Qualification: 
Ph.D, M.E
s_srihari@cb.amrita.edu

Dr. Srihari S. currently serves as Assistant Professor at Department of Mechanical Engineering, School of Engineering, Coimbatore Campus. His areas of research include IC Engines and Thermal Engineering.

Thrust Area of Research

Alternate fuels, IC Engines, LTC

Teaching/Research Interests

Major Subjects Taught

  • Internal Combustion Engines
  • Thermodynamics
  • Heat Power Engineering
  • Alternate Fuels, Emissions and Control

Research Interests

  • Low Temperature Combustion
  • HCCI/PCCI Engines
  • Alternate Fuels/Bio-Fuels for Engines
  • Emission Reduction Techniques
  • Combustion Studies in Engines

Publications

Publication Type: Journal Article

Year of Publication Title

2020

Srihari S., Chaitanya, B., and Dr. Thirumalini S., “Experimental study on influence of diphenyl ether and diethyl amine on exhaust emissions of diesel engine”, Materials Today : Proceedings., 2020.[Abstract]


Modification of fuel properties to reduce emissions have become imperative due to enforced regulations. Experimental studies conducted earlier indicate that reduction of pollutants like HC, CO is possible using oxygenated fuel additives such as ethers, alcohols and carbonates. Anti-oxidant additives are used to reduce the NOx in the exhaust emission. The present work investigates the influence of oxygenated fuel additive to emissions of diesel fuel blended with synthetic oxygenated compound such as Diphenyl ether (DPE) along with an anti oxidant additive Diethyl amine (DEA). Diesel fuel blends which contain DPE of volume 10% and 15% of diesel and 5% of DEA were prepared. The influence of these blends on emission characteristics were investigated. These blends were tested at constant speed under various loading conditions. The results indicate a significant reduction of emissions like HC, CO and PM. With the DEA 5 addition to the DPE 15 blend a reduction in NO up to 20% and smoke opacity of 30% was observed.

More »»

2020

C. H. Sree Harsha, Suganthan, T., and Srihari S., “Performance and Emission Characteristics of Diesel Engine using Biodiesel-Diesel-Nanoparticle Blends-An Experimental Study”, Materials Today: Proceedings, vol. 24, pp. 1355–1364, 2020.[Abstract]


Rapid increase in the rate of fossil fuel depletion has raised concerns all over the world. People are starting to use alternative renewable fuels along with the fossil fuels. One of the largely used alternative fuels is the biodiesel, which can be used directly along with the diesel without making much modification to the engine. The commonly observed disadvantages while using biodiesel- diesel blends are: increased TFC, increased BSFC, decreased BTE and increased NOx emission. The aim of this work is to study the effect of adding nanoparticles in a biodiesel- diesel blend on the performance and emission attributes of a diesel engine. Biodiesel obtained from calophyllum -inophyllum seed oil is used in this study. Nanoparticles of cerium oxide and multi-walled carbon nanotubes are used as additives. The fuel blends used in the experiments are viz-a-viz neat diesel, B20 (20%Biodiesel- 80%Diesel), BCM20 (20%Biodiese -80% Diesel- 20 ppm Cerium Oxide -20 ppm MWCNT) and BCM40 (20%Biodiesel - 80%Diesel- 40ppm Cerium Oxide - 40ppm MWCNT). BTE is increased for BCM20 when compared with B20 and diesel respectively. It is observed that the fuel consumption and emissions such as NO, CO and smoke are decreased for BCM20 and BCM40 blends..

More »»

2020

K. K Sriram, Dr. Radhika N, Sam, M., and Srihari S., “Studies on Adhesive Wear Characteristics of Centrifugally Cast Functionally Graded Ceramic Reinforced Composite”, International Journal of Automotive and Mechanical Engineering, vol. 17, no. 4, pp. 8274–8282, 2020.[Abstract]


Functionally graded material containing LM13 aluminium alloy as matrix and alumina as reinforcement (10 wt. %) was fabricated (Φ<sub>out</sub>150 × Φ<sub>in</sub>90 × 100 mm) by centrifugal casting. Samples were machined from the cylindrical cast along its longitudinal axis. Variation in hardness along the radial cross-sectional wall revealed 33.7% improvement at the outer periphery due to higher presence of alumina. This zone was preferred for dry sliding wear experiments, designed based on Taguchi L27 orthogonal array by varying the process parameters like sliding velocity, sliding distance and load using pin-on-disc tribometer. Analysis of variance revealed velocity as most influential wear factor, next to load. An optimal condition to minimise adhesive wear was determined at a load of 15 N, sliding velocity of 3.5 m/s and sliding distance of 1250 m. Scanning electron microscope analysis on abraded surfaces showed formation of tribolayer at high velocities and delamination at high loads.

