Abstract
A combustion phenomenon produces heat. General combustion phenomenon is the reaction of forming water. The combustion gas contains lots of water. Heat recovery drops the combustion gas temperature. A drop of the combustion gas temperature causes the formation of the condensation water. The condensation water causes the damage of heat exchanger. In this research, it pays attention to the condensation water formed with the high efficiency water heater of heat exchanger. In this paper, it is reported about the quantitative evaluation of condensation water's formation mechanism in the high efficiency water heater.