Abstract
Recently, the reduction in CO_2 emissions is taken up as a worldwide problem. For household gas water heater, improvement in the thermal efficiency by latent heat recovery from the exhaust gas is required. In this report, a compact vertical tube bank heat exchanger was designed by a numerical analysis based on analogy of heat and mass transfer. It is expected that the designed heat exchanger improve the HHV based thermal efficiency 12.8%. Two prototypes using SUS smooth tubes with 8 and 6mm O.D. had been manufactured and tested.
