Earth-Air Tunnel System used for Air Conditioning

Earth air tunnel or earth air heat exchange is a pre-cooling or pre-heating system which consists of a pipe or network of pipes buried at reasonable depth below the ground surface. It either cools the air by rejecting heat to the ground or heats the air absorbing heat from the ground. It utilizes the fact that the deep earth temperature remains almost same as the annual average mean air temperature of the location.

The present paper discusses the designing of metallic earth-air tunnel system taking under consideration all the variables like cooling load, heating load of the auditorium,

HVAC Design

optimum underground temperature, and weight of the soil acting on the underground duct. Duct is of Zigzag pattern and its cross-section is of square shape. The zigzag pattern resulted in less area occupied and shorter length of the duct required for proper air-conditioning effect. Part of the duct leading to the classroom is insulated in order to stop the temperature change of the conditioned air after coming in contact with atmospheric conditions. The results showed a 13oC reduction in temperature during summers. Heating effect in winters was relatively less, with just 5oC increase in temperature.