Experimental investigation and theoretical analysis of an ejector refrigeration system

The ejector refrigeration system can be powered from low-grade thermal energy such as solar generated hot water or waste heat, especially when electricity supply is limited or does not exist. An experimental investigation of an ejector refrigeration system was conducted to determine the effects of nozzle size, axial nozzle location, high-temperature evaporator temperature, and refrigeration temperature. The tested conditions include the effects of the high-temperature evaporator (HTE) temperatures ranging from 120 to 135 °C, low-temperature evaporator (LTE) temperatures ranging from 5 to 15 °C, and condenser temperatures of 7–30 °C. It was found that an optimum nozzle location which can produce a maximum coefficient of performance (COP) exists for a given set of operating conditions. At the same time, a mathematical model has been developed to predict the system COP, which agrees well with experimental data. The experimental results show that the ejector refrigeration system can achieve a COP of 1.7, which is much higher than the results typically reported in the literature, but at the expense of critical backpressure. Current investigation demonstrates that the ejector refrigeration system is a very promising alternative to the status quo vapor compression systems.

► We model the performance of the ejector refrigeration system.
► We develop a system coefficient of performance (COP) map which can help to design a new ejector refrigeration system for a given application.
► An optimum nozzle location exists for a maximum COP at a given set of operating conditions.