Experimental investigation of gamma Stirling refrigerator to convert thermal to cooling energy utilizing different gases

Abstract

In recent years, combined cooling, heat, and power (CCHP) systems have attracted increasing attention worldwide. Owing to their advantages of high overall thermal efficiency, fuel flexibility, low noise and vibration, and low emissions, Stirling engines are promising candidates for micro-CCHP systems. The Stirling Cycle is one of the thermodynamic cycles that is close to the Carnot cycle in terms of theory, and these advantages cause to use of Stirling engines in wide industries. The main objective of this research is an experimental investigation of the Stirling Gamma engine for refrigeration. In this investigation, the effect of working fluid air and Helium, the operating pressure of the working fluid, and dynamo power on refrigeration generation have been investigated. Results show that using air fluid with a power of 520.8 Watts and operating pressure of 3 bar in 10 minutes could reach to the temperature of -23° Celsius and using Helium fluid with a power of 420 Watts and operating pressure of 6 bar and in 10 minutes could reach to temperature -21° Celsius. In the experimental implementation, it has been tried to reach lower than 10 % error results in various parts of the engine like insulation, leaking, belt lash, and measurement devices. Results show that increasing power supply, mean gas pressure, power supply turning on duration, and using fluids such as air and helium are effective in refrigeration. Also, by using helium instead of air, the amount of cooling output and engine output power decreases while engine efficiency increases.