Experimental And Simulating Study Of Natural Convection Heat Transfer Of Molten Salt Around Fine Cylinder

In recent years, with energy shortage and environmental pollution getting worse,the solar thermal power generation technology of high temperature has receivedextensive attention gradually. The solar energy resources are rich in our country. It isvery important to use solar thermal power generation to solve the problem of energyshortage and environment pollution.The equipment of heat storage for solar thermal power generation system isimportant. It is not only good for the stable operation of whole system, but can alsoreduce power generation cost. Natural convection heat transfer of molten salt plays avery important role for study of heat storage tank. There is a good guide in designingthe molten salt heating system. At the same time, the nuclear fission energy is passedto the molten salt by natural convection. In addition, the molten salt is a typicalrepresentative of the Pr number. Natural convection heat transfer of molten salt hasnot been reported publicly. So the study of the natural convection heat transfer ofmolten salt can fill in the blank of Pr number. There is very important significance inacademic too.Using Joule heating method, the natural convection of molten salt was researched.Choosing the fine wire as heating unit can reduce the experiment size and simplify theresearch method. This article adopts experiment and numerical calculation to researchthe natural convection heat transfer rule of molten salt.The paper studied the natural convection heat transfer of air and water aroundhorizontal cylinder by experiment firstly. The reliability of experiment method andexperimental system were verified. Based on the aforementioned experiment, thenatural convection heat transfer of molten salt LiNO₃was studied. The naturalconvection heat transfer of air and water proved that the Nu number is close to Fand’scorrelation which is considered viscous dissipation in low Ra number. The research ofnatural convection heat transfer of molten salt indicated that the experiment date ofLiNO₃associated with±20%of Fand’s correlation. Relative to the results of air andwater, the Nu number of molten salt have large difference with Fand’s correlation.The error may come from the temperature control deviation of thermostatic oven andtemperature stratification of molten salt.The numerical simulation was carried out on the natural convection heat transfer ofwater, LiNO₃and Hitec salt around the fine wire. Reach a conclusion that the Nunumber is most closely with the Fand’s correlation if ignore the temperaturestratification. The Nu number is between the-10%and+10%of Fand’s correlation.Compared with the result of numerical simulation, the experiment data has more deviation with correlations.Through the research of natural convection heat transfer coefficient found thatthe natural convection heat transfer coefficient increased with the decrease of thecylinder diameter on different cylinder diameters with experiment and numericalsimulation.