Effect of various process parameters on the performance of earth-air heat exchanger (eahe): a review

The current study reports the systematic review of various parameters on the performance of Earth- Air Heat Exchanger. Various modeling and experimental studies were explored, revealing that EAHE is more suitable for the dry climate than the humid. Moreover, it is also geographically specific as there are many temperature variations globally. It is best suited for semi-arid and the worst for humid climates. The moisture has a significant effect on the cooling performance of EAHE. It is found that the sand proportion in soil significantly improves the density and conductivity of soil concerning the performance of EAHE. It was observed that the increase in salinity of the soil decreases the performance of EAHE because the thermal conductivity of the soil is decreased. Many numeric models like finite volume method, computational model, finite element model, CFD with finite volume, etc., were studied at various geographical conditions with various types of soil varying from very sandy clay, moist clay, and fully saturated clay to dry sand to saturated sand. The findings were also supported through experimental studies, and the performance of EAHE is found better at higher conductivity of the soil. The moisture content of the soil ranged from 0.37 to 0.43 g/cm3 which resulted in a temperature decrease of 1.6 oC. A maximum temperature of 14 oC with a cooling potential of 8972 W was reported. EAHE is very much suitable for urban buildings where space is a constraint, and these have the potential for decreasing the carbon load on the environment as they can provide air conditioning using renewable resources.