Upcoming SlideShare
×

# 007

484 views
404 views

Published on

1 Like
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

Views
Total views
484
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
0
0
Likes
1
Embeds 0
No embeds

No notes for slide

### 007

1. 1. LECTURE UNIT NO. 7Fluid in Motion: The Energy EquationDevices that transfer energy in the fluid 1. Pumps – mechanically adds energy to the fluid 2. Hydraulic motors or turbines – mechanically remove energy from the fluid 3. Pipes, fittings, valves, filters and strainers – used to control the distribution, flow rate, pressure, and cleanliness of the fluid. These components inadvertently offer frictional resistance to flow and thus transfer some of the fluid’s pressure and kinetic energy into thermal energy (heat).Comments on energy transfer devices and frictional losses 1. Pumps – add pressure energy or kinetic energy to the fluid to shaft work. 2. Hydraulic motors or turbines – remove pressure energy or kinetic energy from the fluid via shaft work. 3. Pipes, fittings, valves, filters and strainers – transform elevation energy, pressure energy, and kinetic energy from one form to another and transform some of these energies into heat.THE ENERGY EQUATIONFor the Pump t s = td Qs = QdAssumptions: - Perfectly insulated - Isentropic Process or Reversible Adiabatic Process - Constant Volume Pumping Process
2. 2. Water or Hydraulic PowerMass Density of Water 1. If tW = tS = td is given, use steam tables 2. If tW = tS = td is not given Use: Standard mass density of water ρw = 62.4 lb/ft3 = 1,000 kg/m3 = 8.33 lb/galTotal Dynamic HeadSource: Suction Lift TDH = potential head + velocity head + pressure headEnergy Equation From Law of Conservation of EnergySource: Suction Lift [Ein = Eout] - PEs + KEs + Us + Wfs + WP = PEd + KEd + Ud + Wfd + (hfs + hp + hfd) Us, Ud = 0, since Internal energy is a function of temperature and knowing that t W = ts = td . . . But: Vs = Vd = VW
3. 3. Mass of WaterMass density of any working substance other than waterPump Specific Speed RPM required by the impellerEng’g Units:SI Units:Pump Affinity Laws
4. 4. 1. Rate of discharge or rate of flow or volumetric flow rate Q = N D3 ρ a 2. Total Dynamic head H = N2 D2 ρ b 3. Water or hydraulic power P = N3 D5 ρ c Where: N = rotative speed D = impeller diameter ρ = mass density a, b ,c = constants A. Same Pumps (D1 = D2) 1st Condition 2nd ConditionPump Efficiency - Pump Efficiency - Motor Efficiency a.) Solve for the new rate of discharge
5. 5. b.) Solving for new total dynamic headc.) Solving for new power inputB. Similar Pumps (N1 = N2) - but with different impeller diameter 1st Condition 2nd Conditiona.) Solving for the rate of dischargeb.) Solving for the new total dynamic head
6. 6. c.) Solving for the new power inputSingle Impeller – Single Suction Centrifugal PumpSingle Impeller – Double Suction Centrifugal Pump2 Pumps in Parallel
7. 7. Multi-Stage Centrifugal PumpPumps in SeriesProblems: