Capability of a novel impingement heat transfer device for application in future solar thermal receivers

Abstract

CSP receivers are designed to permit higher outlet temperatures in order to enable higher theoretical efficiencies of the associated thermodynamic cycles. For pressurized air receivers, it is attempted to increase the operating temperature of metallic pre-heaters to then achieve high air outlet temperatures with cascaded ceramic receivers. Two limitations of metallic pressurized air receivers are cost and material creep at elevated temperatures and pressures. Therefore, it is necessary to maximize heat transfer from the receiver surface to the working fluid while minimizing the material surface temperature. Current research has demonstrated that jet impingement heat transfer devices are appropriate for application in thermal receivers because of the associated desirable heat transfer characteristics. However, it is shown that significant pressure losses are caused by such impinging jets because of the sudden expansion phenomenon. A novel enhanced impingement heat transfer device is presented in this paper. Experimental testing was conducted to investigate the domain comparatively with impinging jet configurations. The device is shown to be capable of delivering an enhanced surface heat transfer coefficient while affecting a lower total pressure loss around the domain when compared with similar impinging jet configurations. The geometry of the device can also be chosen to achieve a favorable combination of heat transfer and pressure loss characteristics. The device is applicable within the SCRAP concept and may be implementable within the SOLHYCO and SOLUGAS receivers. The device may also find an application in a parabolic dish collector. Finally, a novel receiver concept that incorporates the device in a tessellated structure is introduced – the SUNflower.