AN EXPERIMENTAL INVESTIGATION ON ENGINE PERFORMANCE … · AN EXPERIMENTAL INVESTIGATION ON ENGINE...

http://www.iaeme.com/IJMETasp 132 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET)

Volume 6, Issue 11, Nov 2015, pp. 132-144, Article ID: IJMET_06_11_016

Available online at

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=6&IType=11

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication

AN EXPERIMENTAL INVESTIGATION ON

ENGINE PERFORMANCE OF A LOW HEAT

REJECTION (MULLITE COATED) SINGLE

CYLINDER DIESEL ENGINE WITH AND

WITHOUT TURBOCHARGER

Parvezalam Shaikh and S.P. Yeole

Department of Mechanical Engineering,

P.R Pote (Patil) Group of Educational Institutions, Amravati, India

ABSTRACT

In Present Investigation at the first stage, experiments were conducted on

baseline (Conventional) engine and hence combustion and emission

Parameters were recorded. At second stage Mullite, which is a compound of

SiO2 and Al2O3 with composition 3Al2O3.2SiO2 (Aluminium oxide 60% and

Silicon dioxide 40%), was used as a (TBC) thermal barrier coating material.

The piston crown, cylinder valves and cylinder head of diesel engine were

coated with a 0.5 mm thickness of 3Al2O3.2SiO2 (mullite) over a 150-µm

thickness of Nickel Chrome Aluminium Yttrium (NiCrAlY) bond coat using

plasma spray technique to achieve less heat loss and combustion and emission

Parameters were recorded for LHR engine. The operational parameters i.e.

air-fuel ratio and engine speed conditions were maintained constant for both

conventional as well as Low Heat rejection engines. In Third stage, the

experiments were conducted on turbocharged low heat rejection (LHR) single

cylinder diesel engine with advanced injection timing. The main objective of

the study was to evaluate combustion parameters and overall engine

performance of these engines. The experiments were carried out for various

loads via. 0%, 25%, 50%, 75% and maximum loads, then the results were

compared. The evaluation of experimental data showed that the brake thermal

efficiency and brake power values of Low heat rejection (LHR) engine were

slightly higher than that of conventional diesel engine. It was also found that

heat lost to coolant is reduced and there is increase in energy of exhaust gases

for Low heat rejection (LHR) engine when compared with the conventional

single cylinder diesel engine. Emission characteristics such as NOx are

increased and there is decrease in HC and CO in case of LHR Engine when

compared with conventional engine. Whereas Low heat rejection (LHR)

engine with turbocharger showed deterioration in the engine performance

when compared with Low heat rejection (LHR) diesel engine without

turbocharger.


http://www.iaeme.com/IJMET.asp 133 [email protected]

Keywords: Baseline Engine, LHR, Mullite, TBC, Turbocharger.

Cite this Article: Parvezalam Shaikh and S.P. Yeole. An Experimental

Investigation on Engine Performance of A Low Heat Rejection (Mullite

Coated) Single Cylinder Diesel Engine with and without Turbocharger,

International Journal of Mechanical Engineering and Technology, 6(11),

2015, pp. 132-144.

http://www.iaeme.com/currentissue.asp?JType=IJMET&VType=6&IType=11

1. INTRODUCTION

Because of increasing requirements of governments and customers, car manufacturers

and researchers are always trying to reduce fuel consumption while maintaining the

best engine performance. The insulation of the combustion chamber surfaces strongly

influences the performance and exhaust emissions of direct injection diesel engines.

Thermal barrier coatings (TBCs) have been a topic of great scientific interest

worldwide for several decades. They have been used for engine components, in

turbines and aircraft engines in order to achieve improved engine performance and

fuel efficiency by increasing the actual temperature of engine operation.

