Parametric Estimation of Wall Temperature in a Parabolic Trough Solar Collector Using Supercritical CO₂ as Heat Transfer Fluid for Process Heat Production

In this paper, studies on a commercial parabolic trough solar collector (PTSC) using supercritical CO₂ (s-CO₂) as the heat transfer fluid (HTF) are presented. When compared to other HTFs, supercritical CO₂ can operate at higher temperatures which is useful for power plants. The collector module used for this study is LS-2 module. The effect of mass flow rate and inlet temperature of the HTF on receiver wall temperature, thermal loss, heat transfer coefficient and thermal efficiency is analysed. CO₂ is taken in supercritical state in order to facilitate the direct integration of the collector to high-temperature power cycles. It is found that higher mass flow rate results in lower wall temperature and higher heat transfer coefficient. At any particular mass flow rate, lower operating pressure results in higher wall temperature. Rise in HTF inlet temperature results in an increase in wall temperature and reduction in thermal efficiency of the collector. However, variation in operating pressure results in negligible change in wall temperature.