APPLICATION OF A HEAT BALANCE MODEL TO DESIGN A FOG COOLING SYSTEM FOR GREENHOUSES

A certain system to overcome high temperature should be introduced for the stable year round cultivation in greenhouses.
There are efficient methods to overcome high temperatures in greenhouses such as the ventilation system with shading screen, fan and pad cooling system, and fog cooling system.
In the evaporative cooled greenhouse, the heat balance of a fog system is different from that of fan and pad system, but there is no design standard for the fog cooling system separately.
This study was carried out to find a means to determine the capacity of ventilation and fog cooling systems.
Heat balance equations for the fog cooling system were established and verified by experimental results in a greenhouse.
The calculated ventilation rates from heat balance equations showed good agreement with the measured ones.
The evapotranspiration coefficient (E value) was the most important parameter affecting the required ventilation rate among input parameters, with the exception of weather data.
As the E value increased 1%, the required ventilation rate decreased 1.3%. Therefore the data of E value should be given by various experiments and then design standards and selection guidelines should be provided.
The simulation results for the same design conditions showed that the required air exchange rate and evaporating water of the fog cooling system were 5.1 to 7.7% and 6.8 to 9.3% less than those of the fan and pad cooling system, respectively.

International Symposium on High Technology for Greenhouse Systems: GreenSys2009

S.-W. Nam, Y.-S. Kim

evaporative cooling, fog system, greenhouse design, ventilation

https://doi.org/10.17660/ActaHortic.2011.893.19