Superheated steam at 20 MPa, 560 deg C enters the turbine of a vapor power plant. The pressure at the exit of the turbine is 0.5 bar, and liquid leaves the condenser at 0.4 bar at 75 deg C. The pressure is increased to 20.1 MPa across the pump. The turbine and pump have isentropic efficiencies of 81% and 85%, respectively. Cooling water enters the condenser at 20 deg C with a mass flow rate of 70.7 kg/s and exits the condenser at 38 deg C. For the cycle, determine (a) the mass flow rate of steam, in kg/s. (b) the thermal efficiency.

Superheated steam at 20 MPa, 560 deg C enters the turbine of a vapor power plant. The pressure at the exit of the turbine is 0.5 bar, and liquid leaves the condenser at 0.4 bar at 75 deg C. The pressure is increased to 20.1 MPa across the pump. The turbine and pump have isentropic efficiencies of 81% and 85%, respectively. Cooling water enters the condenser at 20 deg C with a mass flow rate of 70.7 kg/s and exits the condenser at 38 deg C. For the cycle, determine (a) the mass flow rate of steam, in kg/s. (b) the thermal efficiency.

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

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

See similar textbooks

Similar questions

Steam is supplied to a two-stage turbine at 40 bar and 350 oC. It expands in the first turbine until it is just dry saturated, then it is reheated to 350 oC and expanded through the second stage turbine; the isentropic efficiencies of the first and second stage turbines are 84 % and 78 % respectively. The condenser pressure is 0.035 bar. Sketch the process on a T-s diagram and calculate;The work output and heat supplied per kg of steam for the plant assuming ideal processesThe thermal efficiency of the cycleThe specific steam consumption
Steam is supplied to a two-stage turbine at 40 bar and 350 o It expands in the first turbine until it is just dry saturated, then it is reheated to 350 oC and expanded through the second stage turbine; the isentropic efficiencies of the first and second stage turbines are 84 % and 78 % respectively. The condenser pressure is 0.035 bar. Sketch the process on a T-s diagram and calculate; i. The work output and heat supplied per kg of steam for the plant assuming ideal processes ii. The thermal efficiency of the cycle iii. The specific steam consumption
4. Steam is supplied to a two-stage turbine at 40 bar and 350°C. It expands isentropic ally until it is just dry-saturated. Then it is reheated to 350°C at constant pressure and expanded in the second-stage turbine to the condenser pressure of 0.03 bar. If the isentropic efficiency of the second stage is 78%. Calculate the specific steam consumption and the thermal efficiency.
Steam enters the turbine of a Rankine cycle at 16 MPa, 560°C. The condenser pressure is 8 kPa. The turbine and pump each have isentropic efficiencies of 85%, and the mass flow rate of steam entering the turbine is 120 kg/s. Determine the net power developed, in kW. the rate of heat transfer to the steam passing through the boiler, in kW. the thermal efficiency.
(3). A gas turbine unit consists of a compressor, combustion chamber, turbine and heat exchanger. The unit has a pressure ratio of 6:1 and a maximum cycle temperature of 600°C. The isentropic efficiencies of the compressor and turbine are 0.8 and 0.85 respectively. The air enters the compressor at 15°C at a rate of 17kg/s. the heat exchanger effectiveness is 80%. If the compressor and turbine are connected by a rigid shaft, calculate: (a). the net power (b). the thermal efficiency (c). the thermal efficiency with the heat exchanger bypassed.
2. In a reheat cycle steam enters the high pressure turbine at 40 bar and 400°C. It expands isentropic ally to 6 bar and is reheated at constant pressure to 400°C. This steam is expanded isentropic ally in the low pressure turbine to the condenser pressure of 0.1 bar. Calculate the thermal efficiency and steam consumption for 10 MW output.
In a steam plant 100 kg/min of dry-saturated steam at 30 bar enters the turbine. After expanding isentropic ally the exhaust steam enters the condenser. The condenser pressure is maintained at 0.1 bar by the cooling water taken from a nearby river. Calculate the following: a. Heat supplied to the boiler KJ/sec b. Heat rejected to the cooling water KJ/sec c. Efficiency of the plant and Net power output.
1. Steam is supplied to a two-stage turbine at 140 bar and 400C. It expands isentropic ally until it is just dry-saturated. Then it is reheated to 350C at constant pressure and expanded in the second-stage turbine to the condenser pressure of 0.2 bar. If the isentropic efficiency of the second stage is 78%. Calculate the specific steam consumption and the thermal efficiency. Determine the pressure in reheater also to solve the whole problem
Air enters the compressor of an ideal Brayton refrigeration cycle at 100 kPa, 270 K. The compressor pressure ratio is 3 and the temperature at the turbine inlet is 310 K. Determine:The above Brayton refrigeration cycle is modified by introducing a regenerative heat exchanger. In the modified cycle, the compressed air enters the regenerative heat exchanger at 310 K and is cooled to 280 K before entering the turbine. Determine for the modified cycle:f).the net work input per unit mass of air flow, in kJ / kg. g).the cooling capacity, per unit mass of air flow, in kJ / kg.h).the coefficient of performance.
Superheated steam at a pressure of 300 bar and a temperature of 550 ℃ enters a turbine made up of two stages. Steam exits the first stage of the turbine at 35 bar and gets reheated at a constant pressure at 550 ℃. Each stage of the turbine has an isentropic efficiency of 80%. The isentropic efficiency of the pump is 85%. The pressure of the condenser is 10 kPa. (a) Sketch the cycle in a T-s diagram and calculate the enthalpy at each point of the cycle. (b) Calculate the flow rate of the working fluid if the power output of the turbine is 100 MW. (c) Calculate the thermal efficiency of the cycle. (d) Double check the result for the heat rejected in the condenser.
(1) Steam generated in a Rankine steam power cycle at 80 bar and 600°C is fed to a turbine. Exhaust from the turbine enters a condenser at 100 kPa, where it is condensed to saturated liquid which is then pumped to a boiler. C. d. If the Rankine cycle produces 100 MW of power, what is the mass flow rate of steam in kg/s? If the isentropic efficiency of the turbine and compressor are 75%, recalculate the mass flow rate of steam in kg/s.
The production well of a typical geothermal power plant is at 230°C saturated liquid and ground water flow rate of 230kg/s with separator pressure of 0.5MPaa while its condenser pressure is at 0.01MPa. the turbine and generator efficiencies are 83% and 87% , respectively. Sketch the T-s diagram of the system. Determine the amount of mass flowing into the reinjection well from the separator, generator output, heat rejection in the condenser and overall plant efficiency.