Engineering Answers

As a part of traffic management measure, it is proposed to ban the heavy vehicle from a city street. It has been observed that the mean free speed is 60 km/hr. The percentage flow is 1200 veh/hr. per lane, the composition being: Private Cars: 80, Commercial vehicle: 09 and Buses: 11. The average occupancy of the vehicle is privale cars: persons per cars and Buses: 35 persons per bus. 2%, After the commercial vehicles are banned, it is expected that 15% new cars are in the street and attraction 10% of cars in the street. But the average space occupied for new and attractive cars 1.0 persons per car. The average space occupied by each types of vehicles when stationary in the jamming condition is: Private car: 6m, commercial vehicles: 10m and bus: 8m. Find: (i) The maximum capacity of the street before and after the imposition of the ban on heavy vehicles. (ii) The mean speed of traffic in km/hr. before and after the imposition of the ban on heavy vehicles.

A pump driven at 1440 rev/min having a displacement of 12.5 ml/rev and a volumetric efficiency of 87% is used to supply fluid to a circuit with two cylinders. If the cylinder dimensions are 63 mm bore x 35 mm rod x 250 mm stroke, and 80 mm bore x 55 mm rod x 150 mm stroke, find the minimum cycle time for both cylinders to extend and retract fully.

A hydraulic cylinder having a bore of 125 mm, a rod of 80 mm diameter and a stroke of 350mm is fully extended and retract in a total time of 15 sec. The extend thrust to be exerted by the cylinder is 20 tomes, the retract thrust being 10 tormes. Determine:

(a) The theoretical pump delivery required

(b) The theoretical system pressure when the cylinder is extending.

(c) The theoretical system pressure when the cylinder is retracting.

(d) The actual pump displacement if the volumetric efficiency is 90% and the pump drive at 1440 rev/min. (e) The maximum power input to the pump if the torque efficiency is 85%.

A machine tool cylinder is connected regeneratively to give a rapid approach speed of 10 m/min for a stroke of 1 m with a theoretical thrust of 2.5 tonnes. It is then switched to conventional connection to provide a pressing speed of 0.25 m/min for 0.5 m with a theoretical thrust of 10 tonnes. The maximum pressure at the cylinder is to be 200 bar.

(a) Select a suitable standard size metric cylinder.

(b) Calculate the pump delivery required for both parts of the extend stroke.

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The reservoir problem containing 45 kg of liquid with an initial temperature of 45 ° C has one inlet and one outlet equal to the mass flow rates. Liquid water enters at 45 ° C and a mass flow rate of 270 kg / h. A water-cooled cooling coil dissipates energy at a speed of 7.6 kW. The water is mixed well with the help of a vane wheel so that the water temperature is uniform everywhere. The input power from the impeller to the water is 0.6 kW. Inlet and outlet pressures are equal and all kinetic energy and potential effects can be ignored. Determine changes in water temperature over time.

The water problem flows at a constant mass flow rate of 7 kg / s into a vertical cylindrical tank. Water is discharged near the base of the tank at a mass flow rate proportional to the height of the liquid in the tank, ime = 14 kg / s, where L is the instantaneous height of the liquid, in m. The base area of ​​the circle is 0.2 m2. Water density is constant at 1000 kg / m3. If the tank is empty at first, determine the change in liquid height over time.

One kmol of a gas at 298 K and 1 bar traces the path A and B as follows:

1-2 Compressed adiabatically to 10 bar pressure

2-3 heated at constant pressure to 623K

3-4 Expanded at constant temperature to 1 bar

2-1 Cooled at constant pressure to 298 K

Calculate Q, W, ΔU and ΔH for each step and for entire cycle, Cp = 29.17 kJ/kmol-K.

Calculate the work done for the adiabatic compression of ethane from 150 kPa to 600 kPa

at 20°C. Assume ethane to be an ideal gas. The heat capacity of ethane is given by

𝐶𝑝

0= 1.48 + 4.124 X 10-2 T + 1.23 X 10-5 T

2

- 1.74 X 10-9 T

3

( T in K, Cp = Cal/mol-K)

 A saturated liquid ethyl acetate compressed from 400kPa to 1000Kpa at 300K. Calculate 

the change in enthalpy and entropy during this compression process.

For Saturated liquid ethyl acetate at 300K; VL = 2×10-3 m3

/kg and β = 3 × 10-3 K-1