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In this work, photovoltaic thermal-compound parabolic concentrators (PVT-CPC) are integrated to a single slope solar still (SS-SS) through a heat exchanger placed in the basin. A continuous water flow is provided over the condensing cover of SS-SS for yield enhancement. An effect of cooling condensing cover on energy and exergy analysis (thermal and electrical) together with the production cost of distilled water (₹/kg) has been studied for the following three cases: (I) the proposed partially covered photovoltaic thermal-compound parabolic concentrator single slope solar still (PVT-CPC-SS-SS), (II) fully covered thermal-compound parabolic concentrator single slope solar still (PVT-CPC-SS-SS), and (III) flat plate thermalcompound parabolic concentrator single slope solar still (FPC-CPC-SS-SS). Design parameters have been optimized for maximum distillate output (energy) and exergy on annual performance basis. Moreover, higher daily yield (37.9 kg) is obtained for case (iii). In addition, higher electrical module efficiency (13%) is obtained for case (ii) for the month of January when the solar cell temperature is 55 °C at the optimized conditions. However, the proposed system gives daily yield (35.78 kg) and generates electricity at module efficiency of 12%. The energy payback time of the proposed system is estimated to be 2 years.

Abstract:In the present work the ground temperature has been validated for climatic condition of Sriperumbudur near Chennai, India to evaluate thermal conductivity and diffusivity of the soil. For the evaluated thermal conductivity of the soil, an EAHE has been designed for a given dimension of room with optimized values of number of air changes, length of pipe, radius of pipe and depth at which heat exchanger to be installed below the surface of the earth. It has been observed that there is a decrease of 5 -6 0 C in the outlet air temperature in summer for a number of 5 air changes with 0.10 m and 21 m optimized diameter and length of pipe respectively.

In this communication, an analytical expression for slurry temperature as a function of design and climatic parameters of photovoltaic thermal (PVT) integrated biogas system has been derived. Also, exergy analysis of the given system has been carried for the month of January for Srinagar (Kashmir), India. The effects of mass flow rate (ṁf), number of PVT collectors, length of heat exchanger (L), and heat capacity of slurry on slurry temperature (Ts) have been studied under forced mode of operation. For a given capacity of slurry a system comprising of PVT collectors in series combination has been studied for achieving optimum slurry temperature (Ts) of ∼35 °C to ensure maximum biogas production. The results have been analysed for three cases namely: case (i) conventional flat plate collectors, case (ii) partially covered flat plate collectors and case (iii) fully covered photovoltaic module. It was concluded that the system consisting of partially covered flat plate collectors as discussed in case (ii) is highly sustainable and efficient for functioning in harsh cold climatic conditions that exists in Srinagar (Kashmir), India because it produces both thermal as well as electrical energy simultaneously.

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