A study on measuring the indoor environment for determining dew condensation at the underground utility tunnel during winter

Abstract

The underground utility tunnel is a very important infrastructure in modern urbanization. But it is true that a lot of problems are being pointed out such as the reduction of air quality, reduction of ventilation volume, dew condensation and non-emission of poisonous gas due to the lack of smoke ventilating facilities in case of a fire breaking out in a utility channel because, in relative contrast to the rise in demand of underground utility tunnels in the city, the factors of underground space had not been reflected properly in the design and construction of underground utility tunnels and its maintenance system. Therefore, the purpose of this study is to establish a database for the environmental information of underground utility tunnels by measuring the temperature, humidity, surface temperature and air velocity in underground utility tunnels, and to use it as base data for determining dew condensation. The underground utility tunnel located at Gyeonggi-do, Korea was selected as the subject for the study. It was measured in January, one of the representative point of time during the winter season, for 4 days. The point of measurement was the halfway point between the inlet and outlet of the utility channel. The air velocity with and without mechanical ventilation operation were compared and they were summarized in Table as shown below. The measured air velocity was 0.28m/s and 0.37m/s on average during operation/non-operation of the mechanical ventilation in the entire section. The air velocity increased by approximately 33% during mechanical ventilation. The temperature at the inlet of the utility pipe tunnel and power cable tunnel was reduced by 0.48°C and 9.35°C, respectively during the operation of mechanical ventilation and the temperature of the outlet increased by 0.66°C and 0.09°C each. The surface temperature of the utility pipe tunnel was higher than that of the power cable tunnel by -0.48°C on average. As a result of measuring the underground utility tunnel which was the subject of this study, unlike general underground space, it is considered that there will be almost no damages such as the weakening of structural durability, corrosion of indoor facilities and electric leakage of electric power facilities because the conditions for dew condensation have not been met.