Week 11: Project 2 - Emission characterization on a CAT3410 engine

Emission characteristic Analysis On Diesel Engine with open-w and Omega shape piston

Introduction

Diesel engines are more efficient than gasoline engines for two reasons: (i) higher cylinder pressure and corresponding higher temperatures lead to improved thermal efficiency for the diesel engine; (ii) the air throttling required to control the gasoline engine power output reduces engine efficiency and is not used on diesel engines. Truck drivers and farmers are very aware of the reduced fuel costs associated with running a diesel engine as compared to a gasoline engine. The trucks and tractors include an extended range of gear ratios so the diesel engine operates at nearly optimum RPM (Rounds Per Minute) as the load changes.

Step 1 INTAKE (DOWN) STROKE 1

The piston moves down drawing air into the cylinder

Step 2 COMPRESSION (UP) STROKE 1

• The piston moves up compressing the newly drawn air in the cylinder
• Before the piston reaches top-dead-center (TDC), diesel fuel is injected directly into the cylinder
• This result is the combustion of diesel fuel

STEP 3 INTAKE STROKE (DOWN) 2

The piston draws down but the intake and exhaust valves are not open

STEP 4 COMPRESSION STOKE (UP) 2

The piston moves up forcing the combusted diesel fuel out of the cylinder in the form of exhaust

A diesel engine offers an efficient method to produce power. It relies on compression for combustion, which results in increased fuel efficiency compared to other types of engines

In the direct injection engine, the air movement takes the form of a swirl about the cylinder axis, which is generated during the induction stroke by a suitable design of the inlet port. The rate of swirl increases during the later part of the compression stroke as the rotating mass of air above the piston moves into the smaller diameter cavity. The principle of conservation of angular momentum suggests that the swirl rate will increase in proportion to the square of the ratio of the two diameters although, as will be, there are a number of complicating factors. At the end of the compression stroke, the airflow pattern is also strongly influenced by a radial movement, known as squish. At TDC the gap between the cylinder head and the piston crown (the “bumping clearance”) is very small. As the piston rises, the air trapped above its surface is forced inwards into the cavity; this squish interacts with the swirl to produce considerable turbulence. In order to increase the swirl, the piston cavity is deeper and of a smaller diameter than that of a quiescent chamber engine.

Emission

Diesel emissions include also pollutants that can have adverse health and/or environmental effects. Most of these pollutants originate from various non-ideal processes during combustion, such as incomplete combustion of fuel, reactions between mixture components under high temperature and pressure, combustion of engine lubricating oil and oil additives as well as combustion of non-hydrocarbon components of diesel fuel, such as sulfur compounds and fuel additives. Common pollutants include unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx) or particulate matter (PM).

From the government restriction according to BS standard and EURO standard which is an update norm to reduce the pollutant. Engineers and scientists are working on various methods after combustion like the catalytic converter, changing the injection methods, Design changes etc to find the best solution for pollution reduction

Design Analysis

Our analysis is done on open-w and omega profiles to find the performance and emission characteristics in converging CFD

For system, power Demand it is better to analyze section view of the cylinder from the entire 360 models because mathematically it solves radially.

Geometry

Model Creation using profiles

Tools-Make engine sector surface by giving details Bore=0.13716 m, store= 0.1651 m, connection rod= 0.263 m, compression ratio= 17.5 we can extract the section surface for analysis, 45 degree of model extraction by section angle option

Open-w

Extraction Part Geometry

Omega

Extraction Part Geometry

Boundary Condition

Application type		crank angle-based IC Engine
Physical Parameter
cylinder bore	0.13716	m
stroke (2*crank radius)	0.1651	m
crank speed	1600	RPM
Reference
piston surface ID	Piston
Liner ID	cylinder wall
Head ID	cylinder head

Materials
Gas Simulation
import therm.dat
Parcel simulation
Predefined liquids from that select DIESEL2
Reaction Mechanism
Select mech.data file and check the property loaded
species
parcel	Query available list to select Diesel 2