More »»

2019

N. V Kumar, Raja, R. S. Pranav, Sanjeevi, K. S., Dr. Anbuudayasankar S. P., and Srihari S., “Multi-Criteria Engine Selection for Unique Purpose using AHP”, IOP Conference Series: Materials Science and Engineering, International Conference on Advances in Materials & Manufacturing Applications, IConAMMA 2018, vol. 577, p. 012118, 2019.[Abstract]


In this automotive world the selection of a vehicle based on engine plays a major role, in which all the parameters of the engine need to be considered. The engine selection for three purposes has been considered in this paper. Most influencing 10 parameters of each purpose have been shortlisted with the help of experts in the respective field. Then the parameters are ranked with the help of Analytical Hierarchy Process (AHP). It helps to prioritise the parameters while selecting an engine for specific purpose. In AHP the relative matrix is formed by using pairwise comparison with the help of experts then the relative matrix is squared and eigen vector is found. The eigen vector is used to rank the parameters and is reported as per the priority for the respective purpose. The method proposed in this paper can be used as a decision-making tool while selecting an engine for a specific purpose.

More »»

2019

M. S. Vishnuprasad and Srihari S., “Study on the performance and emission characteristics of a CI engine using diesel-calophyllum inophyllum blends”, IOP Conference Series: Materials Science and Engineering (International Conference on Advances in Materials & Manufacturing Applications, IConAMMA 2018), vol. 577, p. 012021, 2019.[Abstract]


The limited supply of fossil fuels and modern emission norms necessitates the use of mixture of alternate fuels with fossil fuels. Bio-diesel is a renewable source of energy obtained from agro-wastes or agro-based products. Oils obtained from these products maybe edible or non-edible. In this study, the suitability of Calophyllum inophyllum oil (CIO), a non-edible oil, as a bio-diesel source is studied. The bio-diesel fuel is first synthesized from the oil obtained through various stages, including transesterification. The performance characteristics such as brake thermal efficiency (BTE), specific fuel consumption (SFC) and emission variables such as CO2, NOx, HC, CO and smoke are studied. The blend percentage by volume used in the investigation are 10%, 20%, 30%, 40% and 100%. It is observed that HC and CO emissions are less for B10 blend. B10 blend has 20.3% less NOx emissions when compared to that of diesel fuel. BSFC is decreased by 8% and BTE is increased by 9.5% in B10 blend. Among all blends used, the lowest soot concentration is obtained with B10 blend. B10 blend provides the most suitable combination of characteristics to be used as an alternate fuel blend.

More »»

2019

S. P. M. Vignesh, Srihari S., and Dr. Thirumalini S., “Effect of dual fuel injection on the emission characteristics of a single cylinder ci engine using alcohol diesel blends with preheated air”, International Journal of Engineering and Advanced Technology, vol. 8, no. 5, pp. 1395-1402, 2019.[Abstract]


In this study, experimental investigation is carried out on the performance and emission characteristics of diesel-methanol fuel blends with pilot injection. A single cylinder, four stroke, air cooled diesel engine is used for the study. The various methanol blend percentage by volume used in the engine are 5% and 10% in diesel. The engine is maintained at a constant speed of 2300 rpm with variable load conditions. Performance and emission parameters are observed on the engine using pilot injection and main injection strategy by preheating the intake air at the intake manifold. The methanol-diesel fuel blend is prepared by using mechanical stirring technique. The performance and emission characteristics are observed and compared with the base line diesel. It is observed that the brake thermal efficiency is increased for both the blends at higher load conditions when 10% pilot injection is used. A reduction in BSFC is also noticed for M5 and M10 blends. The emission parameters such as smoke, CO and HC are reduced when compared to baseline diesel. © BEIESP.

