Optimization Of Heat Transfer Performance Of Star Finned Tube Vaporizer

Air ambient vaporizer(AAV)is not only energy saving and environmental protection,but also has a simple structure,but its heat transfer efficiency is relatively low.In the process of operation,the surface of fin tube is easy to frost.The frost on the surface of vaporizer induces the decline of AAV's heat transfer performance,which results in the gas's temperature too low at the outlet of the vaporizer or appearing the liquid entrainment phenomenon at the outlet of the vaporizer,which may cause safety issues about equipment and production.The air ambient vaporizer takes the air in the environment as the heat source,by a number of star finned tube composition.In this paper,there are proposed the methods of the surface modification,as well as changing the inclination angle of the wall,and be heating by the solar energy in order to reduce the thickness of the frost on the surface of the fin wall.In addition,those methods have been experimental analyzed at the finned tube vaporizer.In this paper,the experimental platform of low temperature wall and the experimental system of vaporizer are built.The improved method is checked and verified by the experimental platform of low temperature wall.Liquid nitrogen is used as refrigerant,under the condition of controlling a single variable,the heat transfer performance and frosting conditions of the ordinary vaporizer,the vaporizer with hydrophobic performance,and the vaporizer with solar endothermic films were compared.It shows that the influence of liquid nitrogen flow rate on the process of frost formation and the outlet gas temperature of the vaporizer experimental system is obvious.The vaporizer experimental system has the best flow rate on the process of heat transfer.Through experiments,we can find that,the influence of light on the heat transfer performance of the vaporizer is obvious.With the hydrophobic performance of the vaporizer,it can effectively reduce the frosting on the surface of the fin and increase the outlet gas temperature.With solar endothermic films of the vaporizer,it can increase the outlet gas temperature.The elbow affects the frosting thickness of the adjacent fin.The frost layer on the fin surface is ladder-like stratification,and the boundary line is curved,the boundary of the adjacent step of the ordinary wall is not obvious,however,the boundary of the adjacent step of the hydrophobic wall is obvious.The study found that in the optimum flow vaporizer experimental system,the vaporizer has hydrophobic performance compared to the ordinary vaporizer,the heat transfer amount per minute more than 2%,the heat transfer coefficient is higher than 167%.When the heat transfer area of the vaporizer with the hydrophobic performance is 50 m2 under the same production capacity,the ordinary vaporizer needs 133.5m2 heat exchange area,and the vaporizer with the hydrophobic performance can save about 3100 Yuan of investment cost.The vaporizer has solar endothennic films compared to the ordinary vaporizer;the heat transfer amount per minute more than 1.2%,the heat transfer coefficient is higher than 47.4%.In this study,the methods to optimization heat transfer performance of the finned tube vaporizer is obtained,which is of great significance to improve the heat transfer performance and safety performance of the vaporizer.