文档介绍：Use of Underground Air Tunnels for Heating and Cooling Agricultural and Residential Buildings
1
. Goswami and . Biseli2
INTRODUCTION
Soil temperature, at a depth of about 10 feet or more, stays fairly constant throughout the year, and is approximately equal to the average annual ambient air temperature. The ground can, therefore, be used as a heat sink for cooling in the summer and as a heat source for heating in the winter.
A simple method of using this concept is to pass air through an underground air tunnel. The air thus cooled or heated can be used directly for the conditioned space or indirectly with air conditioners or heat pumps. The methods, their applicability, and the necessary information for the design of systems based on this concept are described in this document.
UNDERGROUND AIR TUNNEL SYSTEMS
An open loop, underground air tunnel system cools or heats the ambient air passing through it. This air is then introduced directly into the conditioned space of a building. In order to reduce the required tunnel length, a closed loop system may be used. In this system, the air from the conditioned space, with some ventilation air, is recirculated through the underground tunnel. Open
and closed loop systems can be useful for air conditioning agricultural buildings. However, the threat of air contamination from any possible bacterial growth
or radon in the