Boiling Experimental Facility And Test On Enhanced Surface With Micro-pits

Pool boiling heat transfer enhancement technology is a very important aspect in the field of heat transfer.With the maturity and application of micro-nano processing technology,people have been able to prepare a variety of micro-nano scale surface structures for boiling heat transfer enhancement research.The micro-pits structure on the boiling surface is an efficient means of heat transfer enhancement,which can improve the heat transfer performance effectively and improve the heat transfer efficiency greatly.In order to explore the boiling heat transfer performance of different micro-pits array surfaces,this paper builds a visual pool boiling experimental platform,which mainly includes four parts: test cavity,electric heating system,data measurement system and image capture system.Among them,the boiling experimental chamber and the test copper column are completely designed and processed independently,and are also the main components of the experimental system;the data measuring system is used to display the dynamic temperature change data of the test copper column;the image capturing system is under different heating steady state bubble growth and detachment of the boiling surface is photographed and stored.In addition,the error analysis of the experimental system was carried out,and the relative error of the heat flux density measurement on the boiling test surface was found to be 2%.As the heat flux density increased,the heat loss of the whole experimental system was also greater,but the relative error was gradually reduced.Deionized water was used as the working fluid for boiling experiment in this paper.The effects of diameter,depth and spacing of surface micro-pits arrays on surface heat transfer performance were investigated.The heat transfer properties of boiling surfaces of different micro-pits arrays were measured,and the boiling experimental data of different micro-pits arrays and smooth surfaces were compared and analyzed.The experimental results show that the boiling test system built in this paper can accomplish the quantitative measurement and qualitative observation of the heat transfer performance of the boiling surface of different micro-pits arrays.Compared with the smooth surface,the micro-pits array can improve the heat transfer performance of the boiling surface obviously.Under different heat flux,the boiling surface temperature of different types of micro-pits arrays decreases to some extent compared with smooth surface,and the boiling heat transfer coefficient increases with smooth surface.When the diameter of micro-pits varies in the range of 150-350?m,the boiling heat transfer performance of micro-pits array surface increases with the increase of diameter;when the depth of micro-pits increases from 100 to 300?m,the boiling heat transfer performance of micro-pits array surface decreases gradually;The boiling surface with micro-pits spacing of 2500?m is slightly better than the boiling surface with micro-pits array spacing of 2000?m and 3000?m,but it's not significant.