(242a) Development of low-cost Receivers for Parabolic Trough Assembly for developing countries like India: Optical and Thermal optimization

India’s energy consumption has seen an exponential growth of 91% between 1990 to 2008. As per International Energy Agency (IEA), India’s energy demand will increase by 50% by 2030, and by 2040 India will have the largest increase in energy demand. This will indeed lead to an increase in pollution and carbon footprint. For sustainable development, India has to develop renewable energy technology at a higher pace. Amongst renewable sources, solar energy has seen a massive development in the past couple of years. Installed capacity has increased from 12.3 GW to 37 GW from 2017 to 2020 which is roughly 4% of total power generation. Based on India’s ambitious policy, more than 40% of the total power generated will be solar power. Presently, PV and CSP contribute 34.62 GW and 500 MW respectively. PV is the cheaper and more developed form of solar technology as compared to CSP. With advances in thermal energy storage (TES) systems, CSP can be made cheaper than PV. The worldwide installed capacity of CSP has increased from 1.3 GW to 6.3 GW in the last decade.

Among CSP, Parabolic Trough Collector (PTC) is the most mature technology. The worldwide installed capacity of PTC has increased from 632 MWe to 4.7 GWe in the last decade. Receiver tubes constitute nearly 30% of total solar field cost and hence play a vital role in deciding the cost of power production. The minimum cost of power production in India is INR 10.5 at Diwakar, Rajasthan. This cost is incompetent concerning PV and hence low-cost receivers have to be deployed to bring down the production cost.

A patented novel PTC design has been fabricated to harness solar energy efficiently. The cost of assembly is $75/m²-aperture. To bring down the cost of assembly, a single parabolic reflector has been replaced by multiple linear mirror strips of 30 mm width and 1 m length placed on a laser-cut parabolic frame. This provides operational flexibility and easy replacement in case of breakage. The proposed square cavity receiver is optimized by an in-house solar ray-tracing code. The maximum optical efficiency attained by the system is 83% for highly reflecting glasses and a highly absorbing solar selective coat on the absorber tube. Based on the optimization, a cavity of 60 mm width (aperture width) and 71 mm height is used for further thermal optimization. The center of the absorber tube is positioned at a height of 1.6.45 m from the vertex of the parabolic frame.

CFD technique has been applied to predict the thermal performance of the proposed air-filled square cavity receiver. Heat loss value at various absorber tube temperatures was: 44.75 W(200 ⁰C), 64.27 W(250 ⁰C), 87.89 W(300 ⁰C), 116.36 W(250 ⁰C), 150.5 W(400 ⁰C), 191.24 W(450 ⁰C) and 239.42 W (500 ⁰C). Simulations have been carried out to study the effect of key performance parameters like emissivity of solar selective coat, orientational of receivers, the reflectivity of optical cavity and casing of receiver, wind flow around the receiver, and insulation material. To compare the performance of the proposed receiver, data has been compared with commercialized SCHOTT PTR® 70 Receivers. Heat loss from proposed receiver against SCHOTT at respectively