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

2001学年，设计制造了多层气-气换热器，进行了基础数据采集、模拟程序开发以及关键参数对系统总热回收率、有效热回收率和外壁温度的影响研究。对于二至五层换热器结构，在高温段入口烟气温度T_lt；gho&gt；=400~600℃，多孔金属板光学厚度τ_0=7.7，除雾器厚度h=55 mm，有翅片和无翅片壁面，平均工作气流速度um=0.15，0.23m/S的条件下进行了一系列实验。结果表明，通过增加热回收段，目前的换热器在有效隔热的同时获得了良好的热回收效率，即使在T=600℃的情况下，五层结构的总热回收率也可达到40%左右。…在此基础上，提出了一种新的模拟系统温度分布和热回收效率的计算方法，将Excel电子表格应用于一维辐射与对流耦合换热的耦合方程，并将其应用于实际计算。在下一学年的2002学年，将开展更广泛条件下的数据采集、换热性能和非稳态特性的评价以及简单关联式的提出等重要课题。具有代表性的关键参数是T_&lt；Gho&gt；=300~700，℃，τ_0=0~15.4，除雾器位置，以及鳍片形状。通过实验和理论研究，得出了许多有价值的结论。即总热回收率随层数增加而增加，光学厚度为8就足以获得足够的热回收率，需要设计具有高有效发射率的翅片，锯齿形翅片的壁面是提高热回收率的有效方法，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能量的发射和吸收，多孔金属板具有良好的非稳态特性，系统的暂态响应由主体和换热器的壁面决定，此外，关于总的热回收率，给出了τ_0=0，7.7时典型光学厚度的简单关联式。较少

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