Cogeneration Plants with Solar Radiation Concentrators

Abstract

Results from experimental studies of a solar cogeneration system with linear photovoltaic modules of a fundamentally new design are presented. The Ʌ-shaped frontal walls are installed face-to-face at an angle to each other and mutually shield their own thermal radiation, which decreases the radiation heat losses by 27% compared with linear photovoltaic modules of the known designs. The photocurrent generated by cooled solar cells is directed to a system for charging chemical batteries and the thermal energy released is transmitted to the unconsumed intermediate heat-transfer fluid and then, through the surface of coil pipes of counter-current heat exchangers, to the consumed process water of the outer circulation circuit. The further transportation of thermal energy to the storage system occurs by natural circulation of the consumed process water through the temperature gradient formed by the control system over the height between the heat source, the heat exchanger, and the heat receiver, an insulated container (a heat accumulator). For the first time, efficient controlled transportation of heat has been implemented without using a circulation pump owing to the excess thermal energy released during the conversion of solar energy by the solar cells and a photo-selective film installed in the focal spot of the optical concentrator. Thus, a possibility of increasing the temperature of the heat-transfer fluids at the cogeneration system outlet has been offered. A two-circuit circulation system allows for separation of unconsumed heat-transfer fluids (antifreezing solutions) and the consumed fluid (the process water) by the pressure in the channels and installation of a linear counter-current heat exchanger that performs the functions of a supporting platform’s mechanical axis along the rotational axis of the optical concentrator. The system uses a dual-axis solar tracking concentrating system comprised of flat mirrors installed at an angle to the horizon. The arrangement of the Ʌ-shaped photovoltaic modules on the supporting framework in series along the heat-transfer-fluid path allows for a reduction in the overall dimensions of the channels, an increase in the total efficiency of the solar cells, and simplification of the encapsulation technology. A method for calculating the output of the cogeneration plant is provided. The method is based on the experimentally measured characteristics of silicon solar cells and heat losses in the channels of the linear photovoltaic modules.