抄録
The purpose of this study is to develop the compact auxiliary water heater for home CHP (combined heat and power). The tubular flame is formed in a swirling flow field by injecting the air-fuel mixture tangentially into the cylindrical chamber. In this study, the effect of the swirl intensity on heat transfer characteristics is investigated. In this experiment, the swirl intensity S_w was changed by the thickness of the inlet slit nozzles, as S_w = 3.9-14.3. The heat transfer characteristics on the coiled tube was investigated under the combustion and non-combustion conditions. The combustion rate was 5-15 kW at the air ratio of 1.5. The swirling flow causes the high heat transfer coefficient than that at the non-swirling flow condition at the same flow rate. Averaged heat transfer coefficient on the coiled tube at S_w = 14.3 showed about 1.7 times higher than that at S_w = 3.9. Averaged heat transfer coefficient on the coiled tube heat exchanger agreed with the Dhir's correlation, which was conducted under the swirling flow under the non-combustion condition.
