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Research on Characteristic of Far-infrared Radiation Heating by Heat Carrying Fluid

Author: RenQingHua
Tutor: ZhangShuTing
School: Tianjin University
Course: Thermal Power Engineering
Keywords: desulphurized flue gas infrared radiation heating radiation heat transfer quantity
CLC: TK123
Type: Master's thesis
Year: 2008
Downloads: 35
Quote: 0
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Abstract

The direct emissions of wet desulphurized flue gas will cause flue pipe and chimney corrosion and so on a series of questions, therefore the wet desulphurized flue gas should be reheated. Indirect heating method which is one of flue gas reheat patterns is widely used in actual projects, but the heat transfer efficiency of indirect heating is low, and the cost is high. Therefore, it is important to explore an new high efficient and low-cost heating technology. Infrared radiation heating has an advantage of quick heating speed and big heat flux density. But radiation forces of far-infrared radiation heating is proportional to the fourth power temperature, so electric energy is widely used and the cost is very high. If low-temperature heat sources especially waste heat is used as a heat source for far-infrared heating, which can achieve low-cost and efficient heating. Therefore, a new type of desulphurization flue gas with high efficient energy saving and heat transfer coefficient is explored by studying far infrared gas phase radiation heating characteristic. The final steady gas temperature and the average heating rate are taken as heating effect target, the influences of following factors on which are inspected by changing radiation heating distance, conduction oil temperature, entrance gas temperature and import gas flow and so on factors. The radiation heat transfer coefficient is computed.With the increase of conduction oil temperature, the radiation heat transfer quantity increases. When the oil temperature improves from 150℃to 200℃, the total heat transfer quantity of non-coating tube increases by 7.62W from 11.08W to 18.70W, and that of radiation coating tube increases by 9.99W from 15.63W to 25.53W. Ratio of radiation heat transfer quantity to the total heat transfer increases from 5.9% to 7.9% and from 23.2% to 32.6% separately. Radiation heat-transfer capability of radiation coating enhances greatly with the increase of heating medium temperature.With the reduce of radiation heating distance, the radiation heat transfer quantity increases. When the heating distance decrease from 150℃to 200℃, the total heat transfer quantity of non-coating tube increases from 15.17W to 15.78W, and that of radiation coating tube increases from 20.59W to 21.38W. Ratio of radiation heat transfer quantity to the total heat transfer increases from 5.0% to 5.5% and from 20.9% to 23.8% separately. Radiation heat-transfer capability of radiation coating enhances greatly with the reduce of heating distance.With the reduce of gas flow, the radiation heat transfer quantity increases. When the gas flow decrease from 5.8m3/h to 3.8m3/h, the total heat transfer quantity of non-coating tube increases 0.34W, and that of radiation coating tube increases 0.43W. Ratio of radiation heat transfer quantity to the total heat transfer increases from 5.5% to 6.1% and from 23.8% to 24.7% separately. Radiation heat-transfer capability of radiation coating enhances with the reduce of gas flow.With the reduce of entrance gas temperature, the total heat transfer increase. When the gas temperature decrease from 60℃to 30℃, the convection quantity of non-coating tube and radiation coating tube increase 15.2% and 18.4% separately. Radiation heat transfer quantity increase 12.4% and 15.3%.Along with the change of oil temperature, heating distance, import gas flow and temperature, the total heat transfer and the radiation capacity of two kind of radiation coating tube change tendency is same, the heating performance of Japanese coating is superior to that of domestic coating.

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CLC: > Industrial Technology > Energy and Power Engineering > Thermal engineering, heat > Thermal Engineering Theory > Engineering Thermodynamics
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