|Budget Amount *help
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥2,400,000 (Direct Cost: ¥2,400,000)
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
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