Abstract

The increased efficiency of solar air heaters has been of great importance in recent years. In this study, the effects of environmental parameters on the performance of a new generation of combined solar air heaters were investigated. Using a novel method in an optimization algorithm, the mixing ratio of fresh air and heated air from this type of heater’s reheat system was optimized. The differential equation was modified for this geometry and boundary conditions. As part of the study, the heat recovery system and the preheating of inlet air were applied to increase the efficiency of the air heater. A version of the air heater with a heat recovery system and a version without one were analyzed using Reynolds numbers in the range of 1000 to 8000. In addition, the recovery and preheating cycles were set to close and open, respectively. Note that an air heat exchanger is responsible for transferring the recovery system’s fluid energy to the air heater inlet fluid. The calculations of the numerical modeling of air heaters and closed-cycle recovery systems were independently performed in this study. The research study’s results showed that adding a recovery system to a solar air heater increased the efficiency and the Nusselt number by 15.23% and 7.8%, respectively. The mean temperature of the air heater was dependent on the mixing rate between fresh inlet air and heated air in the heat exchanger in the recovery cycle. In addition, the results indicated that through optimization, the Nu could be increased up to 23%.

摘要

近年来，提高太阳能空气加热器的效率非常重要。在这项研究中，研究了环境参数对新一代组合式太阳能空气加热器性能的影响。采用优化算法中的一种新方法，对来自该类型加热器再热系统的新鲜空气和加热空气的混合比进行了优化。针对该几何和边界条件修改了微分方程。作为研究的一部分，热回收系统和进气预热被用于提高空气加热器的效率。使用 1000 到 8000 范围内的雷诺数分析了带有热回收系统和不带热回收系统的空气加热器版本。此外，回收和预热循环分别设置为关闭和打开。请注意，空气热交换器负责将回收系统的流体能量传递给空气加热器入口流体。空气加热器和闭式循环回收系统的数值模型计算在本研究中独立进行。研究结果表明，在太阳能空气加热器中添加回收系统可将效率和努塞尔数分别提高 15.23% 和 7.8%。空气加热器的平均温度取决于回收循环中热交换器中新鲜入口空气和加热空气之间的混合速率。此外，结果表明，通过优化，Nu可以提高到23%。空气加热器和闭式循环回收系统的数值模型计算在本研究中独立进行。研究结果表明，在太阳能空气加热器中添加回收系统可将效率和努塞尔数分别提高 15.23% 和 7.8%。空气加热器的平均温度取决于回收循环中热交换器中新鲜入口空气和加热空气之间的混合速率。此外，结果表明，通过优化，Nu可以提高到23%。空气加热器和闭式循环回收系统的数值模型计算在本研究中独立进行。研究结果表明，在太阳能空气加热器中添加回收系统可将效率和努塞尔数分别提高 15.23% 和 7.8%。空气加热器的平均温度取决于回收循环中热交换器中新鲜入口空气和加热空气之间的混合速率。此外，结果表明，通过优化，Nu可以提高到23%。空气加热器的平均温度取决于回收循环中热交换器中新鲜入口空气和加热空气之间的混合速率。此外，结果表明，通过优化，Nu可以提高到23%。空气加热器的平均温度取决于回收循环中热交换器中新鲜入口空气和加热空气之间的混合速率。此外，结果表明，通过优化，Nu可以提高到23%。