Description

Wet Wall Cooling Pads 1970x600x150

WHAT IS WET WALL COOLING:

Wet wall cooling is a low cost and efficient system for greenhouse cooling.
Operating really well when humidity is not too high, reducing temperatures by 10C-15C degrees.
The theory with this system is to make the air inlet into the greenhouse through a porous material that can be saturated with water.
The air is drawn through the greenhouse in volume, due to the air speed. The water is then picked up from the pads and evaporates in the greenhouse to provide cooling.
Systems are installed with fans at one end (or side). The wet wall at the other, preferably with a maximum distance of 40 meters.
Consideration should be given to making sure that air cannot be drawn in through vents, doors and cladding. Thus reducing the volume through the wet wall.

COMMON CALCULATIONS FOR FAN REQUIREMENTS:

In order to calculate the air throughput required, we would take the cubic capacity of the greenhouse; Width x length x average height (wall height + half of truss height).
For example; Greenhouse 40m x 20m x 4.5m = 3600 m3 (cubic meters). To change the air once it is important to pump in or draw out 3600 cubic meters of air.
Optimum ventilation level is about 50 air changes per hour for this type of system. Total air movement per hour for the example greenhouse would be 3600 x 50 = 180,000m3/hour.

Wet Wall Cooling Pads 1970x600x150:

For the wet wall 100mm thick cooling panels are used. These will carry an adequate amount of water without creating too much resistance to air flow. The panel is framed with a perforated header pipe on top and a bottom drainage channel. This is so that a continuous flow of water will keep all of the cooling panels saturated. The water is recirculated through a small tank that requires water treatment to make sure that there is no Legionnaires disease that is common to most evaporative systems.

The wet wall, greenhouse structure and contents create a resistance to the airflow so when we are working out the fan requirement we allow a reduction of 18% from the fan throughput rating.

Wet wall pads are 2m x 0.6m so we would fit either 32 in one row to form one large wall 19.2m long, or a number of smaller walls to add up to the same surface area (this can help the air distribution within the greenhouse).

RECOMMENDATIONS:

It is recommended to fit a 50 mesh insect net over the wet wall. This filters incoming air and reduces dust input into the greenhouse.
It is important that has 200% of the wet wall surface area. Evaporative Cooling Pads are fabricated from special cellulose material that has been treated with unique ingredients to achieve high cooling efficiency and degradation resistance.