Development of Self-Insulated Gas-to-Gas Heat Exchanger Using Functional Porous Media

1997学年，考虑到对主要参数换热特性的综合认识，同时简化了数值计算，设计并制造了一维平板式气体-气体换热器。在高温段入口烟气温度为400-600ﾟC，多孔介质光学厚度为2.6，6.5，高温段平均气速为0.33m/S，热回收段和低温段平均气速为110t；mh&gt；=0.11，0.22，0.33m/S，进退流均为0.11，0.22，0.33米/S。结果表明，通过增加热回收段，换热器得到了有效的隔热，系统的有效热回收率提高了近一倍。此外，目前的热交换器是…总换热系数K=20-60W/m^2ﾟC。在下一学年，设计并制造了圆筒型换热器。根据平板模型得到的结果进行了实验和基于平板模型获得的结果的简化计算，其中T=400-600ﾟC，tau0=6.5，(iota；lt；mh，&gt；iota_&lt；MR，&gt；，iota_&lt；mi，&gt；)=(0.10，0.07，0.16)，(0.07，0.05，0.11)，(0.05，0.04，0.08)m/S。从实验和理论研究表明，与平板系统相同，换热器的外壁温度保持在较低的水平，并通过增加热回收段获得了良好的热效率。此外，采用基于平板型模型的简化计算方法对圆柱体系统的H&lt；ef&gt；进行了预测，误差在30%以内。此外，在低速情况下，实验表明，在速度为0.07或0.05m/S的情况下，平板系统比圆柱体系统的H&lt；Eff&gt；高约10%。对于换热器的非稳态特性，也得到了较好的实验和理论结果，即目前的换热器在加热后5~10min内达到稳态。较少

In the academic year 1997, considering synthetic understanding of heat transfer characteristics for principal parameters and at the same time simplification of numerical calculations, one-dimensional flat plate type of gas-to-gas heat exchanger was designed and fabricated. Fundamental experiments and corresponding one- dimensional numerical calculations were conducted under the conditions of the inlet gas temperature of the high temperature section T_<gho>=400-600ﾟC, the optical thickness of the porous media tau_o=2.6, 6.5, the mean gas velocity of the high temperature section IOTA_<mh>=0.33m/s, and the mean gas velocities of the heat recovery and the low temperature sections IOTA_<mh>=IOTA_<mI>=0.11, 0.22, 0.33m/s, for both the approaching and receding flows. As a result, it is shown that, by adding the heat recovery section, the heat exchanger is effectively insulated, and the effective heat recovery rate H_<eff> of the system is almost doubled. Further, the present heat exchanger is … More shown to have the overall heat transfer coefficient K=20-60W/m^2ﾟC.In the next academic year 1998, cylindrical type of heat exchanger was designed and fabricated. Experiments and simplified calculations based on the results obtained from the flat plate type model were performed for T_<gho>=400-600ﾟC, tau 0=6.5, (IOTA_<mh, > IOTA_<mr, >, IOTA_<mI,>)=(0.10, 0.07, 0.16), (0.07, 0.05, 0.11), (0.05, 0.04, 0.08) m/s. From the experimental and theoretical studies, it is shown that, in the same manner as the case of the flat plate system, the outer wall temperature of the heat exchanger is kept at a low level and favorable H_<eff> is obtained by adding the heat recovery section to the system. In addition, H_<eff> of the cylindrical system is shown to be predicted within 30% error by using proposed simplified calculation method based on the flat plate type model. Furthermore, in the case of lower velocity case of IOTA_<mh> =0.07 or 0.05m/s, it is shown experimentally that H_<eff> of the flat plate system is some 10% higher that that of the cylindrical system. As for the unsteady state characteristics, favorable experimental and theoretical results are also obtained, that is, the present heat exchanger reaches steady state within about 5 to 10 minutes after heating. Less