2002 Fiscal Year Final Research Report Summary
Heat Transfer Characteristics of Carbon Dioxide at Super-critical Pressure in Minutia-channels
| Project/Area Number |
13650225
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Kyushu University |
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Principal Investigator |
KOYAMA Shigeru Kyushu University, Institute for Materials Chemistry and Engineering, Professor, 機能物質科学研究所, 教授 (00153693)
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| Co-Investigator(Kenkyū-buntansha) |
KUWAHARA Ken Kyushu University, Institute for Materials Chemistry and Engineering, Assistant Professor, 機能物質科学研究所, 助手 (90243964)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Carbon Dioxide / Supercritical Pressure / Sub-critical pressure / Single Phase Flow / Two Phase Flow / Minutia Channel / Experiment / Numerical Analysis |
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| Research Abstract |
Heat transfer coefficient and pressure drop characteristics of carbon dioxide at supercritical pressure were investigated numerically for the in-tube laminar forced convective cooling process and the following conclusions can be drawn : (1) The radial distributions of axial velocity and temperature deform continuously in the axial direction due to the change of physical properties. (2) The local heat transfer coefficients show peak values as the bulk temperatures approach the pseudo-critical temperature. (3) The average heat transfer coefficient shows a maximum value when the average bulk temperature is nearly pseudo-critical. The maximum value of average heat transfer coefficient increases when the system pressure approaches the critical pressure. (4) The total pressure drop increases slightly as the average bulk temperature approaches to pseudo-critical temperature for the case of near critical pressure. The proportion of momentum change to total pressure drop increases as the heat f
… More
lux increases.
Both the local and average heat transfer and pressure drop characteristics of supercritical carbon dioxide in horizontal mini channels in a cooling condition were investigated experimentally. An aluminum test section (500 mm long, 20mm wide and 2mm thick), which has 10 multi-port extruded circular channels with each 1.31mm inner diameter, was tested under pressures ranging from 7.4 to 8.5MPa, temperatures from 22 to 53℃, heat fluxes from 0.8 to 9 kW m^<-2>, and mass velocities from 113.7 to 418.6kg m^<-2>s. The main conclusions are as follows : (1) Heat transfer is enhanced greatly in the near-critical region, with a maximum heat transfer coefficient obtained at the corresponding pseudocritical temperature. (2) The system pressure, the mass velocity, and the temperature of CO_2 all have significant effects on heat transfer performance, especially in the near-critical region. The maximum heat transfer coefficient decreases as the pressure increases. The larger the mass velocity, the higher the heat transfer coefficient. (3) Correlations available in the literature deviate the experimental data. Based on the experimental data, a new Dittus-Boelter type correlation was developed for forced forced convective heat transfer of supercritical carbon dioxide in horizontal mini channels in cooling case. Less
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Research Products
(10 results)
