3rd Class Thermodynamics exam help from Martin's Marine Engineering Page

# Canadian Third Class ME  Thermodynamics

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Martin

1. 15 kg of steel ball bearings @ 100 C are immersed in 25 kg of water @ 20 C. Assuming no loss of heat to or from the container, calculate the final temperature of the water after equilibrium has been attained.
Specific heat of steel : 0.4857ki(kgK)
Specific heat of water : 4.187 kJ(kgK)

2.
(i) State Charle's Law.
(ii) An air receiver carries a pressure of 3500 kPa absolute @ a temperature of 25 C. A fire occurs near the receiver which causes the temperature to rise to 80 C. Neglecting the increased volume of the receiver due to expansion, calculate the air pressure at this temperature.

3. A diesel engine is being assembled in a shop where the temperature is kept @ 20 C. At this temperature, the length of a steel valve push-rod is 460 mm. Calculate the clearance required if the engine is expected to reach an operating temperature of 96 C.
Linear coefficient (steel) : (12)(10-6)/ 0C.

4. The following related values of the pressure p in kN/m2 and the volume V in cubic meter where measured from the compression curve of an internal combustion engine indicator diagram. Assuming that P and V are connected by the law PVn: C, find the value of n.
p 3450 2350 1725 680 270 130
V .0085 .0113 .0142 .0283 .0566 .0991

5. A continuous flow calorimeter was used to obtain the calorific value of a sample of fuel and the following data collected:
Mass of fuel: 2.25kg
Inlet water temp: ll C
Quantity of water: 360 L
Outlet water temp: 60 C
Calorimeter efficiency: 85 %
Calculate the calorific value of the sample (kJ/kg).

6. The steel cables supporting the "Lion's Gate" suspension bridge are approximately 1200 metres long. If the temperature ranges from -9 to 26 C between winter and summer extremes, calculate the variation in the length of thg cables.
Linear coefficient (steel) : (12)(10-6)/OC.

7.
(i) State Boyle's Law.
(ii) A receiver contains 0.25 m3 of air at a pressure of 1700 kPa and a temperature of 18 C. After a long period of time, the pressure is found to be the same as that of the atmosphere due to an extremely small leak. If the expansion is assumed to be isothermal, calculate the volume of air at the reduced pressure.

8. The following data were taken during a one-hour trial run on a single cylinder, single acting, four-stroke diesel engine with a cylinder diameter of 175 mm and a stroke of 225 mm, the speed being constant @ 1000 rpm
Indicated mep: 5.5 bar
Dia. of rope brake: 1066 mm