Research Of Thermal Properties Of Forced-draft Water Heater

This paper with the forced-exhaust water heater for sample, the author adopts the way of orthogonal experiment arranges experiment, and accords to the experiment data to regression analysis and to draw up to match with curve to elaborates the thermal characteristics of the water- heater. Through experimental researches the author found out the thermal characteristics parameter to get the taller heat efficiency of the water-heater under the condition of certain and the lower volume percentage of the carbon monoxide and NOx in the fume.At first, the author elaborates on the theory of the combustion, flame stability, and transmitted heat the process of the forced-exhaust water heater, especially expounds the combustion of the premixed combustion burner theoretically. The article elaborates on the theory of flame stability, combustion equilibrium,and some factors affecting flame propagation speed, putting forward the scope of the flames stability and the heat exchange enhancement.The forced-exhaust water heater makes use of the breeze machine eject the fume to indoor completely and compulsorily. Because the rotate speed of breeze machine is fixed and constant, causing the air quantity of the water-heater not with the gas pressure change, make it when the low heat input, the excess amount of air is partial to greatly. The heat efficiency of the water- heater is lower while the heat input is low. And although the fume ejects indoor completely, it results in pollute to the atmosphere. To build up of the environmental protection meaning along with the people, must eject lower the carbon monoxide and NOx in the fume to atmosphere. Through the orthogonal experiments research, the author found out the major factor affecting the combustion and thermal characteristics from the gas pressure, water pressure. The author used the regression analysis to get relationship between the two factors listed above and the heat efficiency, oxygen's volume percentage in the fume, volume percentage of the carbon monoxide, volume percentage of the NOx in the fume, and the fume temperature. The curves showing the relationship and analysis about them are given. Through the analysis the author found out the extra air coefficient is a very important parameter to the heat efficiency of gas water-heaters. So we should take from the extra air coefficient, and let the rotate speed of breeze machine of the forced-exhaust water heater with the heat input change, when gases are complete combustion. We will...