Investigating the wall temperature on the chimney suction of gas-burning appliances using two-phase flow

In this study, the numerical study of the effect of wall temperature change on the suction of gas-fired boiler chimneys in residential buildings was investigated using two-phase flow in ANSYS Fluent software. The finite volume method was used to numerically solve the continuity, momentum, and energy equations, and the analysis was verified with previous works. Considering the high use of chimneys in residential buildings and the importance of proper chimney suction in the optimal use of gas-fired appliances and the exit of combustion products, the temperature of the wall and chimney insulation are of special interest. After ensuring the independence of the solution from the network, the results indicate that the speed of the combustion products exiting the chimney increases with increasing wall temperature. With a decrease in wall temperature, the buoyancy force due to the difference in density caused by the temperature difference decreases, and at the same time, the phase change from gas to liquid increases, which causes a decrease in the flow speed in the chimney, and as a result, the chimney suction decreases. Also, by reducing the wall temperature from 360 to 330 Kelvin, the difference in inlet pressure compared to outlet decreases by 23 percent, which indicates a decrease in chimney power.