The measurement methods used in the dry lab portion of the project were needed to ensure that the theoretical model reflected the actual outputs of our device. We needed to be able to design, predict, and understand what was going to happen when we created new ideas that we wanted to add to the physical design. This would mean predicting the behaviour of the temperature of our kettle, tolerancing 3D printed parts for assembly, or assessing the behaviour of basic elements in a circuit. All these ideas went into the final design of our device.
The Dry lab's filtration system took very crucial measurements when designing the filtration system. Tolerancing mechanical parts to fit together was a large task. The team had to design parts for manufacturing as well as 3D printing, which in reality will never be as accurate as drawn up to be. Knowing this, we decided to design and manufacture our aluminum kettle first since this was the only part which we couldn't take multiple attempts to create due to cost factors. After creating it, we added a .05 mm tolerance to all of our 3D printed parts to allow for a snug fit which also wasn't too loose. This tolerance was also used to create the housing for the mechanical filter and the bolts which were used to fasten all parts together.
To ensure proof of concept of our kettle device, we developed a mathematical model predicting the temperature of boiling water in our kettle device. We took into account heat loss to the environment, assumed the temperature of the water was equal to the temperature of the wall and assumed the initial temperature of water was at room temperature. We acknowledge that these parameters might not be the case in a real-life scenario, however for simplicity and estimation purposes these parameters were used.
Assumptions:
- Assuming the temperature of the liquid = the temperature of the aluminum walls
- Constant specific heat capacity of liquid (CpL)
- Constant specific heat capacity of wall (CpW)
- Constant density
- Neglect work
- CpL = CvL
- CpW = CvW
- Initial condition at t = 0s, T = 298 K (water initially in the kettle is at room temp)
Constants:
- Power in: Q = 3000 W = 3 kW
- Area of kettle: A = 0.21434 m2
- Tref = Tenv = 298 K
- Volume of kettle: V = 1.89x10-3 m3
- Density of water: p = 1000 πππ3
- Specific heat capacity of water:
πΆπ£πΏ=4.182ππ½/πππΎ
- Mass of wall: mw = 0.49414 kg
- Specific heat capacity of wall (aluminum):
πΆπ£π=0.9ππ½/πππΎ
CvW=0.9kJ/kgK
- Heat transfer coefficient: 0.74074 kW/m2K
In MATLAB:
Steady state value at 373K (100 deg) which is anticipated for boiling water in a kettle. The time it takes to get 99% of the way to 373K is about 1043s or about 17 mins. The time it takes to reach 338K (65 deg) is 2.65 min. These values are on par with typical water boiling on a stove, proving our device is feasible in the aspect of boiling.
