Development in household water heaters by replacing the shell and tube heat exchangers by inclined flat ones having rectangular fins

Abstract The main part of a gaseous water heater is a shell and tube heat exchanger whereby the heat is transferred between water and hot gases produced by combustion. In this paper, an attempt is made to replace a shell and tube heat exchanger by a finned flat plate in a household water heater to achieve higher efficiency values. Since, the governing equations are highly nonlinear and very hard to implement, an experimental setup is developed to examine a flat plate heat exchanger and compare its performance with the shell and tube ones. Experiments show that the slop of the plate (angles less than 20°) with respect to horizon besides the volumetric flows of water (7.4 L/min) and natural gas (0.013 cubic meter/min) have effective impacts on the efficiency values of the proposed heat exchanger. It is also concluded that the angle 20° corresponds to the highest rate of heat transfer between two fluids. Investigations show that the proposed heat exchanger may help to achieve the higher values of efficiency (increasing between 20% and 50%) for water heaters compared to those including shell and tube configurations.