RESUMO
The solar receiver is a vital component of concentrated solar collectors that absorbs solar radiation and converts it into heat. One of the challenges the research community faces is minimizing heat loss from the receiver at higher temperatures to maximize the thermal performance of parabolic dish collectors and achieve the system's cost-effectiveness. Cavity receivers have a complex design that makes them more challenging to manufacture and entails higher costs for improved thermal performance. Implementing innovative receiver designs is essential to maximize the absorption of solar radiation and minimize heat losses. In this experimental study, a cost-effective solar receiver was fabricated with fins to study heat transfer. The solar receiver is examined using water as heat transfer fluid with three flow rates of 0.097 kg/s, 0.125 kg/s, and 0.152 kg/s. The residence time of water is increased by adopting integrated fin receiver designs. The provision of fins in the solar receiver enhances heat transfer by increasing the turbulence in the fluid flow and results in higher thermal efficiency. The average energy and exergy efficiencies are 67.81 % and 8.93 %, respectively, with a 0.152 kg/s flow rate. At the highest water flow rate (0.152 kg/s) considered in this study, a lesser heat loss of about 3776.2 W occurred due to the effective heat transfer. The cost metrics, like levelized cost of electricity, net present value, and the payback period, are about 0.21 $/kWh, 923 $, and 3.38 years, respectively, at 0.152 kg/s flow rate. The proposed solar receiver produces optimal thermo-economic performance and lower initial investment for steam generation than other receiver designs. The current experimental study's findings could benefit the entire solar industry by presenting an effective solar receiver design for solar collectors.
RESUMO
Parabolic dish collectors (PDC) efficiently produce hot fluids for medium-temperature applications. Thermal energy storage employs phase change material (PCM) due to its high energy storage density. This experimental research proposes a solar receiver for the PDC with a circular flow path surrounded by PCM-filled metallic tubes. The selected PCM is a eutectic mixture of KNO3 and NaNO3 (60%:40% by wt). At a peak solar radiation of about 950 W/m2, the receiver surface reached a maximum of 300 °C. The modified receiver is tested outdoors with water as a heat transfer fluid (HTF). The energy efficiency of the proposed receiver is about 63.6%, 66.8%, and 75.4% for the HTF at 0.111 kg/s, 0.125 kg/s, and 0.138 kg/s, respectively. The receiver's exergy efficiency is recorded at about 8.11% at 0.138 kg/s. The receiver with a maximum reduction of CO2 emission is about 1.16 tons recorded at 0.138 kg/s. The exergetic sustainability is analyzed using key indicators, like the waste exergy ratio, improvement potential, and sustainability index. The proposed receiver design with PCM effectively produces maximum thermal performance with a PDC.
