a hybrid system design: natural gas combustion chamber and concentrated solar collector

The solar-natural gas hybrid system is a suitable solution for medium-scale energy supply for domestic and industrial use. this study considers a spherical concentrator with a spherical cavity receiver as a solar system and a combustion chamber that burns natural gas. the effect of various design parameters is investigated to obtain the best-configured system for shahrekord city, iran. the results show that the optimum receiver tube should use a 5 mm diameter tube that turns 17 loops inside the receiver. therminol as a working base fluid with three different nanoparticles of copper, copper oxide, and alumina is examined. the highest performance is achieved at reynold number 200 by a 5% volume concentration of copper nanofluid. natural gas combustion provides heat energy to reach the target temperature (600 k). the effect of the number and distances of the burners for straight and u-shaped tubes has been compared in the combustion chamber. the best configuration is found and the performance of this system is calculated for four sample days of a year. this calculation shows that using solar energy can save 30 to 50 % of natural gas combustion depending on the season of the year.