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### Topic: continuous flow hot air popcorn production system  (Read 6549 times)

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#### choppix

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##### continuous flow hot air popcorn production system
« on: December 09, 2007, 05:15:54 AM »
Hello,

I have a design project to make continuous flow hot air popcorn production system
Criteria to be met :
- feed is popping kernels at flowrate 200g/min. moisture content is 14% by weight
- feed obtained from storage at ambient T,P
- popped product is delivered into the top of storage bin at ambient pressure
- heat is supplied by electrical resistance heaters
- heated air applied to kernels enters at 230 C
- kernels pop when center temperature is 187 C

This is my first design project so I hope someone could help me figure out what should be figured out.. I'm a little bit confused on what to find.

So, what i did first is to collect data that I might need. But I'm confused about the kernels.
I'm thinking that the kernels would be thought as 0.14 of water and 0.96 of starch. So, for example, heat capacity of kernels are calculated by x1*Cp1 + x2*Cp2. Am I right?
Does anyone know where to find starch data? I found starch data in Perry's but it didn't have Cp and thermal conductivity..

This case is a forced convection case right?
Moreover, can I assume that center and surface temperature of kernels would be the same?
Is ambient pressure 1 atm?
What would happen with the pressure? Does Criteria #3 imply that pressure would stay the same?

#### lemonoman

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##### Re: continuous flow hot air popcorn production system
« Reply #1 on: December 09, 2007, 12:53:40 PM »
Quote
I'm thinking that the kernels would be thought as 0.14 of water and 0.96 of starch.

I think you mean 0.86 - might just be a typo

Quote
So, for example, heat capacity of kernels are calculated by x1*Cp1 + x2*Cp2. Am I right?
Does anyone know where to find starch data? I found starch data in Perry's but it didn't have Cp and thermal conductivity..

If you can access the article, there's an article here about "Estimating the specific heat capacity of starch/water/glycerol systems as a function of temperature and composition".  If you can't access the article, let me know.  I'll access it and then give you the value that you would get for your system.
Article is here

Quote
Moreover, can I assume that center and surface temperature of kernels would be the same?
Is ambient pressure 1 atm?

I would say the answer to both of these is yes.

I don't know the answers to the others, I'm not an engineer lol

#### choppix

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##### Re: continuous flow hot air popcorn production system
« Reply #2 on: December 09, 2007, 02:18:29 PM »
Thanks for the *delete me*

I can't access the article (I need to pay for it), so if you could access it, it helps a lot =)

#### lemonoman

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##### Re: continuous flow hot air popcorn production system
« Reply #3 on: December 09, 2007, 04:53:35 PM »
They found that, over the temperature range of 40 to 120 deg C:

Normal Maize had a CP = 1.26 + 5.24×10–3 T + 2.54×10–2M + 1.66×10-2 G; r2 = 0.8788
Waxy Maize had a CP = 1.62 + 6.14×10–3 T + 2.21×10–2M + 3.15×10-3 G; r2 = 0.9172

where Cp is the specific heat capacity in J/g/K, T is the temperature (°C), M is the moisture content (g water/100 g total weight) and G is the glycerol content (g glycerol/100 g total weight).

These relationships correlate better when G is close to 0 (which it is for you), so I think extrapolating to higher T shouldn't be a problem.

Make sure to cite your source, and that you're extrapolating from data that only goes up to 120C.

Good luck man!