冷热电联产(combined cooling,heat and power,CCHP)系统的效率评价指标对其优化设计、经济运行等至关重要。基于小功率燃气轮机为核心的CCHP系统基本元件的变工况典型解析特性,对比分析了CCHP系统当量火用效率、经济火用效率、总能利...冷热电联产(combined cooling,heat and power,CCHP)系统的效率评价指标对其优化设计、经济运行等至关重要。基于小功率燃气轮机为核心的CCHP系统基本元件的变工况典型解析特性,对比分析了CCHP系统当量火用效率、经济火用效率、总能利用率、节能系数等"效率"形式及其影响因素。采用不同的效率指标评价以小功率燃气轮机为原动力的2类CCHP系统的全工况性能,以说明不同效率指标的差异。分析表明,前述效率形式都不能给出完全合理的评价结果。但相对而言,节能系数能比较合理评价文中所述两种CCHP系统的优劣,但部分评价结论仍存商榷之处;CCHP系统的部件匹配及经济运行,可综合按全工况节能系数及经济火用效率来评价。展开更多
Cooling of coal mines in the Bowen Basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be ...Cooling of coal mines in the Bowen Basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures over 50 °C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures(WBT) to below 27 °C at which point the risks of heat stroke or other heat related issues are manageable. The capacities of these systems are in the range of 6–10 MW refrigeration power. The relationship between high working temperature environment and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long term cooling pathways to effectively manage the thermal hazards. Thermodynamic modeling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarizes the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers(BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants,are discussed in this paper. Finally, the comparison of ‘rental' versus ‘ownership' of cooling plants is analysed as part of long-term cooling strategies.展开更多
文摘冷热电联产(combined cooling,heat and power,CCHP)系统的效率评价指标对其优化设计、经济运行等至关重要。基于小功率燃气轮机为核心的CCHP系统基本元件的变工况典型解析特性,对比分析了CCHP系统当量火用效率、经济火用效率、总能利用率、节能系数等"效率"形式及其影响因素。采用不同的效率指标评价以小功率燃气轮机为原动力的2类CCHP系统的全工况性能,以说明不同效率指标的差异。分析表明,前述效率形式都不能给出完全合理的评价结果。但相对而言,节能系数能比较合理评价文中所述两种CCHP系统的优劣,但部分评价结论仍存商榷之处;CCHP系统的部件匹配及经济运行,可综合按全工况节能系数及经济火用效率来评价。
基金support received from Anglo American Metallurgical CoalAnglo American Operations (Pty) Ltd in preparing this paper
文摘Cooling of coal mines in the Bowen Basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures over 50 °C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures(WBT) to below 27 °C at which point the risks of heat stroke or other heat related issues are manageable. The capacities of these systems are in the range of 6–10 MW refrigeration power. The relationship between high working temperature environment and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long term cooling pathways to effectively manage the thermal hazards. Thermodynamic modeling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarizes the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers(BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants,are discussed in this paper. Finally, the comparison of ‘rental' versus ‘ownership' of cooling plants is analysed as part of long-term cooling strategies.