- Modes of Heat Transfer 

 - Heat vs. Temperature

 - Thermal Conductivity

 - Thermal Resistance: Parallel & Series

 - Convective Heat Transfer Coefficient

 - Convective Fins & Efficiency

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Workshop #1 - Introduction to Heat Flux Sensors

This is a simple exercise to help students understand heat transfer (or heat flux) as a physical quantity. This workshop provides an introduction to the mobile sensor system. The difference between temperature and heat flux is emphasized along with typical values that should be measured.

 

Workshop #2 - Body Metabolism Introduction

This is a simple exercise to help students understand heat transfer (or heat flux) as a physical quantity and easily relate to the concept of caloric food intake. Also, this workshop has students perform simple measurements on their own bodies to acquaint students with the heat flux measurement system.

 

Workshop #3 - Introduction to Fins

Students learn the basics of thermal fins by taking measurements of heat flux and temperature from a heated aluminum fin (included in the lab kits). Fin efficiency can then calculated and compared with theoretical values. Most importantly, students have the chance to actually feel the temperature decrease from the base to the tip of the fin to understand how a fin works.

 

Workshop #4 - Introduction to Transient Lumped Capacitance

This exercise allows students a hands-on experience in learning lumped capacitance heat transfer using a transient energy balance and the usual exponential solutions. Actual plots of thermal measurements taken on a small aluminum block as it is heated which helps them see the correspondence between heat and temperature. They also get to “feel” the change in temperature of the aluminum block with time to relate to the measured values. The match between the predictions and the actual data gives students a connection between the theory and the real world.

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Workshop #5 - Transient Thermal Resistance Introduction

This exercise combines the topic of transient heat transfer in semi-infinite media with thermal resistance. The thermal conductivity of concrete and carpet are different by over an order of magnitude which has a huge effect on the resulting heat transfer, but much less on the change of temperature. Students use measurements to make calculations and find out why concrete might “feel” much colder than the carpet, even though they're at the same initial temperature.

 

Workshop #6 - Introduction to Heat Sinks and Energy Balances

Students learn about heat sinks by collecting thermal measurements on two different sink materials (metal and carpet) while heat transfer is provided by a heater. Temperature and heat flux responses are used to determine quality of the sinks. Students are encouraged to draw the system and energy balance to help visualize and obtain the corresponding equations.

 

Workshop #7 - Thermal Resistance Introduction

This workshop introduces the concept of thermal resistance and emphasizes the significance of adding different thermal resistances. Heat is provided from the students hands to combinations of different materials while taking measurements so they are able to actually "feel" the difference between the scenarios. This application also extends to heat exchangers when considering the effect of fouling.

 

Workshop #8 - Convection Introduction

Fluid convection is introduced by having the students characterize convective heat transfer from their own wrists under different thermal conditions.  Students use heat flux and temperature measurements to calculate convective heat transfer coefficient, Reynolds number, & Nusselt number in each scenario.

 

Workshop #9 - Introduction to Jets

Blowing air on something to heat or cool it is common. The concept of convective jets is experienced by students while performing simple experiments of them blowing air over an aluminum block. Heat flux and temperature measurements allow them to calculate convective heat transfer coefficient as well as the corresponding lung pressure from Bernoulli’s equation.

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Workshop #10 - Window Conduction Introduction

Students learn about heat transfer in the common application of building windows. Surface temperature and heat flux measurement are made on both sides of a pane of glass. Students gain practice drawing a control volume around the system that shows heat flux to the glass must equal the heat flux leaving it. They can then relate what they see in the textbook with values they actually measure.

 

Workshop #11 - Introduction to Water Evaporation

This is a repeat of Workshop 8, but now with a wet cloth to provide mass transfer in addition to convective heat transfer from the students wrists. The Lewis relation is used to relate the heat transfer coefficient and the mass transfer coefficient. Students calculate the simultaneous heat and mass transfer then infer relative humidity of the air from total energy transfer. They should see that the energy transfer from the evaporation dominates the overall energy transfer from the surface.

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Workshop #12 - Introduction to Heat Transfer Coefficients

This workshop uses a heater and thermal sensors mounted to a building wall to calculate heat transfer coefficients as the surface temperature changes in time. It illustrates the importance of how the value of h is defined and how the apparent value can change with varying conditions. It also shows how changing the surface temperature locally where the heater is can increase the apparent heat transfer coefficient. This has sometimes been called the “heat island effect”.

 

Workshop #13 - Radiation Introduction

This workshop introduces thermal radiation which is often a difficult subject for students to grasp from a lecture. A heated aluminum plate is used as a radiation source. Flat black spray paint covers one-half of the plate while the other half is left polished metal. Students are able to both feel and measure the difference in radiation heat flux from the two halves of the plate and then determine emissivity. This helps the students appreciate the effect of surface emissivity on radiation exchange.
 

Workshop #14 - Experimental Creativity

This is one of the student favorites workshops because they are not limited to predetermined exercises. Students get to use their creativity to measure the heat flux in their own experimental problem that they come up with. They give a short report on their problem and their results while relating the applicable heat transfer concepts.