基于风冷式冷水机的长大隧道局部降温技术研究

Local Cooling Technology of Long Tunnels Based on Air-Cooled Chillers

在高地温地区进行隧道施工时,通常采用增加送风量、洒水和制冰等降温措施。为解决长大隧道送风管路较长导致送风难的问题,提出一种隧道施工区域局部降温方案,可有效降低长大隧道内局部空间的温度。该方案采用风冷式冷水机组、表冷器和冷却水循环系统等设备,将施工区域局部空间的热量送至非施工区域,可作为一种长大隧道辅助降温措施。通过对比计算得出,局部降温方案制冷功率远大于直接送冰方案,降温效率高,降温效果好。同时,理论计算出隧道内的传热量,得出降温系统的降温参数,并且在国内某长大隧道中开展试验,试验系统距离掌子面60 m,采用20 kW的冷水机和8 kW的表冷器。试验表明:1)表冷器出风口温度为27.9℃,较进风口36℃的气温降低了8.1℃,达到了隧道施工规定的温度要求;2)表冷器出风口送风距离和送风量较小,主要原因是表冷器余压较低。根据现场试验情况提出了4点方案优化建议:增加冷凝水回收装置、进风口安装除尘设备、系统设备性能优化、提高系统的集成度。

Cooling techniques such as increasing air supply,sprinkling water,and using ice blocks are commonly used when tunneling in areas with a high ground temperature.Because the long-distance air supply is difficult,a local cooling technology is proposed to effectively reduce the internal temperature of a tunnel.The local heat is transferred to the nonconstruction area through an air-cooled chiller,a surface cooler,and a cooling water circulation system device.The comparative calculation results show that the local cooling effect is far higher than that of ice blocks.Furthermore,the heat transfer in the tunnel is calculated theoretically,and the cooling parameters of the cooling system are obtained.The test is conducted in a long tunnel in China,with the test system 60 m away from the tunnel face,and a 20 kW chiller and an 8 kW surface cooler are used.The test results show the following:(1)the temperature of the outlet of the surface cooler is 27.9℃,which is 8.1℃lower than that of the inlet one and meets the temperature requirements specified in tunnel construction;(2)the air supply distance and volume of the air outlet of the surface cooler are small,resulting from the low residual pressure of the surface cooler.According to the result of the field test,four optimization recommendations are made as follows:adding condensate water recovery device,installing dust removal equipment in the air inlet,optimizing the performance of system equipment,and improving the integration degree of the system.