Week 10: Project 1 - FULL HYDRO case set up (PFI)

Introduction

PFI engine mixing fuel with air in the carburetor before it entered the combustion chamber was still the main technology being used in gasoline vehicles

PFI engines use a three-way catalytic converter, exhaust sensors, and computer-controlled engine management to constantly adjust the fuel-to-air ratio injected into each cylinder

CI8H18 is fuel is almost equal to gasoline fuel

Converge Setup

Engine Geometric Parameters

Parcel simulation

Species

Define

Boundary conditions

Piston temperature - 450K

Liner temperature - 450K

Head temperature - 450K

Spark Plug temperature - 550K

Spark Plug electrode temperature - 600K

Exhaust ports temperature - 500K

Exhaust outflow - 1 bar

Exhaust outflow temperature - 800k

Exhaust species concentration

Stoichiometric calculation
Species	moles	MW(g/mol)	Mass	Mass Fraction
Co2	8	44.01	352.08	0.192304
H2O	9	18.01528	162.1375	0.088559
N2	47	28.0134	1316.63	0.719137
Total			1830.847	1

Exhaust valve top temperature - 525K

Exhaust valve angle temperature - 525K

Exhaust valve bottom temperature - 525K

Intake port - 1 temperature 425K

Intake port - 2 temperature 425K

Inflow pressure - 1 bar total pressure

Inflow temperature - 363K

Inflow species - Air

Intake valve top temperature - 480K

Intake valve angle temperature - 480K

Intake valve bottom temperature - 480K

Region & Initialization

• Cylinder
  • Pressure - 1.85731 bar
  • Temperature - 1360K
  • Stoichiometric composition

• Intake port - 1 (closer to combustion chamber)
  • ic8h18 - 0.025508
  • o2 - 0.20157
  • n2 - 0.77292
  • Temperature - 390k
  • pressure - 1 bar
• Intake port - 2 (away from combustion chamber)
  • Air
  • Temperature - 370K
  • Pressure - 1 bar

• Exhaust
  
  • Pressure - 1.85731 bar
  • Temperature - 1360K
  • Stoichiometric composition

Case setup

Injection Parameters

Time & Temperature

1. Fuel flow rate = 7.5e-4 Kg/second
2. Injection start time = -480.0
3. Injection duration = 191.2
4. Fuel temperature = 330K

Spark Ignition Parameters

• Start of spark = -15 deg
• Spark duration = 10 deg
• Spark location = -0.003 0 0.0091
• Spark radius = 0.0005m

spray model

Profile

Spray Plot analysis

Extracting values

Nozzle positions and parameters

Nozzle diameter = 250 micro-meter

Circular injection radius = Nozzle radius

Spray cone angle = 10

• Nozzle 0
  • center 0.0823357 0.00100001 0.07019
  • Align Vector -0.732501 0.210489 -0.647408
• Nozzle 1
  • center 0.0823357 -0.00099999 0.07019
  • Align Vector -0.732501 -0.210489 -0.647408
• Nozzle 2
  • center 0.0823357 -0.0004 0.07019
  • Align Vector -0.5 -0.2 -0.647408
• Nozzle 3
  • center 0.0823357 0.0003 0.07019
  • Align Vector -0.5 0.2 -0.647408

Combustion modeling

models

Embedded Setup

for refinement embedded in spark plug, cylinder, injector

AMG Time scale

which clearly shows AMG Timing at the combustion stage

Adaptive Mesh

Adaptive mesh assign for both velocity and temperature value for better result output

SOURCE SETUP

2. Why do we need a wall heat transfer model? Why can't we predict the wall temperature from the CFD simulation

actually, we are giving a guess value for the initial state (p*) for boundaries from the combustion the initial value will change to combustion wall heat transfer model if it is not the result will not be realistic this clearly state Conjugated Heat Transfer Model (CHT) this wall heat transfer result from different Boundaryues are studied and manipulate for engine life (i.e- for cooling of the engine like a radiator)

Result

Conversion of result

Working mode setup output

Section view

above clearly define the region and refinement near sparkplug & AMG refinement

Graphs

Pressure

maximum pressure at approximately at 30 degrees P=3.85MPA

Temperature

maximum Temperature 2500 k at 30 degree

Heat Release Rate

maximum heat release Rate 59 J/s with a 30degree crank angle

Mass Of Fuel

fuel spray starts at-530 degrees to -100 degrees where peak fuel spray at -440 degrees

CO2

o to 30-degree combustion start there is a sudden increase in Co2 and reducing after cmbustion

engine performance Calculation

Formula

Compression ratio

Compression ratio= maximum volume/ minimum volume

Volume vs Crank angle

from graph extracted

V_min=5.754e-5 m3
V_max=0.000574215 m3

combustion efficiency

Integrated Heat release Rate

`eta=`Total Heat Release rate/ Total energy of fuel

The Total Heat Release rate is calculated from the graph in maximum Integrated Heat Release

max_IHR=1241 j

Total energy of fuel= mass of fuel*Lower Heat Value (LHV)

LHV=44.78e6 J/kg which is obtained from IC8H18

Torque

power=(work done/time)

In Engine performance calculator

apply

1. Bore =0.086 m
2. Stroke = 0.09 m
3. to get the value of engine performance

Duration of combustion=240.12 deg

combustion timing=5.55e-5 s
from that, we can calculate the power

Torque

from power `P=(2*pi*N*T)/60`

`T=(P*60)/(2*pi*N)`

Python

""" 
Engine Performance calculation 
Program by Jagaveerapandiyan
"""
import numpy as np
#min & max volume
V_min=5.754e-5
V_max=0.000574215

#compression ratio
r=V_max/V_min
print('Compression_ratio=',r)

#Engine efficiency
max_IHR=1241 #j
#IC8H18
LHV=44.78e6 #J/kg
#mass of fuel
mf=3e-5 #kg
#Total energy of fuel
TF=mf*LHV
print('Total energy of fuel=',TF,'j')

#combustion efficiency
c_eff=(max_IHR/TF)*100
print('combustion efficiency=',c_eff)

#Torque
N=3000 #rpm
WD=464.646 #Nm
#combustion timing
td=5.55e-5 #s
#Duration of combustion
D=240.12
ct=D*td
#power (workdone/time)
P=WD/ct
print('Power=',P,'W')
#Torque from P=2*pi*N*T/60
T=P*60/(2*np.pi*N)
print('Torque=',T,'Nm')

Values

5. the significance of ca10, ca50, and ca90

CA is the combustion of different percentages (fuel burn)

CAD10 is 10% of combustion at 6.83717 degree

CAD50 is 50% of combustion at 18.4632 degree

CAD90 is 90% of combustion at 31.701 degree

From this, we can easily locate combustion crank angle function properties change in the combustion chamber

Conclusion

The study of the PFI engine has been analyzed and engine characteristics is studied using converge and find out maximum work done= 468.64 Nm at 240.99 with respective Torque is calculated as T=110.98 Nm with 92.37% combustion efficiency