In this study, biogas is used in a CI engine in dual fuel mode with diesel as pilot fuel. Biogas has been replicated using a mixture of methane (CH4) and carbon dioxide (CO2), whose flow rates can be independently varied. This helps in evaluating the effect of biogas composition on engine performance. Apart from the conventional diesel-only mode, the engine is operated in dual fuel mode with induction of (a) pure CH4 and (b) CH4 + CO2 mixtures with variable CH4:CO2 ratios, representing biogas. Dual fuel operation is observed to have better brake thermal efficiencies compared to diesel-only mode at high loads. Though volumetric efficiency is almost identical in diesel-only and diesel–CH4 dual modes, induction of biogas causes it to drop. Exhaust gas temperatures were higher in diesel–biogas mode, followed by diesel–methane and diesel-only modes. Dual fuel mode, especially with biogas, results in higher overall equivalence ratios. Compared to diesel-only mode, dual fuel mode has relatively high unaccounted losses at low loads, while exhaust and coolant losses are greater at high loads. Biogas composition does not significantly affect any of the above parameters except the exhaust gas temperature and air–fuel ratio, which show a slight increase with methane enrichment. © 2016 Informa UK Limited, trading as Taylor &amp; Francis Group.

Feroskhan M

Mechanical

School of Mechanical Engineering

Chennai Campus

Ismail S.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Investigation of the effects of biogas composition on the performance of a biogas–diesel dual fuel CI engine

Biofuels

A Compression Ignition (CI) engine was operated in dual-fuel mode with simulated biogas as primary fuel and diesel as pilot fuel. The effects of four intake parameters, viz. biogas flow rate, methane fraction of biogas, applied torque and charge temperature, on engine performance were investigated under constant speed operation. The number of experimental trials was reduced to 16 using Taguchi's approach. Higher-the-better (HTB) or lower-the-better (LTB) criteria for signal-to-noise ratio (SNR) were used to optimise five performance indices. Lower biogas flow rates and methane fractions provide better performance in general. However, increasing the biogas flow rate and methane fraction enhances diesel substitution. Analysis of variance (ANOVA) showed that engine torque was the main contributing factor for most of the performance indices. Charge temperature and biogas flow rate made significant contributions towards volumetric efficiency. Volumetric efficiency and overall equivalence ratio are also affected by the methane fraction of biogas. © 2017, © 2017 Informa UK Limited, trading as Taylor &amp; Francis Group.

Evaluating the effect of intake parameters on the performance of a biogas–diesel dual-fuel engine using the Taguchi method

This study was carried out on a diesel engine operated in dual fuel mode by introducing biogas in the intake air stream. Cerium oxide (CeO 2 ) nanoparticles in varying concentrations were used as diesel additive. Performance and emission tests were carried out to evaluate the effects of five input parameters, namely, CeO 2 concentration, torque, biogas flow rate, methane fraction of biogas, and intake temperature. Taguchi’s method was adopted to reduce the number of experimental trials. Signal-to-noise ratio variations were studied and analysis of variance was carried out to obtain the optimum combination of operating parameters and their contributions towards the performance and emission indices. Results showed that low biogas flow rates ensure better thermal and volumetric efficiency and low HC and CO emissions. High biogas flow rates provide significant reduction in diesel consumption and NO x emissions. Increasing the methane content of biogas lowers diesel consumption and emissions of HC and CO. Adding 25 mg/L of CeO 2 to diesel improves brake thermal efficiency and lowers all emissions. While manifold heating improves brake thermal efficiency, low intake temperature is preferred from the standpoint of volumetric efficiency and emissions. © IMechE 2018.

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

Optimization of performance and emissions in a biogas–diesel dual fuel engine with cerium oxide nanoparticle addition

This study explores the viability of preheating the intake charge as a means to enhance the performance of a compression ignition (CI) engine operated on biogas and diesel in dual fuel mode. Biogas is the primary fuel, which is mixed with air in the intake, preheated and inducted into the engine. This mixture is compressed and subsequently ignited by means of pilot diesel injection within the cylinder. The influence of charge temperature and biogas flow rate on brake thermal efficiency, volumetric efficiency, diesel fuel consumption, diesel equivalent brake specific fuel consumption, exhaust gas temperature and overall equivalence ratio are investigated under two speeds and various loads. Charge preheating, low biogas flow rates and high speed operation are observed to enhance brake thermal efficiency. Methane enrichment is effective in improving thermal efficiency at low biogas flow rates. While charge preheating and increasing the biogas flow rate reduce diesel fuel consumption, volumetric efficiency is lowered. Displacement of air by biogas increases the overall equivalence ratio and exhaust gas temperature. Low speed mode is characterised by reduced diesel fuel consumption and high volumetric efficiency. Under low speed operation, biogas can provide more than 90% of the total energy release. © 2018 Karabuk University

