电加热水体温度场均匀性的仿真与实验

深圳大学物理与光电工程学院,深圳518060

计算流体力学;水平圆管加热;温度场均匀性;Fluent仿真;电加热;位式控制

Simulation and experimental study of uniformity of temperature field of electrically heated water
LI Xiongjun,WU Mingwei,WAN Langhui,WU Jinjie,and ZHANG Huaiyu

College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, Guangdong Province, P. R. China

computational fluid dynamics; horizontal tube heating; uniformity of temperature field; Fluent simulation; electric heating; stepping control

DOI: 10.3724/SP.J.1249.2022.03314

备注

针对水平封闭圆管内水的电加热方式温度场不均匀问题,采用Fluent软件分别对水平圆管的轴向和径向温度场进行数值仿真.基于位式控制的分段分组加热方式在长度为1.8m、内径为103mm、外径为133mm的水平圆管上进行实验验证.结果表明,圆管非水平放置会令加热后圆管的轴向温度场不均匀;在升温阶段,全壁面均匀加热的方式会使圆管温度在竖直径向出现显著的上高下低的分层现象;而只对圆管下半壁面加热可使圆管上层和下层温度差值从大于8℃降至小于1℃,有效提高了圆管温度场的均匀性;在稳态阶段,分段分组加热方式受位式控制的影响,径向温度偏差升到1.6℃以内.对比全壁面均匀加热的方式,分组加热方式特别是4组加热方式,在达到稳态的时间和稳态时的温度场均匀性仍具有明显优势.研究结果为实现高精度、无超调、温度场均匀性好的水平等压封闭圆管加热方案设计提供了参考.
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.
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