Abstract
The convective and conductive heat transfer between the solar collector and working fluids make photothermal performance limited, and result in a higher rate of heat loss from the surface of the conventional absorber to the surroundings. Direct absorption solar collectors (DASC) are a favorable alternative for their improved photothermal performance. In this study, a simulation based on the performance of a nanostructured solar collector has been carried out using TRNSYS. The connective and conductive heat transfer from direct solar collectors were improved by using nanofluids and three different nanostructured materials, CuO, GO, and ZnO, in this study. The analysis determines the outlet temperature of the working fluids that passed through the direct solar collector. The TRNSYS model consists of a direct solar collector and weather model for Lahore city, the simulations were performed for the whole year for 1,440 h. The stability of these nanostructured materials in the water was investigated by using a UV‐Vis spectrophotometer. Various performance parameters of direct solar collectors were determined, such as variation in outlet collector temperature and heat transfer rates. The numerical model is validated with experimental results. A maximum outlet temperature of 63°C was observed for GO-based nanofluids. The simulation results show that for the whole year, nanofluids improved the performance of direct solar collectors. Significant improvements in the heat transfer rate of 23.52, 21.11, and 15.09% were observed for the nanofluids based on nanostructures of CuO, ZnO, and GO respectively, as compared to water. These nanostructured energy materials are beneficial in solar-driven applications like solar desalination, solar water, and space heating.
Highlights
Due to the rapid increase in population, energy demands are increasing day by day and fossil fuels are being widely used to meet this demand (Kriegler et al, 2017; Grubler et al, 2018)
The direct solar collector of “Type1b” was used, which absorbed the incoming radiation of the sun for a time span of 12 h and transmitted these radiations directly to the working fluid, named “Type 14 h,” for water mixed with nanoparticles
The location used in TRNSYS for simulation was Lahore city and the coordinates are 31.695o North latitude and 74.244o East longitude at an elevation of 220 m above sea level
Summary
Due to the rapid increase in population, energy demands are increasing day by day and fossil fuels are being widely used to meet this demand (Kriegler et al, 2017; Grubler et al, 2018). The burning of fossil fuels causes serious environmental issues (Agbulut and Sarıdemir, 2019); to overcome these problems, alternative energy resources are being explored. Solar energy has gained the attention of many researchers for differing reasons (Dudin et al, 2016; Oh et al, 2018; Guangul and Chala, 2019). Solar energy utilization can be done by converting sun heat energy into a chemical form of energy, an electric form of energy, or a thermal form of energy. Solar collectors have been utilized for the converting of solar radiation into thermal energy (Conrado et al, 2017; Bellos and Tzivanidis, 2019). Solar energy is collected through flat-surface-based solar plates, converting this collected energy into heat and delivering it to working fluid (Amjad et al, 2018a; Dehaj and Mohiabadi, 2019). The major drawback of this conventional surface base flat type is that, as the temperature of the flat plate increases, the radiant loss of heat occurs (Kılkıs, 2000; Sint et al, 2017; Shafieian et al, 2019)
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