EVAPORATIVE COOLING SYSTEM

Evaporative Cooling System

Literature Review

Lot of work has been done on evaporative cooling system. According to Gonzales and Short (2004), effective cooling is produced by an evaporative cooler as it combines a natural process of water evaporation with a reliable and simple air-moving system. Moist pads are used to pull fresh outside air and then it is cooled with the help of evaporation and circulated through a building or house by a large bowler. This lowers the temperature of the outside air up to 30 degrees. In his study, Wang (2004) stated that usually moisture is added to air and blow it around because of the evaporative coolers; they are often called swamp coolers. It is a fact that performance of evaporative cooler is amazingly good as they are provided with the outside air which is desert-like and dry. With the increase in humidity, their ability to lower the temperature of air eventually decreases. Consequently it can be said that swap coolers are not designed to work in swamp-like conditions. On the other hand, air conditioning gained much popularity and showed wonderful results because of it capability of cooling air irrespective of the humidity. According to Gonzales and Short (2004), even on humidity days, central air conditions work well and lower the temperature to a thermostatically controlled temperature. Electricity is also utilized four times greater as compare to swamp coolers. Its installation and maintenance is also much expensive as compare to swamp air conditioners. Ozone-damaging refrigerants are required by air conditioners and same air is circulated over and over. It is mostly used in desert areas; it even works fine in California's more humid climates. For example, in Sacramento, on a typical hot summer it has average of 30 percent humidity and seems to be dry enough for evaporative cooling to work efficiently. However, it is estimated by Dick Bourne of the Davis Energy Group that evaporative cooling is used by fewer than five percent of business and homes in California.

Why Evaporation Lowers Temperature?

Peck (2007) studied that the process of evaporation is carried out 24/7. For example, in hot weather our bodies perspire and the sweat gets dry and our body temperature is dropped through evaporation. Whenever dry air passes over stagnant water, sea water or lake water, it absorbs some of the water. This is the reason that evaporative cooling naturally happens near oceans, lakes, rivers and waterfalls. The absorption depends on the dryness and hotness of air. This happens due to the equivalence of the temperature and vapor pressure of air and water. In the dry air liquid molecules are converted into gas. This process of change of physical state needs energy. According to McDiarmid (2009), in this process heat is transferred from high temperature of air to lower temperature of air. Consequently, air becomes cooler. Further, air turns out to be saturated unable to hold more water resulting in the cease of water. During day time, some of sea-water is evaporated with sunlight due to ...