What are primary fuels List some important primary fuels.

What is the difference between higher heating value and lower heating value of the fuel?

What is a fusible plug State where it is located in a boiler.

Define 'Steam nozzle'. Explain with the help of neat diagrams, the various types of nozzles.

3. In a boiler test, 1250 kg of coal is consumed in 24 hours. The mass of water evaporated is 13000 kg and the mean effective pressure is 7 bar. The feed water temperature was 40°C, heating value of coal is 30000 kJ/kg. The enthalpy of 1 kg of steam at 7 bar is 2570·70 kJ.

Determine:

Equivalent evaporation per kg of coal

Efficiency of the boiler

4. A spark ignition engine has a fuel-air ratio of 0.067. How much kg of air per hour is required for a brake power output of 73·6 kW at an overall thermal efficiency of 20% Calorific value of the fuel is 42000 kJ/kg.

5. At a particular stage of a reaction turbine, the mean blade speed is 60 m/s and the steam is at a pressure of 350 kN/m^2 with a temperature of 175°C. Fixed and moving blades of this stage have inlet angles of 30° and exit angles of 20°. Determine the blade height, if the blade height is one-tenth of the mean blade ring diameter and steam flow is 13·5 kg/sec at 350 kN/m^2 and 175°C. The specific volume of steam is 0·589 m^3/kg.

6. Air is expanded reversibly and adiabatically in a nozzle from 13 bar and 150°C to a pressure of 6 bar. The inlet velocity of the nozzle is very small and the process occurs under steady state flow conditions. Calculate the exit velocity of the nozzle.

7. A turbojet engine flying at a speed of 960 km/h consumes air at the rate of 54-5 kg/s.

Calculate

Exit velocity of the jet when the enthalpy change for the nozzle is 200 kJ/kg and velocity coefficient is 0.97,

Fuel flow rate in kg/s when the air-fuel ratio is 75

Thrust specific fuel consumption,

Thermal efficiency of the plant when the consumption efficiency is 93% and calorific value of the fuel is 45000 kJ/kg,

Propulsive power,

Propulsive efficiency, and

Overall efficiency.

8. An engine uses a fuel of CV of 42000 kJ/kg and has a specific gravity of 0·75. The engine develops a brake power of 29.44 kW. The brake thermal efficiency of the engine is 24%. Determine the volume of the fuel consumed per second.

9. A gas turbine is supplied with a gas at 5 bar and 1000 K and expands it adiabatically to 1 bar. Determine the exhaust gas temperature.

Take Cp 1.0424 kJ/kg
Cv 0·7662 kJ/kg K

10. Air enters the compressor of a gas turbine plant operating on Brayton cycle at 1 bar, 27°C. The pressure ratio of the cycle is 6. If WT =2.5 Wc, where WT and Wc are the turbine and compressor work respectively, calculate the maximum temperature of the plant. Also determine the cycle efficiency.

Take Cp 1 kJ/kg K