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...

We show theoretically that the second layer of He adsorbed on graphite and solidified at 4/7 of the first-layer density is close to the fluid-solid boundary with substantial density fluctuations on the third layer. The solid shows a translational symmetry breaking as in charge-ordered insulators of electronic systems. We construct a minimal model beyond the multiple-exchange Heisenberg model. A...

Steady state and dynamic simulation and optimization are a key step in the design of heating, ventilation, airconditioning and refrigeration (HVAC&R) systems. It is well known that the computation time in such simulations is dominated by the refrigerant thermophysical property calculations. These calculations generally involve calculating all thermophysical properties given one or two independe...

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...

Details of a heat pump assisted solar water heating system, is briefly described. Refrigerants compromising of Fluorocarbons and Chlorofluorocarbons have been generally used as the working fluid. But due to its ozone depletion effect and high Global warming potential, they have been replaced by synthetic refrigerants such as R22, R134 etc. The heat pump utilizing such refrigerants has shown to ...

Abstract: The supersolidus liquid phase sintering characteristics of commercial 2024 pre-alloyed powder was studied at different sintering conditions. Pre-alloyed 2024 aluminum alloy powder was produced via air atomizing process with particle size of less than 100 µm. The solidus and liquidus temperatures of the produced alloy were determined using differential thermal analysis (DTA). The sinte...

Recently, R32 refrigerant, which has low global warming potential (GWP), attracts much attention as an alternative one instead of R410A and has started to be used in practical systems of room air conditioners (RAC), but compared with natural refrigerants, its GWP of 675 is still high and it is required to use refrigerants with much lower GWP. In addition, although R134a (GWP=1300) is widely use...

Two-phase frictional pressure drop data were obtained for condensation of carbon dioxide in single horizontal micro tube of inner diameter ranged from 0.6 mm up to 1.6 mm over mass flow rates from 2.5*10 to 17*10 kg/s and vapor qualities from 0.0 to 1.0. The inlet condensing pressure is changed from 33.5 to 45 bars. The saturation temperature ranged from -1.5 C up to 10 C. These data have then ...

Thermodynamic data on environmental refrigerants have attracted considerable interest in the optimization and design of heat compressors, exchangers and other refrigeration equipment. In this study, An optimization algorithm was used to obtain the constant parameters of the new empirical model by fitting them to the source databank. The model was used to calculate the constant coefficients of t...