thermodynamics of popcorn michael bachmann, tony ghaly, kathlyn herrick, sean rodney ireland, brian...

Thermodynamics of Popcorn

Michael Bachmann, Tony Ghaly, Kathlyn Herrick, Sean Rodney Ireland, Brian Lewis, Mohit Moondra, Neel Patel, Evan Rosenman, Juliet Savits

Advisor: Paul Victor Quinn Sr. Assistant: Evan Kimberly

History of Popcorn

• New Mexico’s Bat Cave

• Aztecs• The Great Depression• Movie Theaters

Why Fluffier Popcorn?• The demand for corn is skyrocketing

– Biofuel consumes about 1/4 of corn crop

– Price has risen from ≈$2.40 to over $3.30– Tortilla prices in Mexico have doubled

• Efficient popcorn is paramount– 40% rise in popcorn prices from 2006 to 2007

S

D

Why Fluffier Popcorn? (cont’d)

• 30% of popcorn is consumed outside the home

– About 5 BILLION quarts at films, stadiums, etc.– Prepopped popcorn is also popular in the home

• Economies of scale are possible– A 10-15% efficiency rise could

mean big profit rise for 36 oz. popper– High market value of popcorn would

offset the cost of vacuum• Few cents of corn pop a $5 dollar bucket

Thermodynamics

• Ideal Gas

PV=nRT

• Adiabatic ProcessP1V1

γ= P2V2γ

• .

Goals

• Increase size of popped kernels (π)

• Increase volume per mass (σ)

• Decrease number of unpopped kernels (ω)

Microwave Apparatus

Microwave ApparatusProcedure

• 10 g. bag samples in microwave chamber

• Vacuum pump reduces pressure

• Pop for 2 minutes 15 seconds

• Measure volume and calculate σ, π, ω

Expansion Volume (σ) vs. Pressure

Flake Size (π) vs. Pressure

Waste Percentage (ω) vs. Pressure

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 5 10 15 20 25 30 35

Pressure (in. Hg less than atmospheric pressure)

ω (

kern

els

un

po

pp

ed/t

ota

l ker

nel

s) y= 0.534exp(-0.276x)+0.101RMSE = .0379

Variables Affecting Microwave

• Age of popcorn kernels

• Limitations of bags

• Lifetime of microwave

• Inconsistency with timing

Movie Maker Apparatus

Movie Maker ApparatusProcedure

• 85 g. samples

• Vacuum pump lowers pressure

• Release vacuum after popping

• Measure volume and calculate σ, π, ω

Expansion Volume (σ) vs. Pressure

y = 0.3001x + 38.177

R2 = 0.9928

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25

Pressure (in. Hg less than atmospheric pressure)

σ(m

L/g

ram

)

Flake Size (π) vs. Pressure

The Popcorn Pot

Popcorn Pot Procedure

• Pre-heat 20 minutes• 20 g. samples• Vacuum pump lowers pressure• Periodically shake pot• Release vacuum and turn off heat• Measure volume and calculate σ, π, ω

Expansion Volume (σ) vs. Pressure

Flake Size (π) vs. Pressure

Waste Percentage (ω) vs. Pressure

Expansion Volume (σ) Comparison

0

5

10

15

20

25

30

35

40

45

50

Microwave Movie Maker Popcorn Pot

σ (

mL

/g)

Atmospheric Pressure

Reduced Pressure

• Decreased pressure increased volume.

Flake Size (π) Comparison

0

1

2

3

4

5

6

7

8

Microwave Movie Maker Popcorn Pot

π (

mL

/nu

mb

er o

f fl

akes

)

Atmospheric Pressure

Reduced Pressure

• Decreased pressure increased individual flake size.

Percent Waste (ω) Comparison

0

10

20

30

40

50

60

70

Microwave Movie Maker Popcorn Pot

ω (

Per

cen

tag

e)

Atmospheric Pressure

Reduced Pressure

• Decreased pressure decreased percent waste for microwave and popcorn pot.

Conclusions

• Decreased pressure resulted in increased volume

• Microwave best demonstrated theory

• Movie Maker is most practical application