A beam-down linear Fresnel reflector integrated with photovoltaics for combined heat and electricity production

A beam-down linear Fresnel reflector coupled with a flat plate receiver and photovoltaics is designed and investigated in optical and thermal terms. The secondary reflector has a triangular shape both for increased efficiency and potentially reduced construction cost, which is a novel design. The main geometrical design parameters of this reflector are investigated and optimized. This design enables easy integration of the beam-down configuration with photovoltaics, taking advantage of the beam-down’s reflector supportive structure. This is a crucial step to tackle one of the main disadvantages of beam-down configurations, which is the lower system efficiency due to the shading of the secondary reflector that affects both the receiver and the primary mirror field. Both heat and electricity can be produced for large-scale industrial applications. The optimum optical performance for the proposed system is equal to 55.2%, whereas the optimum thermal and exergy efficiencies are equal to 52.8% and 26.9%, respectively. The total system efficiency for combined heat and electricity production leads to an average efficiency of 43.0% for a typical summer day, and the total electricity coverage for pressurizing the heat transfer fluid deviates from 44.7% to 100% during this day.