Q3: A steam power plant operates on the reheat regenerative Rankine cycle with a closed feedwater heater. Steam enters the turbine at 12.5 MPa and 550°C at a rate of 24 kg/s and is condensed in the condenser at a pressure of 20 kPa. Steam is reheated at 5 MPa to 550°C. Some steam is extracted from the low-pressure turbine at 1.0 MPa, is completely condensed in the closed feedwater heater, and pumped to 12.5 MPa before it mixes with the feedwater at the same pressure. Assuming an isentropic efficiency of 88 percent for both the turbine and the pump, determine (a) the temperature of the steam at the inlet of the closed feedwater heater, (b) the mass flow rate of the steam extracted from the turbine for the closed feedwater heater, (c) the net power output, and (d) the thermal efficiency.

Q3: A steam power plant operates on the reheat regenerative Rankine cycle with a closed feedwater heater. Steam enters the turbine at 12.5 MPa and 550°C at a rate of 24 kg/s and is condensed in the condenser at a pressure of 20 kPa. Steam is reheated at 5 MPa to 550°C. Some steam is extracted from the low-pressure turbine at 1.0 MPa, is completely condensed in the closed feedwater heater, and pumped to 12.5 MPa before it mixes with the feedwater at the same pressure. Assuming an isentropic efficiency of 88 percent for both the turbine and the pump, determine (a) the temperature of the steam at the inlet of the closed feedwater heater, (b) the mass flow rate of the steam extracted from the turbine for the closed feedwater heater, (c) the net power output, and (d) 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 enters the high-pressure turbine of a steam power plant that operates on the ideal reheat Rankine cycle at 800 psia and 900F and leaves as saturated vapor. Steam is then reheated to 800F before it expands to a pressure of 1 psia. Heat is transferred to the steam in the boiler at a rate of 6 * 104 Btu/s. Steam is cooled in the condenser by the cooling water from a nearby river, which enters the condenser at 45F. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the pressure at which reheating takes place, (b) the net power output and thermal efficiency, and (c) the minimum mass flow rate of the cooling water required.
Scenario (1)The first steam power plant operates on an ideal reheat Rankine cycle. Steam enters the first turbine at 8 MPa and 500 C and leaves at 3 MPa. Steam is then reheated at a constant pressure to 500 C before it expands to 20 kPa in the low-pressure turbine. Assuming that heat is being added to the boiler from a high temperature source at 1800 K and the condenser is transferring heat to a temperature sink at 300 K. Task 1 Investigate the effect of changing turbine efficiency on the overall thermal efficiency of the thermodynamic cycle. (Hint: You will assume different values for the isentropic turbine efficiency such as: 70%, 80%, 90%, 95%, and 100%, then observe how it will change the thermal efficiency of the cycle). Representing the results in a plot is recommended.
A steam power plant with a closed feedwater Heater operates on a regenerative Rankine cycle with reheating. Steam enters the turbine at 8 MPa pressure and 5YX C temperature, 1Y kg/s flow rate, and condenses in the condenser at 2X kPa pressure. The intermediate heating is condensing at a pressure of 3 MPa. Intermediate heating is done at a pressure of 3 MPa and the steam is heated to a temperature of 5X0 C. Some steam is separated from the low pressure turbine at a pressure of 1 MPa, after it is completely condensed in the closed feed water heater, it is pumped to a pressure of 8 MPa before mixing with the feed water at the same pressure. Assuming the isentropic efficiencies of the turbines and pumps are 8Y.X%, calculate (a) the temperature of the steam at the inlet of the closed feedwater heater, (b) the mass flow rate of the steam leaving the turbine for the closed feedwater heater, (c) the net power, and (d) the thermal efficiency.note: x=2,y=7
Consider an ideal regenerative steam cycle with an open preheater. Steam enters the turbine at 15MPa and 600°C and is condensed in a pressure condenser 10kPa. Part of the steam is extracted from the turbine at 1.2MPa and enters the open preheater. Determine the fraction of steam extracted and the thermal efficiency of the cycle.
