A hybrid PV/Thermal solar concentrating collector coupled to a thermal evacuated tubular concentrating collector in series has been modeled and simulated using Matlab coding. The concentrating collectors studied have been already manufactured by ANU (Australian National University). The concentrating ratio was 37x for both parabolic collectors. The main reason for using Matlab was to achieve a comprehensive knowledge of two dimensional behavior of such a solar system with respect to the time in terms of temperature distribution across the system and over a certain period of time.
Effects of non-uniformity of solar irradiation profile along the receiver and also across it were included as well as shading, dirtiness, and hourly changes in angle of incidence of solar radiation in the modeling and programming. The results presented belong to Barcelona site using hourly meteorological data of 11th June. The electrical efficiency of the hybrid collector has been obtained as 8 percent roughly whereas the thermal efficiency was approximately 58 percent and thus the overall efficiency of 66 percent was derived for the hybrid collector. One the other hand, the thermal efficiency of the evacuated tubular concentrating collector was 70 percent averagely. Therefore, an overall efficiency of the system was 68 percent.
The main encouraging reason for the author to investigate and simulate such a system is to survey the possibility of implying this system in a CHP (Combined Heat and Power) plant to provide electricity and hot steam for producing hydrogen in a very clean way by the means of electrolyzer. Water electrolysis is a clean source of hydrogen, yet is not cost effective, mainly due to the high cost electricity and the low efficiencies (25-35%) of conventional thermal power plants supplying the required electrical energy. However, by operating in the vapor phase at high temperatures, it is possible to save up to 38% of the total energy demand, thus resulting in higher thermal efficiencies of up to 50%. The total energy requirement (?H) for the electrolysis process consists of an electrical energy part (?G) and a thermal energy part (Q=T ?S), which provides the heat demand of the endothermic electrolytic reactions. The basic idea of High Temperature Electrolysis (HTE) is to replace part of the required energy by thermal energy produced from renewable energy resources such as thermal solar energy. Therefore, the current project suggests the use of hybrid PV/Thermal solar array system to provide both electricity and heat to run the electroyzer at high temperatures. The main advantages of such concept can be attributed to 1) the use of abundant cheap solar energy, 2) no harmful gas emissions, thus minimum impact on the environment, 3) significant improvement of overall efficiency of electrolytic hydrogen production. However, because of the intermittent nature of solar energy, the intensity of solar radiations are time varying and the electrolytic process will be running under transient condition. Therefore, the objective of this project is to study the dynamic behavior of the hybrid PV /Thermal solar systems. The system operation assumes that saturated steam at 200-300 oC is fed to th...
