Parabolic concentrated solar systems for heating, cooling, and power generation in cold climates and remote communities

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Date
2017
Authors
Mosallat, Faezeh
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Abstract

To date, concentrated solar trough collectors have focused primarily on electricity generation in low latitudes using 400oC thermal oil temperatures. To adapt this technology to remote communities—that rely on diesel and heating oil and reach ambient temperatures of -40°C for extended periods—it is postulated that lowering the fluid temperature below 100oC is a preferred approach to reduce safety risks and operator qualification requirements. This approach mitigates higher heat losses in cold climates and still allows refrigeration and heating loads to be displaced by thermal energy; however, it significantly reduces thermal power generation efficiency. To regain electrical efficiency, the system is redesigned using concentrated photovoltaic cells secured to each receiver tube that can be cooled by glycol, an environmentally safer working fluid compared to thermal oil, operating at temperatures below 100oC. To investigate lower operating fluid temperatures and control issues related to cold climates, the methodology adopted is to design and build a 52-kW parabolic solar trough pilot plant in Winnipeg, as this location is chosen by some industries to perform cold weather testing. In addition, a transient model is developed to investigate how to integrate solar troughs in remote community applications. The model is validated using the pilot plant, predicting the fluid outlet temperature of the solar field with an average deviation of 1°C from measurements during thermal energy generation. A concentrated-photovoltaic-thermal configuration is then introduced to achieve attractive payback periods for remote communities in cold climates experiencing high energy costs and implementing renewable energy. Furthermore, to maximize revenues in these communities, a pump control strategy is implemented to reduce parasitic power by 80%; a multi-objective optimization algorithm results demonstrate the need to adjust the solar field flow rate in cold climates during operations.

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Keywords
Parabolic solar trough, Cold cimates, Remote communities, CPVT
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