微槽群表面喷雾冷却换热特性

在闭式循环喷雾冷却系统中,以蒸馏水为工质,喷雾体积通量从0.938 L/(m2·s)增至12.73 L/(m2·s)的情况下,实验研究了微槽群表面的槽道尺寸对喷雾冷却换热性能的影响.结果表明:微槽群表面可明显提升换热效果,提升程度取决于槽道尺寸和喷雾流量.小流量(1.146~1.604 L/(m2·s))时,最佳槽面结构槽深、宽、间距分别为0.5、0.4、0.6 mm;大流量(12.73 L/(m2·s))时,最佳槽面槽深、宽、间距分别为0.5、0.2、0.4 mm,在表面温度为80℃时,其热流密度达202.5 W/cm2.从光面喷雾与微通道流动换热相结合的角度,给出了微槽群表面喷雾冷却强化换热机理;推导了反映蒸发换热特性和槽道尺寸对换热影响的微槽群表面量纲一换热准则方程,可方便用于工程设计.

Heat Transfer Characteristics of Micro-grooves Surface Spray Cooling

With water as the working fluid,experiments were conducted to study the influences of structure parameters of micro-grooves surface on heat transfer during spray cooling in a closed loop system for volumetric flux varing from 0. 938 to 12. 73 L /( m2·s). Test results indicated that heat transfer was obviously enhanced for micro-grooves surface, however enhanced effects depended on structure parameters of micro-grooves surface and volumetric flux. When the groove depth,width and spacing equaled 0. 5,0. 4,and 0. 6 mm,respectively,the surface had the optimum heat transfer performance at lower volumetric flux( 1. 146- 1. 604 L /( m2·s)). However,for higher volumetric flux( 12. 73 L/( m2·s)),the optimum groove depth,width and spacing were 0. 5,0. 2,and 0. 4 mm,respectively,whose heat flux reached 202. 5 W /cm2,when the wall temperature was80 ℃. The enhanced heat transfer regime about micro-grooves surfaces was given in the view of smooth surface spray cooling and micro channel flow heat transfer. Non-dimensional criterion equations about micro-grooves surface were derived,in which the influence of surface temperature and structure parameters of micro-grooves surface on heat transfer were considered.