A gravity pipeline with two pipes in series will be altered to deliver a higher

Question

A gravity pipeline with two pipes in series will be altered to deliver a higher discharge of water supply between two large municipal reservoirs that have a water elevation difference of 25 metres. At the junction of the two pipes, an Ajax 250x250-­400 pump is to be installed to boost the discharge. Pump curve is attached. The pipe connected to the upper reservoir is 245 mm in diameter, 85 metres long and made of cast iron. It contains two 90o elbows and a gate valve that is fully open. The lower pipe is made of asphalted cast iron and is 1300 metres long, has a diameter of 300 mm and contains a swing check valve fully open. All pipeline fittings with the reservoirs are flush.

If the pump is operated at 1500 rpm, determine the operating point for this pump, by plotting the system resistance curve for increments of 50 L/s on your copy of the pump curve. Record the pump efficiency, and then calculate the power required at the pump shaft. Clearly identify the operating point on your pump curve, and clearly detail the pump head, discharge, and efficiency at the operating point. Use the Moody diagram and Darcy-­Weisbach to determine friction headloss.

Explanation / Answer

According to Darcy-­Weisbach to determine friction headloss

=> Hf = 0.031 * f * L * Q2/d5

=>   the pump efficiency   =   1500/(3.14 * 0.245 * 0.245 * 1300 * 25)

                                        = 0.2448          (   about 24.48 % )

=>     the power required at the pump shaft   =   130000 * (1.15/3)5

                                                                     = 1076.034 W

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.