See the engineering science fair project on indoor air quality that you can do in regards to buildings that do not have windows that open.
Grade: 12 Age: 17
New Delhi, INDIA
Category: Environmental Science
Title: MONITORING INDOOR AIR QUALITY- E- COOLER
Purpose: We are becoming wealthier and moving towards a consumerist society. The pollution level is alarming because as we are consuming more and more, we are also releasing more and more effluents into the environment. This is overwhelmingly threatening, so we need to wake up!!
I have taken a very small step in our school so that we pass on to our generations, a clean and safe environment. “It is essentially said that the indoor air pollution is much more than the outdoor air pollution” quoted by Dr. H.B. Mathur at the Centre for Science and Environment. So, i thought of Monitoring Indoor Air Quality. The purpose of this project is to design an air cooler which can help to replace air conditioners and can also improve the indoor air quality.
On becoming aware of the fact that water vapour is the most important green house gas which contributes to nearly 60% of the total green house gases, we thought of modifying the present desert cooler into an eco-friendly cooler.
It struck our minds that humidity level in Delhi is going up to a great extent and as a result A/Cs are being used indiscriminately in each and every house leading to power woes. The desert coolers have lost their function in the months of July and August when the humidity level is very high.
Our ideology aimed at modifying the desert cooler into an eco-friendly cooler that can help to bring the humidity and temperature to the level of thermal comfort. We got started in the month of July,2007 as the humidity in this season is around 90% or even higher.
Date Relative Humidity
2nd July 90%
13th July 95%
17th July 90%
18th July 85%
21st July 63%
4th Aug 97%
5th Aug 98%
11th Aug 82%
12th Aug 77%
14th Aug 82%
When we talk about humidity, it is relative humidity.
Looking at the alarming scenario, we thought to modify existing desert cooler to suit our climatic conditions so that it could function to provide a comfortable working zone by controlling humidity level.
While searching for the causes of indoor air pollution, we zeroed down on the following: <
* Emission of CFCs by A/Cs and refrigerators leading to ozone layer depletion.
* The release of excessive carbon di-oxide in our homes is also a cause of this pollution
We (I and my mentors) used the following materials to make the e-cooler:
•Hygrometer cum thermometer was used to take the measure the temperature and humidity.
HYGROMETER – an instrument used for measuring relative humidity. It consists of two thermometers- one of which includes a dry bulb and the other of which includes a wet bulb.
Relative humidity is computed from the ambient temperature as shown by the dry bulb thermometer and the difference in temperatures as shown by the wet bulb and dry bulb thermometers.
FEATURES OF HYGROMETER USED BY US
Range of RH:
10% to 99%
Temperature range: -500C to +700C
We zeroed down to the room used by the transportation in-charge of our school just adjacent to the swimming pool. On 3rd of July 2007, at around 9:30 a.m., we got a cooler fitted in that room. Switching on the cooler was not really very effective as the humidity level was very high.
In the summer vacations, we had read about a few chemicals that could absorb moisture from the air and keep it cool. The following chemicals were then procured for the experiments to be performed:
* Aluminium Sulphate
* Aluminium Qxide (Alumina)
* Activated Charcoal
* Silica Gel
* Bentonite Clay (montmorellinonite or fuller’s earth) (Na.Ca) 0.33, (Al, Mg)
* Aluminium Phyllosilicate
We did away with Aluminium Sulphate because from the Internet, we found that in 2005, the U.S. Food and Administration no longer recognized it as a wetness reducer. It is also corrosive. And Alumina is hazardous.
Finally we found that Bentonite Clay was the most effective of all. Now we come to a conclusion that there were two (2) ways to increase the efficiency of the desert cooler even during humid conditions:
? To increase the rate of evaporation
? To use an air filter such that the air being thrown by the cooler into the room would lead to thermal comfort.
The first step we worked upon by replacing the metal body of the cooler with a bamboo structure (the metal tank of the cooler is replaced by the plastic tank). For the second step we worked upon an air filter.
Preparation of the Air Filter
A paste of Bentonite Clay is applied on a sieve and is suitably placed in front of the cooler fan. Cool air from inside the cooler when passes through the sieve, is cooled further and the cooling effect increases. It is a two (2) stage process:
* In the first stage, warm and humid air strikes the pads of coolers and is pre-cooled. Then the air passes through the water soaked pads and becomes cool but humid. So the air thrown out by the cooler has very high moisture content, which is in the uncomfortable zone. In the months of July and August, there is already a lot of humidity and this causes extreme discomfort.
* In the second stage, this cooled air passes through the the sieve containing bentonite clay which is hygroscopic in nature, absorbs water content from the air and brings the relative humidity to a comfort level.
We applied an air filter in front of the fan of the e-cooler which had the covering of bentonite clay over it. This layer absorbs moisture and helps to control humidity.
The metal body of the cooler was replaced by the body made by bamboo. This structure is much eco friendly than the other one as the metal consumption is very high in developing nations. This structure is also very convenient for the people in rural areas as bamboo is easily available over there. Moreover, bentonite clay is easily available. All they need to buy is a fan with a pump.
We compared the cooling effect by desert cooler without and with mesh. The data of the comparison is given below:
July2nd – 38oC, 94%