A heat pipe having an effective length of 80 cm uses methanol as the working fluid. At an operating temperature of 20ºC the methanol flow rate is 12 mg/s, and the heat pipe uses an axially grooved wick arrangement with 60 equally spaced 2.1-mm-deep grooves. Determine the width of the grooves.
What will be an ideal response?
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What is meant by an entrance region?
What will be an ideal response?
Assume that the water is originally at the freezing temperature Tf, that the cooling medium inside the tube surface is just below the freezing temperature at a uniform temperature Ts, and that ho is the total heat transfer coefficient between the cooling medium and the pipe-ice interface. Also show the thermal circuit.
Show that the dimensionless equation for ice formation at the outside of a tube of radius ro is
where
GIVEN
? Water freezing on the outside of a tube
? Tube radius = ro
? Cooling medium temperature = T ? (uniform)
? Heat transfer coefficient between the cooling medium and the pipe-ice interface = ho
FIND
? Draw the thermal circuit and show that the dimensionless equation for ice formation is as shown
above
ASSUMPTIONS
? Steady state
? The thermal capacitance of the ice layer is negligible
? T? is constant
? The water is at the freezing temperature, Tf
? The properties of the ice are uniform
SKETCH
Spectral lines are often referred to as the stars' "fingerprints" because:
A) fingerprints also consist of individual lines that make a pattern. B) both are unique to their source. C) both can be easily categorized. D) both are characteristic of the individual that produced them. E) All of these are correct.
When light passes through common windowpane, its angle of emergence is
A) usually less than its angle of incidence. B) always less than its angle of incidence. C) the same as its angle of incidence. D) usually more than its angle of incidence. E) always more than its angle of incidence.