Effect of Tube Arrangement on the Thermal Performance of a High Temperature Generator of the Absorption System

The present study numerically investigated the effect of tube arrangement on the thermal performance of the high temperature generator (HTG) of a double effect LiBr-water absorption system with the cooling capacity of 210 refrigeration tons. The HTG tubes were located behind the pre-mixed surface flame burner. The HTG was consisted with a set of circular tubes and flattened tubes in series. LiBr aqueous weak solution was flowed into the HTG tube, and then turned to strong solution at the exit of the HTG tube. FLUENT, as a commercial code, was used to estimate the thermal performance of the HTG. Standard k-epsilon model was applied for the turbulent flow of combustion gas around the HTG tubes. Key parameters were the diameter of the circular tube and tube pitch ratio of flattened and circular tubes in the HTG. The combustion gas temperature was increased and its heat transfer rate was decreased as the circular tube diameter was increased, and the pitch ratios of both circular and flattened were decreased.