This paper describes thermal modeling of Vapor Compression Refrigeration System using R134a in primary circuit and AL2O3-Water based nanofluids in secondary circuit. The model uses information of the secondary fluids input conditions geometric characteristics of the system, size of nanoparticles and the compressor speed to predict the secondary fluids output temperatures, the operating pressure...

As one of the earliest natural refrigerants, CO2 has a lot of unique advantages, such as zero ODP, negligible GWP, excellent heat transfer coefficient, high volumetric capacity, non-toxicity, non-flammability, and cost effectiveness. Since it was proposed to applying in the mobile air-conditioning, the transcritical CO2 cycle has been attracting great attentions to replace CFC and HCFC refriger...

The observation of a giant magnetocaloric effect in Gd5Ge1.9Si2Fe0.1 has stimulated the magnetocaloric research in the last two decades. However, the high price of Gd and its proclivity to corrosion of these compounds have prevented their commercial use. To reduce raw materials cost, transition metal-based alloys are investigated to replace rare earth-based materials. Environmental consideratio...

Many fluids of hydrocarbon derivatives were used as working fluids in refrigeration and air conditioning during the past few decades. The phase out of chlorofluorocarbons and hydrochlorofluorocarbons has initiated research on finding an alternative working fluid for the existing. In this article, some working fluids with zero ozone depletion potential have been assessed for their suitability as...

Performance of a reciprocating refrigerator compressor with mixed-refrigerants (MR) was investigated experimentally. The current, standard methods of testing compressors and presenting performance data were found unsuitable for MR, and a new experimental apparatus was designed for a ·direct flowrate measurement with MR. Representative test data for Refrigerant R-12 and for a mixture of R-22/R-1...

Recent interest in natural refrigerants has created a new impetus for studies of CO2 as a working fluid in vapour compression systems for refrigeration and air conditioning. Two major drawbacks to its use are the very high pressure differences required across the compressor and the large efficiency losses associated with the throttling process. To overcome the throttle losses, a number of propo...

Compression of pure refrigerants in the two-phase flow region has a number of advantages for the performance of vapor compression systems. Compressors may be lubricated by liquid refrigerant so that the process side of the cycle is not contaminated by lubricant. The compression process can be realized in the two-phase region preventing superheating with its associated irreversibility losses. Th...

The present paper summarizes the activities at LTT-Erlangen on the field of thermophysical properties research for pure refrigerants and refrigerant mixtures. For the characterization of their thermophysical properties dynamic light scattering (DLS) has been intensively applied as a key tool during the past two decades. Beside a representation of the essential features of DLS for the determinat...

New lubricants have been developed to meet the performance demands of modem refrigerants and system components. A brief review of current refrigeration oil developments is presented. It is well known that the new lubricants used with polar refrigerants tend to absorb water. The ester hydrolysis process and the effect on the essential lubricant properties are described. The effect of increased w...

The imminent phaseout of R-11, R-12, and R·llS because of their high ozone depletion potentials has prompted many independent investigations of alternative or subst:i t:uee refrigeranes, ei eher as pure compounds or as mixtures of t:wo or more environmentally acceptable fluids. There are several motivations for investigating mixtures. There are very few pure compounds which can be used for refr...