brian stanley 2 november 2012 keep the heat/thermodynamics
TRANSCRIPT
OverviewThermodynamicsEvent ParametersDevice SpecificsPreparing for the Written TestWhat to Expect on Competition DayQuestions
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 OverviewBuild a device
Specific materials are prohibited (see official rules)
Creativity is encouragedTest the device
Starting temperature of waterVolume of waterTime of testRoom temperature effects?
Study for written testTopics listed on rules sheet
Device SpecificsDevice 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 PlotsTeams provide up to 4 plots that
demonstrate the performance of the deviceScoring
2 pts. if labeled with school and names2 pts. for appropriately labeled axes and title2 pts. for appropriate units1 pt. for each data plot on a graph or graphs
turned in (up to 4 total pts.)
Written TestTopics:
Temperature conversionUnits of heatThermal conductivityHeat capacitySpecific heatLaws of thermodynamicsHistory/people of thermodynamicsThermodynamic processes
General Test/Study Tips3-ring binder permitted
No limit on size or contentBe practical
Organization is keyLimited time
Print pagesOrganize by parent topicTabs are usefulHighlight specific equations and key
terms/peopleBooks tend to be too complicated/specific
Sample QuestionsWhat is 56oC in:
FahrenheitKelvinRankine
How many BTU’s are in one gram calorie?What is the specific heat capacity of dry air in J/g-K
at 0oC?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 QuestionsCompetition questions may be:
Multiple choiceFill in the blankMatchingShort answer
Intent is not to trick students, but to test their knowledge of basic thermodynamic principles
Practice solving these problems beforehand
What to ExpectOne hour for impound
Expect a lineHint – arrive early to make life easier
Have everything you need organized in a plastic container
Students are responsible for:Device2 identical 250 mL beakersEye protection (splash rated)PlotsWriting utensilsNotesCalculator
What to ExpectEvent supervisors will provide:
Hot waterDevices for transferring water to deviceThermometers
Students may bring thermometers, if desiredStop watchesMiscellaneous
Testing the DeviceCompetition and Testing:
Temperature (60-90oC), volume of water, and time (20-40 min.) is same for all teamsAnnounced after impound when all teams are in
roomTeams given 5 min to setup/modify devicesTeam must be ready to test when supervisor
calls on themTesting set up in staggered sequenceDivision C teams have option of adding up to
50 mL of ice water
TipsNOT a performance building event!
Performance of device is only 25% of final score
Focus is on reliability and repeatabilityTest, test, test and test some more!
Accuracy of predictions matters
Division C – If confident, go for the ice water bonus
Tips for BuildingFor Performance
Make interior tight to limit convection heat transfer
Design for a pluggable hole
Use light materials with good insulation propertiesBalsa wood, sawdust
For ReliabilityLine interior of
device in aluminum foil
Use sturdy materialsThink carefully
about fastening materials togetherPermanent is not
always goodDevices must be easily
disassembled for inspection
What are the judges looking for?Knowledge of rulesKnowledge of device
Do students know why materials were chosen?
Can students efficiently assemble device?CreativityAccuracy of temperature predictionConfidence!