More »»

2019

V. Charitha, Dr. Thirumalini S., Prasad, M., and Srihari S., “Investigation on performance and emissions of RCCI dual fuel combustion on diesel - bio diesel in a light duty engine”, Renewable Energy, vol. 134, pp. 1081-1088, 2019.[Abstract]


Reactivity Controlled Compression Ignition (RCCI) combustion has been established by modification of intake of a diesel engine. Studies were carried out on the existing engine with Conventional Diesel Combustion (CDC) and performance and emission parameters were recorded. Cotton seed biodiesel (COME) as low reactive fuel was injected into inlet manifold through a port fuel injector and diesel as high reactive fuel is injected in the cylinder through direct injection. Modified engine was tested for performance and emission characteristics. Simultaneous reduction in NOx and smoke emissions were observed with introduction of COME. CO2 emissions decreased marginally and unburnt hydrocarbons (UHC) decreased at lower percentages of COME and increased with higher percentages of COME. An increase in the Brake Thermal Efficiency (BTE) of the engine is observed at all loads. Exhaust Gas Temperature (EGT) and Brake Specific Fuel Consumption (BSFC) are lower in RCCI mode as compared to CDC. The optimum operating range of COME is observed with 10–20% of COME, which has 22% of average decrease in NOx and 30% decrease in the smoke emissions. © 2018 Elsevier Ltd

More »»

2018

S. D. Kumar, Srihari S., and Dr. Thirumalini S., “Effect of inlet air temperature on SI engine fueled with diethyl ether-gasoline blends”, Journal of Mechanical Engineering and Sciences, vol. 12, no. 4, pp. 4044-4055, 2018.[Abstract]


In this study the performance and emission characteristics of spark ignition genset engine fueled with gasoline and diethyl ether (DEE) blends are carried out. The DEE blends are varied from 3%, 6% and 9% by volume in gasoline. A four-stroke single cylinder constant speed spark ignition engine is used for the experiments. The variation in fuel consumption and exhaust emission with respect to two different inlet air temperatures are studied. The concentration of exhaust emissions such as HC, CO, NOx is observed. The parameters such as inlet air temperature, brake specific fuel consumption, relative air to fuel ratio are also measured. It is noticed that 6% DEE blend in gasoline reduced almost reduced HC emission about 57% and also considerable reduction in CO emission at lower air intake temperature. The addition of diethyl ether has an improvement in performance and significant reduction in HC, CO and NOx emissions. © Universiti Malaysia Pahang, Malaysia

More »»

2017

Srihari S. and Dr. Thirumalini S., “Investigation on reduction of emission in PCCI-DI engine with biofuel blends”, Renewable Energy, vol. 114, pp. 1232 - 1237, 2017.[Abstract]


Immense potential is seen in Homogenous Charge Compression Ignition (HCCI) engines as an alternative to conventional Compression Ignition (CI) engines as it can simultaneously reduce oxides of nitrogen (NOx) and soot while maintaining high efficiency. The challenges are predominantly control of combustion and limited operating ranges. Mitigation of these challenges using PCCI-DI is explored in this work. A pilot injector is used to supply a small quantity of premixed charge of fuel and air to the engine followed by direct injection through the main injector. An added advantage is dual fuel capability and improvement of combustion characteristics. Two fuels namely diesel and a blend of ethanol and diesel (containing 15% of ethanol by volume, called E15D) are used in four different combinations for the pilot and main injection. The emission characteristics of each combination were then compared with the conventional mode of operation. The four combinations or modes of operation with PCCI setup were Diesel-Diesel (pilot-main fuel), Diesel-E15D, E15D-Diesel, and E15D-E15D. The results of the experiment indicate that the Diesel-E15D mode is comparatively the best mode of operation due to its lower NOx and smoke emissions.

