泡沫金属相变蓄热换热器在余热利用中的模拟

Simulation of heat exchanger based on phase change of foam metals in waste-heat recovery

泡沫金属具有质量轻、体积小、换热面积大和热导率高等特点。利用泡沫金属优秀的导热性能及螺旋管的扰流能力,设计一台带有蓄热功能的螺旋管式烟气余热回收装置,以一台400 kW柴油机烟气数据为依据进行数值计算,考核装置在不同螺旋尺寸下的换热、蓄热能力,并结合工程实践考虑选取30 mm管径、40 mm螺距的螺旋管设计,蓄热材料为泡沫金属复合二元硝酸盐,金属基体为铝,填充材料为质量比3∶2的硝酸钾与硝酸钠混合物,相变材料与金属基的质量分数比为91.6%∶8.4%。结果表明,装置占用平台面积为3.3 m2,装置换热量为184 kW,蓄热功能的加入使余热回收装置对工况变化的敏感度降低了54%。可解决海洋石油平台余热回收面临的空间有限、余热资源不连续等问题。

The foam metal has such characteristics as light weight,small volume,large heat transfer area and high thermal conductivity.Based on the excellent thermal conductivity of foam metals and the spoiler ability of spiral pipes,a spiral tube flue gas waste heat recovery device with the heat storage function was designed.Based on the flue gas data of a 400 kW diesel engine,the numerical calculation was carried out for different spiral tube sizes,in order to analyze the heat exchange and heat storage of the device.Moreover,the spiral tube with the diameter of 30 mm and with the pitch of 40 mm was selected.The thermal storage material is the foam metal composite binary nitrate,the metal matrix is aluminum,the filling material is the mixture of potassium nitrate and sodium nitrate with a mass ratio of 3∶2,and the mass fraction ratio of the phase change material to metal base is 91.6%∶8.4%.The result shows that the platform area occupied by the device is 3.3 m2 and the heat transfer power is 184 kW.The sensitivity of the waste heat recovery device to the change of working conditions is reduced by 54%with the addition of heat storage function.It is expected that,the problems of limited space and discontinuity of waste heat resources faced by the waste heat recovery of offshore oil platform can be solved.