Modified Diesel Engine Research Articles

Effects of compression ratio on performance and emissions of a modified diesel engine fueled by HCNG

In this study, the effects of compression ratio (CR) have been investigated engine performance and emissions characteristics of a modified diesel engine fueled by HCNG (hydrogen enriched compression natural gas) blends (100% CNG, 95% CNG + 5% H2, 90% CNG + 10% H2 and 80% CNG + 20% H2). The experiments have been carried out using a modified Isuzu 3.9 L diesel engine having 9.6, 12.5 and 15 different compression ratios at 1500 rpm under full load conditions. Engine brake torque, brake specific fuel consumption, combustion analysis and emissions parameters (CO, THC and NOX) have been realized at 10 CA BTDC ignition timing and different excess air ratios (λ = 0.9–1.3).The experimental results showed that the highest brake torque and lowest BSFC values were obtained at CR of 12.5 for all blends. When the CR value was 9.6, torque values increased with addition of hydrogen to CNG and CNG lost the advantages at high excess air ratios and low compression ratio due to its low flame speed. In addition, the maximum cylinder pressure (PMAX) and the rate of heat release (ROHR) values closed to top dead center with increasing CR and addition of hydrogen to CNG. The THC emissions were generally lower than Euro VI standards. NOX emissions increased with hydrogen addition to CNG. Finally, experiments showed that a compression ratio of 12.5 was a reasonable value for the modified engine.

Effect of Turbo Charging on the Performance of Dual Fuel (DF) Engine Operated on Rice Bran Oil Methyl Ester (RBOME) and Coconut Shell Derived Producer Gas Induction

Producer gas operated diesel/biodiesel dual fuel engines suffer from 20-30% derating due to lowered gas energy content and reduced volumetric efficiency. These drawbacks of dual fuel (DF) engines can be overcome by using a suitable turbocharger (TC) matched to the modified diesel engine. Concept of the turbo-charging is an attractive solution to considerably improve the performance with lower emissions for DF engines. In view of this, comprehensive experimental study was carried out on a diesel engine fitted with TC operated in DF mode using biodiesel of rice bran oil and producer gas derived from Coconut shell induction. From the study it is observed that DF engine could operate at higher loads of 3.33 kW (up to 90% load) compared to normal aspirated (NA) DF engine which operated at 2.96 kW (80% load). Results showed that the turbo-charging facilitated improved performance of TCDF at higher loads with maximum brake thermal efficiency of 22.5% and 10-25% reduced emissions of smoke, HC and CO compared to NADF engine.

Performance, Emission and Combustion Characteristics of Dual Fuel (DF) Engine Fuelled with Hydrogen Induction and Injection of Honne and Honge Methyl Esters

Renewable fuels like hydrogen and biodiesels can very well suit to diesel engine applications as they address problems of energy scarcity, foreign exchange savings and emission norms. Production of hydrogen and biodiesel to industrial scale with low cost techniques can pave way for their efficient use in engine applications. In view of this, an attempt has been made to operate a modified diesel engine on these high potential renewable fuel combinations. An experimental study was carried out to evaluate the performance, combustion and emission characteristics of diesel engine operated in dual fuel (DF) mode fuelled with esters of honne (EHNO), honge (EHO) oils and hydrogen induction. The study revealed that the brake thermal efficiency increased up to 20% hydrogen energy ratio (HER) and then it decreased. The emissions such as hydrocarbon (HC), Carbon monoxide (CO) and smoke decreased with HER while oxides of nitrogen (NOx) increased. The combustion parameters like peak pressure, ignition delay and heat release rate (HRR) increased with HER.

Effect of hydrogen addition to CNG in a biodiesel-operated dual-fuel engine

Alternative fuels for diesel engine applications are gaining more prominence as they have numerous advantages compared to fossil fuels. They are renewable, biodegradable; provide food and energy security and foreign exchange savings. They address environmental concerns and socio-economic issues as well. Gaseous fuels such as compressed natural gas and hydrogenated compressed natural gas (HCNG) appear more attractive fuels for diesel engine applications operated in dual-fuel mode. Such dual fuel engines can replace considerable amount of liquid-injected pilot fuels by gaseous fuels besides being friendly to the environment. A small quantity of liquid fuel injected towards the end of the compression stroke initiates combustion of the inducted gas in the dual-fuel engines. The main advantage of dual-fuel engines is their lower nitrogen oxides (NOx) and particulate emissions. Hence renewable fuels such as biodiesels and gaseous fuels can be used predominantly for transportation and power generation applications. Gaseous fuels are clean burning and are more economical as well. A suitable carburettor was designed to supply a stoichiometric mixture of air and HCNG to the modified diesel engine operated in dual-fuel mode. The biodiesel used in this study is derived from Honge oil called the Honge oil methyl ester (HOME). This paper presents the performance, combustion and exhaust emission characteristics of a single cylinder, four stroke, direct injection, stationary diesel engine operated on HOME and HCNG in dual-fuel mode. From the results it is observed that HOME–HCNG combination gave lower brake thermal efficiency (BTE) and improved emission levels when compared with diesel/HOME in single fuel operation. Lower smoke and particulate matter were obtained with dual-fuel operation. Comparative measures of BTE, peak pressure, pressure–crank angle variation, smoke opacity, hydrocarbon, carbon monoxide and NOx emissions have been made and analysed.

An experimental investigation of the engine operating limit and combustion characteristics of the RI-CNG engine

In this paper, the radical induced (RI) ignition method was applied into a compressed natural gas (CNG) engine to achieve rapid bulk combustion. The experimental RI-CNG engine was modified from a diesel engine. The combustion chamber of the modified diesel engine was divided into a sub-chamber and a main-chamber. The sub-chamber is physically separated from the main-chamber above the piston and is connected to the main-chamber via several passage holes. CNG is injected into the sub-chamber during the intake stroke and then ignited before the top dead center (TDC) by a spark plug. As the ignition occurs in the sub-chamber, the pressure rises, forcing the gases which contain a number of active radicals out into the main-chamber to ignite the unburned mixture. The purpose of this paper is to study the engine operating limit and the combustion characteristics of the RI-CNG engine. The engine operating limit was accessed with different engine speeds and injection timings. The obtained data including the coefficient of variation (COV), brake specific fuel consumption (BSFC), mass fraction burned and emissions were analyzed.

A modified diesel engine for natural gas operation: Performance and emission tests

A diesel engine was modified for natural gas operation to optimize performance using gaseous fuel. A variation of combustion ratios (CR) including 9.0:1, 9.5:1, 10.0:1 and 10.5:1 was utilized to evaluate engine performance and emissions from the same engine over the engine speeds between 1000 and 4000 rpm. Tested engine performance parameters include brake torque, brake power, specific fuel consumption (SFC) and brake thermal efficiency. Emissions tests recorded total hydrocarbon (THC), nitrogen oxides (NO x ) and carbon monoxide (CO). The results showed that a CR of 9.5:1 had the highest thermal efficiency and the lowest SFC while a CR of 10:1 showed a high torque at low speed. THC emissions were directly proportional to the CR. NO x emissions increased with increasing CR and then declined after a CR of 10:1.

Combustion and emission characteristics of a diesel engine fuelled with biodiesel/dimethyl ether blends

Biodiesel and dimethyl ether (DME) are two promising alternative fuels. The use of their blends in direct-injection (DI) engines seems beneficial since the blending could not only compromise the viscosity between biodiesel and DME but also could improve atomization by initiating flash boiling. Therefore in this work the combustion and emission characteristics of a DI engine fuelled with biodiesel/DME blends were investigated with DME per centage varying from 0 to 100 (wt.%). The experiment was carried on a modified diesel engine. The results show that the increased DME per centage results in retarded ignition time and reduced peak value of heat release rate of premixed combustion, but has little effect on the overall combustion duration. With increasing DME blend ratio, the maximum pressure rise rate is depressed linearly, but the exhaust gas temperature rises for all loads. Also a remarkable decrease in power occurs because of the low heat value of DME. Oxides of nitrogen (NO x) and smoke emissions decreased simultaneously with increasing DME per centage in the blend fuel. Similar behaviour can be seen with different engine speed. Owing to the improved atomization, high DME blend fuel generates more fine particles. In addition, the increase of DME ratio in the blend fuel also leads to decreased carbon monoxide (CO) emission at high loads but increased HC emissions at low loads.

A Comparative Study of Engine Performance on Modified Diesel Engine with Gasoline, LPG and Biogas Fuel

A Comparative Study of Engine Performance on Modified Diesel Engine with Gasoline, LPG and Biogas Fuel

Experimental and modeling study of performance and emissions of SI engine fueled by natural gas–hydrogen mixtures

Based on CFD software and reaction kinetics software, multi-dimensional CFD Model coupled with detail reaction kinetics is built to study the combustion process in H 2/CNG Engine. Detail reaction mechanism is used to simulate the chemistry of combustion and a combustion model considering the turbulent mixing effects was also applied. To reduce the computation time, the coupled software is reprogrammed to have the function of parallel computing and the revised software is computed in a Massively Parallel Processor. The model is validated using the experiment data from a modified diesel engine. The results show: cylinder pressure from simulation has a good agreement with experiment data and CO and NO x emission is well predicted by the model in a wide range.

Combustion Characteristics, Emissions and Heat Release Rate Analysis of a Homogeneous Charge Compression Ignition Engine with Exhaust Gas Recirculation Fuelled with Diesel

This paper focuses on the study of heat release rate (HRR) and in-cylinder pressure on the homogeneous charge compression ignition (HCCI) process in a modified diesel engine (Deuzt Diter FL1 906). A zero-dimensional thermodynamic model was used to calculate the HRR. The effects of inlet temperature, compression ratio, and exhaust gas recirculation (EGR) on the HRR and engine-out emissions have been investigated experimentally at speed range (1200−2400 RPM), where the start of injection has been fixed at 45° before top dead center (BTDC). The EGR, a well-known and widely used method to depress NOx emission in diesel engines and in HCCI combustion mode, is also used as a basic method to control the ignition timing and burning rate. The total combustion duration was prolonged with an increase of EGR, and the start of combustion was delayed. The HCCI combustion mode shows a HRR clearly different from the HRR correspondent to conventional diesel combustion as it is approached in Wiebe’s function of two modes.

