A significant decrease in the solar-thermal conversion efficiency of parabolic trough collectors occurs at high operating temperatures, mainly due to the massive radiant heat loss from the parabolic trough solar receiver incurred in this case. In this paper, a novel parabolic trough solar receiver integrated with vanadium dioxide-based thermochromic coating is proposed to effectively reduce the radiant heat loss and improve the overall performance of solar receivers. The thermochromic layer, deposited on the glass envelope’s inner surface in the negative thermal-flux region, has a reversible transition from a monoclinic (M) phase to a rutile (R) phase at the critical temperature of 68 °C. The occurrence of the phase transition in the thermochromic coating induces beneficial self-regulation of the spectrum-selectivity characteristics of the glass envelope, i.e., transmittance, reflectance, and absorptance (emittance) of glass envelope to solar and infrared radiation, for enhancing the thermal performance of solar receivers. Comprehensive heat transfer models based on the finite volume and spectral radiant heat transfer methods are established in this study. It is validated the models can predict the thermal performance of the solar receivers with high accuracy. In this framework, the total heat loss, thermal efficiency, and exergy efficiency of parabolic trough collector systems integrated with the proposed novel solar receivers are investigated and analyzed. Besides, the effects of transmittance of thermochromic coating (M phase) and emittance of thermochromic coating (R phase), two key parameters, on the overall performance of proposed solar receivers are also studied. The results show that no matter under the M phase or R phase, the thermochromic coating can play unique advantages to improve the thermal performance of the proposed solar receivers. The heat loss and thermal efficiency of the proposed solar receivers are effectively reduced and enhanced by 18.2% and 4.8% at the absorber temperature of 600 °C and inlet fluid temperature of 580 °C, respectively.

在高工作温度下，抛物槽式集热器的太阳热转换效率显着下降，这主要是由于在这种情况下，抛物槽式太阳能接收器产生了大量的辐射热损失。本文提出了一种新型的抛物槽式太阳能接收器，并结合了基于二氧化钒的热致变色涂层，以有效降低辐射热损失并提高太阳能接收器的整体性能。沉积在负热通量区域玻璃外壳内表面上的热致变色层在68°C的临界温度下具有从单斜晶（M）相到金红石（R）相的可逆转变。热致变色涂层中相变的出现引起玻璃外壳的光谱选择性特征的有益的自调节，即玻璃外壳对太阳和红外辐射的透射率，反射率和吸收率（发射率），以增强热能。太阳能接收器的性能。本研究建立了基于有限体积和光谱辐射传热方法的综合传热模型。经验证，该模型可以高精度预测太阳能接收器的热性能。在此框架下，研究和分析了与所提出的新型太阳能接收器集成的抛物槽收集器系统的总热损失，热效率和火用效率。除了，还研究了两个主要参数热致变色涂层的透射率（M相）和热致变色涂层的发射率（R相）对所提出的太阳能接收器整体性能的影响。结果表明，无论在M相还是R相下，热致变色涂层都可以发挥独特的优势来改善所提出的太阳能接收器的热性能。所提出的太阳能接收器的热损失和热效率在吸收器温度600°C和入口流体温度580°C时分别有效降低和提高了18.2％和4.8％。热致变色涂层可以发挥独特的优势，以改善所提出的太阳能接收器的热性能。所提出的太阳能接收器的热损失和热效率在吸收器温度600°C和入口流体温度580°C时分别有效降低和提高了18.2％和4.8％。热致变色涂层可以发挥独特的优势，以改善所提出的太阳能接收器的热性能。所提出的太阳能接收器的热损失和热效率在吸收器温度600°C和入口流体温度580°C时分别有效降低和提高了18.2％和4.8％。