Pool boiling heat transfer has been extensively studied over decades, but the effect of boundary heating conditions on boiling received little attention. In this work, heat transfer coefficients during pool boiling of five different refrigerants (R123, R245fa, R236fa, R134a, and R22) on the outside surface of a smooth copper tube were measured at the saturation temperature of 6.7 C; water flows...

Vortex tube is a simple energy separation device, also known as Ranque tube or Hilsch tube, which can separate a high-pressure stream into two different hot and cold streams. Since its simple structure and unique temperature separation characteristics, vortex tube has been widely used in various industries. In recent years, with the in-depth study of the vortex tube, it has been found that comp...

The impact of man-made chemicals on the environment, and in particular, the ozone layer, has been investigated over the last 20 years. The phaseout of CFCs under European Regulations and the Montreal Protocol has already taken place and HCFCs are set to follow. A wide range of alternative refrigerants with zero ozone depletion potential have already been developed as replacements for the refrig...

Abstract—In present paper, the performance of various alternative refrigerants is compared to find the substitute of R22, the widely used hydrochlorofluorocarbon refrigerant in developing countries. These include the environmentally friendly hydrofluorocarbon (HFC) refrigerants such as R134A, R410A, R407C and M20. In the present study, a steady state thermodynamic model (includes both first and...

Refrigerants that are used in refrigeration systems, cause environmental difficulties such as depletion of ozone layer and greenhouse effect. Thus, we must find substitutes for such refrigerants, in this paper, the effect of refrigerant on the thermodynamics performance of refrigeration cycles are studied. To do this, a refrigerator that has designed for R12, is simulated. Results show that pur...

Refrigerants that are used in refrigeration systems, cause environmental difficulties such as depletion of ozone layer and greenhouse effect. Thus, we must find substitutes for such refrigerants, in this paper, the effect of refrigerant on the thermodynamics performance of refrigeration cycles are studied. To do this, a refrigerator that has designed for R12, is simulated. Results show that pur...

Average Nusselt numbers were measured for R22, R290, R290/600a, and R32/152a undergoing evaporation and condensation in a brazed plate heat exchanger. The refrigerants experienced wavy, stratified flow at low heat and mass fluxes, 1.3 kW/m2 to 8.3 kW/m2 and 1.6 kg/m2 s to 19 kg/m 2 s, respectively. Heat transfer correlations from the literature for in-tube and channel flow of refrigerants with ...

this study represents effect of four variables in performance of a heat-pump in two cities of tehran and rasht. a computer program has been developed, simulating a certain heat pump acting in different environments with different refrigerants in heating season. the analysis is based on a homogeneous model. effect of different refrigerants, depth of the buried heat exchangers and moisture conten...

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) recently completed the second phase of its Low Global Warming Potential Alternative Refrigerants Evaluation Program (Low-GWP AREP). This industry-wide cooperative research program identified and evaluated promising alternative refrigerants over the past five years. Seventeen low-GWP refrigerants were tested during the second phas...

Evaporative air cooling is an effective and environmentally benign method of cooling. Scientific evidence demonstrating that chlorofluorocarbon refrigerants (CFCs) are contributing to the destruction of the stratospheric ozone layer have prompted legislative action aimed at reducing the production and use of certain CFCs. Enacted legislation, by necessitating the introduction and use of alterna...