Agroscope Reckenholz-Tänikon Research Station ART, CH-8356 Ettenhausen

Optimum animal house climatization even in summer, thanks to heat recovery systems

Traditional air to air heat recovery systems (HRS) are only useful at low outside temperatures as long as heat is required in animal housing. The incoming air can also be cooled by the heat exchanger if a high pressure water atomizer is installed in the HRS. If the outgoing air is humidified to saturation point before it passes through the heat exchanger it cools to 10 Kelvin, which means that heat is extracted from the incoming air in the heat exchanger. The better the thermal efficiency of the heat exchanger, the greater the reduction in temperature of the incoming air. The water content of the air in the housing does not increase during this diabatic process. This is the case if the incoming air is humidified after passing through the heat exchanger. Unlike high pressure atomization in animal housing, not all the cooling is effected adiabatically when a heat recovery system with outgoing and incoming air humidification is used, but some of it also takes place diabatically due to heat exchange between outgoing air and incoming air. The reduction in housing temperature can be calculated with a dynamic calculation model. Additional costs are incurred by the integrated high pressure atomizer and the larger heat exchanger, which must also be adequate for the summer airflow rate. On the other hand the system also becomes simpler, as bypass valves and flues are dispensed with. Thanks to the cooling, moreover, maximum air rate and consequently fan capacity can also be reduced. Pilot plant trials will be conducted to find out whether the system can meet expectations in respect of stall climatization, economic viability and environmental relevance.

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