In the present investigation, Mullite, which is a compound of SiO2 and Al2O3 with

composition 3Al2O3.2SiO2 (Al2O3= 60%, SiO2= 40%), is used as a thermal barrier

coating material for single cylinder diesel engine. Mullite is an important ceramic

material because of its low density, high thermal stability, stability in severe chemical

environments, low thermal conductivity and favorable strength and creep behavior. It

is a compound of SiO2 and Al2O3 with composition 3Al2O3.2SiO2. Compared with

YSZ, mullite has a much lower thermal expansion coefficient and higher thermal

conductivity, and is much more oxygen-resistant than YSZ. Yttria-stabilized zirconia

(YSZ) has emerged as the preferred TBC material due to its low thermal conductivity

(~1 W/mK) over a range of temperatures. The ceramic, mullite, though, has the

advantage of having reduced thermally activated time-dependent behavior compared

to YSZ [1]

. Diesel engine rig tests performed in the past have demonstrated that

mullite coatings on pistons experienced decreased surface cracking and increased life

compared to YSZ coatings on pistons [2]

. For the applications such as diesel engines

where the surface temperatures are lower than those encountered in gas turbines and

where the temperature variations across the coating are large, mullite is an excellent

alternative to zirconia as a TBC material. Life of Mullite coating is more than the

zirconia coating tested under same condition. Mullite is most promising coating

material for the SiC substrate because their thermal expansion coefficients are similar.

The objective of this investigation have been also to evaluate the effect of thin

mullite coating on engine exhaust emissions for both the LHR and conventionally

cooled diesel engines.

In the present research work, the concept of an adiabatic turbo compound diesel

engine has been introduced. The pulse turbocharger (suits to the specification of given

diesel engine), which utilized the kinetic energy of exhaust gases of low heat rejection

(LHR) diesel engine, has been used for experimentation. The objective of this

investigation has been to study the effect of pulse turbocharger on the engine

performance parameters of low heat rejection (LHR) diesel engine. The thermal

barrier coatings (TBCs) enable to lower temperature (Fig.2.1) (at approx. 170°C) of

operating elements, exposed to creeping, in a hot section of gas turbine (e. g.

combustion chambers and directing and rotating blades) to a range, which enables to

operate for a long time in conditions of high temperature influence and prolongs

http://www.iaeme.com/currentissue.asp?JType=IJMET&VType=6&IType=7

An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite

Coated) Single Cylinder Diesel Engine with and without Turbocharger


operation of them even three or four times, simultaneously reducing consumption of

fuel [3]

.

In an experimental study performed by A. Gilbert et al [4]

, the thermal shock

behavior of three coating architectures, (i) monolithic YSZ, (ii) monolithic mullite

and (iii) a YSZ–mullite composite with 40% YSZ and 60% mullite by volume, was

compared. All three coatings had a nominal thickness of 1 mm. It was found that at

similar surface temperatures, the YSZ coatings developed the longest surface and

horizontal cracks while the mullite coatings developed the shortest cracks.

A major breakthrough in diesel engine technology has been achieved by the

pioneering work done by Kamo and Bryzik [5-6]

. As a result of their pioneering efforts

in the area of adiabatic engine technology, many governments, industries and

academic sources worldwide have begun to work in this area. An improvement of 7%

in the performance was observed [6]

.

Hejwowski and Weronski [7]

showed that brake specific fuel consumption (BSFC)

was 15–20 per cent lower in the LHR engine. A significant improvement in engine

performance was found at high engine speeds, power was increased by 8 per cent and

brake torque by 6 per cent. Exhaust gas temperature was found to be 200 K higher

than in an engine with metal pistons.

The investigation undertaken by R.H. Thring [8]

using ceramic coated single-

cylinder DI diesel engine reported improvement in fuel economy of about 7 % in

Turbocharged (TC) engine and about 15 % in Turbocompounded (TCO) engine. It

also reported 80% reduction of smoke and 50% reduction of HC and CO emissions,

but NOx emissions increased by 15%.

2. EXPERIMENTAL SETUP

A four stroke, direct injected, water-cooled, single cylinder, naturally aspirated diesel

engine was used for investigation. Details of the engine specifications are given in

Table 1.

