Carbon dioxide (CO2) as a natural refrigerant is one candidate alternative to HFC refrigerants. But CO2 system has lower efficiency and is not yet competitive concerning the COP. The most effective method to improve the efficiency of the transcritical CO2 system is to replace the throttling device with an expander. In this paper, a two-cylinder rolling piston expander without inlet valve has be...

This review presents the nucleate/convective boiling performance for a variety of important low global warming potential (LGWP) alternatives to commonly used high-global (GWP) refrigerants (such as R-134a, R404A, and R-410A, etc.). Efforts are stressed on assessment their evaporation pressure drop heat transfer coefficient (HTC) characteristics. These include R-1234ze(Z), R-1234ze(E), R-1233zd ...

Prediction methods to evaluate liquid dynamic viscosity and thermal conductivity along the saturation line are presented in this paper for pure and mixed refrigerants. The thermal conductivity correlation presented here is an extension to the new refrigerants of an equation previously proposed by one of the authors. The viscosity correlation has been improved upon a previous version in order to...

A performance analysis on a vapour compression refrigeration system with various eco-friendly refrigerants of HFC152a, HFC32, HC290, HC1270, HC600a and RE170 were done and their results were compared with R134a as possible alternative replacement. The results showed that the alternative refrigerants investigated in the analysis RE170, R152a and R600a have a slightly higher performance coefficie...

As global warming has raised more critical concerns in recent years, refrigerants with high global warming potentials (GWP) are facing the challenges of being phased out. R410A, with a GWP of 2,088, has been widely used in residential air-conditioning and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. This paper investigates the performance difference of R41...

The use of heat pumps is increasing worldwide, and knowledge their properties becoming more important. Although numerous tests regarding have been performed, due to the large number influencing variables, entire range input parameters not covered, there no overall picture coefficient performance (COP) output parameters. This study extends existing research provides a much detailed comparison re...

This study proposes a procedure for a risk analysis for leakages of flammable refrigerants into a poorly ventilated three-dimensional space. It also presents several test cases of risk analyses on flammability and ignitions to a leaked refrigerant. Concentration of a leaked flammable refrigerant at a leakage window, Cin, is determined by mass balance, providing information on the capacity of an...

As global warming has raised more critical concerns in recent years, refrigerants with high global warming potentials (GWP) are facing the challenges of being phased out. R410A, with a GWP of 2,088, has been widely used in residential air-conditioning and heat pump systems. A potential substitute for R410A is R32, which has a GWP of 675. This paper investigates the performance difference of R41...

A solar cooking system using vacuum-tube collectors with heat pipes containing a refrigerant as working fluid has been fabricated, and its performance has been analysed experimentally. The experiments were conducted during clear days in July and August of 2002 in Elazı g, Turkey under similar meteorological conditions for three refrigerants and water. Detailed temperature distributions and thei...

ARTICLE INFO a The temperature of earth is increasing drastically in the past few years due to which water temperature is also increasing. Water cooler is a device used to cool the temperature of water so that it is suitable for drinking purpose. This system works on the principle of vapour compression refrigeration system. CFC 22 is currently used in the system, but because of its high GWP and...