Is the pressure drop significant for variable diameters?
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I would like to ask how the pressure drop due to diameter change is calculated. I used the formula in the attachment; for natural gas flowing at a speed of 30 M/S, there is a diameter change from 6 inches to 10 inches, with an angle of 45 degrees. The pressure drop actually reached 1 bar. Personally, I find this pressure drop incredible. I would like to ask everyone a few more questions: 1. In the calculation of the K value, is it true that the K value for a 6\"x10\" expansion fitting is higher than that of a 10\"x6\" reduction fitting? 2. What is the pressure drop for a normal diameter change? 3. Is the U used in calculating the diameter change the average flow velocity inside the diameter change section, or the flow velocity at the inlet of that section? 4. Regarding the calculation of pressure drop for tees, no difference in the resistance coefficients between equal-diameter tees and tees with different diameters was found. Is there such a difference? Could you please provide relevant information? The referenced document in the attachment is HG-T 20570.7-1995 for the calculation of pipeline pressure drop
Based on the figures you provided, a rough calculation shows that with k=1 and a density of 20 atmospheres, the value is 10; the pressure drop is only 4.5 kPa, which is still a long way from 1 bar (100 kPa). Under normal conditions, a pressure drop in a tapered pipe should not be as high as 4.5 kPa
Thank you for the calculations. Could you provide a formula? It’s natural gas under non-constant pressure; the flow rate is 39,824 NM3/h, the density is 0.75 KG/NM3, the operating temperature is 24 degrees Celsius, and the operating pressure is 13.75 barg
I used the formula in the attachment and got K=1.51 for a diameter change from 6 inches to 10 inches. How did you determine your K value?
I used the formula in the attachment and got K=1.51 for a diameter change from 6 inches to 10 inches. How did you determine your K value?
I used the formula in the attachment and got K=1.51 for a diameter change from 6 inches to 10 inches. How did you determine your K value?
It was chosen arbitrarily; even using 1.51, it doesn’t equal 1 bar. The density value of 0.75 kg/Nm3 seems strange – what concentration of natural gas gives such a density? The unit here is standard cubic meters
This density is the density under standard conditions, that is, at 1 atmosphere of pressure and 0 degrees Celsius. Do you need to calculate it based on the density under actual operating conditions?
Could you take the time to answer my question? Should we use the operating condition density? Could you provide the calculation process? Upload a picture so I can learn from it