Abstract: The double-bile single-tube electric water heater is an economical and efficient design scheme, which reduces the manufacturing cost of the water heater by heating the water in two inner tanks simultaneously through one heating tube. However, there is a problem in this design, that is, the water temperature of the upper and lower gallbladder is very different. Through computer simulation and experimental test, it is found that the structure of the inner tube, the length and bending mode of the heating tube and the power of the heating tube are the main factors affecting the temperature difference between the upper and lower gallbladder. By optimizing these parameters, the temperature difference between the upper and lower gallbladder can be significantly reduced, thereby improving the user experience. Take the following measures in the design process: first, appropriately increase the inner diameter of the liner connecting pipe, greater than 45 mm is preferable; secondly, the structure of the heating tube is changed to make it focus on the connecting port, which is more in line with the demand of hot water circulation; finally, the reasonable choice of heating tube power as far as possible to control between 1500 W~3000 W, to avoid too large or too small. The research result has important practical significance for improving the user experience of double-bile single-tube electric water heaters and promoting their popularization in the market.

Key words: Electric water heater, Temperature difference, User experience