Keep the Heat/Thermodynamics

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?