Simulation Parameters
Run parameters
solver	Transient
temporal type	crank angle-based Engie simulation
simulation mode	full hydrodynamic
Gas flow solver	compressible
Liquid flow simulation	Incompressible
Simulation parameter
start time	-147	degree
End time	135	degree
initial time-step	5.00E-07	s
Minimum time-step	1.00E-08	s
Maximum time step	2.50E-05	s
Solver parameter
Navier-strokes solver scheme		PISO

Boundary Conditions

Piston

Boundary Type- wall

wall motion type- translating

Surface movement- moving- Law of wall- piston motion

Temperature- law of wall- 553 k

Front_face

Boundary Type- Periodic

Periodic Type- stationary

Periodic shape- Rotational

Angle- 45

Back_face

Boundary Type- Periodic

Cylinder_wall

Boundary Type- Wall

wall motion type- stationary

surface movement- Fixed- law of wall

Temperature- law of wall- 433 k

Cylinder_head

wall motion type- stationary

surface movement- Fixed- law of wall

Temperature- law of wall- 523 k

Initial Conditions and Events

From stoichiometric balance

`C_xH_y+a(O_2+3.76N_2)rarr xCO_2+(y/2)H_2O+3.76aN_2`

`a=x+y/4`

from this extraction product

`C_7H_16+11(O_2+3.76N_2)rarr7CO_2+8H_2O+41.36N_2`

convert molar fraction to input data

Region name- In_cylinder_region

Region
In cylinder region
Temperature	355	k
Pressure	197000	pa
Species
CO2	0.0014304
H2O	0.0006296
N2	0.76765
O2	0.23029
Total	1
Passive
Hiroy soot	0
Nox	0

Physical Model

switch on spray modeling, combustion modeling emissions modeling, Turbulent

Spray modeling

General

Injectors

Initial data setup from 'Injector_0'

DIESEL2: interpolated density for 341 (K) is 848 (kg/m^3)

Sources updating: No changes detected. Skipped.

********************************

Inj dur_inject = 21 (CA)

Inj dur_inject = 2.1875 (ms)

Peak Injection Pressure = 1097.05 (bar)

Peak Injection Velocity Old = 356.064 (m/s)

Peak Injection Velocity New = 471.45 (m/s)

Spray Rate output graph

Injector configuration

Nozzle position

Nozzle diameter-0.000259

spray cone angle-9 degree

circular injection radius-0.0001295

spray

Injection Rate shape

Profile rate shape plot

injection profile important

Time/Temp/Mass

Fuel Calculation
RPM	1600
Fuel mass per cycle	2.70E-05
RPS	26.6666667
DPS	9600
Time per Degree	1.04E-04
Time per 720 Degree	7.50E-02
Fuel flow rate	3.60E-04

Combustion

Timing starting time=-10 deg, end time=135 deg

Combustion- Models

Combustion- Models-emission

on-Nox model-Thermal Nox model (Extended Zeldovich)

on-Hiroyasu-NSC soot model

Turbulence

RANS-RNG-`k-epsi`

Grid Controls

Base grid

dx,dy,dz-0.004 m

AMG

velocity & Temperature for an accurate result by finer mesh in setup output data

maximum cells:2000000

Releasing Frequency:25

Velocity

Embedded type; SGS

max embedded level- 2

sub-grid criteria - 2 m/s

checking Time scale Data

timing control - permanent

use AMR when parcel count exceed-50

Temperature

Embedded type; SGS

max embedded level- 2

sub-grid criteria - 5 k

timing control - Sequential

start=-12 degree

end=180 degree

Fixed Embedding

Embedding1

for nozzle

mode-sequential

scale=2

start time=-12 degree

End time=15 degree

Radius1=0.001

Radius2=0.003

Legth=0.01

Embedding2

piston

mode-sequential

scale=1

embedded layer=1

start time=-20 degree

End time=180 degree

Embedding3

cylinder head

mode-sequential

scale=1

embedded layer=1

start time=-20 degree

End time=180 degree

checking Time mapping

Simulation Output

openw

Omega

openw took 8166.34 sec to complete the analysis is power-consuming compared to omega.

