Project 2 - Rankine cycle Simulator

AIM: Create a Rankine Cycle Simulator using MATLAB.

OBJECTIVE:

• Calculate each state points of the Rankine Cycle (any type of your choice) based on user inputs.
• Plot the corresponding T-s and h-s plots for the given set of inputs.
• Calculate Efficiency.

THEORY:

The Rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work while undergoing a phase change. It is an idealized cycle in which friction losses in each of the four components are neglected. The heat is supplied externally to a closed loop, which usually uses water as the working fluid.While many substances could be used as the working fluid in the Rankine cycle (inorganic or even organic), water is usually the fluid of choice due to its favorable properties, such as its non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties. For example, water has the highest specific heat of any common substance – 4.19 kJ/kg K. Moreover it has very high heat of vaporization, which makes it an effective coolant and medium in thermal power plants and other energy industry. In case of the Rankine cycle, thei ideal gas law almost cannot be used (steam do not follow pV=nRT), therefore all important parameters of water and steam are tabulated in so called “steam tables“.

• Four components of the Rankine cycle:

1. Pump : Compression of the fluid to high pressureusing a pump
2. Boiler : The compressed fluid is heated to the final temperature(which is at boiling point), therefore, a phase changeoccurs from liquid to vapor.
3. Turbine: Expansion of the vapor in the turbine.
4. Condenser: Condensation of the vapor in the condenser (where the waste heatgoes to the final heat sink (the atmosphere or a large body of water.

• Four processes of the Rankine cycle:

1-2: Isentropic Expansion

Turbine (1-2): Superheated steam enters into the Turbine and expands isentropically resulting in the production of work. The shaft of the turbine is connected to the generator. This results in the production of electricity i.e Mechanical energy gets converted into electric energy. Work produced by the turbine, WT = m(hi – h2)K

2-3: Constant Pressure Heat Rejection

Condenser (2-3): The expanded vapour is then passed through a condenser, where it gets condensed and converts into liquid again. This liquid is again pumped to the boiler. Qr = m(h2 - h3)K

3-4: Isentropic Compression by the Pump

Pump (3-4): The water enters into the pump in a saturated state. Then the liquid is compressed isentropically until it meets the boiler pressure. Work done by the pump is, Wp = m(h3 – h4)K

4-1: Constant Pressure Heat Addition

Boiler (4-1): The water enters into the boiler as compressed and leaves as superheated from the boiler. Thus the phase changes from liquid to vapour. The heat supplied by the boiler is

Qb = m(hı – h4)K

Here we take mass flow rate m =1 for this code.

• The efficiency of the Steam Cycle is given by

n = W. WI - Wp Qi Qi

• Applying the Steady Flow Energy Equation (SFEE) to all the process, neglecting the Friction losses and changs in Kinetic & Potential Energy,

QI=hl-h4 @Boiler

Wt=hl-h2 @Turbine

Q2=h2-h3 @Condenser

Wp=h4-h3 @Pump

• The Capacity of the Steam Plant is often expressed interms of Steam Rate (SR) or Specific Steam Consumption (ssc) .

Required Inputs:

Turbine Inlet temperature = 400° C

Turbine Inlet Pressure = 30 bars

Turbine Outlet Pressure = 0.05 bars = Condenser Inlet Pressure

Main code:-