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Chemical and Material
Engineering Department
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CHE435L UNIT OPERATIONS
LABORATORY
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Instructor:
Thuan Ke Nguyen Office
Hours
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Superheat
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The Limit of Superheat
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Our process engineers are currently developing a new process that requires an intimate liquid/liquid contact of a volatile and nonvolatile liquid. Since the temperature of the nonvolatile liquid is greater than the boiling point of the volatile liquid, vapor explosion is definitely a concern. They want to know the superheated limit of the volatile liquid to avoid mixing the two liquids with the temperature of the nonvolatile liquid near this limit.
Please perfect the technique of droplet superheating in an immiscible host liquid with the equipment available in our lab. You can use n-heptane and cyclohexane as the volatile liquid and glycerol as the host liquid. The hydrocarbon liquid might be introduced into the glycerol through a hypodermic syringe. A rope heater powered by a Variac should be wrapped around a Pyrex tube, with the pitch decreasing in the vertical direction. Thus hydrocarbon droplets will be exposed to increasing temperatures as they rose. You must be very careful to keep both liquids clean and free from gas bubble otherwise you will not be able to superheat the liquid droplets.
Obtain the superheated limit of n-heptane and cyclohexane. Compare the experimental
data with the values predicted by Peng Robinson equation of state. Be sure to
account for the unsteady heating of the liquid drop so that an accurate temperature
for the superheat can be obtained.