Pressure Drop in Two - Phase Flow Boiling of R134a, R123 and Their Mixture in Horizontal Tube

Experiments were conducted to investigate pressure drop characteristics during flow boiling of non-azeotropic refrigerant mixtures of R32/R134a(mass ratio 25%/75%) in micro-tube(0.86 mm i.d.) of 200 mm heated length,and bubble behaviors in the exit of micro-tube were observed.Effects of mass flux,mass quality and heat flux on two-phase pressure drop in micro-tube were analyzed and comparisons were made with mini-tube and normal-tube under the same working conditions.The results show that two-phase pressure drop in micro-tube rises with increasing mass quality and mass flux.When heat flux is lower,two-phase pressure drop increases in step with increased heat flux,but two-phase pressure drop rises with a higher value once reaching a higher heat flux.Compared with mini-tube and normal-tube,two-phase pressure drop in micro-tube is much higher under the same working conditions.When considering both heat transfer enhancement and two-phase pressure drop,an optimum micro-channel configuration exists for micro-channel heat exchangers to achieve the best heat transfer economical performance.

Mass flux

Vapor quality

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Experimental investigation on flow boiling heat transfer and pressure drop of refrigerants R32 and R290 in a stainless steel horizontal tube

Journal of Physics Conference Series (2019)

B. Citarella G Lillo R. Mastrullo A.W. Mauro Luca Viscito

Abstract The purpose of this paper is to present new flow boiling heat transfer and pressure drop data in a single, horizontal smooth stainless steel tube of 6.0 mm internal diameter, in which R32 and R290 (propane) are employed as working fluids. The cross sectional average heat transfer coefficients are obtained by measuring the temperatures at the top, bottom, left and right sides of the channel. The experimental trends are analyzed for different operating conditions in terms of mass velocity (from 150 to 300 kg/(m 2 s)) and heat flux (from 10 to 40 kW/m 2 ). The saturation temperature is fixed to 25 °C for the heat transfer data and to 25 and 35 °C for the pressure drop experiments. The effects of the operative parameters and of the working fluids on local heat transfer coefficients and frictional pressure drop are discussed and the experimental data are finally compared with some of the available correlations taken from scientific literature.

Boiling point

Propane

10.1088/1742-6596/1224/1/012041

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Flow Pattern and Pressure Drop in Flow Boiling of Pure Refrigerants and Their Mixture in Horizontal Tube

Memoirs of the Faculty of Engineering, Kyushu University (2002)

Tae Woo Lim Yasunobu Fujita

An experimental investigation on the flow pattern and pressure drop was carried out for both an adiabatic and a diabatic two-phase flow in a horizontal tube with pure refrigerants R134a and R123 and their mixtures as testfluids. The measured frictional pressure drop in the adiabatic experiments increased in the S-curve as equilibrium vapor quality was increased. These data were compared with various correlations proposed in the past for the frictional pressure drop. Chisholm 1 ) correlation considerally underpredicted the present data both for pure fluids and their mixtures in the entire mass flux range 150 to 600 kg/m 2 s covered in the measurements, while Friedel 2 ) correlation was found rather well to correlate the frictional pressure drop data among compared correlations. However a detailed examination showed Friedel correlation underpredicted the present data in the stratified and stratified-wavy flow regions at low vapor quality and overpredicted in the annular flow region at high quality. A new two-phase multiplier was developed from a dimensional analysis of the frictional pressure drop data measured in the adiabatic experiment. This new multiplier was found successfully to correlate the frictional pressure drop measured in the diabatic flow boiling experiments of pure refrigerants and their mixtures with a mean deviation of 20%.

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Vapor quality

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Boiling point

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An Experimental Investigation of Pressure Drop in Flow Boiling of Pure Refrigerants and Their Mixture in Horizontal Tube

JSME International Journal Series B (2005)

Tae Woo Lim Jun Hyo Kim

Experimental investigation of pressure drop for pure refrigerants R134a and R123 and their mixtures as test fluids was carried out for both an adiabatic and a diabatic two-phase flow in a horizontal tube. The measured frictional pressure drop in the adiabatic experiments increased in the S-shaped curve as equilibrium vapor quality was increased. These data were compared to various correlations proposed in the past for the frictional pressure drop. The homogeneous model considerally underpredicted the present data both for pure fluids and their mixtures in the entire mass flux range 150 to 600kg/m2s covered in the measurements, while Friedel correlation was found rather well to correlate the frictional pressure drop data among compared correlations. However a detailed examination showed Friedel correlation underpredicted the present data in the stratified and stratified-wavy flow regions at low vapor quality and overpredicted in the annular flow region at high quality. A new two-phase multiplier was developed from a dimensional analysis of the frictional pressure drop data measured in the adiabatic experiment. This new multiplier was found successfully to correlate the frictional pressure drop measured in the diabatic flow boiling experiments of pure refrigerants and their mixtures almost with a mean deviation of 20%.

Diabatic

Vapor quality

Mass flux

Boiling point

10.1299/jsmeb.48.92

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Citations (6)