06 Aug Design a high-efficiency thermal power plant for a specific application.
we can discuss this
Requirements: As much as project needs
EGR 202 – Thermodynamics
Design Project: Design of a Power Plant
Due date: Last day of classes.
Problem Statement:
You are asked to design a high-efficiency thermal power plant for a specific application.
Your design is based on the ideal Rankine cycle (book, chapter 10). You are going to use water as your working fluid. The video presented in class provides you with the basic information on the high and low temperatures and pressures of the working fluid, the maximum possible efficiency (Carnot efficiency), the typical efficiency of high-efficient power plants, hints on how to enhance efficiency, and the basic equipment of a power plant. Here is the link to that video:
Your goal is to maximize the efficiency of the power plant. To achieve this goal, you will change the cycle’s low and high temperatures shown in the video.
Your task for the project is described here:
Problem Definition. Define the problem and the objective of the project in measurable terms
Literature review. Provide the following explanation
Describe the ideal Rankine cycle
Explain what a Rankine cycle is and its main applications
Describe the advantages of Rankine cycles
Describe how to select the appropriate working fluid based on the maximum temperature of the heat source fluid.
The sources for the project are:
The video presented in class (the link is shown right after the first paragraph of this document)
Book, chapter 10. Rankine cycle
At least one paper on power plants using the Rankine cycle
Thermodynamic tables (NIST)
Baseline Design.
Your baseline design should be one similar to that described in the paper you chose or in the video. For this design, show the T-s and P-v diagrams (the professor will show these diagrams in class).
Provide the following information:
Describe the main components of the cycle (pump, evaporator, condenser, etc.)
Describe the ideal Rankine cycle, indicating the states and processes that form the cycle. Present the description in two tables, one indicating the state properties and the other the processes.
Table 1. Description for each of your processes (isothermal, adiabatic, isentropic…)
Table 2. States of the cycle. For each state, indicate the following:
Temperature
Pressure,
Specific volume
Specific enthalpy
Specific entropy
Phase and quality (if applicable)
Present the T-s and P-v diagram
Pressure and temperature of the source and sink fluids
Baseline Calculations: Completely describe your design for the 10 MWe power plant. Show your equations and calculations for the following
Mass flow rates for the working fluid and the cooling water.
Energy balance for each of the devices in the system: condenser, pump, heating system (boiler, superheating, and heating units), turbines.
Heat and work interactions per unit mass
Carnot efficiency of the power plant without the motor and the generator.
Efficiency of the power plant for the baseline alternative and compare it to the Carnot efficiency.
Improved-design Calculations: Modify some of the conditions described in section 3 (for example, the temperature at the condenser or at the boiler) and repeat the calculations in 4. If the efficiency of this modified cycle is higher than that calculated in 4, then choose this alternative as your proposed design.
Repeat all the calculations in 4.
Compare the efficiencies.
Present the T-s and P-v diagrams of your proposed design
Conclusions and Recommendations:
Discuss the best design based on the efficiencies calculated in 5
Environmental considerations
Ways to improve your design
Summarize your learnings from this project
Scoring
Baseline Design
Main Components of the cycle
Isentropic pump
Adiabatic heat exchanger
Isentropic turbine
Adiabatic condenser
Other components include
Electric generator (connected to the turbine)
Motor (connected to the pump)
Furnace (connected to the heat exchanger)
Cooling tower (connected to the condenser)
Degasifier
Description of the Ideal Rankine Cycle
The working fluid is water. The cycle contains an isentropic pump connected to a motor, an adiabatic heat exchanger connected to a furnace, a set of isentropic turbines connected to an electric generator, and an adiabatic condenser connected to a cooling tower.
The Rankine cycle is illustrated in Figures 1 and 2. In these cycles, there are two turbines in series: a high-pressure turbine and a low-pressure turbine. Table 1 describes each process in these figures. Table 2 shows the properties in each of the eight states depicted in the figures.
Figure 1. Temperature-specific entropy schematic of the Rankine cycle. There are three isentropic processes: 1-2, 5-6, and 7-8.
Figure 2. Pressure-specific volume schematic of the Rankine cycle. There are three isobaric processes: 1-5, 6-7, and 8-1.
Table 1. Description for each of the processes in the ideal Rankine cycle.
Table 2. Baseline design. States of the cycle.
Table 3. Properties of the saturated liquid and saturated vapor for State 6
Based on the properties described in Table 6, we calculated the properties for State 6 shown in Table 2. The calculations were:
Quality
Specific volume
Specific enthalpy
Baseline Calculations
Equations
Energy Balance Equation. Steady Flow Processes
Neglecting kinetic and potential energy changes and rearranging
Isentropic Pump (Process 1-2)
For an isentropic pump, . Also, for a pump, . Hence, from Eq. (1):
Or, in terms of work per mass
Adiabatic heat exchanger equation (Processes 2 to 5 and 6-7)
For an adiabatic heat exchanger, .
If the system is the working fluid flowing through the heat exchanger while being heated up, . Hence, Eq. (1) becomes:
Or, for Process 2 to 5,
And, for Process 6 to 7,
So, the total heat rate to the heat exchanger is
Or, in terms of heat per mass
Isentropic Turbine (Processes 5-6 and 7-8)
For an isentropic turbine, . Also, for a turbine, . Hence, from Eq. (1):
Or, for Process 5 to 6,
Or, for Process 7 to 8,
So, the total power produced by the two turbines is
Or, in terms of heat per mass
Adiabatic Condenser equation (Process 8 to 1)
For an adiabatic heat exchanger, .
If the system is the working fluid flowing through the condenser while being condensed, . Hence, Eq. (1) becomes:
Or, for Process 8 to 1,
Or, in terms of heat per mass
Energy Balance for the Rankine cycle
The energy balance of a cycle is
Or
Or, in terms of heat per mass
Mass flow rate of the working fluid
From the equation for the efficiency of the electric generator
Solving for the mass flow rate of the working fluid is
Combining these equations
Mass flow rate of the cooling water
From the energy balance of the adiabatic condenser (), with and neglecting kinetic and potential energy changes, we get
Hence,
Mass flow rate of methane
There is a combustion reaction of methane in the furnace. From the energy balance in the heat exchanger, the mass flow rate of methane is
Or
Where is the low-heating value of methane, or the heat released by the combustion of 1 kg of methane.
Efficiency of the Rankine Cycle
The efficiency of the Rankine cycle (without the motor and generator) is given by
Carnot efficiency
The Carnot efficiency for the power plant is given by the following equation
Calculations
Energy Balance
Power produced by the turbines
Mass flow rate working fluid (eq. 8)
Mass flow rate of methane
Mass flow rate of the cooling water
Table. Properties of the cooling water
Calculation of the efficiency
Efficiency of the cycle
Maximum (Carnot) efficiency
Alternative Design
Calculations for the alternative process
