THERMAL PERFORMANCE TEST OF EVACUATED TUBE AND FLAT PLATE SOLAR COLLECTORS UNDER CLIMATIC CONDITIONS OF EGYPT

The main objective of the present study is to evaluate the thermal performance of two different solar collectors; evacuated tube collector (ETC) and flat plate (FPC) operated by thermo-siphon phenomenon. This study carried out on the roof of Agriculture faculty, Tanta University (latitude angle of 30.5oN, longitude angle of 30.6oE). FPC and ETC are tested using two different tilt angles (30.5° and 45.3°) and stationary non-tracking. The obtained results revealed that the tilt angle was the most important parameter affection solar collector's thermal performance. The data also showed that, the solar energy available and absorbed solar energy for the FPC were higher than the ETC. Meanwhile, the useful heat gain to storage and overall thermal efficiency for the ETC were higher than that for the FPC. The maximum overall thermal efficiency for the two solar collectors (ETC and FPC), respectively, were 77% and 71.3% which achieved at noon with tilt angle of 45.3° during March month. The difference in thermal performance between the two solar collectors can be attributed almost completely to the absorption efficiency and its effect on overall thermal efficiency. In general, the overall thermal efficiency with 45.3° tilt angle gave was higher values than that with 30.5° tilt angle during winter months due to the solar altitude angle.