Table 1 Engine specifications

Engine type Kirloskar AV1, DI

Stroke number 4

Cylinder number 1

Stroke (mm) 110

Compression ratio 16.5:1

Maximum engine power (KW) 3.7

Maximum engine speed (rpm) 1500

Specific fuel consumption (g/Kwh) 245



Figure 1 Experimental Set up

The first stage tests were performed at different engine loads for conventional

engine. The experiments were conducted at five load levels, viz. 0, 25, 50, 75% of full

load and full load. The required engine load percentage was adjusted by using the

eddy current dynamometer. At each of these loads, engine performance and

combustion characteristics were recorded.

The second stage tests were conducted on engine when combustion chamber

insulation was applied. A piston crown, cylinder head and valves were coated with

ceramic material over super alloy bond coating (NiCrAlY). The bond coat was first

applied to these engine components to avoid mismatch in thermal expansion between

substrate and ceramic material. A piston crown, cylinder head and valves were coated

with 0.5 mm coating of Mullite is commonly denoted as 3Al2O3 .2SiO2 (i.e. 60

mol% Al2O3). The ceramic material was coated by using plasma-spray technique.

The engine was insulated and tested at baseline conditions to see the effect of

insulated surfaces on engine performance and combustion characteristics.

In Third stage, after conducting experiments on LHR (mullite coated) diesel

engine with supercharger, the experiments were conducted on LHR (mullite coated)

diesel engine with turbocharger. The turbocharger was used to utilize the energy of

exhaust gases (which was increased due to mullite coating) of LHR (mullite coated)

diesel engine and to evaluate its effect on the performance of diesel engine. In order to

utilize the exhaust energy (increased due to mullite insulation) of LHR engine, a pulse turbocharger was installed. For LHR engine with turbocharger, the fuel consumption

was increased by advancing injection timing to 320bTDC. The experiments were

carried out on a single cylinder, four stroke, direct injection, low heat rejection (LHR)

diesel engine with and without turbocharger to investigate overall engine

performance.




Figure 1 Photographic view of Mullite coated Engine components.

Figure 3 Photographic view of Pulse Turbocharger

3. RESULTS AND DISCUSSIONS

After conducting long-term experimental investigations on a single cylinder, four

stroke, direct injection, conventional (without coating) and LHR (Low Heat rejection

mullite coated) diesel engines, the engine performance and combustion characteristics

such as brake power, brake thermal efficiency, brake specific fuel consumption,

exhaust gas temperature, NOx, HC, CO for both the Conventional and LHR engines

are evaluated. The engine performance and combustion characteristics are evaluated

for 0%, 25, 50, 75% of full engine load and full engine load condition for both

conventional and LHR diesel engines.



3.1 Comparison of experimental results such as combustion parameters and overall

engine performance characteristics of the conventional (without coating) and LHR

(mullite coated) diesel engines under identical conditions

Fig.4 Engine Load vs. Heat Lost To Coolant

Fig. 4 Shows the comparison of heat lost to the coolant as a function of engine

load for conventional and LHR (mullite coated) diesel engines. It is found that,

mullite coated combustion chamber reduces heat transfer to the coolant. LHR engine

resulted 8.1, 11.3,14.2 and 16% reduction in heat transfer to the coolant for 25, 50,

75% of full engine load and full engine load condition respectively compared to

conventional (without coating) diesel engine. This is due to fact that mullite material

has lower thermal conductivity than metals so that the Heat flow to the coolant will be

reduced which results in higher combustion temperature.

