Influence Of The Ejector On The Performance Of Steam Ejector Refrigeration System

With the increase of the global energy consumption and the intensification of theenvironmental problems, energy conservation and environmental protection have becomethe research hotspots of the refrigeration and air conditioning industry. Ejector refrigerationsystem has aroused more and more concern among researchers for its ability to make fulluse of low grade energy, simple structure and low cost. By the method of combination oftheory and experiment, study has been done with focus on the performance of ejector andthe steam jet refrigeration system.The steam ejector is the key of the steam jet refrigeration system, and the steam ejectorperformance has a decisive influence on the performance of steam jet refrigeration system.For the complexity of the internal flow field of steam ejector, numerical simulation iscarried out to the ejector flow of different geometrical size by using the software of CFDFLUENT, which provides a theoretical basis for optimization design of the ejector. Thebasic size of the steam ejector is designed and calculated based on the theory ofone-dimensional constant pressure. Establishing a CFD three-dimensional model of steamejector and the changes of pressure field image, velocity field image, temperature fieldimage in steam ejector are analyzed. Numerical simulation results show that the workingsteam produces a shock in the nozzle export section, resulting in the nozzle outlet velocitydrop suddenly, the nozzle outlet pressure and the temperature jump.The influences of geometrical parameters including the throat diameter of primarynozzle, diameter and length of constant area mixing chamber on the performance of ejectorare researched when the working parameters of steam ejector are on the same. Numericalsimulation results show that the performance of steam ejector with the throat diameter of10mm, the mixing chamber diameter of40mm and the mixing chamber length of120mm isthe best when the working steam temperature is150℃, the evaporation temperature is4℃,the condensation temperature is37℃. Now, the entrainment ratio of steam ejector is0.6597.The influences of working parameters including the working steam temperature,evaporation temperature and condensation temperature on the performance of ejector areresearched when the geometric sizes of the ejector are fixed. Numerical simulation resultsshow that entrainment ratio increases first and then declines with the increasing of theworking steam temperature, and the performance of steam ejector is the best when theworking steam temperature is160℃. Besides, the entrainment ratio increases with theincreasing of evaporation temperature and decreases with the increasing of condensationtemperature.Setting up a steam jet refrigeration system test bench by using water as refrigerant, and experiments are conducted to study the system. The influences of the working steamtemperature, evaporation temperature and condensation temperature on the performance ofejector and the COP of the ejector refrigeration system are researched. Comparison ofexperimental results with numerical simulation results shows that the variation trend of theexperimental results agrees with the variation trend of the numerical simulation results.