adminpercent less; air coolers use approximately 10 percent of the power of air-conditioners; maintenance costs are much less.
Air coolers are ideally suited to Zimbabwe and other countries with high temperatures and relatively low humidity.
The following table gives approximate cooling effects of evaporative air coolers:
Low humidity Outside temp Dew point Reduced
15% 32’C 2’C temp. 16’C
High humidity Outside temp Dew point Reduced
50% . 32’C 20’C temp. 24’C
1. Operating principal
The cooling effect is similar to the natural cooling of the body, with sweat evaporating off the skin and cooling the body.
In hot dry conditions the sweat cools very quickly and efficiently, whereas in coastal areas with high humidity, sweat is not evaporated off the skin and the body is not cooled effectively.
Water is pumped over a cooling pad, made from paper pulp, the hot external air then evaporates the water and cools the air around the cooling pads and a low power fan then blows this cooled air into the building.
2. Installation and operating costs
Installation is very simple and about 50 percent of the cost of air-conditioner installation as no refrigerants or CFC gases are used, as they use evaporated water for cooling. Evaporative air coolers use much less electricity than air conditioners as they only use a small fan and small water pump which use approximately 130 to 150 watts as opposed to an air-conditioner which use compressors and fans that use over 1 200 watts.
Maintenance is easy as they only have two small working parts (fan motor and water pump) and do not have compressors, fans, refrigerants or re-gassing
3. Environmental friendliness
They are very environmentally friendly as they use very little energy and can be operated from solar power and use water as the natural coolant and don’t use any refrigerants or CFC gasses which cause a depletion of the ozone layer. Due to the constant and high volume of air flow the “age of air” in a building is greatly reduced and can be changed up-to 15 times per hour.
The cooling pads of paper pulp and water are very effective filters to keep impurities and pollution out of a building, the increased humidity in hot dry conditions is good for general health and reduces problems of static electricity.
4. Applications
Doors and windows do not need to be kept closed as is necessary with air conditioners and can be used outdoors because of this.
They can be used for many different applications like: housing; offices; restaurants both outdoor and indoor; commercial kitchens; hospitals and clinics; hotels, bush camps and tents; schools; workshops and garages; agricultural greenhouses and enclosed livestock housing; factories and warehouses.
5. Comparisons
- For cooling machines for 15-30 sqm: An evaporative air cooler of 3 000cbm/hr is equivalent to 24 000btu air-conditioner;
- Power use — Air-cooler 185W compared to air-conditioner uses 1 000W;
- Cost of use at 0,1c per kwh for 10 hours per day for 365 days — Air cooler costs US$67-50/year compared to air conditioner at US$365/year.
- Air change per hour — Air cooler at 30 times and air-conditioner 0 times.
For further information contact [email protected]
Online Reporter