Experimental Study On Heat And Mass Transfer Enhancement By Grooved Tube Of LiBr Solution Absorption Water Vapor

In the context of the world energy crisis and developing of the refrigeration technology,the Absorption Heat Pump which can recovered low taste heat has been extensive researched and rapid developed. But currently there are some shortcomings for Absorption Heat Pump:bulky volume, inefficient heat transfer and large investment etc, to improve its energy efficiency is of great significance.In the Absorption Heat Pump, the heat transfer whose area of absorber accounts for about 40% of units,bearing the two tasks of heat and mass transfer,is a key component of Absorption Heat Pump.The heat and mass transfer effect of absorber directly determines the whole coefficient performance of Absorption heat pump. In the absorption heat pump absorber, refrigerant is absorbed by the vertical tube with falling film outside. This paper studied enhancement absorption process by grooved tube falling film, in which LiBr solution was used as working fluid.The size of the grooved tube in the experiment isΦ20×2×1000mm, whose material is copper. The heat and mass transfer experimental research of falling film absorption was studied with 17 different pitch(p) and groove depth(e) of the grooved tube.Through the research,this paper analyzed and compared the affect of the pitch(p) and groove depth(e) to the heat and mass transfer of grooved tubes,and get the best range parameter of enhanced tubes.The results show that:(1)The main factors effecting the enhancement of the heat and mass transfer of grooved tube are LiBr solution spray density, pitch(p) and the groove depth(e). Different factors'effect of the heat and mass transfer are different.(2) Compared with the smooth tube, grooved tubes'heat and mass transfer effects have been significantly enhanced, but different structure parameters of pitch(p) and groove depth(e) of the grooved tubes, made different reinforced effect of the heat and mass transfer. In the experimental range, the heat transfer coefficient of LiBr solution absorption water vapor enhanced by groove tube is 2.1-3.25 times as that of the smooth tube,and the mass transfer coefficient is 1.25-1.93 times as that of the smooth tube.