SFM_Example

# SFM_Example - An Example with the SFM 1 Saturated steam...

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Unformatted text preview: An Example with the SFM 1 Saturated steam water at 270 ◦ C ﬂows in a round tube of diameter 0.05 m. The mass ﬂow rate is 1.5 kg s−1 . The ﬂow is vertical upﬂow. Assume that the quality is increasing (there is boiling) at a rate of 0.06 m−1 (i.e., dx/dz = 0.06 m−1 ). After 1 meter (assume fully developed ﬂow), the ﬂow quality is therefore 0.06. Void-Quality-Slip Relations Estimate the void fraction, {α} with: 1. HEM 2. The correlation of Bankoﬀ (Equation 11-42) 3. Use Figure 11-7 to determine the ﬂow regime, then use the appropriate Zuber and Findlay drift ﬂux model with Dix’s correlation to estimate {α}. 4. Martinelli-Nelson (Figure 11-17) Using the SFM for Pressure Drop Compute the total pressure gradient with the SFM, including both boiling-related accelerational terms (the ones that include dα/dz and dx/dz ). This can be accomplished as follows: 1. Compute the frictional pressure drop, using a φ2 of 3 and {α} from the drift ﬂux model (#3, lo above). 2. Compute the gravity term. 3. Compute the dx/dz accelerational term. 4. Compute the d{α}/dz accelerational term. You’ll need to estimate d{α}/dz . Note that you’re given dx/dz . 5. Compute the total dp/dzSF M . 6. Should gas compressibility be included this time? If you can make a good argument it does not, you don’t need to compute it. ...
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