Development of Multi-Layered Type of Gas-to-Gas Heat Exchanger Provided with Self-Insulation Function

2001学年设计并制作了多层式气-气换热器，进行了基础数据采集、模拟程序开发、关键参数对系统总热回收率、有效热回收率和外壁温度影响的研究。在高温段入口气体温度T <gho>=400 ~ 600℃、多孔金属板的光学厚度τ 0 =7.7、除雾器厚度h= 55 mm、壁面有无翅片、平均工作气体流速μ m=0.15、0.23m/s的条件下，对2 ~ 5层换热器结构进行了一系列实验研究。结果表明，通过增加热回收段，本换热器在有效隔热的同时，还获得了良好的热回收率，即使在T <gho>=600℃时，五层结构的总热回收率也可达40%左右。 ...更多信息 在此基础上，提出了一种利用Excel电子表格对一维辐射与对流耦合方程进行数值模拟的新方法，并在实际计算中取得了较好的效果。对传热性能和非稳态特性进行了评价，并提出了简单的关联式。具有代表性的关键参数为T = <gho>300 ~ 700℃、τ 0 =0 ~ 15.4、除雾器位置和翅片形状。通过实验和理论研究，取得了许多有价值的成果.即，总热回收率随着层数而增加，8的光学厚度足以获得足够的热回收率，需要具有高有效发射率的翅片设计，具有锯齿形翅片的壁对于增加热回收率是有效的，除雾器在系统中的位置需要考虑工作气体的流动条件和辐射的发射和吸收来确定在能量方面，多孔金属板表现出良好的非稳态特性，系统的瞬态响应主要由主体和壁面决定。此外，对于代表性的光学厚度τ_0=0，7.7，给出了关于总热回收率的简单关联式。少

In the academic year 2001, the multi-layered type of gas-to-gas heat exchanger was designed and fabricated, and fundamental data acquisition, development of simulation code, and investigation on effects of key parameters on the total and effective heat recovery rates and the outer wall temperature of the system were conducted. A series of experiments were performed under the conditions of the inlet gas temperature of the high temperature section T_<gho>=400〜600℃, the optical thickness of the porous metal plates τ_0=7.7, the thickness of the demister h=55mm, the walls with and without fins, and the mean working gas velocity u_m=0.15, 0.23m/s for two to five-layered heat exchanger structure. As a result, it has been clarified that, by adding the heat recovery section, the present heat exchanger is effectively insulated and at the same time good heat recovery rates are obtained, and even for T_<gho>=600℃, the total heat recovery rate of about 40% is attained by the five-layered structure. … More Further, a new calculation method for simulating the temperature distributions and 1he heat recovery rates of the system, which applies the spread sheet of Excel to the coupled equations of one-dimensional combined radiation and convection heat transfer, is proposed and is shown effective for practical calculation purposes.In the next academic year 2002, such important subjects as data acquisition under broader conditions, evaluations of heat transfer performance and unsteady state characteristics, and proposition of simple correlation equations were performed. The representative key parameters are T_<gho>= 300〜700℃, τ_0=0〜15.4, positions of the demister, and fin shape. From the experimental and theoretical studies, a lot of valuable findings have been obtained. Namely, the total heat recovery rate increases with the number of layer, the optical thickness of 8 is enough for obtaining sufficient heat recovery rates, fin design with high effective emissivity is required, walls with zigzag fins are effective for increasing heat recovery rates, position of the demister in the system needs to be decided by taking account of the flow conditions of working gas and emission and absorption of radiation energy, the porous metal plates exhibit good unsteady state characteristics and the transient response of the system is dominated by the main body and the walls of the heat exchanger, In addition, concerning the total heat recovery rate, simple correlation equations are proposed for the representative optical thickness of τ_0=0, 7.7. Less