Abstract
Seoul Metro has operated the air cooling equipment established in a machine room of a station building to improve our services focused on our customers who use Seoul Metro during the summer season. However, a new set of problems has arisen with the cooling tower to support a heat exchange of cooling water. One of them is loss of efficiency in the air conditioner. The leading cause of this problem is that we use an underground type of the cooling tower. As the machine room of a station building is located in the underground of inner city because of the nature of the subway, it is difficult to establish the cooling tower on the ground. The underground structure of the No. $1{\sim}4$ subway line is unsuitable for the location requirements of the underground type of the one because it has a limited space to set up the air cooling equipment, for example, the cooling tower and a ventilating opening. As a result of such an unfavorable condition, the cooling tower doesn't work efficiently and the warmth of cooling water because of insufficiency of a heat exchange and a refrigerator's technical obstacle such as a high-temperature and a high-pressure has arisen. Accordingly, the efficiency of the air conditioning is getting lower and lower. Another problem is too wasteful with water. Each station uses the water over 30 tons every day with waterworks to replenish the cooling tower such as a evaporation, a scattering and a distribution of water. Nevertheless, the more an air conditioner increase, the more the use of water supply increase. For this reason, we can't help wasting an enormous amount of water and discharging the congelation of a low temperature(about $15^{\circ}C$) occurred in a heat exchanger inside an air conditioner. The purpose of this study is to analyze the utility of congealing water to improve efficiency of the air cooling equipment and save energy as a supplementary water for the cooling tower.