Thermodynamic Performance Analysis of a Novel Vortex Tube Integrated Vapour Compression Cycles

摘要

In last two decades, the upheaval in refrigeration sector has led to replacement of conventional refrigerants with non-ozone depleting and low global warming potential refrigerants. Most of alternate refrigerants which have low global warming potential, have usually low coefficient of performance (COP). To overcome the problem of low COP, a novel Vortex Tube integrated Vapour Compression cycle (NVTCR) has been proposed. The paper emphasizes on improvement in thermodynamic performance of a simple Vapour Compression cycle (VCR) by utilizing a vortex tube in the scheme of VCR. The proposed cycle operates at three pressure levels viz. lowest pressure (in evaporator), intermediate pressure (in vortex tube) and highest pressure (in condenser). A computer program has been formulated in EES software for the analysis. The results have been computed for NVTCR and compared with VCR and Vortex Tube cycle based on Keller model (VCRK) for R134a. The results show that the COP of NVTCR (with liquid vapour heat exchanger (LVHE)) is higher than the COP for both VCR and VCRK The COP (corresponding to T_e=-25°C and 10°C respectively) of VCR, VCRK, NVTCR and NVTCR (with LVHE) varies between 1.59 to 4.16, 1.7 to 4.24, 1.65 to 4.20 and 1.74 to 4.28 respectively. The effect of various parameters like evaporator temperature, condenser temperature, vortex tube nozzle efficiency (η_v), cold mass fraction (μ), bifurcation of cold mass fraction stream (z)for subcooling in heat exchangers (installed after condenser and separator) and effectiveness of liquid vapour heat exchanger (ε_(lvhe)) on COP of NVTCR have been examined. The effect of ε_(lvhe)on COP of NVTCR is maximum among the parameters ε_(lvhe), η_v, μ and z considered for analysis. It is observed that percentage increase in COP of the NVTCR (with LVHE) with respect to COP of VCR varies by 4.46% and 10.05% corresponding to ε_(lvhe) equal to 0.1 and 1 respectively.