2nd Class Applied Heat exam help from Martin's Marine Engineering Page

# Canadian Second Class ME  Applied Heat (Thermo)

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01 Mass analysis of a fuel is 84.6% carbon, 11.4% hydrogen, 0.4% sulphur, 2.4%oxygen, and 1.2% impurities. Calculate the heating value of the fuel and the theoretical mass of air required for complete combustion of 1kg of fuel.
Take mass analysis of air as oxygen 23% and nitrogen 77%

Element/heating value(MJ/kg)/relative atomic mass
hydrogen/144/1
carbon/33.7/12
sulphur/9.3/32
oxygen/0.0/16

02 The pressure in a steam condenser is 4.0 kPa, the temperature is 20.43*C and the internal volume is 12 m3. The dryness fraction of the steam is 0.8. - R air = 0.287 kJ/kgK
Calculate

(a)mass of air present in the condenser

(b) mass of steam in the condenser

03 The nozzle of a turbines inclined at an angle of 22* to the plane of the rotor wheel, the blade entrance angle being 40* and the steam velocity leaving the nozzles is 760 m/s. Assume the blade entrance and exit angles are equal and that no friction losses occur as the steam flows over the blades.
Determine graphically or analytically:

04 Steam is admitted to an engine at a pressure of 750kPa, exhausted at 150 kPa and the cut-off takes place at 0.375 of the stroke.
Calculate hypothetical mean pressure

05 In a refrigeration plant, the specific enthalpy of the refrigerant as it leaves the condenser is 135 kJ/kg, and as it leaves the evaporator 320 kJ/kg. If the mass flow of the refrigerant is 5 kg/min, calculate refrigerating effect per hour.

06 An ingot of dimension 0.5 x 1 x 3 m has just been removed from the soaking pit of a steel mill and its temperature is 600*C. Assuming black body radiation, calculate the energy radiated from the entire surface of the ingot each second.
Note: Power, (W) = e & A T to the fourth
&=5.67 x 10 to the -8

07 A gasoline engine has a compression ratio 9.5 to 1. The temperature of the fuel/air mixture at the beginning of the compression stoke is 24*C and the charge is compressed polytropically according to PV1.36 = constant. Calculate temperature and pressure of the mixture at the end of compression stroke. Take atmosphere to be 100kPa.

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01 -  When developing a certain power, the specific fuel consumption of an internal combustion engine is 0.255 kg/kwh. Mechanical efficiency = 86%. Calorific value of the fuel is 43.5 MJ/kg.
a) Calculate indicated thermal efficiency and brake thermal efficiency.

02 - A copper sphere has a diameter of 40 mm. Calculate the increase in volume when the temperature is raised 180 C. Co-efficient of expansion = 0.0000167/C

03 -  Using steam table find the specific enthalpy and volume of 1 kg steam at pressure 24 kg and dryness fraction 0.86.
Calculate additional energy required to completely dry the steam.

04 -  During a certain part of a liquefaction process, air is expanded adiabatically through a turbine from a pressure of 8000 KPA and temperature 15 C to a pressure of 100 KPA. Adiabatic index = 1.4 Calculate final temperature.

05 -  Single cylinder steam engine, Bore = 200mm, stroke = 300mm running at 3.5 revs/sec, develops 510 KPA mean effective pressure. Calculate indicated power.

06 -  Cold Room 30m x 23m x 3m

inside temperature = -30 C

Outside temperature = 21 C

Ground temperature = 10 C

Walls and ceilings insulated with 25cm granulated cork h = 0.049 w/mk
Floor insulated with cork board 15 cm thick h = 0.043 w/mk
Calculate heat transfer per hour.

07 -  Mass analysis of fuel A = 88.5% Carbon, 11.5 % hydrogen
Fuel B requires 6% more air than fuel A for combustion. Calculate mass analysis of fuel B using following values.

Atomic Weights = Carbon = 12

Hydrogen = 1 oxygen = 16

Mass content of oxygen in air = 23%

08 -  The nozzle of a turbine is inclined at an angle of 20 C to the plane of the rotor wheel and the blade entrance angle is 33 C. The steam leaves the nozzle at a velocity of 450m/s and the mean diameter of the rotor blade ring is 600mm
Determine either graphically or analytically

1. The linear velocity of the blades so that the steam enters without shock.

2. Rotational speed of rotor in revs/sec.

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