An ideal reheat 210 MW Rankine cycle with water as the working fluid operates the boiler at 15 MPa, the reheater at 2 MPa, and the condenser at 10 kPa. The temperature is 500 0C at the entrance of the high-pressure and low-pressure turbines. Determine (a) the quality of the steam at the low-pressure turbine exit, (b) the thermal efficiency of this system, and (c) the rate of heat transfer in the reheater.
In a steam power plant operating according to the ideal Rankine cycle at 4MPa pressure and 400CIt enters and condenses in the condenser at a pressure of 100kPa. Determine the efficiency of the cycle.What would the efficiency be if the steam entered the turbine at 5MPa pressure and condensed at 90kPa pressure.
Scenario (1)The first steam power plant operates on an ideal reheat Rankine cycle. Steam enters the first turbine at 8 MPa and 500 C and leaves at 3 MPa. Steam is then reheated at a constant pressure to 500 C before it expands to 20 kPa in the low-pressure turbine. Assuming that heat is being added to the boiler from a high temperature source at 1800 K and the condenser is transferring heat to a temperature sink at 300 K. Task 11. Draw a TS diagram showing all the states and processes2. Determine the total work output from the turbines3. Determine the thermal efficiency of the cycle
A steam power plant operates on the Rankine cycle with reheat and has a net power of 120 MW. Steam enters the high pressure turbine at 9 MPa and 600 °C, and the low pressure turbine at 1 MPa and 600 °C; It leaves the condenser as a saturated liquid at a pressure of 10 kPa.a) Show the cycle in the T-s diagram including the saturated liquid and vapor curves.b) The degree of dryness of the steam at the turbine exit.c) The thermal efficiency of the cycled) Determine the mass flow rate of the steam.
In a reheat cycle steam at 15 MPa, 540°C enters the engine and expands to 1.95 MPa. At this point the steam is withdrawn and passed through a reheater. It reenters the engineat 540°C. Expansion now occurs to the condenser pressure of 0.0035 MPa. (a) A 60,000 kw turbine operates between the same state points except that the steam enters the reheater at 1.95 MPa and 260°C, departs at 1.8 MPa and 540°C. The steam flow is 147,000 kg/hr, generator efficiency is 96%. For actual engine, find, ek, mk, and nk, (b) Determine the approximate enthalpy of the exhaust steam if the heat lost through the turbine casing is 2% of the combined work.
Consider a reheat-regenerative vapor power cycle with two feedwater heaters, a closed feedwater heater and an open feedwater heater. Steam enters the first turbine at 8000 kPa and 480oC and expands to 700 kPa. The steam is reheated to 440oC before entering the second turbine, where it expands to the condenser pressure of 8 kPa. Steam is extracted from the first turbine at 2000 kPa and fed to the closed feedwater heater. The feedwater leaves the closed heater at 205oC and 8000 kPa and enters the boiler to complete the cycle. The condensate from the closed feedwater heater is throttled into the open feedwater heater. Steam extracted from the second turbine at 300 kPa is also fed into the open feedwater heater, which operates at 300 kPa. The stream exiting the open feedwater heater is saturated liquid at 300 kPa. The net power output of the cycle is 100 MW. If the working fluid experiences no irreversibilities as it passes through the turbines and pumps, determine: (a) mass flowrate of…
Consider a steam power plant that operates on a reheat Rankine cycle. The plant maintains the boiler at 7 MPa, the reheat section at 1200 kPa, and the condenser at 10 kPa. The mixture quality at the exit of both turbines is 93 percent. Assume the isentropic efficiency for the Pump, high-pressure turbine, and low-pressure turbine as 80%, 75%, and 75%, respectively. Determine the (a) temperature at the inlet of each turbine in kelvin and (b) the cycle thermal efficiency
A steam power plant operates on the reheat Rankine cycle. Steam enters the high-pressure turbine at 12.5 MPa and 550C at a rate of 7.7 kg/s and leaves at 2 MPa. Steam is then reheated at constant pressure to 450C before it expands in the low-pressure turbine. The isentropic efficiencies of the turbine and the pump are 85 percent and 90 percent, respectively. Steam leaves the condenser as a saturated liquid. If the moisture content of the steam at the exit of the turbine is not to exceed 5 percent, determine (a) the condenser pressure, (b) the net power output, and (c) the thermal efficiency.