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Forced Convection Heat Transfer Characteristics of Slush Nitrogen in Turbulent Pipe Flows

湍流管流中氮泥强制对流换热特性

基本信息

批准号：
18360096
负责人：
OHIRA Katsuhide
金额：
$ 5.97万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18360096/
关键词：
Cryogenic Fluid Forced Convection Heat Transfer Two-phase Solid-liquid Flow Slush Nitrogen Slush Hydrogen Renewable Energy Reusable Space Shuttle Superconducting Equipment 水素

项目摘要

Slush Fluids, such as slush hydrogen and slush nitrogen, are two-phase (solid-liquid) single-component cryogenic fluids containing solid particles in a liquid. The objectives of the present study are to investigate the forced convection heat transfer characteristic and thermo-fluid instability of slush nitrogen flowing in a pipe, and to develop the numerical code to evaluate the thermo-fluid phenomenon of the slush fluid flowing in a pipe.Experimental tests were performed with the slush nitrogen in the ranges of solid fraction from 0 to 40 wt% and mean velocity from 1 to 6m/s to obtain both the forced convection heat transfer coefficient and the frictional pressure drop flowing in a horizontal copper pipe. Compared with the experimental results of subcooled liquid nitrogen, the deterioration phenomena of heat transfer coefficients for slush nitrogen caused by the pressure drop reduction were found and cleared in the present study. This is the important and useful result for applying the slush fluid as a refrigerant to superconducting equipments.Three-dimensional numerical simulation method including the gravity effect based on the two-fluid model has been developed to clarify the characteristics of the cryogenic two-phase slush fluid in a straight pipe flow. It was found that the calculated results were in good agreement with the velocity distributions of solid particles measured by the new PIV (Particle Image Velocimetry) method. In consequence, the developed numerical code has been verified to be able to calculate the slush flow characteristics with sufficient accuracy.

泥浆液体，如泥氢和泥氮，是两相(固-液)单组分低温液体，在液体中含有固体颗粒。为了研究泥浆氮在管内的强制对流换热特性和热流不稳定性，开发了评价泥浆流体在管内流动热流体现象的数值程序。在固体含量为0~40wt%、平均流速为1~6m/S的范围内，对泥浆氮进行了实验研究，得到了水平铜管中的强迫对流换热系数和摩擦压降。通过与液氮过冷实验结果的对比，发现并消除了液氮压降减小引起的液氮换热系数恶化现象。这是将泥浆流体作为制冷剂应用于超导装置的重要而有益的结果。为了阐明低温两相泥浆流体在直管流动中的特性，基于双流体模型建立了考虑重力效应的三维数值模拟方法。计算结果与新的PIV(粒子图像测速)方法测得的固体颗粒速度分布吻合较好。结果表明，所开发的数值程序能够以足够的精度计算泥浆的流动特性。