Thermodynamics-1.pdf

# Q 5 the power developed by a turbine in a certain

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Q 5: The power developed by a turbine in a certain steam plant is 1200 kW. The heat supplied to the steam in the boiler is 3360 kJ/kg, the heat rejected by the system to cooling water in the condenser is 2520 kJ/kg and the feed pump work required to pump the condensate back into the boiler is 6 kW. Calculate the steam flow round the cycle in kg/s.

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Mechanical Engineering Department Thermodynamics ASSIGNMENT 2 Q 1: 1kg of gaseous CO2 contained in a closed system undergoes a reversible process at constant pressure. During this process 42 kJ of internal energy is decreased. Determine the work done during the process.Take cp = 840 J/kg°C and cv = 600 J/kg°C. Q 2: A fluid is contained in a cylinder by a spring-loaded, frictionless piston so that the pressure in the fluid is a linear function of the volume (p = a + bV). The internal energy of the fluid is given by the following equation U = 42 + 3.6 pV Where U is in kJ, p in kPa, and V in cubic metre. If the fluid changes from an initial state of 190 kPa, 0.035 m3 to a final state of 420 kPa, 0.07 m3, with no work other than that done on the piston, find the direction and magnitude of the work and heat transfer. Q 3: 90 kJ of heat is supplied to a system at a constant volume. The system rejects 95 kJ of heat at constant pressure and 18 kJ of work is done on it. The system is brought to original state by adiabatic process. Determine: (i) The adiabatic work; (ii) The values of internal energy at all end states if initial value is 105 kJ. Q 4: 0.2 m3 of air at 4 bar and 130°C is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate: (i) The work done; (ii) The index of expansion, if the above processes are replaced by a single reversible polytropic process giving the same work between the same initial and final states. Take cp = 1 kJ/kg K, cv = 0.714 kJ/kg K.
Mechanical Engineering Department Thermodynamics ASSIGNMENT 3 Q 1: A fish freezing plant requires 40 tons of refrigeration. The freezing temperature is 35°C while the ambient temperature is 30°C. If the performance of the plant is 20% of the theoretical reversed Carnot cycle working within the same temperature limits, calculate the power required. Given: 1 ton of refrigeration = 210 kJ/min. Q 2: A Carnot cycle operates between sources and sinks temperatures of 250°C and 15°C. If the system receives 90 kJ from the source, find: (i) Efficiency of the system; (ii) The net work transfer; (iii) Heat rejected to sink. Q 3:A reversible heat engine operates between two reservoirs at temperatures 700°C and 50°C. The engine drives a reversible refrigerator which operates between reservoirs at temperatures of 50°C and 25°C. The heat transfer to the engine is 2500 kJ and the net work output of the combined engine refrigerator plant is 400 kJ.

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