Water flowing at the rate of 1 kg/s through a system is heated using an electric heater such that the specific enthalpy of the water increases by 2.50 kJ/kg and the specific entropy increases by 0.007 kJ/kg·K. The power input to the electric heater is 2.50 kW. There is no other work or heat interaction between the system and the surroundings. Assuming an ambient temperature of 300 K, the irreversibility rate of the system is ___ kW (round off to two decimal places).
Explanation
Energy balance confirms the process is adiabatic (Q=0): ṁΔh=1×2.50=2.50 kW=Ẇin, so no heat crosses the boundary. Entropy generation Ṡgen=ṁΔs−Q/T=1×0.007−0=0.007 kW/K. Irreversibility rate I=T0·Ṡgen=300×0.007=2.10 kW.
Source: GATE ME 2019 Session 2 (Set 3) (2019)
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