TRANSIENT ANALYSIS OF THERMOSIPHON SOLAR AIR HEATER WITH BUILT-IN LATENT-HEAT THERMAL-ENERGY STORAGE-SYSTEM

The thermal performance of a thermosyphon solar air heater with built-in latent heat thermal energy storage system is presented. Phase change materials (PCM) of different melting temperatures (T-m,) of 61, 51, 43 and 32 degrees C are studied and compared with the system with no storage material. The results are presented for two limiting values of the maximum (noon) solar intensities of 700 and 900 W m(-2) and the average ambient temperature of the city of Alexandria, Egypt. It was found that the heaters with T-m = 51 and 43 degrees C show the best performance. For T-m= 43 degrees C, the heater thermal load of minimum outlet air temperature of 8 degrees C above ambient, and minimum air how rate of 0.01 kg s(-1) (30 m(3) h(-1)), is delivered for the whole day. The hot air flow rate varies from 0.006 kg s(-1) (18 m(3) h(-1)) for 24 h, to 0.036 kg s(-1) (111 m(3) h(-1)) for 10 h, depending on the system flow resistance. The proposed air heater is simple in design and adds no operational or maintenance complexities over conventional air heaters.