HW5_FINAL

# HW5_FINAL - – 7 points In a separate test where the...

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ENU 4134 – Homework Assignment #5 – Fall 2011 – D. Schubring 1 ENU 4134 – Homework Assignment #5 – Fall 2011 DUE: Monday, October 24 ALLOWED COLLABORATION: This assignment may be completed in groups of up to 2, who may turn in one paper. Task 1. Computing CHF – Biasi – 9 points Assume the tube in tasks 2-4 of HW 4 is 3.5 m long and is constantly heated. The entrance conditions are saturated liquid at 250 C. Neglect pressure loss. Compute the critical heat ﬂux, the critical quality, and the critical total power using the Biasi correlation. For this sort of problem, CHF will ﬁrst occur at the end of the tube. Properties, etc.: P = 3 . 978 MPa (1) ρ g = 19 . 98 kg m - 3 (2) ρ f = 799 kg m - 3 (3) k f = 0 . 616 W m - 1 K - 1 (4) k g = 0 . 0495 W m - 1 K - 1 (5) Pr f = 0 . 859 (6) Pr g = 1 . 39 (7) h fg = 1 . 715 × 10 6 J kg - 1 (8) μ f = 1 . 087 × 10 - 4 kg m - 1 s - 1 (9) μ g = 1 . 751 × 10 - 5 kg m - 1 s - 1 (10) σ = 0 . 02619 N m - 1 (11) R = 461 . 5 J kg - 1 K - 1 (12) D = 0 . 012 m (13) G = 1000 kg m - 2 s - 1 (14) L = 3 . 5 m (15) Task 2. Computing CHF – Bowring – 9 points Repeat Task 1, using the Bowring correlation. Task 3. Post-CHF Heat Transfer

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Unformatted text preview: – 7 points In a separate test where the saturation temperature is now 340 ◦ C (same ﬂow rate and ﬂow facility), the ﬂow quality and heat ﬂux at some location are 0.3 and 2.1 MW m-2 , respectively. Assume CHF has occurred and compute T wall using the Groeneveld correlation. (Note: none of our post-CHF correlations work for the lower pressure region which has been studied above, so we need a new pressure and some new properties). ρ g = 92 . 8 kg m-3 (16) ρ f = 610 kg m-3 (17) ENU 4134 – Homework Assignment #5 – Fall 2011 – D. Schubring 2 k g = 0 . 114 W m-1 K-1 (18) μ g = 2 . 27 × 10-5 kg m-1 s-1 (19) Pr g = 2 . 36 (20) (21) Deliverable • Hard copy solutions/discussion, as required in the tasks above, with the tasks individually numbered (in order) and stapled. Do not include this assignment sheet. Do not include your UFID#....
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HW5_FINAL - – 7 points In a separate test where the...

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