The simple Rankine cycle is an example of a heat engine, which traditionally uses water as the working fluid. The water circulates in a closed loop and is periodically evaporated and condensed. The heat engine is assumed to be operating in a steady state. In the pump, saturated liquid water is compressed from the condenser pressure (P. = P.) to the boiler pressure (P = Ps) using the input pump power (Wpump). In the boiler, energy is supplied as heat (Q = Q₂) to the working fluid at constant pressure without work being added or removed. This converts the water from a subcooled liquid (state 2) to superheated steam (state 3). In the steam turbine, which is assumed to be adiabatic, the steam expands from the boiler pressure to the condenser pressure. The expansion process drives the rotation of the turbine blades, producing power on the turbine shaft (Wturbin). At the turbine outlet, the water is usually either superheated steam or a saturated steam-liquid mixture with high steam quality (typically >90%). In the condenser, the working fluid is cooled at constant pressure from the state at the turbine outlet (state 4) back to saturated liquid. The heat output Qout = Q₁ is rejected to the surroundings. In a given Rankine cycle, water (the working fluid) enters the pump as saturated liquid at 30 kPa (state 1). The pressure is increased to 5 MPa (state 2) by supplying 25.4 kW of power to the pump. The subcooled water from the pump (state 2) is heated, evaporated, and superheated to a temperature of 600°C at 5 MPa at the turbine inlet (state 3). At the outlet of the adiabatic steam turbine (state 4), the water has the same pressure as at the pump inlet and a steam quality of 95%. The mass flow rate of the working fluid is 5 kg/s. You can neglect the kinetic and potential energy of the working fluid and their changes. a) Calculate the specific enthalpy of the water at the pump outlet in kJ/kg. b) Calculate the heat input Qinn in the boiler in kW or MW. c) Calculate the power output of the steam turbine Wurbin in kW or MW. d) Calculate the net power output of the cycle in kW or MW and the thermal efficiency of the heat engine. e) The heat input to the working fluid (Qinn) comes from the combustion of waste, which has a higher heating value (HHV) of 23 MJ/kg. How many tons of waste must be burned per hour if the boiler has a combustion efficiency of 70%?

The simple Rankine cycle is an example of a heat engine, which traditionally uses water as the working fluid. The water circulates in a closed loop and is periodically evaporated and condensed. The heat engine is assumed to be operating in a steady state. In the pump, saturated liquid water is compressed from the condenser pressure (P. = P.) to the boiler pressure (P = Ps) using the input pump power (Wpump). In the boiler, energy is supplied as heat (Q = Q₂) to the working fluid at constant pressure without work being added or removed. This converts the water from a subcooled liquid (state 2) to superheated steam (state 3). In the steam turbine, which is assumed to be adiabatic, the steam expands from the boiler pressure to the condenser pressure. The expansion process drives the rotation of the turbine blades, producing power on the turbine shaft (Wturbin). At the turbine outlet, the water is usually either superheated steam or a saturated steam-liquid mixture with high steam quality (typically >90%). In the condenser, the working fluid is cooled at constant pressure from the state at the turbine outlet (state 4) back to saturated liquid. The heat output Qout = Q₁ is rejected to the surroundings. In a given Rankine cycle, water (the working fluid) enters the pump as saturated liquid at 30 kPa (state 1). The pressure is increased to 5 MPa (state 2) by supplying 25.4 kW of power to the pump. The subcooled water from the pump (state 2) is heated, evaporated, and superheated to a temperature of 600°C at 5 MPa at the turbine inlet (state 3). At the outlet of the adiabatic steam turbine (state 4), the water has the same pressure as at the pump inlet and a steam quality of 95%. The mass flow rate of the working fluid is 5 kg/s. You can neglect the kinetic and potential energy of the working fluid and their changes. a) Calculate the specific enthalpy of the water at the pump outlet in kJ/kg. b) Calculate the heat input Qinn in the boiler in kW or MW. c) Calculate the power output of the steam turbine Wurbin in kW or MW. d) Calculate the net power output of the cycle in kW or MW and the thermal efficiency of the heat engine. e) The heat input to the working fluid (Qinn) comes from the combustion of waste, which has a higher heating value (HHV) of 23 MJ/kg. How many tons of waste must be burned per hour if the boiler has a combustion efficiency of 70%?

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter44: Geothermal Heat Pumps

Section: Chapter Questions

Problem 13RQ: If 14 gpm of water is flowing through an open-loop heat pump with a temperature difference of 7F,...

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