Effect of tube arrangement on the performance of a high temperature generator of the absorption system

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.The present study numerically investigated the effect of tube arrangement of the high temperature generator (HTG) on the thermal performance of a double effect LiBr-water absorption system with the cooling capacity of 210 refrigeration tons. The HTG tubes were located after a metal fiber burner. The HTG was consisted with a set of circular tubes and flattened tubes in series. LiBr aqueous weak solution was flowed into the generator tube, and then turned to strong solution at the exit of the HTG tubes. FLUENT, as a commercial code, was used to estimate the thermal performance of the HTG. Standard k-ε model was applied for combustion gas-side turbulent flow around the HTG tubes. Key parameters were size of the circular tubes and spacing ratio of flattened and circular tubes in HTG. Temperature and velocity profiles around the tubes of the HTG with the same total heat transfer area were calculated to estimate the thermal performance of the HTG and to find out the optimal condition. The minimum exhaust temperature of the HTG was 214 at the spacing ratio of flattened tube of 0.73.