Last updated 7/7/2014



MEC 213 Engineering Artifacts (DRAFT!)



1. Heat Exchanger


2. Radiation Shield – used to insulate floor of vehicle passenger compartment from the hot catalytic converter and exhaust pipe below



3. Copper Heat Pipes from a laptop (left, with evaporator end in contact with CPU, condenser end adjacent to fan), a desktop (middle, with two pipes providing additional heat transfer path (besides conduction along the fins) to the outer end of the fins) and a high-end server (right).



4. Innards of Shell-and-Tube Heat Exchanger.   Only nine of the approximately 60 total tubes are currently installed.   With the rest of the tubes installed, the baffles (the perforated plates which each extend only about two-thirds of the way across the diameter) direct the condensing shell-side fluid (a refrigerant) in a serpentine path through the exchanger.  Heat transfer on the shell-side is thus, for the most part, forced convection normal to a tube bundle.  The cooler fluid (water) flows within the tubes.  Looking from the ends, one can see that the water is actually flowing in the annulus between two concentric tubes with “turbulizers” installed between them to enhance tube-side heat transfer.



5 Welded Plate Heat Exchanger – Unlike a “gasketed” plate heat exchanger, this type cannot be taken apart for periodic cleaning.


6 "Honeycomb" Design Heat Exchanger (oil cooler from early 20th century automobile)




7.  Nuclear Reactor Control Rod Drive Mechanism.  The fingers extending downward in the control rod drive mechanism are made of neutron-absorbing materials that allow the reactor operator to control the fission chain reaction taking place within the fuel rods.  In pressurized water reactors (PWR’s) the control rod drive mechanism is driven into the reactor core by gravity.




8.  Pressurized Water Reactor (PWR) Fuel Rod Mockup.  A typical PWR core includes 20-40,000 fuel rods like this, each of them about 12’ (~3.6m) long.  The tube (clad) is made of Zircaloy, a highly corrosion-resistant zirconium alloy.  In a real reactor the fuel pellets are made of uranium dioxide, a ceramic.  The spring keeps the pellets firmly in position and the space around it gradually fills with longer half-life, gaseous fission products. Although the outside diameter of the fuel rod is less than 0.5” (1.3cm), the temperature difference between the center of the rod and its outer surface can be as much as 2500oF (1370oC) in normal operation.




9. Pratt & Whitney Piston (half).  Probably from either R-2800 or R-3350 Engine.  At some point this particular one (obviously a “reject”) was sawn in half to make a pair of bookends.  Others would be used face down as ashtrays.


10. Gas Turbine blades.  The two pieces on the left are the same blade sawed lengthwise to show internal passages for cooling air.  This air is bled off a compressor stage and is relatively cool compared to the combustion products passing over the blades in the turbine section.  The turbine blade on the right uses film cooling, i.e., there are small holes from which relatively cool air (also bled off the compressor) exits to create a protective boundary layer between the blade and the hot combustion gases passing over it.


11 Steam Turbine Blade.  Note “fir tree” arrangement for attaching the blade to its corresponding disk and the gradual change in twist and camber going from root to tip, the latter to compensate for the increase in blade tangential velocity with radius. 


12 Francis Turbine


13. Multi-layer Insulation (MLI) used for spacecraft thermal control.   If new, this single sheet would cost about $1k.  Used in evacuated cryogenic and space applications to block radiative heat transfer, MLI has an “effective” thermal conductivity three orders of magnitude less than that of more common insulators like urethane foam.   Note the holes allowing air to escape as ambient pressure drops during launch and the “scrim” that keeps the metalized layers separated.   



14.  Centrifugal Flow Compressor