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External-cooling indirect evaporative coolers with different configurations and working air sources are incomprehensively analyzed and compared so far. This paper investigates the mechanism and theory of operation of indirect flat-panel evaporative coolers based on X-analysis. Then, based on the second law of thermodynamics analysis, the entropy production rate of the flat-plate heat exchanger of the cooler is calculated. As a result of this analysis, the optimal energy efficiency-evaporation efficiency and cooling capacity values are presented in terms of effective parameters in the design.

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 Carnot cycle in term of theory, and these advantages cause to using Stirling engines in wide industries. The main objective of this research is experimental investigation of Stirling Gamma engine for refrigeration. In this investigation, effect of working fluid air and Helium, operating pressure of working fluid and dynamo power on refrigeration generation have been investigated. Results show that with using air fluid with power 520.8 Watts and operating pressure 3 bar and in 10 minutes could reach to temperature -23° Celsius and with using Helium fluid with power 420 Watts and operating pressure 6 bar and in 10 minutes could reach to temperature -21° Celsius. In experimental implement, it has been tried to reach lower than 10% error results in various part of engine like, insulation, leaking, belt lash and measurement devises. Results show that increasing power supply, mean gas pressure, power supply turning on duration and using fluids such as air, 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.