More »»

2017

P. B. Bhaskar and Srihari S., “A Study of Emission and Performance Characteristics on HCCI Engine Using Methanol Blend”, SAE Technical Papers, vol. 2017-28-1963, pp. 1-6, 2017.[Abstract]


In recent times control of emissions has been the major issue resulting strict emission norms. Oxides of nitrogen (NOx) reduction is a major concern over the years and diesel engine has big hand when compared to gasoline. Several promising techniques have been developed, homogeneous charge compression ignition (HCCI) is one of the effective ways to trim down the NOx emissions by keeping thermal efficiency identical to diesel engine. However, this concept lags in controlling CO and HC emissions. Methanol fuel blends are chosen as it significantly improves the combustion quality. Oxygen content in methanol drags attention as it can compensate HC and CO emissions caused by HCCI mode of combustion. In this work conventional diesel engine is converted into HCCI engine by mounting diesel vaporizer at inlet manifold to attain homogenous mixture. An experimental investigations have been carried out to analyse performance and emission characteristics using different methanol blends. Results have shown decent reduction in NOx, HC and CO emissions were also under control. Copyright © 2017 SAE International and Copyright © 2017 SAE INDIA.

More »»

2017

Srihari S., Dr. Thirumalini S., and Prashanth, K., “An experimental study on the performance and emission characteristics of PCCI-DI engine fuelled with diethyl ether-biodiesel-diesel blends”, Renewable Energy, vol. 107, pp. 440 - 447, 2017.[Abstract]


Abstract The possible depletion of fossil fuels has created the need for alternate fuels worldwide and engine developers are prompted to investigate the viability of such fuels. Further, stringent emission norms have created the need for low emission engines. The objective of this work is to evaluate the effect of diethyl ether in biodiesel-diesel blends on the performance and emission characteristics in a Premixed Charge Compression Ignition-Direct Injection (PCCI-DI) engine. Biodiesel obtained from cotton seed oil is used for this study. PCCI-DI engine is operated with main injection and pilot injections with varying percentages of \{DEE\} along with 20% biodiesel blended with neat diesel. The emission characteristics show a discernible reduction in emissions (NOx, \{CO\} and HC) vis-a-vis biodiesel-diesel blends. Benefits like reduction in the quantum of smoke produced and improvement in Brake thermal efficiency are also noticed in specific cases.

More »»

2016

K. Prashanth and Srihari S., “Emission and performance characteristic of a PCCI-DI engine fuelled with cotton seed oil bio-diesel blends”, ARPN Journal of Engineering and Applied Sciences, vol. 11, no. 9, pp. 5965-5970, 2016.[Abstract]


In this research work, experimental studies have been carried out on emission and performance characteristics of a pre-mixed charge compression ignition (PCCI) setup using cotton seed bio-diesel blends. Port fuel injection strategy is the basic concept of PCCI engine. Bio-diesel was used in PCCI engine for further reduction in emissions. Bio-diesel was produced by trans-esterification process. Cottonseed oil (CSO) was selected for biodiesel production. The experiment was conducted with PCCI setup using diesel-diesel, blends of bio-diesel with varying percentage from 10% to 30% by volume. The experiments were conducted in PCCI setup with bio-diesel blends and compared with conventional diesel mode of operation. The experimental results showed that there was decrease in carbon monoxide (CO), nitrogen-oxide (NOx) and increased hydrocarbon (HC) emissions. There was a reduction in smoke emission and increase in brake specific fuel consumption (BSFC) with increase in blends of bio-diesel in PCCI modes.

More »»

2015

H. A., Srihari S., and V., B., “Design of a crankshaft driven external gear type lubricating oil pump for a multi-cylinder diesel engine”, International Journal of Applied Engineering Research, vol. 10, pp. 37630-37634, 2015.

2015

A. Hareendaran, Srihari S., and V., B., “Design of a Crankshaft Driven External Gear Type Lubricating oil Pump for a Multi Cylinder Diesel Engine”, International Journal of Applied Engineering Research (IJAER), vol. 10, no. 17, pp. 37630-37634, 2015.[Abstract]


