PROBLEM 1

Problem 13.11. Helium, at an inlet pressure of 10 bar and an inlet temperature of 220 K, flows through

a rectangular channel with very small cross-section aspect ratio, and leaves with an average

temperature of 245 K. The channel is assumed to be subject to a constant surface heat flux. Helium

velocity at inlet is 5 m/s.

Find the size of the channel that defines the threshold between continuum and slip flow regimes

Consider a channel whose hydraulic diameter is 1/2 of the threshold calculated in part (a), and

has a length-to-hydraulic diameter ratio of 150. Calculate the pressure drop and heat flux

assuming fully-developed flow and neglecting the compressibility effect.

c) Repeat part (b) this time neglecting rarefaction effect as well.

Assume a = ath = 1.0.

a)

b)