Abstract

Solar energy exploitation is growing consistently, as it is the cheapest and most accessible amongst all forms of renewable energies. Increasing the performance of solar air heaters can aid in developing clean energy use and subsiding the greenhouse gas emissions in the world. This study, therefore, seeks to improve the thermo-hydraulic performance of solar air heaters using sinusoidal extended surfaces. The results show that the Reynolds number increment contributes to the enhancement of Nusselt number and thermo-hydraulic performance, while it does not affect the friction factor considerably. The highest value of the Nusselt number belongs to the case with the highest fin amplitude and wavy fins configuration by about 7 times higher value in comparison to the simple solar air heater. It is shown that the wavy configuration can render higher thermo-hydraulic performance than that of raccoon fins, by about 10 percent. The finned configurations feature better fluid flow mixing at the outlet and lower maximum and gradient of temperature on the absorber plate compared to those of simple and common solar air heaters.

摘要

太阳能开发持续增长，因为它是所有形式的可再生能源中最便宜和最容易获得的。提高太阳能空气加热器的性能有助于发展清洁能源的使用并减少全球温室气体排放。因此，本研究旨在提高使用正弦扩展表面的太阳能空气加热器的热工水力性能。结果表明，雷诺数的增加有助于提高努塞尔数和热工水力性能，而不会显着影响摩擦因数。努塞尔数的最高值属于具有最高翅片振幅和波浪形翅片配置的情况，与简单的太阳能空气加热器相比，该值高出约 7 倍。结果表明，波浪形配置可以提供比浣熊鳍高约 10% 的热液压性能。与简单和普通的太阳能空气加热器相比，翅片配置在出口处具有更好的流体流动混合以及吸收板上更低的最大温度和温度梯度。