Application of a Shape-Stabilized PCM in Direct-Absorption-Storage Solar Collectors Accompanied by Constructing a Large-Scale Solar Simulator

Solar thermal collectors suffer from remarkable radiative heat losses after the absorber part reaches high temperatures avoiding further heat absorption. Also, the heat absorption part and the heat storage medium are considered as separated units occupying more space. To encounter these issues, a storage system, such as phase change materials must be designed in order to store the excessive heat, and subsequently, reduce the heat losses. In this project, a shape-stabilized phase change material (SSPCM) was utilized to serve this purpose in a solar collector design as well as the shape-stability property leads to avoiding leakage problems during the melting process of the material. In addition, the SSPCM was developed with the possession of a high absorptivity value; hence, it was directly used as the absorber plate and the heat storage medium to remove the thermal barriers for the heat storage process. On the other hand, a large-scale solar simulator was designed and built to be able to test any solar system in the lab regardless of the climatic conditions providing sufficient radiation intensity. The SSPCM was synthesized at various concentrations of the related components to find out an efficient compound for heat storage purposes. Furthermore, the proposed solar collector-storage system was discharged at 10, 27, and 40 litres per hour (LPH) flow rates to optimize the solar system discharging performance. It was revealed that the design with light concentration leads to overheating of the material and the manufactured evacuated tube solar collector presented a heat absorption efficiency of 82% as a result of the high thermal conductivity of the phase change material. Also, it was shown that argon gas reduces the heat losses from the collector as well as 2.68 kWh/m2 of electromagnetic energy is required to fulfil the material charging process thoroughly. In addition, it was revealed that changing the flow rate from 10 to 27 LPH does not considerably reduce the heat gain of the collector; however, using the flow rate of 40 LPH plunges the heat exchange time of water and the pipe. Ultimately, cost and carbon footprint analyses of the designed system were conducted and a payback period of around 6 years and an annual reduction of 5.4 tons of CO2 emissions were reported.