ISHS Acta Horticulturae 614: VI International Symposium on Protected Cultivation in Mild Winter Climate: Product and Process Innovation
NOVEL MEANS OF HUMIDITY CONTROL AND GREENHOUSE HEATING |
| Authors: | G. Assaf, N. Zieslin |
| Keywords: | Latent Heat Convertors, exchanger, brine evaporator |
| Abstract:
A novel model of Latent Heat Convertors (LHC) or Agam units capable to reduce the air relative humidity in the greenhouse as well as supply energy required for greenhouse heating has been developed. The structure of Agam units is based upon direct contact of air with flowing downward hygroscopic solution known as brine. Two Agam units were installed in 120m X 30m greenhouse with an additional convential house used as a control. Each of the units is composed from separate heat exchangers A and B. Following contact of the humid greenhouse air with the brine of exchanger A, the vapor is condensed on the brine. The sensible heat of the condensation heats the brine and the warm brine heats the air which is introduced back with a lower RH into the greenhouse. The warm brine accumulated in the reservuar of exchanger A, pumped on top of exchanger B is distributed downward on the exchanger. The warm brine of exchanger B exchanges heat with the cooler outdoor air, the temperature of the outdoor is elevated and the air is introduced also into the greenhouse. The brine with reduced temperature following the exchange with outdoor air is accumulated in reservuar of exchanger B and pumped on top of exchanger A. The deluted brine is concentrated in a brine evaporator heated with hot water from the greenhouse general boiler while the heat from the brine evaporator is also introduced into the greenhouse.Two Agam units were exami in spring 2001 in a 3600 m2 (120m X 30 m) greenhouse. At ambient temperature of 110C and RH of 90%, a continuous maintanence of 180C during 12h night the combined heat from two Agam heaters and greenhouse boiler was 963 kWh, RH of 87%-88% in comparison to 1545 kWh and RH of 90%-95% in the neighboring greenhouse with a conventional heating system. | |
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