Passive Air-Conditioning: Flow Through Rock-Lined Tunnels Tempers Air*

The insulating properties of rock sun.o,rrtding underground openitzgs haoe been used to advantage in creating environments that have stable leml>eratu,m a n d are characterized b,y the mmn annual cli?natic condiliotz a t a particular geographic locafion. However, significant floru rates of a i r a t surface tcm/)o.atures into subsurface space uiN cause much of the insulated advantage of the tempered environment to be lost unless the a i r is first passioely conditioned bypassage through a rock-lined tunnel. Changes in temperature a n d enthalpy as a i r passes along a length of rock-lined tunnel will he ajpcted by manyparameters, the more impot'tant of which include:. the airwav len~tl>. I & a n d grolind tempe~atures at del~1b. ihros of charr~.ec bue, tune must be consrdeicd u,hen deszgntnn an.. "--airway. An in-situ studji to examine these conditions over tinle was undertaken a t the Universitj, of Missouri-Roila Bx[lerimental Mine. Air was passed tbrough a 185-tn length ofpassageuJyy in dolomite. Conliftuous measui'eme?zt of air/rock for 2.5 days gave data that can be used to ascertain appropriate design onditio?zs for a particular application. To exatnine seaso,rul efjects, these tests were conducted during the summer, fa4 a n d winter months. Therrrrodytzamic conditions a1 t lx air/ro & interface are intpor-tan1 it2 ventilation engineering ofdeep underground mine.?. AirJoui heat transfer studies are oJparticular significance in hot mines in which a i r refrigeration is necessary. I'rok va~tous tudies, tl~eorel-ical relationships have been developed for predicting beat flow across the interface. Results of this study are compa~ed with the theoretical relationships from tlihich conclusions are drawn