Experimental Study On The Effect Of Dual Alcohol Additives On Spray Cooling

Spray cooling is a hot research direction of today's cooling technology.It has the characteristics of strong heat dissipation,small coolant flow,uniform temperature distribution and low superheat.Spray cooling has broad application prospects in many industrial fields: in the field of metal(alloy)material heat treatment,because the cooling rate has a great influence on the microstructure of the metal,the faster cooling rate can make the mechanical properties of the material better,therefore,the use of unsteady-state spray cooling technology in the heat treatment process is a good choice;in the field of electronic component heat dissipation,due to the high heat flux and high integration of electronic components,steady-state spray cooling becomes one of the most promising cooling technologies.The experiments of unsteady-state spray cooling and steady-state spray cooling were carried out using dual alcohol-water mixture as working fluid to explore its heat transfer characteristics.The main contents include the following aspects:First,the experimental system of spray cooling is designed.The whole system consists of four subsystems: the hot wall heating system,the spray cooling circulation system,the data acquisition system and the temperature control system.Then the influence of the volume concentration of dual alcohol additive on its surface tension and contact angle was explored.For single-alcohol-water mixtures,the surface tension and contact angle of working substance decrease with the increase of volume concentration;for dual alcohol-water mixed solution,the surface tension and contact angle decrease with the increase of volume concentration of propanol in 4% ethanol-water mixed solution;Surface tension and contact angle decrease with the increase of volume concentration of octanol in 4% ethanol-water mixed solution.The surface tension and contact angle of 4% ethanol-500 ppm octanol-water solution was the lowest among all the measured working fluids.Since the surface tension and contact angle of the dual alcohol-water mixture were lower than that of the single alcohol-water mixture,ethanol,propanol and octanol were selected as additives to prepare the dual alcohol-water mixed solution for unsteady-state and steady-state spray cooling experiments,so as to find the best mixed coolant and the ratio.The experimental results show that the addition of alcohol can effectively enhance the heat transfer performance of spray cooling.For the single alcohol-water mixed solution: for the ethanol-water mixed solution,the effect is best when the volume concentration of ethanol is 4%;for the propanol-water mixed solution,the optimum volume concentration is 2%.For dual alcohol-water mixed solution: adding propanol in 4% ethanol-water mixed solution,4% ethanol-2% propanol-water mixed solution performs best.;for the solution with 4% solute,4% ethanol-water mixed solution has the best heat transfer effect;for the solute solution of 6%,the 4% ethanol-2% propanol-water mixed solution has the best heat exchange effect;the optimal volume exists when adding octanol in the 4% ethanol-water solution and it is 300 ppm.