Document Type : Research Paper
Authors
1 University of Benin
2 Department of Welding and Fabrication Engineering, Faculty of Engineering, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Akwa Ibom State, Nigeria
Abstract
Cooling refrigeration systems ingest prime energy and contribute to universal negative impacts due to ecologically unfavorable working fluids used. Hence, the quests to improve the performance of VCRS with more efficient and eco-friendly refrigerant such as nanoparticles is imperative. In this study, performance analysis of Hybrid Nanofluids-Zeotropic Mixtures in a VCRS were experimentally investigated to determine the best operating optimum performance using exergy based approach. To achieve this, varying concentrated mixtures were selected using ternary graph. Results revealed that all the designated ratios of the mixed refrigerant with different fractions achieved good performance improvement with the optimum values obtained at (011) zero gram of TiO2, 7.5g-Al2O3/CuO. All the selected hybrid mixtures led to an improved outcome in terms of Coefficient of Performance (COP), less power consumption and high performance exergetic efficiency, with COP values ranging from 0.31 % to 3.10 % and exergetic efficiency from 0.32 % to 1.43 %. The values for thermal conductivity, dynamic viscosity, density and specific heat were found to be highest (0.0958 W/m.K; 0.00164 W/m.K; 686.82 kg/m3 and 359.82 kJ/kg.K) at the same concentration of zero grams TiO2 in the mixtures. Comparison made from the performance characteristics curve (with global parameters) indicated that maximum power coefficient and cooling capacity for the various concentrations were found at (001) 7.5g-TiO2, zero grams Al2O3/CuO equal to 2.2 kW, and the minimum value at concentration 5 was 0.61 % at (111) 5g-TiO2/Al2O3/CuO, and 0.87 % for (121). An increase was observed in the maximum power coefficient, cooling capacity and COP increased by 13.51 %, 5.78 % and 10.33 %. It was observed that hybrid nanofluid-zeotropic refrigerant worked seamlessly with VRCS, making it a sustainable, green and clean as well as eco-friendly alternative with near-zero to zero negative effects on public health safety and environment.
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