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Abstract

Investigation of ring type spacer effects on performance of heat transfer and flow behaviour of R-134a flow at supercritical pressure, using CFD in an annular channel has been carried out. ANSYS Fluent has been used for simulation and turbulent model used in present study is SST k-ω. Present investigation is carried out at supercritical pressure 4.5MPa using fluid as R-134a.The objective is to focus the flow behaviour and thermal characteristics due to ring type spacer used for study. Pressure, velocity, temperature at wall and performance of heat transfer & corresponding mechanism in an annular channel have beenanalysed in detail. The results show that the wall temperature sharply reduced and the local heat transfer greatly enhanced at the location of spacer due to the flow area reduction. Due to spacer as flow obstruction, the static pressure is decreased and the velocity is greatly increased at spacer end. Comparison between CFD result for the ratio of coefficient of heat transfer for blockage ratio 0.3 and experimental data along with correlations given by several researchers at pressure of supercritical condition has been performed. The results of the ratio of coefficient of heat transfer (CHT/CHT*) is found in good agreement with the experimental data. The ratio of CHT without spacer annular channel is used to analysis the ratio of CHT with spacer in downstream.

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Keywords

Ratio of coefficient of heat transfer, supercritical R-134a, annular channel with spacer, CFD.