Fan blade daigram

Model of the ceiling fan

Tackling the problem

Sudipto collapsed ideas and put Shaun, Vidur and me into the same group. We all had similar ideas, to do with modifying the blades of the fan. To maintain the shape of the fan we decided to use a canvas glove on all the blades. This would retain water and remain damp for long. Now we needed to find a way of transporting water onto the blades. Shaun had an idea about using centrifugal force. If we put a container of water onto the rotating shaft, that is connected to the shaft and has small holes leading to the blades, it will force water out onto the blades when the fan is in motion. To facilitate that movement, we also decided to drill holes in the fan blade itself. 

The problem with the sponge idea

Later, I realized that the fan becomes slower with the sponge on it. It doesn't throw out as much air as it should. So it was cooling, but a very small area and over a long period of time. I tried to tackle this problem by making the sponge thinner. It was still taking very long to cool. Sudipto suggested that instead of trying to attach things to the fan, I should make blades from water absorbing material. This way the shape of the blades will be maintained. 

Testing the ceiling fan

First I made two fan blades out of plastic coated cardboard. I then stuck thin long pieces of sponge on the edges. I realized that they were okay as prototypes but they were not functional.

Since we could not experiment on a ceiling fan, we bought a table fan and dismantled the cage. I cut up long thin pieces of the yellow “scotch brite” and stuck them in a line on the edges of the fan on both sides, the back and the front. I used a paint brush to dampen the sponge slightly and then turned it on. It worked. 

Materials for the ceiling fan

I had to decide what kind of sponge to use on the fan. The sponge needed to be tough to survive through being damp and turning at high speed for hours. It also needed to absorb water well and become wet easily without the use of too much water. It also had to hold onto this water well without dripping. And my last but so important criteria was that it shouldn’t take too long to after the fan was turned off. This way there was less chance of algae, etc.

 I chose 3 sponges to test on. I cut small thin sections of them and then dropped droplets of water on them and shook them vigorously (at this point, I did not have access to a fan). I counted the number of drops I needed to damp the sponge. While shaking it, I checked whether the water dripped or not, and finally how long it took for the sponge to dry.

Green sponge- The green sponge was tough and thin perfect for putting on the blades of a fan. Except it water porous and didn’t hold water.

Pink sponge- the pink sponge was extremely durable and but very thick. Even a thin section of the sponge did not allow penetration of water. A lot of water was required to dampen it.

Yellow sponge- was the softest and most delicate sponge therefore it was not durable at all. But it absorbed water really well, held it and then dried up very quickly as well.

I am going to use the yellow sponge. It reduces chances of rusting or algae because it dries up very quickly but might need to be changed every now and then. This should not be a very big disadvantage because the sponge is very cheap. 

Ceiling fan cum desert cooler

We were asked to take inspiration from a desert cooler and make changes in the ceiling fan such that its blades held moisture and helped make a room cooler. I decided to use sponge on the blades of the fan to hold moisture. But if I covered the entire blade in sponge, the purpose of the blade being thin and able to cut through air would be lost. So I decided to put sponge only on the two long edges. Then I had to figure out how to dampen the sponge. So I decided to put create some sort of dripping system from the motor itself. Water would drop from the down through a thin pipe, into a container in the rotating shaft. That would have a second pipe that infiltrates the sponge and keeps it damp. The two pipes had to be separated because otherwise they would get very tangled when the fan rotated.