在夏季高温国家，隧道内空气温升问题于高车流量长公路隧道为日渐重要之严肃课题，针对台湾雪山隧道研究喷雾降温系统应用于隧道降温之可行性。雾滴粒径为喷雾降温系统的重要设计因子，首先建立喷雾降温系统雾滴之数学模式计算不影响驾驶能见度之雾滴粒径，及以计算机数值分析隧道相对湿度、喷雾水量、水温及隧道风速对喷雾降温系统之影响，同时由模拟结果拟定喷雾降温系统之设计参数，并于雪山隧道内设置喷雾降温设施，进行全尺度试验。实验结果显示，喷雾降温可在不影响驾驶能见度条件下有效降低隧道温度。

The issue of high air temperature inside busy long vehicular tunnels becomes more and more noticeable and serious in countries with a hot summer time. This paper studies on the feasibility and applicability of the water mist cooling system in Hsuehshan tunnel. The water mist diameter is the key point for proper water mist cooling design in tunnel. The droplet diameter was calculated according to mathematical model and it should not affect drivers’ visibility. A Computational Fluid Dynamics (CFD) program was adopted to investigate the key parameters in water mist cooling, such as relative humidity, tunnel air speed, water flow, and water temperature. Based on the results, the design parameters were finalized. A full scale model was setup to investigate the performance of the water mist cooling technology to be adopted in Hsuehshan tunnel. From the results of the full scale test, it was concluded that air temperature could be effectively decreased without reducing visibility.