جستجوی مقالات مرتبط با کلیدواژه « Household Gas Water Heater » در نشریات گروه « مکانیک »

In this research for the aim of optimizing the gas consumption, increasing the thermal efficiency of a household gas water heater has been investigated numerically. The optimal design and configuration of the baffles in the middle tube of the gas water heater prevents the quick exit of the exhaust gases and consequently increases the retention time of the hot gases inside the middle tube and reduces the wasting of their thermal energy. The combustion process in the gas water heater is a chain process and completing this process occurs along its path in the middle tube. Therefore for obtaining the maximum thermal efficiency, the numerical analysis of the combustion process and designing and configuration of the baffles inside the middle tube have been carried out and conducted simultaneously. The Ansys Fluent computational fluid dynamics code has been employed for the computational simulation of the combustion of the gas, the heat transfer from the contents of the middle tube into the water tank and distribution of the velocity of the exhaust gases along their path inside the middle tube and around the baffles. Computational simulation of the problem under investigation has been carried out by considering different geometries and configurations of the baffles along the path of the exhaust gases. Numerical results show that the mass fraction of the methane gas and the carbon dioxide in the exhaust gases is negligible and consequently all of the methane gas has been consumed. The numerical results have been verified by the experimental results.

In this paper improvement of efficiency of a household gas water heater has been investigated experimentally. For this purpose, six baffles have been used for deceleration of the hot exhaust gases in the middle tube of the water heater. Three of the baffles have almost the same geometry and dimension and the other three are different from geometry and dimension points of view. Also the same distances between the baffles have been considered. The geometry and dimension of the baffles have been chosen by experimental tests. Experimental results show that by employing the optimum geometries and dimension of the baffles and by selecting the optimum arrangement of the baffles, the thermal efficiency of the household gas water heater has been improved and increased up to 82.5 percent. Experimental results also show that by improvement of the thermal efficiency of the household gas water heater, pollutant emissions which have been measured by the gas analyzers at the laboratory remained almost at the lowest level. Finally by taking into account the effective parameters on the uncertainty for the thermal efficiency, in terms of the level of almost 95 percent for insurance against the reported number for the efficiency, the total uncertainty of the final optimized model for the thermal efficiency is ± 0,17.