COMBINED CYCLE SIMULATION USING VISUAL BASIC

SUBMITTED BY:ANAND PRAKASH MODI (ME10201)ASHOK KUMAR DHAKAR (ME10205)RAJESH KUMAR MEENA (ME10236)

Under the guidance of Dr. M. UDAYA KUMARHead of Department,Department of Mechanical Engineering

OBJECTIVE:

1. To find out combined cycle efficiency as well as individual cycles.2. To find out effects of various parameters on combined cycle efficiency.3. To find out the parameters operating range .4. To develop a Graphical User Interface using visual basic to communicate with the user input parameters .

INTRODUCTION:

Combined cycle analysis can be divided into individual cycle analysis and then combining both the cycles together.

Analysis of Brayton and Steam Rankine cycles individually.

Combined cycle simulation using simulator (developed in visual basic )

BRAYTON CYCLE ANALYSIS

Process details:

1-2 Isentropic compression (in a compressor)

2-3 Constant pressure heat addition 3-4 Isentropic expansion (in a

turbine) 4-1 Constant pressure heat rejection

Compressor and Turbine Efficiencies

RANKINE CYCLE ANALYIS:

COMBINED CYCLE ANALYIS: 1-2 Isentropic compression 2-3 Constant pressure heat addition 3-4 Isentropic expansion (Gas turbine) 4-1 Constant pressure heat rejection 5-6 Isentropic compression in pump 6-7 Waste Heat utilization (Heat rejected by

Brayton cycle 4-1) 7-8 Isentropic expansion (steam turbine) 8-1 Constant pressure heat rejection

(condenser)

COMBINED CYCLE ANALYIS:

1-2 Isentropic compression2-3 Constant pressure heat addition 3-4 Isentropic expansion (Gas turbine)4-1 Constant pressure heat rejection5-6 Isentropic compression in pump6-7 Waste Heat utilization (Heat rejected by Brayton cycle 4-1)7-8 Isentropic expansion (steam turbine)8-1 Constant pressure Heat rejection (condenser)

SIMULATION OF INDIVIDUAL AS WELL AS COMBINED CYCLE

To analyze rankine cycle a steam property calculator has been designed by using IF- 97 (IAPWS ) standard equations

All the process efficiency has been taken into account.

SIMULATION FLOW CHART

SIMULATOR DETAILS:

The outlook of the simulator is shown in next image.

It has GUI environment. To start an analysis go to sub menu

by line by line.

STEAM PROPERTY CALCULATOR

SIMULATION RESULTS:Notations used in simulation: m1= mass flow rate in brayton cycle m2= mass flow rate in rankine cycle xsb=m1/m2 T4b =the lowest temperature upto which

we can utilize waste heat Combined cycle efficiency= (m1*(h3-

h4+h1-h2)+m2*(h7-h8+h5+h6))/(m1*(h3-h2))

Rankine cycle analysis (Individually) Input parameters: T-s plot : Ideal Case: p5=.1 MPa p6=10 Mpa Heat Added =3000KJ/Kg Pump Efficiency=100% Steam Turbine Efficiency =100%

Rankine cycle output and T –s plot

Rankine cycle parameters effect on cycle efficiency

BRAYTON CYCLE ANALYIS :

For non ideal case: Input parameters: Pressure ratio=10 Compressor efficiency =85% Combustor efficiency=90% Turbine efficiency= 87% T3=1000K

T-s plot

COMBINED CYCLE ANALYSIS: Case 1 : Ideal Case p1=.1 MPa rp=10 T1=300 K T3=1000 K Condenser pressure(p5) =.1 MPa Boiler pressure(p6) =10MPa All process efficiency are 100% Mass flow rate (Brayton ) m1 =25 kg/s Mass flow rate (Rankine ) m2 =1 kg/s xsb=m1/m2 T4b=350 k

Output:

Parameters effect on combined cycle efficiency:ideal case

CONCLUSION:

The simulator gives results very close to the manual calculations .

The steam property calculator has less than .5% error so it can be used in all other application where ever it is required.

The parameters of combined cycle are optimized using the simulator

FUTURE SCOPE: This simulator can be extended to triple

cycle and hence its parameters can be optimized

In brayton cycle the effect of multistage compression with intercooler and regeneration can be analyzed.

In rankine cycle the effect of feed waters and reheat and sub cooling and regeneration can be analyzed .

THANK YOU