A new theoretical approach to determine the air outlet temperature of an air-to-ground heat exchanger.

In this study, the control volume method is used to determine the air temperature at the outlet of an air-to-ground heat exchanger. Its implementation consists in dividing the duct of the ground-air heat exchanger into micro-volumes of identical size. An energy balance is then established for each micro-volume. The input parameters used to implement this model are related to the city of Yaoundé in the equatorial zone. The results show that when the total length of the air-to-ground heat exchanger duct varies between 0 and 100 m, the air temperature at the outlet also varies between 34.5 and 24 °C. The air-to-ground heat exchanger operates in cooling mode. As the length of the air-to-ground heat exchanger duct increases, the temperature of the air at the outlet of the air-to-ground heat exchanger decreases, approaching that of the ground. Based on the results obtained using the control volume model, the minimum total length of air-to-ground heat exchanger duct recommended for this zone is 40 m. Admittedly, air pressure drops, air humidity and the geometry of the air-to-ground heat exchanger are aspects that have not yet been taken into account in the implementation of this model. Nevertheless, the control volume method can be used to optimise the parameters influencing the thermal performance of an air-to-ground heat exchanger.•The control volume method is implemented here by dividing the air-to-ground heat exchanger duct into identical micro-volumes and then establishing an energy balance for each micro-volume;•In this work, the control volume method was used to optimise the total length of the duct of a ground air heat exchanger installed in an equatorial zone;•Some important aspects such as air pressure drops, air humidity, and the geometry of the air-to-ground heat exchanger are not yet taken into account in the implementation of the control volume method.

Dataset for studying the average monthly change in ground temperature in an equatorial zone during the dry season.

Data presented in this paper were collected with the aim of describing the mean monthly temperature evolution of a lateritic soil in an equatorial zone during the dry season. The site is located in Cameroon and has the following geographical coordinates: latitude 3.879444° North and longitude 11.468333° East. Data collection involved measuring the water temperature and depth of existing wells at the site and determining their geographical coordinates. The data were collected manually. The temperatures of the various wells were measured daily throughout February 2022, and the average monthly temperatures were then calculated. These are presented in this paper, along with the other measured data. Several pieces of equipment were used for this purpose. An infrared laser thermometer was used to measure the temperatures of the various wells. A UTM GPS (Universal Transverse Mercator Global Positioning System) unit was used to determine the geographical position of each well in the study area. A plumb line was used to measure the depths of the various wells. The length of the plumb line inserted into the well was measured using an ankle brace. An infrared rangefinder was used to measure the distance, surface area, and volume of each well. The Coordinate Converter application was used to convert the east longitude and north latitude of each well in the study area into decimal degrees. Microsoft Excel was used to draw up tables of measured and converted data and to plot a graph. Surfer software was used to produce isothermal maps. The data collected provide information on changes in the average monthly temperature of the soil at the site as a function of its depth and geographical position. This information facilitates the installation of heat pumps and other heat exchangers to meet the heating and cooling needs of buildings in the area. Additionally, this data can be reused to identify suitable locations for the construction of new water wells and buildings at the site.