Air conditioning of an off-grid remote school with an earth to air heat exchanger coupled indirectly to a solar cooling system

Abstract

Abstract This work presents the results of indirectly coupling an Earth to Air Heat Exchanger to a 35 kW absorption cooling system. The study considers the weather, building, and soil conditions of a school located in the off-grid remote community of Puertecitos, Baja California, Mexico. TRNSYS simulation software was used to analyze the thermal behavior of the Earth to Air Heat Exchanger under different operation modes, in order to reduce the thermal load of the classrooms. The results show that during the months of May and June an Earth to Air Heat Exchanger with a diameter of 0.15 m, operating from Mondays to Fridays with and mass flow of 715 kg/h, is capable to reduce the thermal load of each classroom by 268.4 kWht, equivalent to 25% of the energy to be removed for maintaining the classrooms at 25°C, which is reflected in a reduction of 12.89% and 18.25% of the electrical energy and water consumption, respectively. For the period from August to October, the thermal load was reduced by 225.2 kWht, equivalent to 15.4% of the energy to be removed for maintaining the classrooms temperature at 25°C, causing an increase of 1.33% in electrical energy consumption, but reducing the consumption of auxiliary heat and water by 94.82% and 11.07%, respectively. The annual savings in auxiliary heat, electrical energy and water are 513.52 kWht, 136.05 kWhe and 6,084.03 kg, which represent 94.82%, 4.61% and 14.3% of the annual consumption of these resources.