Analysis

Below show the twelve analyses that were made on the environmental aspect of the JCATI oven. The requirement of the enclosure include:

The surface temperature of the outer shell shall be no greater than 45C.
The inner temperature shell is allowed to exceed 500C.
The oven should remove 99% of the resin from the plastic.
The purging of gas needs to be less than 10 scfh.
The leakage should be directed to the fume hood.
The oven should allow for a conveyor belt to pass through it.
The O2 level inside the shell is less than 5%.
The weight should be less than 75lb.
The time to fill the enclosure should be less than 5 minutes.
The oven should heat up and cool down in 30 minutes
The life cycle should be at least 10 000 hours.

Thermal Conductivity

For the environmental aspect of the oven, it should be able to maintain an inside heat of 500°C while having an outside temperature of 45°C. This encloser should also be a closed environment. In doing such the enclosure has to be made of a certain material and thickness to have a temperature change. A couple of solutions could be made with these criteria but a solution a 1/8 inch thick steel shells (inner and outer) and 2-inch mineral wool of an r-value of 8 was selected. These calculations are enclosed in Appendix A1 and show that this system gives a surface temperature of 49°C. This is within an acceptable range since calculations are made in an ideal setting.

Figure 1: Analysis 1 Thermal Conductivity

Weight

Steel is a heavy material despite it being thin. It is important that anyone can easily place and remove the enclosure without straining or causing any plausible harm. The requirement is to have the enclosure be less than 75b. The inner of the enclosure has six sides that are sized 14.375inx16.375inx .125in. The drawing for one side of the enclosed is in Appendix B and the analysis is in Appendix A2. This analysis showed that one side weights roughly 8.35lb making the whole inner enclosure be exactly 50lb. The outer enclosure has a dimension of 20.5in x 18.5 x .125 in making each side be 13.46lb and the whole enclosure including cut-outs is 63.43lb. The outer shell is in an acceptable range to be lifted.

Figure 2: Analysis 2 Weight

Flow Rate of Resin Removal

In order to meet the requirement of making sure that there is a 99% resin removal from the oven, an analysis of the mass flow rate of the resin was made. Assuming that the amount of resin is 1kg the mass flow rate is .2179 g/s. Based on the amount of time that the resin spends in the oven using the mass flow rate a change of mass can determine the removal of resin.

Figure 3: Flow Rate of Resin Removal Analysis 3

Flow Rate of Argon

In order to know the amount of leakage in the enclosure the mass flow rate of argon needs to be determined first. Using Bernoulli’s principle for flow analysis the mass flow rate of argon was determined to be 0.00058 kg/s. These calculations are found in Appendix A-4

Figure 4: Analysis 4 Flow Rate of Argon

Time to Fill Enclosure

Using the mass flow rate of argon from Analysis 4 the time to fill the enclosure can be determined. Using the volume flow rate, it was determined it will take roughly 13 minutes to fill the enclosure. This does not meet the requirement that the enclosure should fill up in under 5 minutes. These calculations are found in Appendix A-5 and in drawings 3 & 4 in Appendix B.

Figure 5: Analysis 5 Time to Fill Enclosure with Argon

Heat Analysis of Parts

In order to construct the enclosure, corner braces and latches will be used. To select the proper items that can undergo the environmental conditions a heat analysis of the enclosure needs to be made. Using the information from Analysis 1 it was found that T3 was 50 °C and T2 was 470.17°C. This gave the temperatures of the sides of the gap of the enclosure to find the different distances a slope was made and a table of different distanced and their temperature was made. This analysis will help with finding parts to construct the enclosure. These calculations are found in Appendix A-6.

Figure 6: Analysis 6 Heat Analysis of Parts

Leakage of Conveyor Hole

The oven needs to have a conveyer belt that runs through the enclosure creating a 12in x 3in hole on both sides. The requirement is that the leakage of the argon cannot exceed 10 scfh. Using Bernoulli’s analysis and information from Analysis 4, it was found that the velocity of the argon exciting was 1.09 m/s or a volume flow rate of 05.m3/s (63566.4 scfh). Since the volume flow rate is way above the required flow rate out a cover must be added to the holes in order to meet all requirements. These calculations are found in Appendix A-7 and in drawings 5 & 6 in Appendix B.

Figure 7: Analysis 7 Leakage Rate of Conveyor Hole

Reducing Leakage

Using the given information from Analysis 7 a vinyl cover/strip cover will be used to reduce the area of the hole in order to reduce the mass flow rate of argon exiting. It was found that the vinyl cover has to be 12inx 1 31/32in leaving 1/32 of clearance between the cover and the 1in thickness for the conveyor belt. This led to having the mass flow rate reduced to 0.000043 kg/s or a volume flow rate of 0.000076 m3/s (9.66 scfh) which is within specs of the requirement of 10scfh of argon exiting. These calculations are found in Appendix A-8

Figure 8: Analysis 8 Reducing Leakage

Pressure Regulator

In order to operate the argon cylinder, a pressure regulator is added to control the flow of argon into a system. In order to find the mass flow rate of argon (analysis 4) and eventually the time it takes to remove argon from the system, a regulated pressure must be calculated as shown in Appendix A-9. The calculations for a G/G2 argon cylinder were made and rearranging a mass flow rate equation the pressure regulated was found to be 6.5 Pa in an 8hr workday.

Figure 9: Analysis 9 Pressure Regulator

Time to Remove Argon

Based on the calculations from Analysis 9 time to remove all argon from the system can be made. Appendix A-10 shows that after rearranging a mass flow rate equation the time to remove all argon from the inner enclosure takes 2.19 minutes. This is within the range of requiring the enclosure to remove all argon in 5 minutes.

Figure 10: Analysis 10 Time Remove Argon

Time to cool the Oven

Using Newton's Law of Cooling time was able to be solved using the known values for Biot and temperature. This analysis shows that it will take the oven 21 minutes to cool to room temperature with a 10 minute accuracy.

Figure 11: Analysis 11 Time to cool the Oven

Life Span

Using information on the web it gave that at 500c Sheetmetal can last a total of 10,000hr non stop with no constant pressure added to the enclosure.

Figure 12: Analysis 12 Life Span