage technology solves the problem of intermittence and fluctuation in the process of heat application,and is an important measure to ensure the stable operation of the system.Direct contact heat storage technology has the advantages of fast heat storage speed and high heat exchange efficiency,which is one of the research hotspots in the field of heat storage.By analyzing the application cases and policies of direct contact heat storage,this paper makes clear the application technology of direct contact heat storage:the mobilized heating system has been put into use in Sweden,Germany and other countries,recycled the waste heat resource to provide heat service for the nearby residents.In China,mobilized heating system has developed pilot projects.Further through consulting and analyzing the policy of waste heat recovery and utilization and the relevant road transportation specifications,the conclusion is drawn:the financial subsidy policy for the mobile heating technology is not clear;the special road transportation regulations for the mobile heating vehicle are still lacking.However,the initial policy support has shown the commercial potential of direct contact heat storage in the field of heating in China.In this paper,a new method is put forward to solve the problem that the flow of heat transfer material is blocked in the process of direct contact heat storage.The experimental study on the breakup of PCM jet has been carried out and the following results have been obtained:Designed and built the PCM jet breaking experiment platform,including four parts:heat source side,molten material storage and injection system,jet breaking device and shape feature capture system.Designed and selected the experimental equipment used in each part.Explained the materials selected in the experiment,sodium acetate trihydrate and KS-QC310heat transfer fluid,and introduced the thermal physical parameters.The important equipment such as nozzle and,working fluid pump were described,the measuring equipment was calibrated.A high-speed camera system was used to photograph the broken shape of PCM jet,and the surface deformation of the jet in different zones was described.Under certain conditions,changing different jet parameters can change the breaking length L_P and breaking cone angleβof the two macro characteristic parameters:increasing jet pressure,reducing nozzle diameter and reducing PCM temperature will reduce the breaking length L_P and increase the breaking cone angleβ,which is more conducive to the occurrence of jet breaking.Under the experimental conditions,the viscosity,the coefficient of surface tension and the interaction between the jet and the surrounding fluid are the main factors affecting the jet breakup.The jet breakup morphology is in line with our expectations,which provides the research basis for the heat exchange mode of granular floating bed in the subsequent development of direct contact heat storage.