Design Process
Design Functionality & Specifications
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Morph Chart
Our project morph chart lays out the design specifications and functionality for our project, as discussed in the Engineering Design Textbook Chapter 6. Using our morph chart, we designed and tested several prototypes before arriving at our final design.
Prototype 1: The Original Design, Insulated CoolerAt the end of the Fall 2016 semester, we completed the conceptual design shown below. This design consisted of a manufactured box surrounded by water. During the day, a solar panel would power peltier plates which would freeze the water. Overnight, this ice would keep the milk cool inside the box.
We quickly discovered that this design was infeasible and inefficient. Freezing water required an amount of energy we could not provide for under 100USD, and the box would have to be custom manufactured. We decided to explore other solutions, leading to the prototypes shown below. |
Prototype 2: The LidOur first prototype consisted of 3 peltier plates mounted on a lid. The lid was placed on top of the jerry can inside the cooler. This method involved cooling the entire volume of milk at once, which proved to be an inefficient use of the peltier plates. We achieved poor results with this prototype, only cooling the test water 0.11F every 5 minutes.
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Prototype 3: The PVC Cooling ChamberOur second iteration took advantage of the ability of the peltier plates to cool small volumes of liquid very rapidly. In this design, milk is pumped from the jerry can into a small PVC chamber, modeled below. On the bottom of this chamber is an aluminum plate attached to a peltier plate. The small volume of milk is cooled quickly by the peltier and pumped back into the jerry can. The milk is recirculated to ensure even and thorough cooling. We saw promising results in our testing; we cooled the milk to 60F before the results leveled.
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Final Design: The Channel PrototypeThe final iteration of our prototyping is the channel prototype. This design builds off of the success of the PVC chamber prototype by reducing the volume of milk being cooled and increasing the number of peltier plates. The volume of the channel is approximately 1.3 sq in. Like the previous iteration, milk is pumped from the jerry can to the channel where it is cooled rapidly and then circulated through the system until the entire volume reaches the target temperature of 45F. We saw great success with this prototype; we were able to cool test water from ambient temperature (~75F) to our target temperature of 45F in 135 minutes. Although the time to cool test water from 101F to 75F was increased, approximately 75 minutes, the overall results satisfied our requirement of cooling milk from 101F to 45F in 4 hours or less.
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