Experimental investigation of the increasing thermal efficiency of an indirect water bath heater by use of thermosyphon heat pipe

Natural gas must be preheated prior to pressure reduction in city gate stations (CGSs). Indirect water bath heaters are employed in CGSs for preheating, consume a considerable amount of natural gas for the process. This type of heater has a low efficiency therefore a significant amount of energy is wasted. Due to the high capacity of thermosyphon heat pipe (THP), its utilization in CGS heater were investigated experimentally in this paper. For this purpose, a heater setup was manufactured and its thermal efficiency was calculated. THPs were then designed, manufactured, and utilized between the fire tube and the gas tube. Further the type of working fluid and the range of filling ratio (FR) were discussed and the most effective state was suggested. Moreover, the thermal efficiency of the heater in the presence of THPs was investigated. The obtained results showed that the thermal efficiency of the heater improved up to 13% with the addition of THPs. The most effective state of THPs was associated with the water as working fluid with 20% FR in the front route and methanol as working fluid with 30% FR in the back route of the fire tube.