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The following data was obtained during a test on a gaseous fuel using a Boys’ gas-type calorimeter. Gas supply pressure 20 mm H2O ,Gas supply temperature °C ,Volume of gas burned 0.010 m3 ,Exhaust gas temperature 19 °C ,Atmospheric pressure 99.5 kPa ,Cooling water inlet temperature 15 °C ,Cooling water outlet temperature 38 °C ,Mass of cooling water collected 2.55 kg ,Mass of condensate collected 5.15 g ,Determine the gross and net calorific values of the fuel measured in MJ m−3 at a normal temperature and pressure of 15 °C and 101.325 kPa, respectively. The specific heat capacity of water is 4187 J kg−1 K−1 and its specific latent heat of vaporisation is 2453 kJ kg−1.

A coal sample consists of 82.1% carbon, 4.5% hydrogen, 1.5% sulphur, 3.0% oxygen and the remainder incombustible material. If 1 kg is burnt with 20% excess air, determine (i) the mass of air required per kilogram of fuel and (ii) prepare an analysis by mass of the products of combustion per kilogram of fuel.

An oil- fired boiler takes in feed water at 75°C and produces wet steam at a pressure of 5 bars. The steam flow rate 1.50 tons/hr with a dryness fraction of 0.89. The fuel consumption rate is 6.10kg/min and its net calorific value is 41MJ/Kg. Determine the thermal efficiency of the boiler.

A sample of wet steam is passed through a simple throttling calorimeter. The steam entry pressure recorded on a gauge is 9 bar. Immediately after throttling, the temperature is 110 °C, where the steam is at atmospheric pressure of 1 bar. Calculate the dryness fraction of the steam sample.

Consider the Isentropic expansion of air from fixed, given reservoir conditions (i.e. total pressure and temperature). Investigate the behaviour of the value of the Reynolds number of the flow Re=(rho*U*L)/mu (based on a fixed reference length L), as a function of the Mach number M of the expanded flow.

For small values of M the thermodynamic properties of the flow will not deviate significantly from the reservoir conditions, hence Re increases linearly with U and therefore with M.

Show that for increasing expansion (i.e. increasing M) the value of Re will eventually decrease by investigating the limit behaviour for M>>1. For the temperature dependence of viscosity, employ, Sutherlands expression and the power law where w=1.5 - T_0/(T_0+S).

T_0=288K

S=111 K

For small values of M the thermodynamic properties of the flow will not deviate significantly from the reservoir conditions, hence Re increases linearly with U and therefore with M.

Show that for increasing expansion (i.e. increasing M) the value of Re will eventually decrease by investigating the limit behaviour for M>>1. For the temperature dependence of viscosity, employ, Sutherlands expression and the power law where w=1.5 - T_0/(T_0+S).

T_0=288K

S=111 K

A steam turbine is supplied with superheated steam at a pressure of 20 bar and a temperature of 350 °C. The steam exhausts to a condenser at a pressure of 0.1 bar and dryness fraction of 0.85. If the steam flow rate is 2 tonnes per hour and the power output is 420 kW, calculate the thermal efficiency of the energy conversion process.

A boiler takes in feed water at 70 °C and generates steam at a pressure of 10 bar and dryness fraction of 0.92. The wet steam enters a superheater and emerges with the same pressure at a temperature of 400 °C. If the steam flow rate is 5 tonnes per hour, determine (i) the rate at which heat transfer takes place in the boiler and (ii) the rate at which heat transfer takes place in the superheater.