In IC Engines, basically the oil pump is driven either by a drive gear integrated with camshaft or a gear mounted on the crankshaft. In the older engines the oil pumps were mostly camshaft driven with a skew gear arrangement which becomes unique and tailor made for the given engine as part of the engine cylinder block sub-assembly. This arrangement calls for complex machining and the number of parts involved are more compared to a crankshaft driven oil pump as being seen in the modern engines. A crankshaft driven oil pump basically calls for a study of the envelope constraints and boundary conditions and finalising the mounting and maximum envelope possible for accommodating the oil pump. The challenge lies in arriving at a very compact pump with the required delivery for the given engine within the envelope limitations. From the different oil pump types, the external spur gear type was selected for the design as it is the most popular and cost effective with manufacturing friendliness for mass production. The basic design computation was done based on the amount of heat carried away by the lubricating oil and the circulation rate of oil in the system. Through the step by step procedure the gear size and the power required to drive the pump was calculated. Based on the gear size and the some preselected parameters, all the important gear parameters were calculated. The pump discharge was computed and it was verified that the discharge increases in direct proportion with the increase in engine speed, by a plotting a graph of oil pump discharge against engine speed and obtaining a linear trend in it. The design of the relief valve for the pump was also carried out. The physical dimensions of the compression spring were chosen and all the other important parameters were calculated and ensured that the pressure in the lubrication circuit remains within the prescribed limit.

More »»

2015

B. Pavan Bharadwaja and Srihari S., “Effect of Exhaust Gas Recirculation on Emissions of a Diesel Engine Fuelled with Castor seed Biodiesel”, Applied Mechanics and Materials, vol. 813-814, pp. 819-823, 2015.[Abstract]


In this study the effect on exhaust gases of a diesel engine fuelled by biodiesel and coupling Exhaust Gas Recirculation (EGR) has been done. EGR is a pre-treatment technique to trim down NOx from diesel engines as it is expected to reduce the flame temperature and the oxygen concentration in the combustion chamber. Fossil fuels so-called biodiesel is picked as the blending fuel. Existence of oxygen in Biodiesel aids complete combustion and anticipated to reduce CO and HC emissions. Exhaust Gas Recirculation technique can capably reduce the amount of NOx. EGR may tend to increase the CO and HC emissions, biodiesel which has higher oxygen content is blended to diesel so that it may compensate CO and HC emissions. The performance and emission characteristics of EGR along with biodiesel in a diesel engine are discussed.

More »»

2015

D. Vignesh and Srihari S., “Investigation on performance and emission behaviour of a single cylinder diesel engine fuelled with mixture of cottonseed and sunflower biodiesel blends along with diesel”, International Journal of Applied Engineering Research, vol. 10, no. 19, pp. 40265-40269, 2015.[Abstract]


Nowadays alternative fuels are gaining more importance because of depleting crude oil resources, high rise in fuel prices, and environmental degradation due to exhaust pollutants. Transesterification process is mostly preferred for conversion of vegetable oils into useable bio diesel fuel. In the present work, performance investigation and emission examination is done on single cylinder diesel engine by usage of mixture of methyl esters of cottonseed oil and sunflower oil without doing any modifications in the engine. Here cotton seed oil methyl ester addition was kept constant as 5% by volume. For the study, both oil methyl esters were mixed and were added to diesel fuel, by volume of 10%, 15%, 20%, 25% and 30%. The effect of blends on brake specific fuel consumption and brake thermal efficiency were compared with baseline pure diesel values. Emission tests were conducted for finding the effect of blends on unburnt hydrocarbons, carbon monoxide, nitrogen oxides and smoke. A slight increase in brake thermal efficiency was found for lower blends across various loading conditions. Smoke and exhaust emission decreases on usage of higher biodiesel blends. The results indicated that 20% biodiesel blend can be replaced without any major engine modifications as it gives better performance and emission characteristics. © Research India Publications.

More »»

2013

Srihari S., P. Nanthakumar, Mathew, S. Koshy, and .N, S., “Study on the performance of PCCI engine run on palm oil bio-diesel blends”, Interdisciplinary Engineering & Sustainable Management Sciences, vol. 22-23, 2013.

2013

M. K. Lalith, Dinesh, A., Unnikrishnan, S., Radhakrishnan, A., Srihari S., and Dr. Ratna Kishore V., “Modeling of homogeneous mixture formation and combustion in GDI engine with negative valve overlap”, ISRN Mechanical Engineering, vol. 12, no. 1, 2013.[Abstract]


Mixture homogeneity plays a crucial role in HCCI engine. In the present study, the mixture homogeneity was analysed by three-dimensional engine model. Combustion was studied by zero-dimensional single zone model. The engine parameters studied include speed, injector location, valve lift, and mass of fuel injected. Valve lift and injector location had less impact on mixture formation and combustion phasing compared to other parameters. Engine speed had a noticeable effect on mixture homogeneity and combustion characteristics. © 2013 M. K. Lalith et al.

