I am trying to cool a 60' x 24' x 10' greenhouse, it has double poly clear plastic inflated. I really only need a few degrees cooling, the temperature outside gets up to 32 degrees and I need it down to 26 degrees Celsius. I currently have evaporative cooling but it cannot keep up. I was thinking of using 2 chiller evaporators with 3 ton condensers do you all think this will work ?

 

Where are you located?

Since you say evaporative coolers don't work that leaves traditional air conditioning.

 

I am located in The west Indies

 

Cooling from ..... 32°c - 90°f down to 26°c - 79°f.

There really isn't a formula you can use. Most formulas are based on insulated areas with minimal sun penetration. You have an awful lot of heat load to over come there. I'm guessing the green house is in the sun all day.

What is the average humidity ?

 

It usually between 60 to 80 depends on time of the year.... I saw some greenhouse using these freezer or chiller room units and was wondering if those can work

 

Evaporative coolers only work well in climates with much lower humidity levels than yours.
There are high capacity commercial swamp coolers available that could have more capacity than yours but might be fairly costly.
What swamp coolers do you have?

Calculating the size of mechanical units you would need is beyond the scope of a forum like this.
You would do well to see if those greenhouses who use this type of air conditioning might be open to sharing the details about what they are using.

 

What is a "freezer or chiller room units"? They are most likely some type of compressor based refrigeration like regular refrigeration or air conditioning.

 

That humidity level is pretty much what I was considering based on your location.
Like Greg said.... a swamp cooler adds humidity so that isn't the answer.

Unfortunately..... you are looking at an expensive proposition to cool that greenhouse.....both in cost of equipment and the electric to run it.

 

A freezer or chiller room unit is an airconditioning system that uses a commercial cooler evaporator instead of an air handling unit in the conditioned space.
With this type of coil you can set up the system to operate with higher room temps.
Plus you don't have a need for an air handling unit and ductwork.

 

Pool room equipment is ideal for this type of application.
You can control both temperature and humidity, plus the equipment is designed to operate at higher set temperature.
A refrigeration evaporator, like the one pictured above, can be used but must be engineered for the desired temperature application.

 

Thanks everyone great advice

 

My distant cousins have a garden center and glass greenhouse: They used an opaque black tarp to shade the greenhouse and drop the temperature. -(Glass reflects long/thermal IR light, a greenhouse works by light warming the plants, and the glass reflecting the thermal IR back. By creating thermal IR outside the glass, the glass reflected the thermal IR away from the greenhouse.)-

Depending on whether the poly plastic you have is infrared reflective, you might able to use a lightweight heat reflective plastic to shade the plastic greenhouse.

Cousins watering setup used misters/sprinklers, normally used an outside storage tank (e.g. warm water), but they had cool groundwater from a well (52F / 12C). Caribbean, groundwater temperature should be ~70F / 23C. Actually, you COULD also use water as "thermal mass" to even out the day/night temperature swings- just fill a bunch of 200 liter steel drums with water.

Are you in the tradewinds? If so a venturi or vent stack could be used to pull LOTS of air through the greenhouse to cool it.

 

Thanks guys great advice ..............