RUDN engineer propose a green split system in houses using ground warmth

The residential sector consumes a third of the energy produced and emits almost a third of all carbon monoxide into the atmosphere. Therefore, it is important to optimize the energy consumption processes in homes, in particular, air cooling systems. One possible approach is to use ground-to-air recovery systems, or ground collectors, instead of air conditioners. This is a house “breathing” system, in which air from the street enters pipes buried in the ground. Due to the temperature difference, the air underground cools in hot weather and heats up in cold weather, and then enters the room. A RUDN engineer with colleagues from Iran has developed a new model of a soil collector, which allows maximizing energy benefits.

“Low-carbon and renewable energy sources can reduce air pollution. One of the effective strategies in this direction is geothermal energy. It is affordable, does not pollute the environment and can play an important role, for example, in heating or cooling rooms. Ground-to-air recuperation is considered passive heating. In this system, the pipes are buried underground to a depth of 2-3 m. The pipes absorb heat from the soil and transfer it to the outside air by natural convection to meet the needs of the buildings. In addition, this method helps to reduce noise pollution,” Esmail Lakzian, PhD, researcher at the RUDN University.

The engineers proposed a model with a new pipe geometry. Steel pipes with a diameter of 15 cm are arranged in a “snake” at a distance of 50 cm from each other. RUDN researchers performed computer calculations and ran the model in test mode to check the energy performance. The work of the model was tested on the example of Mashhad, the second largest city in Iran.

Depending on the thermal conductivity of the soil, the outlet temperature is reduced by 6-21%. Moreover, the system has shown itself well in the long-term mode of operation. The outlet air temperature in 24-hour operation is lower than in one-hour operation.

“The proposed serpentine ground-to-air recuperation geometry gives good system performance. It has shown applicability to the steppe climate of Mashkhad and will suit other similar climatic conditions around the world,” Esmail Lakzian, PhD, researcher at the RUDN University.

The results are published in Sustainable Energy Technologies and Assessments.