ME LAB 2

A single acting, twin cylinder, Ammonia compressor with bore equal to stroke is driven by

an engine at 250 rpm. The machine is installed in a chilling plant to produce 700 kW of

refrigeration at -18°C evaporating temperature. At this temperature the cooling effect per kg

mass is 1160 kJ. The specific volume of vapor entering the compressor is 0.592 m3 per kilogram.

Assume 85% volumetric efficiency, determine the bore in mm.

• A. 400 mm

• B. 300 mm

• C. 450 mm

• D. 500 mm

A 150 Hp motor is used to drive the compressor. If the heat loss from the compressor is 25

kW and the mass flow rate of the refrigerant entering the compressor is 0.50 kg/s, determine

the difference of the enthalpies between the inlet and outlet of the compressor.

• A. 143.80 kJ/kg

• B. 153.80 kJ/kg

• C. 173.80 kJ/kg

• D. 183.80 kJ/kg

A single acting air compressor with a clearance of 6% takes in air at atmospheric pressure

and temperature of 85°F and discharges it at a pressure of 85 psia. The air handled is 0.25

ft3 /cycle measured at discharge pressure. If the compression is isentropic, find the piston

displacement per cycle, if the compressor is running at 750 rpm.

• A. 0.0750 ft3 /cycle

• B. 0.025 ft3 /cycle

• C. 1.030 ft3 /cycle

• D. 1.090 ft3 /cycle

A water tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3,

boiler rating is 200%, boiler efficiency is 65% and heating surface area is 0.91 m2 per bo.Hp. And

the heating value of fuel is 18,400 kCal/kg. The total coal available in the bunker is 50,000 kg.

Determine the no. of hrs. to consume the available fuel.

• A. 853.36 hrs

• B. 706.57 hrs

• C. 979.46 hrs

• D. 100.75 hrs

The heating value of fuel supplied in a boiler is 40,000 kJ/kg. If the factor of evaporation is

1.10 and the actual specific evaporation is 10, what is the efficiency of the boiler?

• A. 62.07%

• B. 53.08%

• C. 78.05%

• D. 54.97%

The ____ valve protect the fuel oil lines and pump from excessive pressure.

• A.Safety

• B.Relief

• C.Bypass

• D.Stop

Regardless of the type of fuel oil used the fuel oil must be _____ before it enters the boiler furnace.

• A.Pressurized

• B.Treated

• C.Atomized

• D.Measured

The ______ of fuels oil is the lowest temperature at which it will flow as a liquid.

• A.Fire point

• B.Pour point

• C.Flash point

• D.Viscosity

A leak on the fuel oil suction line between the tank and the suction side of the fuel oil pump would result in :

• A.The suction gauge pulsating

• B.Air entering the suction line

• C.Pulsating of the fire in the boiler

• D.All of the above

At 0 psig, how many BTU are necessary to change 1 lb of water at 212⁰F of steam?

• A.144

• B.970

• C.180

• D.1190