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TSJ 1 Proof of Concept In this experiment we will test the ability of mica powder to radiate heat upwards. Procedure: All of our measurements will be at 100 degrees Celsius, 1.944 inches above the hot plate. We will start by putting aluminum foil on the hot plate to test as a control. We will then measure with the above standards every two minutes. Next, we will wait for the hot plate to cool, then pour mica powder evenly on the hot plate. After getting to our temperature, and measure using the previously mentioned procedure. Results: Mica Powder first test
Control Run Mica
time (min) Temp (F) time (min) Temp (F)
0 72 0 72
2 72 2 74
4 72 4 75
6 73 6 75
8 73 8 75
10 73 10 75
12 73 12 76
14 73 14 76
Discussion: The control only rose by 1 degree F in 14 minutes while the mica rose 4 degrees. This shows that adding mica powder improves the heating capabilities at a distance. This temperature change might seem small, but this was a proof of concept test to determine whether mica would improve heating efficiency. Now that mica has been proven effective, we can make the process efficient in several ways. First, we used raw mica powder without a binder, meaning that there was a lot of air between the mica particles. If we replace this with a binder, we can make the mica particles hotter and therefore more efficient. Also, the hot plate was a fairly inefficient way to put heat into mica, and that can be improved with our heating element design. The hot plate works by contact heating, and since the powder has a large amount of air in between the particles, they do not heat up very much. If
we put the powder in a binder, and apply the binder to a resistive heating element, it will heat the mica much more efficiently. TSJ 2 Preston Shaw Zaq Mills MSNE 311
Binder Experiment
Idea Mica powder is toxic and when considering the household implementation of our product we should try to minimize chemical risk for the users. One solution to this problem would be to create a mica paste that could be applied to the silicone layers and then evaporating the solvent. This would leave a stable mica network that would not leave loose mica powder and would still have similar thermal conductivity values. Method We took the following materials and mixed them in a 20 mL scintillation vial. ∙ 350 mg Poly(vinylidene fluoride) and Poly(imide) ∙ 10.5 mL 1Methyl2Pyrrolidinone ∙ 4.25 g Cosmetic Mica powder We used a vortex mixer to fully dissolve the binding powder into the solvent and subsequently we added the mica powder to the solution. We then made aluminum weighing boats and poured the mixtures into their own separate boats and placed them on the hotplate at 100 degrees Celsius to evaporate the solvent. We then removed them from the hotplate and allowed them to equilibrate for 30 minutes before testing.
TJS 3 John Hamel Omri Fried
Proof of Concept In this experiment we will test the ability of mica composite (taken from heater) to radiate heat upwards. Procedure: All of our measurements will be at 100 degrees Celsius then again at 200C, 1.944 inches above the hot plate.We will follow the same procedure as the first heating experiment. We will forgo the control test because testing will be done under the same conditions as before but with the new composite. Results: Mica Composite from heater test
Mica composite (100C)
Mica composite (200C)
time (min) Temp (C) Temp (F) time (min) Temp (C) Temp (F)
0 23 73 0 23 73
2 23 73 2 23 73
4 23 73 4 23 73
6 23 73 6 23 73
8 23 73 8 23 73
10 23 73 10 73
Discussion: We saw no noticeable change in the temperature from the thermometer, however the air felt hotter to our hand with the composite. Last time it felt considerably hotter at 200 C so we ramped up the temperature to 200 C hoping to make a readable temperature change. However, none was found.
TSJ 4 George Han Zachary Mills Ryan Newell Benjamin Young Goal: test effectiveness of nichrome wire as a resistive heating element Procedure: 32 GA nichrome wire is tightly wound, connected to a multioutput variable power supply, then suspended inside a shoebox (thermally insulated system). Temperature is measured at 80 second intervals. mcΔT σ(T ₐ⁴ ₑ⁴)Q = = ϵ − T
Q = heat energy (joules) m = mass (kg) =Emissivityϵ = StefanBoltzmann Constant= 5.670373×10−8 W m−2 K−4σ
c = specific heat (Joules/kg*ºC) Ta = final temperature (ºC) Te= initial temperature (ºC) cair=1000 Joules/kg*ºC ρair=1.225 kg/m3 Vbox=0.0055 m3
P=I2*R Theoretical Temperature Change: m=ρair*Vbox Q=ρair*Vbox*cair* TΔ Q= σ(T ₐ⁴ ₑ⁴)ϵ − T ρair*Vbox*cair* =TΔ σ(T ₐ⁴ ₑ⁴)ϵ − T
= /(ρair*Vbox*cair)TΔ σ(T ₐ⁴ ₑ⁴)ϵ − T Theoretical =54.34 ºCTΔ Actual =11.9 ºC (test 1)TΔ
=15.2 ºC (test 2)TΔ The difference in actual temperature change comes from the fact that the box absorbs some of the heat as well, changing the amount of temperature change by the air drastically. Also, because the box was open to air, the open system allowed for air to flow in and out, thereby reducing the temperature. Also, this formula assumes that the air has energy directly put into it, which is not the case, as the wire heats the air. Also, the wire itself is not a blackbody radiator.
