Experimental studies on critical heat flux (CHF) have been conducted in a uniformly heated vertical tube of 12.7 mm internal diameter and 3 m length at different reduced pressures ranging from 0.24 to 0.99 with R-134a as the working fluid. The onset of CHF was determined by the sudden rise in the wall temperature of the electrically heated tube. Experiments were performed over a wide range of p...

A good matching between size and efficiency is a desirable design feature of cooling units for electronic systems, due to high capacity to size ratio and small weight. For this purpose, Embraco developed a new refrigerating system for small enclosures and telecommunication stations, which makes use of a new miniaturized linear microcompressor. The air-conditioning cooling unit consists of finne...

HFC-134a is used as working fluid in refrigerators widely. However, how to improve the efficiency of compressor and refrigerator is major topic in the word. The purpose of this study is aimed at the performance evaluation of compressors with different viscosity of POEs oil. A hermetic reciprocating compressor using HFC-134a as refrigerant was adopted and the experimental investigation was carri...

Two-phase heat transfer coefficients for internal flows play a critical role in the design and analysis of evaporators and condensers. Previous studies propose empirical relations that combine the effects of nucleate and convective boiling onto the overall heat transfer coefficient. Although these relatively simple empirical relations offer physical insight on the nucleation, boiling and flow p...

Application ofHFC refrigerants for air conditioners and refrigerators has been studied. Development of a common oil, based on a combination ofpolyolester and additive packages, is aimed for R-22 and HFCs refrigerants, and the evaluation tests of reliability in compressor and refrigeration system brought about good results. This refrigeration lubricant is already partly commercialized in HFC ref...

In the last quarter of the century, a substantial amount of research work has been conducted on optimization of energy consumption by refrigeration systems and on proper design and construction of household refrigerator-freezers. The importance of such energy optimization schemes stems from the environmental impacts of Freon (R-12) used as the working refrigerant in household refrigerator – fre...

In this paper, a detailed combined 1-D model of HVAC systems vehicle were developed by using the LMS imagine LAB AMESIM software package. The numerical simulations considered for soaking and cool down analysis under different environmental conditions. thermal performance refrigerants as R-134a R-1234yf evaluated in terms energy consumption. According to simulation results, cabin air temperature...

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