Related MCQs

• If the pressure at station Q is 50 kPa, the change in entropy (sQ sp) in kJ/kgK is
• Steam enters a well insulated turbine and expands isentropically throughout. At an intermediate pressure, 20 percent of the mass is extracted for process heating and the remaining steam expands isentropically to 9 kPa. Inlet to turbine: P = 14 MPa, T = 560 C, h = 3486 kJ/kg, s = 6.6 kJ/(kgK) Intermediate stage: h = 276 kJ/kg Exit of turbine: P = 9 kPa, hf = 174 kJ/kg, hg = 2574 kJ/kg, sf = 0.6 kJ/(kgK), sg = 8.1 kJ/(kgK) If the flow rate of steam entering the turbine is 100 kg/s, then the work output (in MW) is____.
• A gas is heat ed in a duct as it flows over a resistance heater. Consider a 101 kW electric heat ing syst em. The gas ent ers the heat ing section of the duct at 100 kPa and 27 C with a volume flow rate of 15 m /s. If heat is lost from the gas in the duct to the surroundings at a rate of 51 kW, the exit temperature of the gas is (Assume constant pressure, ideal gas, negligible change in kinetic and potential energies and constant specific heat: Cp = 1 kJ/kg. K; R = 0.5 kJ/kg K).
• In order to burn 1 kilogram of CH4 completely, the minimum number of kilograms of oxygen needed is (take atomic weights of H, C and O as 1, 12 and 16 respectively)
• One kg of air (R = 287 J/kgK) undergoes an irreversible process between equilibrium state 1 (20 C, 0.9 m3) and equilibrium state 2 (20 C, 0.6 m3). The change in entropy s2 s1 (in J/ kgK) is ______.
• An ideal gas of mass m and temperature T1 undergoes a reversible isothermal process from an initial pressure P1 to final pressure P2. The heat loss during the process is Q. The entropy change S of the gas is
• One kg of an ideal gas (gas constant R = 287 J/ kgK) undergoes an irreversible process from state-1 (1 bar, 300 K) to state-2 (2 bar, 300 K). The change in specific entropy (s2 s1) of the gas (in J/kgK) in the process is _______.
• An ideal gas undergoes a process from state 1 (T1 = 300 K, p1 = 100 kPa) to state 2 (T2 = 600 K, p2 = 500 kPa). The specific heats of the ideal gas are: cp = 1 kJ/kg-K and cv = 0.7 kJ/kg-K. The change in specific entropy of the ideal gas from state 1 to state 2 (in kJ/kg-K) is _________ (correct to two decimal places)
• One kg of an ideal gas (gas constant, R= 400 J/ kgK; specific heat at constant volume, cp = 1000 J/kgK) at 1 bar, and 300 K is contained in a sealed rigid cylinder. During an adiabatic process, 100 kJ of work is done on the system by a stirrer. The increase in entropy of the system is _______ J/K.
• A turbocharged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m3 (25.9 liters). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure (in MPa) is closest to