Abstract
A two-phase closed loop thermosyphon (TPCLT) is a high-efficiency two-phase heat transfer device, which is composed of evaporator, condenser, vapor head, vapor line, liquid head and liquid line. The basic concept is the phase change of a working fluid is used to transport heat from evaporator to condenser through natural circulation without any external driving forces. The device is capable to transport heat for a long distance, so it is proper to apply on the building integrated solar thermal systems. This study presents the possibility of the TPCLT apply on the solar thermal storage system. This experiment contains two different types of TPCLT, the small one and the large one. In small TPCLT, experimental results show that when heating power is 360W, the non-symmetric TPCLT’s efficiency is 70.88%, the top-U-symmetric TPCLT’s efficiency is 74.6% and the both-U-symmetric TPCLT’s efficiency is 76.1%. When the porous material is put in the top-U-symmetric TPCLT, the efficiency increases to 81%. In large TPCLT, experimental results show that the storage efficiency is 69% in filling ratio 70% with heating power 630W. The storage efficiency is 63% in filling ratio 60% with heating power 630W. When the system is in filling ratio 70%, the lowest start-up heating power is 270W. When the system is in filling ratio 60%, the lowest start-up heating power is 180W.