Rankine power generation cycle

A Rankine power generation cycle using steam operates at a temperature of 100 C in the condenser, a pressure of 3.0 MPa in the evaporator, and a ma,ximum temperature of 600°C. Assuming the pump and turbine operate reversibly, plot the cycle on a 7-S diagram for steam, and compute the efficiency of the cycle. 

It is desired to improve the thermal efficiency of the Rankine power generation cycle. Two possibilities have been suggested. One is to increase the evaporator temperature, and the second is to decrease the condenser temperature (and consequently the pressure) of the low-pressure part of the cycle. 

A Rankine power generation cycle is operated with water as the working fluid. It is found that 100 MW. of power is produced in the turbine by 89 kg/s of steam that enters the turbine at 700°C and 5 MPa and leaves at 0.10135 MPa. Saturated liqnid water exits the condenser and is pumped back to 5 MPa and fed to the boiler, which operates isobarically. 

Using a T-S diagram, discuss the effect of subcooling in the condenser and superheating in the evaporator on. the efficiency of a Rankine (or other) power generation cycle. 

In apphcation to electric utihty power generation, MHD is combined with steam (qv) power generation, as shown in Figure 2. The MHD generator is used as a topping unit to the steam bottoming plant. From a thermodynamic point of view, the system is a combined cycle. The MHD generator operates in a Brayton cycle, similar to a gas turbine the steam plant operates in a conventional Rankine cycle (11). 

Power plants based on the Rankine thermodynamic cycle have served the majority of the world s electric power generation needs in the twentieth century. The most common heat sources employed by Rankine cycle power plants are either fossil fuel-fired or nuclear steam generators. The former are the most widely used. 

Figure 9-14. Combined Brayton-Rankine Cycle Fuel Cell Power Generation System... 

Another advantage is that the IGCC system generates electricity by both combustion (Brayton cycle) and steam (Rankine cycle) turbines. The inclusion of the Brayton topping cycle improves efficiency compared to a conventional power plant s Rankine cycle-only generating wstem. Typically about two-thirds of the power generated comes from the Brayton cycle and one-third from the Rankine cycle. 

In a Rankine power plant, the steam temperature and pressure at the turbine inlet are 1000°F and 2000 psia. The temperature of the condensing steam in the condenser is maintained at 60° F. The power generated by the turbine is 30,000 hp. Assuming all processes to be ideal, determine (1) the pump power required (hp), (2) the mass flow rate, (3) the heat transfer added in the boiler (Btu/hr), (4) the heat transfer removed from the condenser (Btu/hr), and (5) the cycle thermal efficiency (%). 

Rankine Cycle. The sleam-Rankine cycle employing steam turbines has been the mainstay of utility thermal electric power generation for many years. The cycle, as developed over the years, is sophisticated and efficient. The equipment is dependable and readily available. A typical cycle (Fig. 21) uses superheat, reheat, and regeneration. Heat exchange between flue gas and inlet air adds several percentage points to boiler efficiency in fossil-fueled plants. Modern steam Rankine systems operate at a cycle top temperature of about 800 K with efficiencies of about 40%. All characteristics of this cycle are well suited to use in solar plants. 

Power generation using steam or gas turbines is now well established, however power recovery by the pressure reduction of process fluids is more difficult and less common. In general, the equipment is not considered to be particularly reliable. Rankine cycle heat engines have been developed/adapted to use relatively low-grade waste-heat sources (particularly from organic fluids) to generate power in the form of electricity or direct drives. They tend to be used when the heat source... 

The United States derived about 20 percent of its electricity from nuclear energy in 2002 (EIA, Electric Power Monthly, 2003). The 103 power reactors operating today have a total capacity of nearly 100 gigawatts electric (GWe) and constitute about 13 percent of the installed U.S. electric generation capacity. The current U.S. plants use water as the coolant and neutron moderator (hence called light-water reactors, or LWRs) and rely on the steam Rankine cycle as the thermal-to-electrical power conversion cycle. Other countries use other technologies—notably C02-cooled reactors in the United Kingdom and heavy-water-cooled reactors (HWRs) in Canada and India. 

Example 4.14 Actual reheat Rankine cycle in steam power generation A reheat Rankine cycle is used in a steam power plant (see Figure 4.20). Steam enters the high-pressure turbine at 9000kPa and 823.15K and leaves at 4350kPa. The steam is reheated at constant pressure to 823.15 K. The steam enters the low-pressure turbine at 4350kPa and 823.15K. The discharged steam from the low-pressure turbine is at lOkPa. The net power output of the turbine is 65 MW. The isentropic turbine efficiency is 80%. The pump efficiency is 95%. Determine ... 

The Rankine cycle forms the basis of power generation from nearly all current coal-fired power stations. The... 

Frechette LG, Lee C, Arslan S, Liu YC (2003) Design of a microfabricated Rankine cycle steam turbine for power generation. In Proceedings of the ASME international mechanical engineering congress, Washington, DC, 16-21 Nov 2003... 

Microturbines, pumps, and compressors are key components used to implement thermodynamic cycles for power generation, propulsion, or cooling. Thermodynamic power cycles use a working fluid that changes state (pressure and temperature) in order to convert heat into mechanical work. To achieve high power density, the pressures and temperatures of the fluid in the cycle should be kept to the high levels common at large scale. Common cycles are the Brayton gas power cycle and the Rankine vapor power cycle, described next. 

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