Cryosurgery is a technique for destroying undesirable tissue, such as cancers, by exposing it to a very low temperature. This paper presents a thermodynamic modeling tool that has been developed for a two stage, mixed gas Joule-Thomson (MGJT) cryoprobe used for cryosurgery. A conventional vapor compression (VC) cycle using a pure refrigerant precools the MGJT cycle providing refrigeration at th...

When the re:fiigerant R l34a is mixed with an ester oil and usea m compressor bearing lubrication, no EP action is experienced. The refrigerant contains no chlorine and the lubricant additives can not be chemically active like normal EP additives, not to deposit in and destroy the heat excha..>Jgers. The iubricant film thickness thus needs to be considerably larger for an Rl34a compressor beari...

A multi-tube, spirally-wound, cryogenic heat exchanger, the main heat exchanger (MHE) is the principal piece of heat-transfer equipment in mixed-refrigerant liquefaction cycles for producing liquefied natural gas (LNG). An MHE unit operation model called the spirally-wound tube-bundle module was developed as an integral component of the dynamic simulation capabilities for a process modeling pac...

the examination of available vapor pressure data in the case of the methane, ethane, propane and butane halogenated refrigerants, allowed recommendations of standard equations for this property. in this study, three new models include a general correlation; a substance-dependent correlation and an artificial neural network (ann) approach have been developed to estimate the saturated vapor press...

The effects of compressor speed variation on the heat transfer inside a speed controlled compressor were investigated in this study. Based on the lumped capacitance ntethod, the temperatures of the compressor components, the oil, and the refrigerant gas within the shell were modeled and simulated on a relative scale. A diffenmt heat transfer coefficient correlation was developed to evaluate the...

The application of carbon dioxide as natural refrigerant in commercial refrigeration systems has attracted higher interest in recent years for its promising energy efficiency and ecological sustainability. This paper presented the development of a low side scroll compressor for the bottle cooler application in the trans-critical cycle. Experimental tests were performed in two different temperat...

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...

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...