Figure 5 Engine Load vs Brake Power

Fig. 5 Shows the comparison of brake power as a function of engine load for

conventional and LHR (mullite coated) diesel engines. It is found that, the values of

brake power are slightly higher for LHR (mullite coated) engine as compared to

conventional engine. This is due to fact that effect of insulation; the heat free flow is

restricted, which results in reduction in heat transfer in case of LHR engine. The

2

2.5

3

3.5

4

4.5

No Load 1/4 Load 1/2 Load 3/4 Load Full Load

Hea

t to

Co

ola

nt

(Kw

)

Load (Kg)

Load Vs Heat Lost to Coolant

Conventional Engine

LHR Engine

0 0.5

1 1.5

2 2.5

3 3.5

4


Bra

ke

Po

wer

(K

w)

Load (Kg)

Load Vs Brake Power

Conventional Engine




reduction in heat transfer leads to increase in combustion temperature, which results

in better combustion. The higher combustion temperature will lead to more expansion

work. The increase of combustion temperature causes the brake power to increase up

to 8.68 % with LHR engine at full engine load condition compared to conventional

engine.

Figure 6 Engine Load vs Brake Specific Fuel Consumption

A comparison of BSFC for conventional and LHR engine at various loads is as

shown in fig.6 Because of higher surface temperature of combustion chamber of LHR

engine as compared to conventional engine, the BSFC values of LHR engine is less

than those of conventional engine. The improvement in fuel economy observed in

LHR engine may be due to: higher premixed combustion, reduced heat transfer loss,

lower diffused combustion and higher rate of heat release in the main portion of

combustion chamber. It is found that BSFC value is decreased by 7.52 % for LHR

(mullite coated) engine as compared to conventional engine at full engine load.

Figure 7 Engine Load vs. Brake Thermal Efficiency

It is observed from fig. 7 that, the amount of increase in thermal efficiency for

LHR engine is 2.06 % compared to conventional engine at full engine load while at

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8


BS

FC

(K

g/K

wh

r)

Load (Kg)

Load Vs BSFC

Conventional Engine

LHR Engine

0

5

10

15

20

25

30

35


B.T

H. E

FF

. (Ŋ

%)

Load (Kg)

Load Vs B.TH. EFF

Conventional Engine

LHR Engine



low and medium loads thermal efficiency shows less variation for LHR engine when

compared to the conventional engine. This is because that heat recovered by

insulation which is generally lost to the cooling, is converted into useful work

(indicated work). But all the heat recovered by the insulation may or may not be able

to get converted into some useful work. Therefore, the rate of increasing thermal

efficiency for LHR engine is minor compared to conventional engine.

3.2 Comparisons of experimental results such as engine exhaust emissions of the

conventional (without coating) and LHR (mullite coated) diesel engines under

identical conditions

After conducting long-term experimental investigations on a single cylinder, four

stroke, direct injection, conventional (without coating) and LHR (mullite coated)

diesel engines, the engine exhaust emissions such as carbon monoxide (CO),

Nitrogen-oxides (NOx), Unburned hydrocarbons (UHC), and exhaust gas temperature

all as a function of load for both the Conventional and LHR engines are calculated.

The engine exhaust emissions are found for 25%, 50%, 75% of full engine load and

full engine load condition for both conventional and LHR diesel engines.

Fig.8 shows the comparison of NOx variations as a function of engine load for

conventional and LHR engine. It is found that the NOx emission for LHR engine is

more as compared to conventional engine. The NOx emission for LHR engine at full

engine load is 20.19 % higher than conventional engine. The increase of NOx

emission for in the LHR engine may be due increase in after-combustion temperature

due to the mullite coating. This is due to higher combustion temperature and having

longer combustion duration.

Figure 8 Engine Load vs. Nitrogen Oxide (NOx)

Fig.9 shows the comparison of HC emission variations as a function of engine

load for conventional and LHR engines. Hydrocarbon emission is 24.36 % lower in

the Low Heat rejection engine compared to conventional engine. The decrease in

Hydrocarbon emission in the Low Heat rejection (LHR) engine may be due to an

increase in after-combustion temperature as a result of the decrease in heat losses

going to cooling and also outside due to the ceramic coating, creating more unburned

Hydrocarbon (HC) to be added to the combustion. The result clearly shows that the

ceramic coating improves local conditions such as cylinder gas pressure, cylinder gas

temperature, and makes the combustion continuous in diesel engines. The higher

0

1

2

3

4

5

6

7

8


Nit

rog

en O

xid

e (

g/K

wh

r)

Load (Kg)

Engine Load vs Nitrogen Oxide

Conventional Engine

LHR Engine




temperatures in the gases and at the combustion chamber walls of the LHR engine

allows the oxidation reactions to close to completion results in decreasing the

Hydrocarbon (HC) emissions.

