Keep the Heat/Thermodynamics

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27 Οκτ 2013 (πριν από 4 χρόνια και 11 μέρες)

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Brian Stanley

2 November 2012

Keep the Heat/Thermodynamics

Overview


Thermodynamics


Event Parameters


Device Specifics


Preparing for the Written Test


What to Expect on Competition Day


Questions

What is it?


Definition:


Thermodynamics is the study of thermal energy along with how
it interacts with matter


Description:


Teams must construct an insulated device prior to the
tournament that is designed to retain heat. Students must also
complete a written test on thermodynamic concepts.

Event Overview


Build a device


Specific materials are prohibited (see official rules)


Creativity is encouraged


Test the device


Starting temperature of water


Volume of water


Time of test


Room temperature effects?


Study for written test


Topics listed on rules sheet

Device Specifics


Device MUST fit within 20 cm. cube (K.T.H.) or 15 cm.
cube (Thermo) when fully assembled


250 mL beaker must be easy to get to and remove


Once impounded, changes to the device CANNOT be made


No electrical devices, chemical reactions, other energy
source


Must have a hole (1.5 cm. diam.) in top for thermometer

Temperature Plots


Teams provide up to 4 plots that demonstrate the
performance of the device


Scoring


2 pts. if labeled with school and names


2 pts. for appropriately labeled axes and title


2 pts. for appropriate units


1 pt. for each data plot on a graph or graphs turned in (up to 4
total pts.)

Written Test


Topics:


Temperature conversion


Units of heat


Thermal conductivity


Heat capacity


Specific heat


Laws of thermodynamics


History/people of thermodynamics


Thermodynamic processes

General Test/Study Tips


3
-
ring binder permitted


No limit on size or content


Be practical


Organization is key


Limited time


Print pages


Organize by parent topic


Tabs are useful


Highlight specific equations and key terms/people


Books tend to be too complicated/specific

Sample Questions


What is 56
o
C in:


Fahrenheit


Kelvin


Rankine


How many BTU’s are in one gram calorie?


What is the specific heat capacity of dry air in J/g
-
K at 0
o
C?


Who is considered to be the Father of Thermodynamics?


Who is the Kelvin temperature scale named after?


What is the relationship between Heat Capacity and Specific
Heat?

Sample Questions


Competition questions may be:


Multiple choice


Fill in the blank


Matching


Short answer


Intent is not to trick students, but to test their knowledge of
basic thermodynamic principles


Practice solving these problems beforehand

What to Expect


One hour for impound


Expect a line


Hint


arrive early to make life easier


Have everything you need organized in a plastic container


Students are responsible for:


Device


2 identical 250 mL beakers


Eye protection (splash rated)


Plots


Writing utensils


Notes


Calculator

What to Expect


Event supervisors will provide:


Hot water


Devices for transferring water to device


Thermometers


Students may bring thermometers, if desired


Stop watches


Miscellaneous


Testing the Device


Competition and Testing:


Temperature (60
-
90
o
C), volume of water, and time (20
-
40
min.) is same for all teams


Announced after impound when all teams are in room


Teams given 5 min to setup/modify devices


Team must be ready to test when supervisor calls on them


Testing set up in staggered sequence


Division C teams have option of adding up to 50 mL of ice
water


Tips


NOT a performance building event!


Performance of device is only 25% of final score


Focus is on reliability and repeatability


Test, test, test and test some more!


Accuracy of predictions matters


Division C


If confident, go for the ice water bonus

Tips for Building


For Performance


Make interior tight to limit
convection heat transfer


Design for a pluggable hole


Use light materials with
good insulation properties


Balsa wood, sawdust


For Reliability


Line interior of device in
aluminum foil


Use sturdy materials


Think carefully about
fastening materials
together


Permanent is not always good


Devices must be easily
disassembled for inspection

What are the judges looking for?


Knowledge of rules


Knowledge of device


Do students know why materials were chosen?


Can students efficiently assemble device?


Creativity


Accuracy of temperature prediction


Confidence!

Questions?