NUMERICAL ANALYSIS OF THE INFLUENCE OF BASIC OPERATING PARAMETERS ON THE PERFORMANCE CHARACTERISTICS OF SOLAR-DRIVEN EJECTOR COOLING

Abstract

Researchers are becoming growgly interested in the development of solar-driven ejector cooling systems, primarily due to their potential to be used as renewable energy sources. Absorption and adsorption refrigeration systems not only involve considerable investment but are also much less reliable than the ejector refrigeration systems, which do not contain any movable parts. In addition, ejector refrigeration has the advantage of low capital cost, simple design, reliable operation, long lifespan and almost no maintenance. The only weakness of this system is the low efficiency and its intolerance to deviations from design operation condition.The paper develops a mathematical model with an algorithm which is based on the laws of thermodynamics and the principles of mass and momentum conservation. Based on the obtained model, the influence of temperature on the basic system parameters for two working fluids, R134a and R290, is presented. The working fluid temperature ranges are 80-100°C in the generator, 5-15°C in the evaporator and 33-40°C in the condenser. The important performance indicators are the characteristic ejector area ratio Ar (as a geometrical ejector parameter), ejector entrainment ratio, ejector efficiency and the COP. The results indicate that ejector geometry and working fluid type have a major impact on the ejector cooling system’s performance.