Design and thermal performance evaluation of an air heater with low cost thermal energy storage

In the present experimental study a modified solar air heater (SAH) has been tested which integrated with cylindrical copper tube carrying low cost thermal energy storage (TES) material. The blackened copper tube is flexible to integrate with any flat plate type thermal system for performance enhancement especially for providing the hot air for long deliberating hours in low ambient conditions. Total, three low cost TES materials namely; granular carbon powder (GCP), paraffin wax and a unique combination of these two has been tested to evaluate its significance on the performance of SAH in geographical location of Moradabad city, India. Total three different models of air heater (SAH-B, SAH-C and SAH-D) have been developed and experimentally tested on TES encapsulated flexible copper tubes for performance enhancement. Flexibility of the tube is that it can be easily placed on the solar absorber of SAH whenever required by filling any desired TES material. Results show that all the new developed air heaters have been found better over the conventional air heater (SAH-A) but the model SAH-D has been found the best among all models in terms of heat transfer (485.31 W/m(2) K), thermal efficiency (78.31%) and exhaust temperature (50 degrees C). The overall cost of the modified system is only $67.75 which is much economical to the other studied models.