摘要
如何高效提取矿井排风中蕴含的大量低品位能量,是工程领域内关键问题。针对喷淋式扩散塔热回收装置内,高湿排风与低温喷淋水的热质传递问题,构建并求解了基于传质单元数(NTU_(m))与刘易斯数(Le)的热质传递理论模型,开展了高湿排风与低温喷淋水直接接触式热质传递试验。运用火积耗散理论,明确了热质传递的实际不可逆换热过程,并揭示了Le与火积耗散热阻之间的相互关系。研究结果表明:高湿排风与低温喷淋水的热质传递过程具体表现为减湿冷却过程和类等湿冷却过程。NTU_(m)>0.1,高湿排风进行减湿冷却,经低温喷淋水换热后,最大温差可达到6.3℃,含湿量差为3.12 g/kg,该过程中Le偏离于1,Le与火积耗散热阻呈正比关系,当Le逼近于1,火积耗散热阻逼近于0,可达到最优换热效果;NTU_(m)<0.1,高湿排风进行类等湿冷却,主要表现为高湿排风经过减焓冷却达到饱和状态后,空气状态沿饱和线变化直至换热完成,且排风出口温度接近于排风进口露点温度。值得注意的是,类等湿冷却过程中热质传递火积耗散热阻远大于减湿冷却过程,高湿排风进行减湿冷却更有利于热质传递。在设计喷淋式扩散塔热回收装置时,为使换热单元内高湿空气进行减湿冷却,实现热湿能量的高效提取,风流速度应不大于4 m/s,水气比不低于0.2。
In engineering,the efficient extraction of low-grade energy from mine exhaust is a key issue.Based on the heat-mass transfer between high-humidity exhaust and low-temperature spray in the heat recovery diffuser tower,a theoretical model of heat-mass transfer about the number of mass transfer units(NTU_(m))and Lewis number(Le)is constructed and solved,the direct contact heat-mass transfer test is carried out.Applying the entransy dissipation theory,the irreversible process of heat-mass transfer is clarified,and the relationship between Le and the thermal resistance of entransy dissipation is revealed. The results shows that the heat-mass transfer process between high-humidity exhaust and low-temperat-ure spray is embodied as two processes, which are dehumidification cooling and quasi-isohumidity cooling. When NTU_(m) is greater than 0.1, the high-humidity exhaust is dehumidification cooled. After heat exchange with low-temperature spray, the air temperature can be reduced by up to 6.3 ℃ and the moisture content can be reduced by up to 3.12 g/kg. In this pro-cess, Le deviates from 1, and Le is proportional to the thermal resistance of entransy dissipation. When Le approaches to 1, the thermal resistance of entransy dissipation approaches to 0, and the optimal heat transfer effect can be achieved. On the other hand, when NTU_(m) is less than 0.1, the high-humidity exhaust is quasi-isohumidity cooled. The high-humidity ex-haust enthalpy reduces and cools to saturation, air state along the saturation line changes until the heat transfer complete, and the exhaust outlet temperature is close to the dew point temperature of the exhaust inlet. It is worth noting that the thermal resistance of entransy dissipation in the quasi-isohumidity cooling process is much greater than that in the dehu-midification cooling process. Dehumidification and cooling of high-humidity exhaust is more conducive to heat-mass transfer. When designing the spray diffusion tower heat recovery device, in order to make the high-humidity exhaust in
作者
樊思雨
陈世强
李瑾
黄敏华
吴世先
刘纯玉
吴涛
戚子特
FAN Siyu;CHEN Shiqiang;LI Jin;HUANG Minhua;WU Shixian;LIU Chunyu;WU Tao;QI Zite(School of Civil Engineering,Hunan University of Science and Technology,Xiangtan411201,China;School of Resource&Environment and Safety Engineering,Hunan University of Science and Technology,Xiangtan411201,China;School of Energy and Built Environment,Guilin University of Aerospace Technology,Guilin 541000,China;Dongpang Coal Mine,Jizhong Energy Group,Xingtai 054000,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第6期2475-2483,共9页
Journal of China Coal Society
基金
国家自然科学基金资助项目(51774134)
交通运输行业重点科技资助项目(2021-MS5-126)
湖南省研究生科研创新资助项目(QL20210235)。
关键词
高湿排风
热质传递
传质单元数
刘易斯数
火积耗散热阻
high-humidity exhaust
heat-mass transfer
the number of mass transfer units
lewis number
thermal res-istance of entransy dissipation
