Sunday, August 31, 2008

Greening of Home Cooling

When you ask for water in a United States restaurant, they serve it chilled, usually with ice. However, in Asia and some places in Europe, they ask you if you want the water at room temperature or cold.

Similarly, the cooling temperature at which people set their air-conditioners also changes from Individual to Individual. I like to keep it at 29 C, whereas some of my friends like it at 20-24 C.

This conveys the requirements for convenience change from person to person.

In India, people have been using earthen pots, like the picture I am attaching here for cooling water. It works on the principle of water evaporating from the pores of the earthen pot utilizing latent heat and making the remaining water cooler. In fact the higher is the outside temperature, the lower is the temperature of water in the earthen pot. My family prefers to use drinking water from an earthen pot, rather than from the refrigerator, as the temperature is much cooler than the tap water but warmer than the refrigerator water.

The electricity which is used in traditional air-conditioning systems is 3 to 4 times higher than the electricity being used by desert coolers or evaporative coolers.

These evaporative air cooling systems work on the basis of air being forced thru wet evaporative pads. Due to the latent heat being utilized for partial evaporation of water in the pads, it makes the air passing thru the water-soaked pads very cool. However, the humidity of the water goes up in the process and therefore these systems can be used only in relatively dry places and weather.

Wiki explains the process well at

In order to reduce the humidity, 2 stage air-cooling systems have been recommended. Frankly speaking though I have seen many single stage air-cooler systems, I am yet to come across any installation of a 2 stage air-cooler system. Here the air being forced thru water-soaked pads, is first pre-cooled thru a heat exchanger thus reducing the moisture carrying capacity of the air.

However, these 2 stage air-cooler systems still produce air with 50-70% humidity.

While thinking about how to make an efficient condensing process/reducing the moisture-holding capacity of air while still keeping the electricity requirements low, I came across the idea of a a marriage of the water-cooling earthen pot systems with the 2 stage air-cooling systems.

Essentially, the heat-exchanger system could utilize the cool water from a Large earthen material Tank in the first stage of the 2 stage air cooling systems.

I do not think that this design would be acceptable to all people in advanced western countries, but there are chances of it becoming popular to most cost conscious people of the developing world.

No comments: