Power, Energy, and Efficiency

Two electrostatic precipitators (ESPs) are in series. The fractional efficiencies of the upstream and downstream ESPs for size d_p are 80% and 65% respectively. What is the overall efficiency of the system for the same d_p?

A CNC vertical milling machine has to cut a straight slot of 10 mm width and 2 mm depth by a cutter of 10 mm diameter between points (0, 0) and (100, 100) on the XY plane (dimensions in mm). The feed rate used for milling is 50 mm/min. The milling time for the slot (in seconds) is

In a single pass drilling operation a through hole of 15 mm diameter is to be drilled in a steel plate of 50 mm thickness. Drill spindle speed is 500 rpm, feed is 0.2 mm/rev and drill point angle is 118⁰. Assuming 2 mm clearance at approach and exit, the total drill time (in seconds) is

In a power plant, water (density = 1000 kg/m³) is pumped from 80 kPa to 3 MPa. The pump has an isentropic efficiency of 0.85. Assuming that the temperature of the water remains the same, the specific work (in kJ/kg) supplied to the pump is

The values of enthalpy of steam at the inlet and outlet of a steam turbine in a Rankine cycle are 2800 kJ/kg and 1800 kJ/kg respectively. Neglecting pump work, the specific steam consumption (in kg/kW-hour) is

Two identical ball bearings P and Q are operating at loads 30 kN and 45 KN respectively. The ratio of the life of bearing P to the life of bearing Q is