1 – Primary purpose for using the device (cooking, heating/cooling, mixing/separating, etc.). This is your
“desired outcome.” Express this in terms of some measurable property of the system at the end (temperature
(of what, where?), extent of reaction, etc.).
2 – Type of chemical process unit
– reactor, heater/cooler, separator, etc.
– batch, semibatch, steady state flow, unsteady state flow, etc. – indicate number of feeds (NF),
number of product streams (NP), and whether or not there is an initial charge
3 – Secondary processes that occur within the device, and where they occur
– heat transfer (what kind? Where? Driven by what? Resisted by what? – answer for each
process that occurs)
– mass transfer (same questions as for heat transfer – answer for each process that occurs)
4 – Inputs and outputs
– mass and energy, and for each, say
o is it fed as an initial charge, continuous flow, or pulse
o source of all inputs; destination of all outputs
5 – Fully labeled block diagram, with
– one or more labeled boxes, indicating type of unit (written inside), constants (e.g. T, P, etc.,
written on top), and if chemical reactor write out reaction (written below)
– straight unbroken arrows to indicate flow of material
– straight dashed arrows to indicate one or more pulses of material
– jagged unbroken arrows to indicate flow of energy
– jagged dashed arrows to indicate one or more pulses of energy
– “source” and “disposal” units for all mass and energy inputs and outputs, depicted in each case as
a box with a question mark (?) and some words explaining what it is.
6 – Write out a “walk” through the device.
– Describe the initial conditions of the
o device (empty, partly full, full; cold, warm, etc.)
o inputs (phases, temperature, etc.)
– Describe all of the processes that the inputs undergo. Analyze in terms of
o mass and energy transfer, and other required equations (use word equations if
necessary)
– Describe the “final” state of the system and/or its contents. Steady state? Equilibrium? Some
desired end point? Don’t forget to include a discussion of what happens with time.
– Include a discussion of any relevant and/or interesting design features that promote the
occurrence or efficiency of each aspect of these processes. Insert these comments in ALL
CAPS in the appropriate place in the text.
7 – Answer the following:
– What hardware factors influence the outcome (materials of construction, various size
parameters or dimensions, proximity of various parts of the unit to each other or to the
processed material, surface-to-volume ratio considerations, etc.)? Explain for each case.
– What operating conditions influence the outcome (initial conditions of the unit and/or the
inputs, T, P, specific mass or energy flow rates, time of operation, etc.)? Explain for each case.
8 – What aspects of the process can and should be controlled at the source (e.g. temperature, flow rates of any
inputs, pressure in the unit, run time, etc.). Include a sensitivity analysis of the outcome (and state which
outcome you’re analyzing) with respect to each of the controlled variables.
Continued on next page…..
Please consider the following 5 appliances:
1 – TOASTER (the kind where you lower the bread into a slot)
2 – ELECTRIC DRIP COFFEE MAKER
3 – GAS BURNER ON A STOVE
4 – CHARCOAL BARBECUE GRILL
5 – STEAM HEATER IN AN APARTMENT BUILDING, WITH THE BOILER IN THE BASEMENT
