Calorimeter components and their functions:

Outer vessel - In the sample diagram it is labeled as the "adiabatic wall", this vessel will hold the water, smaller vessel, thermometer, and the stirrer. It's main function is to hold the smaller vessel and the water, which is crucial to the calculation of the change in temperature that will allow us to find the number of calories in the sample of food.

Inner/smaller vessel - This will be our system, as seen on the previous sample diagram, that will fit into the larger cube shaped vessel that will hold the water. The sample of food will be housed in the system, otherwise known as the inner vessel. This will allow the heat generated by the burning sample to easily transfer from the smaller vessel to the water in the bigger vessel.

Stirrer - This piece of equipment's main function is to evenly distribute the heat transferred from the smaller vessel to the water, this ensures that the temperature is even throughout the water and will allow for accurate results. Without the stirrer it is possible for the temperature to vary throughout different sections of the water, which could possibly produce error in our calculations.

Thermometer - the thermometer will measure the initial temperature of the water inside the smaller vessel and will also measure the temperature of the water after our sample has been burned and the heat has been transferred to the water in the larger vessel, this will be our delta T in the equation. It is essential that we obtain both temperatures to be able to obtain the number of calories in the sample of food.

Source of heat - We will be using a lighter to ignite the sample of food, this will begin the process and will allow heat to be transferred to the water.

Our design:

Large Vessel - Our large vessel will be made out of Acrylic plastic and will be assembled together with Acrylic weld, this will allow the outer vessel to be water tight. The dimensions of the box are 6 inches for the height, 6 inches for the length, and 6 inches for the width. However, in order to be able to interlock the pieces together there will be ridges sticking out at .13 inches, while in the side in which it will interlock there will be a section cut off inwards at .13 inches. There is enough room for the smaller vessel to fit in along with the 1400 ml of water.

The top of the larger vessel will have three holes in order to place the thermometer device, smaller vessel, and the stirrer. The larger hole will hold the smaller vessel; it's diameter is 2 1/2 inches. The smaller holes will have the thermometer and the stirring rod go through them, their diameters are both 1/2 an inch.

We decided on the dimensions of our larger vessel based on the following criteria; the box must be large enough to fit the smaller vessel and 1400 ml of water. However, the amount of water should not be an ample amount, it must be an amount that will allow low error in our calculations. Meaning that if the amount of water is too large some of the heat may become lost, or the change in temperature measured will not be large enough since the heat will have to warm a larger amount of water.

Small vessel - A basic soda can with a height of 5 inches. The can's material will be aluminum, which will allow heat generated by the sample to easily escape into the larger vessel and into the water. The can will be covered at the top, however there will be holes to allow a flow of oxygen to enter the smaller vessel.

The stirring rod will be made out of a simple piece of metal that will be manipulated into an 'L' shape and then manually spun to distribute the heat evenly throughout the body of water.

Thermometer Device - Consists of a temperature sensor, Arduino Nano micro-controller, and a 4-digit seven segment display. The temperature sensor is waterproof and accurate to the hundredth decimal place. The micro-controller calculates the difference in temperature after detecting a temperature drop (post reaction), and inputs said temperature difference into the heat equation mentioned earlier. The value returned represents the amount of calories burned from the food item and is displayed onto a 4 digit seven segment display.

Economics

Prototype Testing

Through trial and error we found that Doritos burned the best. We first tried burning mini peanut butter sandwich crackers, which would only stay lit for a matter of seconds. After seeing that one of the groups was successfully burning Doritos we decided to try those instead.

The serving size listed on a Doritos bag is 28 grams, which is a total of 150 calories. To theoretically find how many calories one gram of Doritos would have we did 150/28 and got approximately 5.36 calories per gram of Dorito.(3)

Outcomes

The chip that we tested came out to weigh about 2.34 grams, so multiplying that by 5.36 the chip should theoretically have about 12.54 calories if it was to burn completely. During our testing the chip would not burn completely, also when we had the lid with the hole covering the flame the chip would stop burning. We decided a different approach, we removed the lid entirely to let in more oxygen to keep the flame going. Since the chip was not burning entirely we decided to weigh the entire calorimeter and then weigh it after the chip stopped burning to try to calculate the amount of calories as a accurate as possible and then compare that value with the value displayed on Sean's thermometer device.

Presentation Day Results

Note: Our error in both our trial and testing day was well over 70% error in both cases.

Error for trial: [(2.36 - 10.72)/ (10.72)] x 100 = 77.9% error

Error for presentation day: [(1.33 - 7.6)/ (7.6)] x 100 = error > 100%

Possible Errors in our Testing Phase

There was plenty room for error and multiple things can be improved in our prototype to ensure that the data collected is as accurate as possible. There is a large margin of error between the reading of the thermometer device and the theoretical calculation of the amount of calories in the amount of chip burned. This could be due to the fact that the thermometer device is extremely sensitive and should have optimal conditions to perform at it's best. What can also be effecting the reading of the thermometer is the amount of water that was used. We had a total of 1400 ml of water in the calorimeter, which may have been too large of an amount, and one chip burning could have not been enough to see a large change in temperature for the thermometer device to read and calculate the amount of calories. As for the thermometer device, to improve it's performance and calorie readings it can be designed to only take into account the grams that have been burned of the sample, which is unique each trial and should be taken into consideration.

Moving Forward

Possible design changes to increase the accuracy of our calorimeter:

1. Decrease the amount of water used to ensure that the thermometer gets a large enough change in temperature to display more accurate results.

2. When testing use larger amounts of food in order to generate more heat.

3. Design a lid that will be ale to cover the flame, but not cause it to go out. In doing so we decrease the amount of heat being lost to the surroundings. What can be done is make a lid that was the ability to provide the flame with an ample amount of oxygen to keep the flame going. This idea would need to be tested with multiple forms of lids and ways of getting an oxygen source to the flame in order to find an optimal functioning method.

4. In a second prototype we could design a removable small vessel so we can measure the before and after weight's of the samples being tested. This could decrease the margin of error in the weights and therefore decrease the margin of error in the manual calculations.

5. Design the thermometer device to only take into account the grams of the sample burned, this fix will lead to increased accuracy in our results.