Figure 9 Engine Load vs. Unburnt Hydrocarbon

Figure 10 Engine Load vs Carbon Monoxide

Fig.10 shows the comparison of CO emissions variations as a function of engine

load for conventional and LHR engines. Carbon monoxide (CO) emission is 29.41 %

lower in the LHR engine compared with the conventional engine. This is due to the

fact that, because of ceramic coating which bears the thermal barrier property, which results in increase in combustion temperature for LHR engine. The decrease in the

amount of heat rejected to the cooling water system which results in an increase in

combustion temperature. Increase in combustion temperature increases the time for

CO oxidation, which results in decreasing CO emission for LHR engine.

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6 1.8

2


Un

bu

rnt

Hyd

roca

rbo

n (

g/K

wh

r)

Load (Kg)

Engine Load vs Unburnt Hydrocarbon

Conventional Engine

LHR Engine

0

1

2

3

4

5

6

7


Ca

rbo

n M

on

ox

ide

(g/K

wh

r)

Load (Kg)

Engine Load vs Carbon Monoxide

Conventional Engine

LHR Engine



Figure 11 Engine Load vs Exhaust Gas Temperature

Fig. 11 shows variations of exhaust gas temperature against the load of the

conventional and LHR engines. As observed in Fig. Exhaust gas temperature

increases as the load on engine increases for both the engines. This is due fact that the

amount of fuel consumption per unit time increases as the engine load increases, and

Hence, more heat is produced. As a result it leads to increase in exhaust gas

temperature. The increase in exhaust gas temperature in the LHR engine, compared

with the conventional engine is 18.03% higher at full engine load. The increase in

exhaust gas temperature for the LHR engine as compared to the conventional engine

may be due to the decreased heat losses going into the cooling water system and

outside the cylinder due to the coating and hence the transfer of this heat to the

exhaust gas.

3.3 Comparison of experimental results such as overall engine Performance

Characteristics of the LHR engine (mullite coated) with and without turbocharger

Figure 12 Engine Load vs. Brake Specific Fuel Consumption

Fig.12 shows variations of brake specific consumption with load of the LHR

engine with and without turbocharger. It is observed that, brake specific consumption

for LHR engine with Turbocharger increases for low and medium engine loads as

0 50

100 150 200 250 300 350 400 450 500


Ex

ha

ust

ga

s T

emp

era

ture

( ()C

)

Load (Kg)

Engine Load vs Exhaust gas Temperature

Conventional Engine

LHR Engine

0.2

0.3

0.4

0.5

0.6

0.7


BS

FC

(K

g/K

wh

r)

Load (Kg)

Engine Load vs BSFC

LHR Engine without Turbocharger

LHR Engine With Turbocharger




compared with the LHR engine without turbocharger. The increase in brake specific

consumption at low engine load is 2.89 % while the increase in brake specific

consumption at full engine load is 2.10 % for LHR engine with turbocharger

compared with the LHR engine without turbocharger. This is due to fact that the

increase of back pressure on the engine due to turbocharger. As the back pressure

goes on increasing, the engine must work harder to pump the gases out of the cylinder

against the higher pressure. The pressure ratios across the turbocharger compressor

and turbine decrease, reducing the mass flow of air through these components and

thus the air available to the engine. At the same time, the fuel flow to the engine

increases so as to provide the extra power required to overcome the increased

pumping losses while maintaining a brake power output constant. As a result the

brake thermal efficiency decreases and brake specific fuel consumption increases

above that for a LHR engine without Turbocharger. Also it is observed that at low and

medium loads the brake thermal efficiency decreases due to the effect of "turbo lag".

