A three phase 30 hp 460 volt 60 hz, 1770 rpm design B induction motor with class F insulation and service factor of 1.0 is operating at rated shaft load in a 40 degree C environment and has an expected 20 yr life. A maintenance check shows line to line voltages to be 449.2 V, 431.3 V and 462.4 volts. The percent unbalanced voltage for this motor is:

the expected temperature rise equals?

The expected insulation life equals?

the rerating in horsepower equals?

Energy flows out of the system in form of a heat in an internally reversible process. What happened to he entropy of the system? Explain

Energy flows out of the system in form of a heat in an internally reversible process. What happened to he entropy of the system? Explain

Consider the design of a wastewater treatment plant (WWTP) for a community with average
daily and peak hourly wastewater design flows of 7570 m3/day and 18925 m3/day. The raw
sewage has an average of 240 mg/L BOD5 and 270 mg/L of suspended solids.

(a) Assume that the primary sedimentation process removes 55% of the suspended solids and
35% of the BOD5 of the raw sewage. Determine the SS and BOD5 concentrations in the
primary sedimentation effluent flow. (1 mark)

The primary effluent is treated by two parallel trains of the complete-mix activated sludge
process. Assume with the average flow conditions and the performance of primary
sedimentation achieved as above. Given the following parameters required for the activated
sludge process:

· Effluent BOD5 (S): 8 mg/L
· Observed biomass yield (Y): 0.55 kg biomass / kg BOD
· Endogenous decay rate (b) = 0.04 /day
· Solids retention time: 8 days
· MLVSS concentration in the aeration tank: 3000 mg/L
· Waste and recycle solids concentration: 12,000 mg/L

By using the formulas shown in appendix, determine the following:
(b) Aeration tank volume (m3).
(c) Mass flow rate of wasted sludge (kg/day). (1 mark)
(d) Volumetric flow rate of wasted sludge (m3/day). (1 mark)
(e) Return (recycle) flow rate (m3/day).
(f) Volumetric BOD loading to the aeration tank (kg BOD/m3.day). (1 mark)
(g) Food to microorganisms (F/M) ratio for the aeration tank (kg BOD day/kg MLVSS). (1 mark)
(h) Design hydraulic retention time (hr). (1 mark)

1. A plant is located at an altitude where the atmospheric pressure head is 31 ft of water and the vapor pressure is 9.34 psi. The pump is placed 10 ft below the water tank with a total suction pipe length of 25 ft, pipe diameter 3 in., and friction coefficient 0.02. Assuming the given atmospheric pressure in the tank (where z1 = 10 ft and negligible velocity) and if the flowrate provided is 180 gpm, determine the available NPSH (ft). Neglect minor losses. ans 17.4 ft

Sketch constant preassure curve in T-s diagram.

A metal bar, initially at 2000K, is placed in a large tank of water at room temperature. Tank is well isolated from the environment. Between the moment bar was placed in the water and the moment when bar and water reached equilibrium, did the entropy of the metal bar increased, decreased, or remained the same? Explain.

Process X is internally reversible from state 1 to 2. Process Y is internally irreversible between same states 1 to 2. What can you say about the change in entropy of the system during process X and Y? Is one larger than the other or are they the same? Explain.

A 1-mm diameter sphere (density=7900 kg/m³) is dropped into a tank of oil (density=900 kg/m³). The sphere develops a terminal speed of 0.25 cm/s, what is the oil's viscosity? You may assume a small Reynolds number. Show your work.

4. Explain why the energy efficiency in the case of ideal quenching is lower than energy efficiency in the regime of super-ideal quenching?

An essay on Engineering

A composite of Al₂O₃ particles in an epoxy matrix contains 10 wt.% Al₂O₃. What are the upper and lower bounds on the elastic modulus of the composite? Data: ρ_Al2O3 = 3.95 g/cm3 , E_Al2O3 = 300 GPa, ρ_epoxy = 2.0 g/cm3 , and E_epoxy = 500 MPa.

A stock steel spur pinion has a diametral pitch of pd=8 teeth/in, a 1.5 in. face, 26 full-depth teeth, and a pressure angle of Φ = 20°. If the pinion is driven against a 55-tooth steel gear at 1200 RPM by a 7 hp electric motor, determine the bending stresses and surface stresses in the pinion.

how could mechanical engineering improve plastic recycle?