Earth Tube Heat Exchangers Show Potential for Farrowing Houses

Earth-tube heat exchangers with non-perforated ribbed tubes are very efficient for air conditioning in farrowing houses, according to researchers from the University of Göttingen in Germany.

30 August 2010

3 minute read

E. F. Hessel of the Georg-August University Göttingen and colleagues presented their work on earth tube heat exchangers for farrowing houses at this year's World Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR) in Canada.

Earth tempering of stable air has attracted great attention as a sustainable air conditioning method in pig houses, explain the researchers. During the summer, air cooling of the incoming air strongly reduces heat stress and required ventilation rates, while heating costs can be reduced during the winter.

They investigated the effect of air conditioning using geothermal energy in a farrowing house. Underneath the foundations of the farrowing house (21.8 × 23.0 metres), 88 non-perforated ribbed tubes (diameter: 20cm) were laid at a depth of 1.6 to 2.0 metres.

Over a period of 12 months, the following data were recorded at hourly intervals and analysed: outside air temperature and outside relative humidity, as well as air temperature and relative humidity in the air supply duct and in the four separate rooms of the house.

During the winter, the incoming air (supply duct) was heated up to 20°C and in the summer cooled reaching up to 15°C compared to the outside air temperature. In contrast to the diurnal variation of the outside air, the temperature fluctuations of the incoming air were reduced by 90 per cent.

Due to cooling of the incoming air during the summer, temperature inside the farrowing house could be limited to a maximal 29°C (maximum outside temperature was 35°C).

Hessel and colleagues concluded that earth-tube heat exchangers with non-perforated ribbed tubes are very efficient for air conditioning in farrowing houses. They are a cost-effective supplement for sustainable cooling and heating of farrowing houses.

Reference

Hessel E.F., C. Zurhake and H.F.A. van den Weghe. 2010. Hating and cooling performance of an under-floor earth tube air-tempering system in a mechanically ventilated farrowing house. Proceedings of the XVIIth World Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR), Québec City, Canada, 13 to 17 June 2010.