Estimation of the Temperature and Humidity of an Underground Air Current

Abstract

In planning underground air conditioning either by ventilation or by equipping with a cooler, it is essential to estimate the underground air temperature and humidity attained after the ventilation or the equipment is completed. The strict calculation of them, however, is very difficult and troublesome, because many factors, known and unknown, are involved. The authors have studied, for several years, the fundamental problems in connection with the temperature and humidity of an underground air current. The present paper describes the method of estimation, proposed by them, in which the evaporation of water on the wall surface, one of the factors having a great influence on the air temperature, is taken into account. The theory of this estimation stands on the fact that the change in temperature of an air current becomes very small after a sufficient period of time, say a year, from the beginning of ventilation, and that the heat quantity transmitted to an air current from rock across a unit area in a unit time is approximately proportional to the heat conductivity of rock and the difference between the undisturbed earth temperature and the air temperature.