Data: Test 1:
Volts Time (interval) Temperature (ºC)
15V, 27.27 Ω 0 25.8
1 25.8
2 27.6
3 27.6
4 27.6
5 32.1
6 34.0
7 35.5
8 35.5
9 36.8
10 37.7
Test 2:
Volts Time (interval) Temperature (ºC)
15V, 27.27 Ω 0 26.2
1 26.4
2 26.4
3 26.4
4 32.3
5 35.2
6 35.2
7 39.8
8 41.4
9 41.4
10 41.4
This was the graph used to extrapolate the temperature that the wire reached given a certain current. This temperature was then plugged in as Ta for the radiation equation given above.
TSJ 5 Commercial Micathermic Heater Test Ryan Newell Heater Settings: Power: min (750 Watts) Heating level: 6 (should not matter) Room size (rough measurement) = 24.7 cubic meters
Time (min) Degrees (C)
0 21.0
1 21.2
2 21.2
3 21.4
4 21.5
5 21.6
6 21.8
7 21.8
8 21.9
9 22.1
10 22.3
The temp change is small, but it is a relatively large room. The thermometer was placed approximately 2 meters away from the heater.
TSJ 6 Omri Fried John Hamel Zachary Mills Benjamin Young Purpose: Comparison test between micacoated nichrome wire and nichrome wire Procedure: 32 GA nichrome wire is tightly wound, coated with 75% binder polyimide/mica mixture, and connected to a multioutput variable power supply, then suspended inside a shoebox (thermally insulated system). Temperature is measured at 80 second intervals Data: Test 1:
Volts Time (interval) Temperature (ºC)
14V, 23.81 Ω 0 23.6
.59 amps 1 23.7
2 25.8
8.4 watt 3 28.8
4 31.8
5 31.8
6 34.4
7 36.6
8 38.3
9 39.9
10 41.1
Test 2: FAILED TEST B/C THERMOMETER WAS KNOCKED OVER
Volts Time (interval) Temperature (ºC)
14V, 23.81 Ω 0 25.5
1 25.4
2 25.4
3 25.5
4 25.9
5 26.2
6 26.6
7 26.6
8 27.0
9 27.4
10 27.9
3640ºC on surface of box. Hotter on the edges of the box than in the middle FOund out that the temperature logger fell over halfway through test, gave incorrect numbers Wire was hot enough to melt plastic.
Temperature difference was 17.5 ºC. The temperature of the top of the box was also measured to be 43.0 ºC at the end. Given the difference in temperature of the cardboard and the heat capacity of the cardboard, assumed to be the same as wood, 1.76 J/g ºC,
TSJ 7 Tile 4/17/15: Zaq, George, John, Ryan Polyamide plastic thin heating strip dimensions: 22.4 cm by 2.5 cm
Simulates “rollup” heater concept Silicone/copper wire square heater: 25 cm by 25 cm
Simulates “mat” heater Goals: To test the effectiveness of the flexible heaters we purchased in terms of heating air, before and after mica is applied. Procedure:
1. Reflective foil from commercial heater applied to adhesive back of polyimide heater
2. Shoebox test of polyimide heater, reflective foil (SnO2ZnO2) facing down:
Thin matt heater
18V
0.2 A
3.6watt
With the low heat emissivity of the polyimide heater and completely open environment, there is a very minimal increase in temperature:
With mica, the polyimide heater heats the air better:
TSJ 8 John, Omri, Ryan, Ben Flexible Heating Element Heating Rate 0 s31 20 s70 40 s86.8 60 s120 Temperatures all in celsius
TSJ 9 Omri, John, Zaq, Preston, Ben We put 75 PI/ 25 Mica solution on top of the above apparatus. We suspended 25 cm x 25 cm foil 11 cm above the surface of the apparatus. No discernable difference between the changes in temperature 22.8>23.6 Without mica 22.8>24.0 With mica With VariAC turned to 60, temperature difference over ten minutes of heating was not significant TSJ 10
As seen above, the temperature logger was hung 12 inches above the mat to record data in open room environment. Test 1: 15 Minutes at 50% Variac on uncovered Mica Mat Highest Temp with gun about 105C. Total temperature change about 4C on logger.
Test 2: 15 Minutes (Experiment called at 5 minutes due to high temperatures) at 70% Variac on uncovered Mica Mat Highest Temp with gun about 210C. Total temperature change about 15F on logger.
Test 3: 60% Variac is the winner 15 Minutes at 60% Variac on uncovered Mica Mat Highest Temp with gun about 180C . Total temperature change about 7C on logger.