Simulation and experimental study of uniformity of temperature field of electrically heated water

Abstract

With the aim of investigating the non-uniformity of the temperature field of electrically heated water in a horizontal stationary circular tube, we numerically simulated the axial and radial temperature fields in a horizontal circular tube using the Fluent CFD package. We then designed a sectioned grouping heating scheme based on a two-position controller for experimental verification. The results show that the axial temperature in the tube is non-uniform if the tube is not placed horizontally. In the heating stage, uniform heating of the entire tube surface leads to significant vertical temperature stratification, with higher temperature in the upper part and lower temperature in the lower part of the circular tube. However, heating only the lower half of the tube's surface can reduce the temperature difference between the upper and lower layers from more than to less than, effectively improving the uniformity of the temperature field. During steady-state operation, due to the limitations of the two-position controller algorithm, the radial temperature deviation rises to a maximum of for the sectioned grouping heating mode. Compared with the whole-tube uniform heating mode, the grouping heating mode, especially the four-group heating mode, has obvious advantages with regard to the time to reach steady-state and the uniformity of the steady-state temperature field. This paper provides a reference for the design of heating schemes for horizontal isobaric closed circular tubes with high precision, minimal overshoot and good temperature field uniformity.