# Transport 2 Project

More Options: Make a Folding Card

Conduction

#### Storyboard Text

• ﻿What a beautiful day in the wonderful city of Philadelphia
• Now that I finished my morning pop its time to do my daily wall touches﻿
• ﻿Hey Charlie... Could you stop hugging the walls again
• ﻿Hey Dennis man, I'm really scared man. I think my hands are different temperatures
• ﻿Stop hugging the walls you are scaring all of the customers
• ﻿Charlie, your hands are not different temperatures
• ﻿What customers? We couldn't get people in here if we paid them
• ﻿SHUT UP D! Dumb bird
• ﻿When I touch the walls my hands feel different temperatures, but when I hold them to my face they feel the same...
• ﻿Hmmm, maybe I'm dying guys, I'm really scared.
• ﻿You aren't dying you, idiot! You are feeling the effects of heat transfer at work
• Of course, not drugs are bad and this is a college learning tool ;) ﻿
• Heat Transfer... Frank are you on drugs again??
• I'm telling you, Charlie, this is heat transfer at work. My friend Lucas gave a lecture about it during Transport II
• Well alright, if this heat transfer thing is real what is it? And will it kill me?
• Let's see if I remember correctly, heat transfer is the movement of thermal energy from one thing to another
• No Charlie, shut up and listen!﻿
• Oh, so heat transfer is some sort of superpower. I want it!
• Heat transfer is caused by a temperature gradient and works to reach equilibrium ﻿
• Where'd you get the chalkboard from, Frank? ﻿
• I found it in the dumpster around back, what a steal right? Now stop interrupting and pay attention! There are three modes of heat transfer
• Hmm.  I think im just going to go kill some rats. This seems too complicated
• ﻿Conduction
• Stay or I'll fire you﻿
• ﻿Which is the random molecular motion of adjacent particles Can be found using-
• ﻿Convection
• ﻿Which is the bulk motion of a fluid or particles  Can be found using-
• Heat Transfer by electromagnetic waves or particles Can be found using-
• So what you are feeling is the combination of conduction and convection through the walls.  ﻿
• Wait so you are telling me that the walls are broken? ﻿
• Let's punch it see if that fixes it ﻿
• No Charlie, look at the wall. It is being heated on one side by the warm summer air ﻿
• The wall is made up o﻿f 3 components; paint, sheet rock, and wood. ﻿
• Each component of the wall has a different K value for conduction. K is the thermal conductivity coefficient
• ﻿﻿Which material do you think would conduct heat better; steel or wood?
• Wood right? My rat club is made of wood and those rats sure feel the heat
• Thats wrong Charlie
• ﻿The Thermal Conductivity coefficient (K)- is a measure of a materials ability to conduct heat. Metals generally conduct heat better than many other materials
• Wood
• Steel
• Similarly, each of the fluids that interact with the wall has a heat transfer coefficient, h
• The summer air is being pushed to the wall and will transfer more heat to the wall than its cold counterpart on the other side﻿
• You lost me, Frank, what does any of this mean and why is it important?
• ﻿Turbulent
• ﻿The Heat Transfer Coefficient (h)- is a characteristic of convective heat transfer between a fluid medium and the surface flowed over by the fluid.  h for turbulent air flow is greater than h for laminar flow due to higher fluid mixing
• ﻿Laminar
• From Professor Landherr's lecture we can talk about a few equations
• Frank, i stopped doing math when I failed the 5th grade for the third time. Sorry but no thank you sir
• Here is the important part though, Charlie. In order to do a lot of these calculations, we need to make assumptions.
• ﻿I'm great at assuming Frank!
• ﻿The Energy Equation
• Now let's simplify
• ﻿The Energy Equation Cont.
• CHARLIE! Wake up! I am almost done
• ZZZZZ....ZZZZZ﻿
• ﻿This means that the flux is the same between all parts of the wall! This makes the math so much easier
• Watch this Charlie﻿
• ﻿One final assumption that we need to make is that the system is continuous. This means that there is no contact resistance.  - The walls are perfectly aligned
• ﻿Now let's go back to your problem with the wall
• Let's find the conduction components for the wall﻿
• ﻿Wait Wait, I'm lost frank! Why is this part conduction?
• Its conduction because we have direct contact between the different layers of the wall. This is also why we are using k.﻿
• ﻿Now let's look at the convective part for this problem
• Before you ask why this is convection it is because the bulk warm air is coming into contact and flowing over the cooler wall
• I understood that part, Frank. Please treat me with respect
• Here's the bread and butter Charlie. We can combine all the equations﻿! !
• I really could go for some bread and butter right about now
• This can be reduced using the overall Heat Transfer Coefficient, U.
• Wait, Frank, I think I get it!  = U
• No Charlie!
• Oh darn so close
• Just a few finishing touches Charlie. Let's talk about resistance!﻿
• No Charlie, shut up and listen!﻿
• I'm having a hard time resisting sleep right now. Does that count?
• Thermal Resistance is the ability of an object to resist heat flow. Here are the equations for both types of heat transfer
• Do you understand now why your hands feel different temperatures and that you aren't dying?
• Well not really, I just know I have to clean the bathrooms during my lunch break now. Thanks, Frank.
• Well before you do that lets summarize
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