Chapter 18, Problem 20P

5. Water is pumped 14.5 km from a reservoir at elevation 30 m to another reservoir at elevation 70 m. The steel pipeline connecting the reservoirs has a nominal diameter of 1400 mm (the actual inside diameter is 1372 mm) with C = 90. If the flow is 1.18 m3/s, the pumping efficiency is 82%, and electricity costs $0.14/kWh. Assuming that the density of water is 1000 kg/m3, what will be the monthly power bill? Sketch the hydraulic and energy grade lines.

At a potential hydro-plant site, the average elevation of headwater is 582m, the tailwater is 480m. The average annual water flow was determined to be equal to that volume flowing through a rectangular channel 8.15m wide, a depth of 1.22m and the velocity is 4.6m. The turbine efficiency is 87%, generator efficiency is 95%, and a head loss is 3.5% of the gross head. Find the following:   a. the generator power in kW 44,150 28,206 36,490   b. the annual energy (kWH per year) that can be produced if the plant operation is 345 days per year 235,154,731 302,142,714 244,334,189   c. the annual income of the plant if the cost of the energy produced is P0.60 per kW-hr 141,092,838 181,285,628 162,653,256

A powerhouse is equipped with impulse turbines of Pelton type. Each turbine delivers a power of 14 MW when working under a head of 900 m and running at 600 rpm. Find the diameter of the jet and the mean diameter of the wheel. Assume that overall efficiency is 89%, velocity coefficient of jet 0.98, and speed ratio 0.46. (Answer: 132 mm, 1.91 m; respectively)

Determine the total energy production of a run-of-river plant having an total efficiency of 85%. It receives flow by means of a penstock, 400m long with 1.2m diameter, and f=0.015 in Darcy-Weisbach equation. The available head is 200m and seasonal fluctuations of upstream and downstream water levels are ignored. The flow duration data are tabulated as below.

Reservoirs A and B have elevations 250 m and 100 m, respectively, and are connected by a pipe having a diameter of 250 mm and a length of 250 m. A turbine is installed at a point in between reservoirs A and B. The discharge in the pipeline is 140 L/s. If the head loss in the pipe due to friction is 8.55 m, which of the following most nearly gives the power generated by the turbine?

1. In a 3.0 m wide rectangular channel, the discharge is 15.0 m⅔. Calculate the critical depth and the specific energy for the flow in the channel.

From a reservoir whose surface elevation is at 30 m, water is pumped to an elevated reservoir at an elevation of 95 m. The head loss in the 60 cm diameter suction pipe is 10 m and that of the 50 cm discharge pipe is 15 m. Determine the following if the discharge is to be maintained at 480 liters per second. Assume total head loss between the two reservoirs is 20 m. Compute the power input of the pump assuming it operates at 80% efficiency.

A centrifugal pump discharging 10 lps against 25 m of head and operating with an efficiency of 60% requires 4.1 kW at 1000 rpm. What is the theoretical discharge if the speed is increased to 1500 rpm assuming the efficiency remains constant? What is the theoretical head and kW at 1500 rpm?

A plant has installed a single suction centrifugal pump with a discharge of 68 m3/hr under 60 m head and running at 1200 rpm. It is proposed to install another pump with double suction but of the same type to operate at 37.22 m head and deliver 90 m3/hr. Determine the speed of the new pump.