Investigations On Absorption And Evaporation Process With Falling-Film In A Vertical Tube

The absorber and the evaporator of ammonia-water absorption GAX cycle is the most important element of energy coupling equipment, which plays a key role on a total performance of the refrigeration system coefficient. Falling film absorption, evaporative heat transfer efficiency, small temperature difference of heat loss and no hydrostatic head of higher boiling point and short residence time were taken as the characteristics. Therefore, the study of falling film absorption and evaporation can provide guidance on the design of GAX absorption and regeneration cycle to achieve a higher coefficient.This paper introduces the background and status of the vertical falling-film absorption and evaporation. We erection of a vertical tube falling film absorption-evaporation of the laboratory-scale experiments intermittent operation of the system from the basic principle of falling film absorption and evaporation with the existing laboratory conditions.In order to know the heat transfer characteristics of vertical failing film, we considers the influence of the falling film Reynolds number and tube heat medium temperature with the feasible experiment parameters. The experimental and theoretical analysis are very consistent: total heat transfer coefficient and falling film-side heat transfer coefficient increases very obviously with the increase of the falling film Reynolds number.A vertical tube falling film evaporator heat transfer experiments were also performed. We consider the influence of inlet temperature of liquid membrane and Falling Film variation of the Reynolds number on falling film side heat transfer coefficient and regress vertical tubes falling film heat transfer coefficient associated with Reynolds number in a certain range. The average error was less than 4.6%.We optimized the Helix specifications. According to analyses a falling-film-side heat transfer coefficient of variation under different conditions of the pitch, silk and falling film Reynolds number, we regressed vertical tubes falling film heat transfer coefficient in the inserted spiral vertical tube. The average error was less than 14.8%.A model for falling film ammonia solution absorption of heat transfer is presented based on the properties of the ammonia solution and film thickness. Simulated data are very consistent with experimental data. We investigate the influence of the outside of convective heat transfer coefficient, absorption tube diameter and tube spray density on the film temperature and the average concentration of liquid film. These factors showed a different dependence: Tube spray density > heat transfer coefficient > inner tube diameter.