Variation Law of Aqua Ammonia Falling Film Absorption Vertically Outside of Transversally Grooved Tube

Abstract

Aqua ammonia absorption refrigeration system involves design of condenser, evaporator, absorber, heat exchange equipment. Absorber is very important equipment in refrigeration system. Aiming at different sizes transversally grooved tube (TGT), a series of experiments are carried out to find approach which can enhance absorption efficiency and to choose an optimal tube type. The experiment results show that ammonia solution can absorb the more ammonia gas following increase of pressure difference and velocity of cooling water inside tube, therefore mass transfer coefficient becomes larger. When spray density of ammonia solution outside tube alters from small to large, mass transfer coefficient increases firstly and then decreases, so that gets a optimum. The group experiment results indicate that transversally grooved tube have better mass transfer ability than smooth tube. For example, when spray density of solution is 472.1 kg m−1 h−1, mass transfer coefficient of transversally grooved tube rise by 109.6 % compared to smooth tube. A common law is discovered during three groups of experiment. Different sizes of TGT have different ability to absorb ammonia gas, and Number 2 tube is the best tube considering absorption efficiency. Flow patterns of blend and vortex flow are compared among three transversally grooved tubes with solutions flowing through grooves. The reason why series of TGT of different sizes have different absorption efficiency is obtained by means of analysis on flow model ammonia solution flowing through TGT.