More »»

Publication Type: Conference Paper

Year of Publication Title

2018

S. P. Anbuuday Kumar, Raja, R. S. Pranav, Sanjeevi, K. S., Dr. Anbuudayasankar S. P., and Srihari S., “Criteria Engine Selection for Unique Purpose using AHP”, in Advances in Materials and Manufacturing Applications (IConAMMA 2018) , Amrita School of Engineering, Bengaluru, 2018.

2018

C. H. Sree Harsha and Srihari S., “Performance and Emission Characteristics of Diesel Engine using Biodiesel- Diesel-Nanoparticle Blends -An Experimental Study”, in International Conference on Advances in Materials & Manufacturing Applications, IConAMMA 2018, Amrita Vishwa Vidyapeetham, Bangaluru, 2018.

2015

B. Pawan Bharadwaja and Srihari S., “Effect of Exhaust Gas Recirculation on emissions of a Diesel Engine Fuelled with Castor Seed Biodiesel”, in International Conference on Mechanical and Manufacturing Engineering, ICMME-2015, SCSVMV University, Kanchipuram, India, 2015.

2014

M. S. Sabarish, Srihari S., Arunaa, T. S. Swathi, and Dr. Dhanesh G. Kurup, “Simulation and design of a chipless passive RFID Tag”, in International Conference on Advances in Electronics, Computers and Communications (ICAECC), 2014 , Bangalore, 2014.[Abstract]


RFID is an object identification and tracking technology worth several billion dollars today. Chipless technology doesn't require communication protocols and IC, making it cheaper. Passive RFID Tags use backscattering technique to send information to the Reader. In this paper, we present a passive RFID Tag based on Ultra-wide band technology. The chipless RFID tag modeled uses passive elements, namely antennas and transmission lines in different architectural orders by varying the lengths and the number of the transmission lines. The unique identities of the tags are characterized by the number and the lengths of the transmission lines and hence a large number of tags can be manufactured economically with a finite number of transmission lines. The technology involves transmission of nanosecond duration pulses which enables high precision time of arrival (TOA) estimation of signal. The software tool used to simulate this system is Linux based open source software development toolkit called GNURadio. It has a predefined set of signal processing blocks and has the provision to code user defined blocks and enables us to represent the RFID system using standard programming languages namely C++ and Python.

More »»

Research Projects

  • Project Execution Member – DST-FIST Project, Power-train Technology - Emission Analyzer for EURO VI. Duration: 2016-2019.

List of Ph. D. Students

Current

  • Mr. M. Sivanesan- CB.EN.D*MEE18002-PT

Industrial Collaboration/Consultancy

  • Automotive Test Systems (India)-Power train/ Engine testing

Conferences/Workshops/Short-term courses (Organized)

  • Organized One day National level seminar on Engines for off-Highway on 24th Nov 2016.
  • Organized One day National level seminar on Emission Analysis for EURO 6 on 29th May 2019.
  • Organized One day National level seminar on EURO 6 Engines on 08th Aug 2019.
  • Organized One day National level Webinar on Noise, Vibration and Harness in Automotives on 12th May 2020.

Key Responsibilities at Amrita Vishwa Vidyapeetham

  • M.Tech ATE Coordinator
  • Project Coordinator at AARTC
  • Faculty Advisor for Amrita SAE Club
  • Faculty Advisor for Supra team
  • NBA Program files in-charge
  • NAAC file “ Workshops, seminars etc., conducted” in Mech-Department in charge.
  • Interview panel member-M.Tech Admissions
  • Doctoral Committee Member
  • BoS Member for M.Tech ATE program.

Membership in Professional Bodies

  • SAEINDIA member

Other Achievements / Activities

  • BoS Member in Hindustan College of Engineering and Technology- Automotive engineering Curriculum.
  • Involved in Setting-up of Amrita Automotive Research and Technology Center(AARTC).