Mesh

at time step 70 combustion starts where properties are changes -9 degree onwards

variable time step

openw

omega

Contours

openw

Fuel

H2O

Pressure

Temperature

velocity

Emission

CO

Co2

NOx

omega

fuel

H2O

Pressure

Emission

Co

Co2

Nox

Graphs

a comparison study on both openw and omega Design for all functional properties with respect to crank angle

Fuel vs Crank angle

Suction -150 to -50 degree

combustion start -50 degree to 15 degree

power -9 to 29

exhaust stroke 40 to 120 degree

fuel start injecting -9 to 21 degree where due to design peak fuel (C7H16) which is 2.2e-6 kg penetrated in omega profile piston

Temperature Vs Crank angle

The temperature took maximum at

1490k @ 25 degrees for openw piston

1650k @ 25 degrees for omega piston

design by comparing omega piston engine has a maximum peak temperature

Pressure Vs Crank angle

maximum 10.8MPA pressure @ 15 degrees for openw

maximum 11.8MPA pressure @ 15 degrees for omega

by comparing both designs which is omega piston give maximum pressure

Cell count Vs Crank angle

Due to AMT from 0 degrees to 45 degrees, gradually cell count increases at peak temperature and pressure at 50 degrees mesh size increase to capture physics open w took high cell count fluctuation and system power compared to omega

Volume vs crank angle

Co2 Vs Crank angel

-9 degrees onward there is CO2 increases gradually at a peak temperature condition after combustion omega release Co2 at 8.2e-5 kg in omega which is high

Co Vs Crank angel

-9 degrees onwards there is a linear increment in coequally at peak temperature where the end of the combustion omega start releasing least co 2.4e5 kg which defines complete combustion than openw piston

Nox Vs Crank angel

openw piston gives Nox=6.2e-7 kg the least temperature where higher temperature obtain higher Nox formation in fuel so omega complete combustion compare to omega Nox=8e-7kg

Integrated Heat Release Rate vs crank angle

omega release maximum= 1200 J

SOOT vs crank angle

minimum volume omega soot=9.5e-7 kg maximum and release gradually

Engine Performance

Torque

power=(work done/time)

In Engine performance calculator

apply

1. Bore =0.1372 m
2. Stroke = 0.1651 m
3. to get the value of engine performance

RPM	1600
Fuel mass per cycle	1.01E-05
Rotation Per Sec	26.6666667
DegreePerSec	9600
Time per Degree	1.04E-04
Time per 270.278 Degree	2.82E-02

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

power=work/time

Torque

from power `P=(2⋅π⋅N⋅T)/60`

`T=(P*60)/(2⋅π⋅N)`

Open-w

Omega

calculation

open-w

power=work/time

Power=482.152/0.028154

P=17.126kw

from power

`T=(P*60)/(2⋅π⋅N)`

`T=(17126.52*60)/(2*1600*pi)`

`T=102.2623 Nm`

open-w

power=work/time

Power=548.985/0.028154

P=19.4993kw

from power

`T=(P*60)/(2⋅π⋅N)`

`T=(19499.32*60)/(2*1600*pi)`

`T=116.437 Nm`

comparing design

S.no	Description	openw	omega	Difference	units
1	work	482.152	548.985	66.833	Nm
2	Torque	0.102262	0.116437	0.0141747	Nm
3	power	17.12552	19.499317	2.3737935	w
4	IMEP	197533	224913	27380	Mpa
5	CAD10	-0.58974	-0.496318	0.093419	degree
6	CAD50	13.7599	13.78	0.0201	degree
7	CAD 90	52.7499	43.9998	-8.7501	degree
8	IHR_max	1050	1200	150	J

conclusion

where omega has higher Heat releasing rate and maximum function of properties such as temperature, pressure, etc with respect to crank angle.

NOx in the omega engine’s exhaust emission is due to high combustion temperature which reacts with nitrogen in the air supplied for combustion.

CO, CO2 emission is lesser in omega which is describe complete combustion

compare to openw & omega give Power =2.3737935 w more than openw