ABSTRACT

Direct absorption solar collectors (DASCs) typically achieve high efficiency due to the volumetric heat absorption process facilitated by the working fluids. In this study, carbon black (CB) nanofluids were utilized as the working fluid to experimentally and numerically investigate the thermal performance of a rectangular DASC. The findings suggest that the nanoparticles have the potential to enhance the efficiency of the DASC.

Direct absorption solar collectors (DASCs) are known for their high efficiency, which is achieved through the volumetric heat absorption process provided by the working fluids In this study, carbon black (CB) nanofluids were used as these working fluids to study the thermal performance of a rectangular DASC. The experiments were conducted using water and nanofluids with 0.05 wt.% nanoparticle concentration, at different flow rates and tilt angles, under a concentrated simulated solar power source. Our results show that the efficiency of the DASC increased as the flow rate increased. The DASC was more efficient when the receiving surface was facing downwards (tilt angle of 0°), and the efficiency was 35% higher than when the receiving surface was facing upwards (tilt angle of 180°). A computational fluid dynamics (CFD) model, which was validated against our experimental results, analyzed the DASC performance under different CB concentrations. According to the simulations, the highest efficiency occurred at a concentration of 0.05 wt.%. The study also highlighted the distribution of temperature and velocity of the nanofluids, as well as the volume fraction of carbon black during the flow process.

摘要

直接吸收式太阳能集热器 (DASC) 通常由于工作流体促进的体积热吸收过程而实现高效率。在这项研究中，炭黑 (CB) 纳米流体被用作工作流体，通过实验和数值研究矩形 DASC 的热性能。研究结果表明，纳米粒子有可能提高 DASC 的效率。

直接吸收式太阳能集热器 (DASC) 以其高效率而著称，这是通过工作流体提供的体积吸热过程实现的。在这项研究中，炭黑 (CB) 纳米流体被用作这些工作流体来研究矩形 DASC。在集中的模拟太阳能电源下，使用水和纳米颗粒浓度为 0.05 wt.% 的纳米流体，以不同的流速和倾斜角度进行实验。我们的结果表明，DASC 的效率随着流速的增加而增加。DASC在接收面朝下（倾斜角0°）时效率更高，比接收面朝上（倾斜角180°）时效率高35%。计算流体动力学 (CFD) 模型，根据我们的实验结果进行了验证，分析了不同 CB 浓度下的 DASC 性能。根据模拟，最高效率出现在浓度为 0.05 wt.% 时。该研究还强调了纳米流体的温度和速度分布，以及流动过程中炭黑的体积分数。