Our items finally arrived in Singapore and so we went down to the MnT lab to test the radiative cooling method. First, we built a frame for our set-up and came up with a rough layout for our various parts. We also calculated the dimensions of our housing and explored ways in which we are able to minimise the size of our portable air cooler. As part of the set-up, Bing Hong and Deborah also learnt to solder wires.

Building the frame for our prototypical set-up!

We then tested the set-up, as shown in Fig. 1 and 2, using 4 TEC1-12706 Peltier modules, and achieved cold temperatures of 21°C, hot temperatures of 30°C and fan speed of 4 m/s. The temperatures were much lower than we expected, probably because it was a rainy day with ambient temperatures of 25°C. From Monday’s set-up and testing, we decided to test other fans with a higher fan speed, as well as to try TEC1-12715 Peltier modules to compare the temperatures.

Fig.1: Photo of our set-up

Fig.2: Labelled sketch of set-up

 

We ordered a set of static-pressure fans which arrived on Thursday. Using the same set-up, we tested 4 TEC1-12715 Peltier modules as well as the new fans. For the set-up with TEC1-12715 Peltier modules, we achieved cold temperatures of 23°C, hot temperatures of 35°C and wind speed of 4.5 m/s. The ambient temperature that day was 30°C. We also took time-dependent measurements of an enclosed volume of cold air and the hot reservoir and found that temperatures plateaued at 22°C and 41°C for the set-up with TEC1-12715 and 24°C and 37°C for the set-up with TEC1-12706. This implies that steady-state temperatures are obtained over time.

Fig. 3: Graph of Temperature against Time for 4 TEC-12715 modules at 12V and 4A

Fig. 4: Graph of Temperature against Time for 4 TEC-12706 modules at 12V and 4A

With our hardware and cooling system largely working, we have started looking in to temperature control using Arduino and Codesys, as well as finalising the layout and dimensions of the final product.