Numerical And Experimental Studies On The Diffusion-Absorption Refrigeration System

In order to improve the efficiency of the Diffusion-Absorption Refrigeration system, thisthesis makes numerical studies on the condenser, generator and evaporator in this system toinvestigate the influence of various factors on the refrigeration system. Then, an experimentalstudy on the refrigeration system is conducted to find out its operation rule. The specific studiesare as follow:Firstly, it makes a numerical simulation of two kinds of condensers, the bank-fin andsmooth tube. The result exhibits that thermal resistance inside condensers’ tube has moreinfluence on the condensation of ammonia liquid than the outside condensers’ tube. When thediameter is fixed, the total clotted ammonia liquid appears to decrease along with the increaseof the inlet velocity. When the velocity comes to a certain value (condenser of bank-fin is0.15m/s, while condenser of smooth tube is0.2m/s), the total condensed liquid remains stillbasically.Secondly, it makes a simulation of thermosyphon with diameters of4mm,5mm,6mmrespectively by virtue of numerical calculation. The result shows the thermosyphon with thediameter of5mm possesses the biggest amount of liquid-lifted at the same heating temperature;the amount of ammonia-vapor for the three thermosyphons is on the increase with the increaseof the heating temperature, while the thermosyphon with the diameter of5mm is more than theothers; when the heating temperature is higher than75℃, the outlet concentration, which isonly and merely under the influence of the heating temperature, decreases with the increase ofthe heating temperature.Thirdly, it makes a numerical simulation of the evaporator with single pipe in terms ofnumerical calculation. The result exhibits the cooling capacity and evaporation of liquidammonia decrease with the increase of filling pressure, while the ammonia liquid flow of evaporators is0.0002kg/s and0.00025kg/s respectively; under the given condition, coolingcapacity in the system decreases with the increase of the concentration of the ammonia, whilethe filling pressure is18bar and the inlet flow of liquid ammonia is0.00025kg/s.Fourthly, the result through an experimental research on the refrigeration system exhibitsthat the starting time of the prototype become shorter when the input power is greater, theminimum starting power is about120W, and minimum operating power is about75W; thecooling capacity of the prototype increases with the increase of the input power, and the coolingcapacity comes to its peak with66W when the input power is280W.This study provides a credibly theoretical basis for the optimization of the condenser,generator and evaporator in the Diffusion-Absorption Refrigeration system.