Abstract
An investigation has been made of the system in which town gas burns in a horizontal water-cooled tube terminating in a vertical flue. This system forms the basis of horizontal gas-fired water boilers. The primary variables chosen for the investigation were:- 1) Primary air to gas ratio. Non-aerated flames and aerated flames at two levels of primary air to gas ratio. 2) Burner characteristics. (a) For non-aerated flames, these were burner jet diameter and gas pressure behind the jet. (b) For aerated flames, these were the burner tube diameter and the gas/primary-air mixture velocity. 3) The amount of Excess air entrained into the system. 4) Tube length. In addition the effect of heat input was also investigated as a secondary variable. The results are presented as a series of regression equations, to show the effect of altering the significant primary and secondary variables upon:- 1) total and radiation heat transfer to the whole tube, 2) heat transfer to every foot length of the water-cooled heating tube. 3) length of visible flame. In addition, equations have been derived relating flue height to tube length, heat input and the amount of air entrained into the tube. It was. found that the effect of altering heat input was highly significant but the primary variables chosen seldom had a significant effect upon the system over and above the effect resulting from the accompanying change in heat input.