Fulltext

Engineering Science and Technology, an International Journal

Effects of charge preheating on the performance of a biogas-diesel dual fuel CI engine

In this study, a conventional compression ignition (CI) engine is modified to operate in dual fuel mode with biogas and diesel as the main and pilot fuels respectively. The effect of biogas flow rate on engine performance was studied. The viability of using cerium oxide (CeO2) nanoparticles as a diesel additive was also investigated. Compared to diesel-only mode, dual fuel mode with biogas flow rates up to 8 L/min was observed to improve the brake thermal efficiency at high loads. Higher biogas flow rates provided significant diesel substitution. Biogas was observed to contribute up to 80% of the total energy release. Volumetric efficiency deteriorated with increase in biogas flow rate, while overall equivalence ratio and exhaust gas temperature increased. After addition of CeO2nanoparticles, various properties of modified diesel were measured and tabulated. Performance tests revealed that modified diesel containing 25 mg/L CeO2marginally improves brake thermal efficiency. In general, the addition of CeO2increases the overall equivalence ratio and exhaust gas temperature. Tests were carried out for all combinations of biogas flow rate and CeO2concentrations. Dual fuel operation with 4 L/min biogas flow rate and 25 mg/L CeO2concentration was found to provide the highest brake thermal efficiency. © 2016 Informa UK Limited, trading as Taylor &amp; Francis Group.

Investigation of the effects of biogas flow rate and cerium oxide addition on the performance of a dual fuel CI engine

Biogas is an environment friendly renewable fuel which is a valuable resource in the current context of increased energy requirement and sustainability. The quality or the proportion of methane in biogas can vary significantly based on the raw material and method of production. This experimental work was aimed at evaluating the influence of such variations in composition on the energy conversion efficiency and emissions of a common rail dual fuel engine under different output conditions. The effects of post and pilot injection of diesel were also studied in this mode. Biogas with methane proportions in the range 24–68% could be utilized without significant changes in efficiency and emissions till a biogas energy share (BGES) of 60% when the injection timing of diesel was suitably adjusted. Higher than normal methane concentrations (normal: 51–53%) only elevated the NO levels with little impact on efficiency. However, when low proportions of methane were used NO could be controlled effectively particularly at low BGES. Simulation studies indicated that this reduction in NO is due to the lowered in-cylinder temperature rather than the reduced concentration of oxygen as a result of increased CO2. When the proportion of methane was decreased from 68% to 24% the start of injection of diesel had to be advanced by 3 °CA (at a BGES of 60%) to compensate for the increase in ignition delay and reduction in combustion rate. With pilot injection there was a reduction in smoke emission because of improved charge homogeneity due to the split injection process. However, post injection which is generally effective in diesel engines was not advantageous in the biogas diesel dual fuel (BDDF) mode because of the diffusion combustion the post injected fuel undergoes. © 2018 Elsevier Ltd

Fuel

Studies on the effects of methane fraction and injection strategies in a biogas diesel common rail dual fuel engine

The biogas diesel PPCCI (predominantly premixed charge compression ignition) mode where in biogas was inducted with air and diesel was injected into the cylinder using a common rail system was investigated. The injection timing of diesel which was in the range 55-70 °BTDC was found to be very influential as it affected combustion rate and phasing significantly. Though the best intake charge temperatures needed were in the range of 50-90 °C for best performance, operation even without charge heating was possible. For best performance about 80% of the total energy had to be supplied by biogas. At the best condition the thermal efficiency of the biogas diesel PPCCI mode was better than the biogas diesel DF (dual fuel) mode. HC (hydrocarbon) and NOx (nitric oxides) levels were in general significantly lower than the DF mode. The limited range of BMEPs (brake mean effective pressures) (2-4 bar) can be extended by combining the PPCCI mode with the normal diesel mode at low BMEPs and with the DF mode at high BMEPs. Thus PPCCI mode is an option for operating a diesel engine using biogas as the main fuel with low exhaust emissions. © 2015 Elsevier Ltd.

Energy

Comparison of the predominantly premixed charge compression ignition and the dual fuel modes of operation with biogas and diesel as fuels

Energy Conversion and Management

Effect of compression ratio on performance, combustion and emission characteristics of a dual fuel diesel engine run on raw biogas

Investigation on combustion performance and emission characteristics of a DI (direct injection) diesel engine fueled with biogas–diesel in dual fuel mode

Journal	Biofuels
Publisher	Informa UK Limited
ISSN	1759-7269
Open Access	0