Design and performance evaluation of low cost Earth to air heat exchanger model suitable for small buildings in arid and semi arid regions

Abstract

An experimental study was performed on a prototype model of Earth to Air Heat Exchanger System (EAHE) equipped with low cost material like PVC pipes and exhaust fans made on temporary platform. Emphasis was given on the design of the duct system suitable for small houses without any space in urban and rural areas. Tests were performed to predict the cooling potential and impact of the material on the performance of EAHE system. Experiment was performed continuously for more than three weeks and the result shows that irrespective to the inlet air temperature (ranges from 34°C to 44°C), outlet air temperature was recorded between 20°C to 22°C, which shows the effectiveness of the system. No significant affect of the material used for making the underground air pipe system was recorded on the performance of the model. The Minimum EER (W/W) ratio calculated for the prototype model was around 3.78, which is equivalent to a Energy Star 5 rating, the most efficient system. The weekly energy saving potential of the model before and after integration of EAHE was analyzed i.e., around 5 kWh/week and 20 kWh/week respectively. This considerable increase in weekly energy savings potential of model due to EAHE leads to mitigation of CO₂ emissions if implemented in the residential, commercial and industrial buildings and the corresponding annual carbon credit of these buildings can be decreased manifold. The Life Cycle Cost (LCC) analysis of model also shows that the payback period is around 3 to 4 years for the investment on EAHE system. After a series of experimental analysis the study also reveals that EAHE system is easily and economically feasible technique which can drastically reduce the consumption of energy in future and eliminate the need for conventional compressor based cooling systems.