Improving the Hybrid Photovoltaic/Thermal System Performance Using Water-Cooling Technique and Zn-H₂O Nanofluid

Abstract

This paper presented the improvement of the performance of the photovoltaic panels under Iraqi weather conditions. The biggest problem is the heat stored inside the PV cells during operation in summer season. A new design of an active cooling technique which consists of a small heat exchanger and water circulating pipes placed at the PV rear surface is implemented. Nanofluids (Zn-H2O) with five concentration ratios (0.1, 0.2, 0.3, 0.4, and 0.5%) are prepared and optimized. The experimental results showed that the increase in output power is achieved. It was found that, without any cooling, the measuring of the PV temperature was 76°C in 12 June 2016; therefore, the conversion efficiency does not exceed more than 5.5%. The photovoltaic/thermal system was operated under active water cooling technique. The temperature dropped from 76 to 70°C. This led to increase in the electrical efficiency of 6.5% at an optimum flow rate of 2 L/min, and the thermal efficiency was 60%. While using a nanofluid (Zn-H2O) optimum concentration ratio of 0.3% and a flow rate of 2 L/min, the temperature dropped more significantly to 58°C. This led to the increase in the electrical efficiency of 7.8%. The current innovative technique approved that the heat extracted from the PV cells contributed to the increase of the overall energy output.

The combined effect of nanofluid and reflective mirrors on the performance of PV/thermal solar collector

“…where the c n and c w are the heat capacity of Al 2 O 3 and water, respectively. The viscosity of nanofluid is given by [16]:…”

“…where δ, fig. 2(a), is the thickness of the solar cell, c p -the specific heat of nanofluid, K -the thermal conductivity of the material, U L -the overall heat loss coefficient of a collector, and h f,i -the convection heat transfer coefficient inside the tube and calculated for the nanofluid from the following relations [16]…”

“…Hussein et al [16] utilized the nanoparticle type (Zn-water) to improve the performance of the hybrid PV/T collector. The results showed that using the nanofluid led to improved electrical and thermal efficiency of the collector.…”

Comparative analysis of CuO-based spiral flow photovoltaic sheet and tube thermal system

“…They found multiwall nanotubewater as better NFs among all as at 0.75 % particle and flow rate of 0.025 kg/sec; energy efficiency of 23.47 % and entropy generation drop of 65.55 % was seen. R. Gangadevi et al (2018) [16] analyzed the thermo physical property of ZnO-water NFs and proposed it as a heat transport medium in the PV/T [17] presented performance improvement using Zn-H2O nanofluid in PV system under Iraqi weather conditions. The actively cooled pipe heat exchanger was designed and heat transport was investigated at five concentration ratios of 0.1, 0.2, 0.3, 0.4, and 0.5%.…”

“…In the work, experiments were conducted at 40L/H and concentration of 0.05, 0.1 and 0.2% respectively. The PVT efficiency was observed up to 93% at an upper volume concentration of 0.2 %.Hashim A Hussein et al (2017).…”