Parvezalam Shaikh and S.P. Yeole Department of Mechanical Engineering, P.R Pote (Patil) Group of Educational Institutions, Amravati, India

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 6, Issue 11, Nov 215, pp , Article ID: IJMET_6_11_16 Available online at ISSN Print: and ISSN Online: 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 SiO 2 and Al 2 O 3 with composition 3Al 2 O 3.2SiO 2 (Aluminium oxide 6% and Silicon dioxide 4%), was used as a (TBC) thermal barrier coating material. The piston crown, cylinder valves and cylinder head of diesel engine were coated with a.5 mm thickness of 3Al 2 O 3.2SiO 2 (mullite) over a 15-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. %, 25%, 5%, 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 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 editor@iaeme.com

2 Parvezalam Shaikh and S.P. Yeole 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), 215, pp 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 SiO 2 and Al 2 O 3 with composition 3Al 2 O 3.2SiO 2 (Al 2 O 3 = 6%, SiO 2 = 4%), 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 SiO 2 and Al 2 O 3 with composition 3Al 2 O 3.2SiO 2. 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. 17 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 editor@iaeme.com

3 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 4% YSZ and 6% 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 2 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 2 K higher than in an engine with metal pistons. The investigation undertaken by R.H. Thring [8] using ceramic coated singlecylinder 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 8% reduction of smoke and 5% 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) 11 Compression ratio 16.5:1 Maximum engine power (KW) 3.7 Maximum engine speed (rpm) 15 Specific fuel consumption (g/kwh) editor@iaeme.com

4 Parvezalam Shaikh and S.P. Yeole 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., 25, 5, 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.5 mm coating of Mullite is commonly denoted as 3Al 2 O 3. 2SiO 2 (i.e. 6 mol% Al 2 O 3 ). 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 32 btdc. 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 editor@iaeme.com

5 An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite Coated) Single Cylinder Diesel Engine with and without Turbocharger 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 %, 25, 5, 75% of full engine load and full engine load condition for both conventional and LHR diesel engines editor@iaeme.com

6 Brake Power (Kw) Heat to Coolant (Kw) Parvezalam Shaikh and S.P. Yeole 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 Load Vs Heat Lost to Coolant Conventional Engine 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, 5, 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 Load Vs Brake Power Conventional Engine 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 editor@iaeme.com

7 B.TH. EFF. (Ŋ%) BSFC (Kg/Kwhr) An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite Coated) Single Cylinder Diesel Engine with and without Turbocharger 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 Load Vs BSFC 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 No Load Load Vs B.TH. EFF 1/4 Load 1/2 Load 3/4 Load Full Load Conventional Engine 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 2.6 % compared to conventional engine at full engine load while at editor@iaeme.com

8 Nitrogen Oxide (g/kwhr) Parvezalam Shaikh and S.P. Yeole 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%, 5%, 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 2.19 % 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 Engine Load vs Nitrogen Oxide Conventional Engine 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 % 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 editor@iaeme.com

9 Carbon Monoxide (g/kwhr) Unburnt Hydrocarbon (g/kwhr) An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite Coated) Single Cylinder Diesel Engine with and without Turbocharger 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 Engine Load vs Unburnt Hydrocarbon Conventional Engine Figure 9 Engine Load vs. Unburnt Hydrocarbon Engine Load vs Carbon Monoxide Conventional Engine Figure 1 Engine Load vs Carbon Monoxide Fig.1 shows the comparison of CO emissions variations as a function of engine load for conventional and LHR engines. Carbon monoxide (CO) emission is % 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 editor@iaeme.com

10 BSFC (Kg/Kwhr) Exhaust gas Temperature( () C) Parvezalam Shaikh and S.P. Yeole Engine Load vs Exhaust gas Temperature Conventional 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 18.3% 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.7 Engine Load vs BSFC without Turbocharger With Turbocharger.3.2 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 editor@iaeme.com

11 Heat lost to exhaust gases (Kw) An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite Coated) Single Cylinder Diesel Engine with and without 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 2.1 % 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. Engine Load vs Heat Lost to Exhaust gases without Turbocharger With Turbocharger 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 % at low engine load while at full engine load the increase in exhaust gas energy is 4.3 % 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 editor@iaeme.com

12 Parvezalam Shaikh and S.P. Yeole 4. CONCLUSION The main conclusions of these experimental investigations are summarized as follows. In case of LHR engine with.5 mm of mullite (3Al 2 O 3.2SiO 2 ) 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.5 mm of mullite (3Al 2 O 3.2SiO 2 ) insulation coating compared with conventional diesel engine. LHR engine with.5 mm of mullite (3Al 2 O 3.2SiO 2 ) 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.5 mm of mullite (3Al 2 O 3.2SiO 2 ) 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.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 % 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 % 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 Expansion of mullite: an in-situ neutron diffraction study up to 16 o C, J. Eur. Ceram. Soc., Vol. 21, pp , 21. [2] Vassen R., Cao X.Q., Tietz F., Basu D., and Stover D. Zirconates as new Materials for thermal barrier coatings, Journal of the American Ceramic Society, Vol. 83, pp , 2. [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 , [4] Gilbert A., Kokini K., Sankarasubramanian S., Surf. Coating Technol., Vol.22 pp 2152, editor@iaeme.com

13 An Experimental Investigation on Engine Performance of A Low Heat Rejection (Mullite Coated) Single Cylinder Diesel Engine with and without Turbocharger [5] Kamo R., and Bryzik W., Adiabatic turbocompound engine performance Prediction, SAE Paper No. 7868, [6] Kamo R., and Bryzik W., Ceramics in heat engines, SAE Paper No , [7] Hejwowski T. and Weronski A., The effect of thermal barrier coatings on diesel engine performance, Surf. Engng, Surface Instrum. and Vacuum Technol.,Vol.65, pp , 22. [8] Thring R.H., Low Heat Rejection Engines, SAE Paper No [9] Dr. V. Naga Prasad Naidu and Prof. V. Pandu Rangadu. Performance Evaluation of A Low Heat Rejection Diesel Engine with Cotton Seed Biodiesel, International Journal of Mechanical Engineering and Technology, 5(2), 214, pp [1] T. Ratna Reddy and M.V.S. Murali Krishna. Studies on Performance Parameters and Exhaust Emissions of Crude Mahua Oil In Medium Grade Low Heat Rejection Diesel Engine, International Journal of Mechanical Engineering and Technology, 5(9), 214, pp editor@iaeme.com