Hand Warmer Design Challenge:
The objective of the hand warmer design challenge was to design and produce either a hand warmer or a hand cooler that had a temperature change of 20°C. The hand warmer also needed to be cost effective and relatively cheap while still being chemically safe and environmentally friendly.
This project had a slower start than other projects we've done in the past because wee needed to learn a lot of the background information before we would be able to fully understand what we were doing. We started by doing a calorimeter lab to determine which salt would produce the most optimal temperature change for our project. The salts we tested included NH4NO3, Na2CO3, and CaCl2. We decided to use CaCl2 because it had the largest temperature change. Our various small scale tests used between 5 ml & 20 ml of water and between 2 g & 10 g of salt and had an average temperature change of 7.2°C.
Below is our presentation on the hand warmer specifically.
This project had a slower start than other projects we've done in the past because wee needed to learn a lot of the background information before we would be able to fully understand what we were doing. We started by doing a calorimeter lab to determine which salt would produce the most optimal temperature change for our project. The salts we tested included NH4NO3, Na2CO3, and CaCl2. We decided to use CaCl2 because it had the largest temperature change. Our various small scale tests used between 5 ml & 20 ml of water and between 2 g & 10 g of salt and had an average temperature change of 7.2°C.
Below is our presentation on the hand warmer specifically.
The beginning of this project took a while because we had so much information to learn before we could actually do it. Once we understood the concepts, the project was much easier. Our group split up into teams to work on each aspect of the project; one team worked on the calculations and another group worked on the physical design of the hand warmer. My team worked on the design of the hand warmer and we used an impact heat sealer to seal all of the edges of the plastic bags. This ended up being really difficult to find the exact right setting and length of time to use the impact heat sealer for and no matter what we did they always seemed to leak. We eventually decided to add a layer of foil on the inside to help insulate the hand warmer more and then cover that in a two layers of sealed plastic on top of that. In all, our group worked really well together and ended up with a very nice product.