抄録
A numerical simulation that the high temperature combustion gas flows upwards across the line of horizontal multi-tubes in which hot water flows has been conducted. The rods which have a role of enhancement of heat transfer are located at the middle of 4 centers of tube in order that the gas flows along the outside wall of water tubes. Under the above flow condition of the gas, the heat energy of outlet gas is compared with that of inlet gas. Finally, the thermal efficiency, η, is evaluated by the expression, (inlet energy-outlet energy)/(inlet energy). Reynolds number of inlet gas varies in the range from 250 to 278000. As the result, η gains 10% with 7.9mm rod in radius in the laminar flow. The rods plays an active role of the enhancement of heat transfer.
