Design and Performance Evaluation of Large Field of Flat Plate Solar Collectors Network for Industrial Application

Abstract

The new national strategy 2030 in the energy sector recommends using solar energy in industrial applications such as heating processes in factories, heating and cooling applications using sorption technology, and seawater desalination. The aims are to fulfill the growing energy demand and to reduce the gas emissions resulting from fossil fuels. The heating loads in the industrial sector are in the order of hundreds of kWs and in some cases, reach to few MWs. The main objective of the present study is to provide a reliable method to design a flat plate solar collectors network that supplies the needed mega-scale hot water duty for industrial processes and commercial applications. In mega-scale applications, more collectors, fittings, and connections will be needed resulting in an increase in the pumping power, hence a considerable increase in the running cost. Moreover, the heating fluid circulates in a closed loop and returns to the solar collector having relatively higher inlet temperatures. The primary concern in the design of a solar system is to determine the minimum number of flat plate solar collectors required and the optimum parallel and series arrangement which is essential to minimize the initial and running costs of the solar system. A mathematical model considering the thermal resistances of all components of a commercial flat plate solar collector module was developed and integrated into all possible arrangements in series and parallel connections. The model was programmed in MATLAB. The effect of various operating parameters on the solar system design such as fluid inlet temperature, the solar intensity, and the ambient temperature was investigated. The impact of using double covers instead of a single cover was discussed for a possible reduction of the total number of flat plate solar collectors. It was found using a double cover has no significant effect at low fluid inlet temperatures while it is recommended when the fluid inlet temperature is higher than 60 °C. The total number of collectors decreases by 14% when the required load is about 126 kW at inlet temperature 60 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C. The model includes a module to calculate the Pressure drop to compromise between the heating duty and the allowable pressure drop for various series and parallel arrangements. The present study provides various charts at various operating conditions that enable customers to specify the required minimum total number of solar collectors and the optimum arrangement based on the thermal duty required.