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In this paper heat losses from cavity receiver of solar concentrators are presented. Convective and radiative losses for specified cavity receiver are estimated by MATLAB programming and effect of the various parameters is studied. Radiation losses are analyzed for operating temperature in range of 127°C to 527 °C and aspect ratio of 0.5 to 2.5. Convective losses are investigated for operating temperature in range of 127°C to 527 °C, inclination angle from 0 to 90o, aspect ratio of 0.5 to 2.5 and wind effect for 0 to 10 m/s. Radiation losses and convective losses increases as operating temperature of cavity receiver increases. The convective losses are more for sidewise facing cavity (0o inclination) and less for downward facing cavity (90o inclination). As aspect ratio and wind velocity increases, convective loss increases.

Original scientific paper https://doi.org/10.2298/TSCI150601165S The highest heat losses are found for wind direction α is 60° with respect to receiver stand and lowest heat losses are found for wind direction α is 0° (side-on wind). The heat losses obtained for wind direction, α, is 30° condition are higher than the heat losses obtained for wind direction α is 0° (side-on wind) condition, while the heat losses obtained by wind direction α is 90° (head-on wind) condition are less than the heat losses obtained for wind direction, α, is 60° condition.

In this paper, analysis of total heat losses has done by constructing an experimental set up of electrically heated spherical cavity receiver of solar concentrator. Hollow spherical cavity receiver of copper material having diameter 385mm and thickness 1.5mm is used in the experimental set up. The numerical analysis has done by using the MATLAB programming. The effect of different opening ratio (0.2, 0.3, 0.4, and 0.5), different cavity inclination angles (00, 250, 500, 750, and 900) and different operating temperatures (100°C to 600°C) are studied for total heat losses for spherical cavity receiver. The maximum convective losses are found at 0 degree inclination angle of cavity while the minimum convective losses are found at 90 degree inclination angle of cavity because of decrease in convective zone of air and increase in stagnation zone of air in to the cavity. Conduction and radiation losses are independent of cavity inclination angles. The convective losses are also found to be decrease with decrease in opening ratio from 0.5 to 0.2 for different cavity surface temperatures. Experimental results of spherical cavity receiver are compared with numerical results and good agreement is found between the experimental results and numerical results.