At low and medium engine loads of the engine, the "turbo lag" occurs in exhaust gas

turbocharger because the mechanical power transmitted from the turbine wheel to the

compressor rotor of the exhaust gas turbocharger is at all no longer sufficient for the

engine to increase the pressure in the intake tract of the engine due to the low exhaust

gas volume flow.

Figure 13 Engine Load vs. Heat Lost to Exhaust Gas.

Fig.13 shows variations of exhaust gas energy with load of the Low Heat

Rejection engine with and without turbocharger. The increase in exhaust gas energy is

more at low and medium load levels for LHR engine with Turbocharger as compared

with LHR engine without Turbocharger. The increase in exhaust gas energy is 17.33

% at low engine load while at full engine load the increase in exhaust gas energy is

4.03 % for LHR engine with turbocharger compared with the LHR engine without

turbocharger. This is due to the increase in exhaust gas temperature at low and

medium load levels for LHR engine with Turbocharger. The exhaust gas temperature

at low and medium load levels increases significantly with increasing back pressure

due to the increased power required (to overcome the additional pumping work) and

the reduced air flow.

0

0.5

1

1.5

2

2.5

3

3.5

4


Hea

t lo

st t

o e

xh

au

st g

ase

s (K

w)

Load (Kg)

Engine Load vs Heat Lost to Exhaust gases

LHR Engine without Turbocharger

LHR Engine With Turbocharger



4. CONCLUSION

The main conclusions of these experimental investigations are summarized as

follows.

In case of LHR engine with 0.5 mm of mullite (3Al2O3.2SiO2) insulation coating on

piston crown, cylinder head and valves of diesel engine, observed reduction in heat

transfer to the coolant at all engine load levels compared to conventional diesel

engine.

The amount of heat energy carried with exhaust gases are considerably increased at

all load levels in case of LHR engine with 0.5 mm of mullite (3Al2O3.2SiO2)

insulation coating compared with conventional diesel engine.

LHR engine with 0.5 mm of mullite (3Al2O3.2SiO2) insulation coating on piston crown, cylinder head and valves of diesel engine exhibits lower brake

specific consumption than the conventional diesel engine.

LHR engine with 0.5 mm of mullite (3Al2O3.2SiO2) insulation coating on

piston crown, cylinder head and valves of diesel engine gives marginal rise in

brake thermal efficiency when compared with conventional diesel engine.

The NOx emission for LHR engines with 0.5 mm coating of mullite thermal insulation on combustion chamber is more than conventional engine. It is

observed that the NOx emission for LHR engine at full engine load is higher

than conventional engine.

The HC emission is lower than in the LHR engine compared with the conventional engine. It is observed that the HC emission for LHR engine at

full engine load is 24.35 % lower than conventional engine.

The CO emission is lower than in the LHR engine compared with the

conventional engine. It is observed that the CO emission for LHR engine at

full engine load is 29.41 % lower than conventional engine.

Exhaust gas temperature increases as the engine load increases for both conventional

and LHR engines. The increase in exhaust gas temperature in the LHR engine,

compared with the conventional engine is 22 % at full load condition

LHR engine with turbocharger exhibits degradation of performance when

compared with LHR engine without turbocharger. LHR engine with

turbocharger exhibits lower brake thermally efficiency while increases brake specific consumption at all engine load levels than the LHR engine without

turbocharger.

5. REFERENCES

[1] Brunauer G., Frey F., Boysen H. and Schneider H., “High temperature thermal

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Ceram. Soc., Vol. 21, pp 2563–2567, 2001.

[2] Vassen R., Cao X.Q., Tietz F., Basu D., and Stover D. “Zirconates as new

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[3] Meier S.M., Gupta D.K., “The evolution of thermal barrier coatings in gas turbine

Applications”, Journal of Engineering for Gas Turbines and Power, Vol.116, pp

250–257, 1994.

[4] Gilbert A., Kokini K., Sankarasubramanian S., Surf. Coating Technol., Vol.202

pp 2152, 2008.




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