Experimental study of the performances of a modified diesel engine operating in homogeneous charge compression ignition (HCCI) combustion mode versus the original diesel combustion mode

Homogeneous charge compression ignition (HCCI) combustion mode provides very low NOx and soot emissions; however, it has some challenges associated with hydrocarbon (HC) emissions, fuel consumption, difficult control of start of ignition and bad behaviour to high loads. Cooled exhaust gas recirculation (EGR) is a common way to control in-cylinder NOx production in diesel and HCCI combustion mode. However EGR has different effects on combustion and emissions, which are difficult to distinguish. This work is intended to characterize an engine that has been modified from the base diesel engine (FL1 906 DEUTZ-DITER) to work in HCCI combustion mode. It shows the experimental results for the modified diesel engine in HCCI combustion mode fueled with commercial diesel fuel compared to the diesel engine mode. An experimental installation, in conjunction with systematic tests to determine the optimum crank angle of fuel injection, has been used to measure the evolution of the cylinder pressure and to get an estimate of the heat release rate from a single-zone numerical model. From these the angle of start of combustion has been obtained. The performances and emissions of HC, CO and the huge reduction of NOx and smoke emissions of the engine are presented. These results have allowed a deeper analysis of the effects of external EGR on the HCCI operation mode, on some engine design parameters and also on NOx emission reduction.

Gasification of biomass/high density polyethylene mixtures in a downdraft gasifier

In this work, an experimental study of the thermal decomposition of mixtures of wood particles and high density polyethylene in different atmospheres has been carried out in a downdraft gasifier with a nominal processing capacity of 50 kg/h. The main objective was to study the feasibility of the operation of the gasification plant using mixtures and to investigate the characteristics of the gas obtained. In order to do so, experiments with biomass only and with mixtures with up to 15% HDPE have been carried out. The main components of the gas generated are N 2 (50%), H 2 (14%), CO (9–22%) and CO 2 (7–17%) and its relatively high calorific value was adequate for using it in an internal combustion engine generator consisting of a modified diesel engine coupled with a 25 kV A alternator.

Gasification of Waste Medium Density Fibreboard as a Route to Power Generation

AbstractMedium density fibreboard (MDF) processing in Northern Ireland generates about 40 tonnes of MDF dust per week, which gives significant disposal problems and costs. The overall aim of this project was to develop an environmentally friendly, energy efficient and economically acceptable means of generating “green” electricity from MDF dust.The project is based on using a down draught fixed bed gasifier with a modified diesel engine generator. Before MDF dust can be used in the gasifier it must first be briquetted. Although many equipment manufacturers claim to be able to briquette MDF dust, only two were able to prove this capability, PLC Products and Kahl. Trials were arranged and as a result a B10 Bio‐Compactor was purchased and installed. However, good quality briquettes could not be produced reliably due in part to a lack of experience in operating the B10 Bio‐Compactor and in part to mechanical failures. Changes were made to the B10 Bio‐Compactor to improve its mechanical integrity and further trials will be performed to establish the conditions required to make MDF briquettes reliably.In order to provide MDF briquettes for the gasification trials it was decided to use MDF off‐cuts sawn to the correct size. The project team was happy that these off‐cuts possess very similar properties to the briquettes produced by the B10 Bio‐Compactor and would therefore give very similar gasification behaviour. The gasification trials were very successful, with 8 hours continuous operation without problems. The calorific value of the fuel gas produced was 4.8 MJ/nm3, which is almost identical to that obtained from normal hardwood chip fuel. From the gasifier a mixture of diesel and MDF fuel gas was fed to the diesel engine generator. This is the normal practice for these types of engines in order to maintain smooth and efficient combustion. No problems were experienced when changing over from diesel to the fuel gas mixture

A study of knock and adiabatic process in multi-fuel engines

For both engine designers and control purposes, a better understanding of the knocking that occurs during combustion in engines can lead to optimal decisions which will make engines operate more efficiently. The rapid rise in diesel engines is recognized as an audible impulse noise, which is known as ‘‘knock.’’ The knock is caused by the spontaneous combustion of a significant volume of fuel/air mixture. The knock produces shock waves within the combustion chamber and results in a great number of combustion chamber resonance frequencies. The engine used in the experiments was a six-cylinder modified diesel engine running in ethanol conditions. The main purpose of this research is to determine the knock phenomena and the adiabatic process. To perform the data analysis a time-frequency spectral approach was used. The results revealed both radial and circumferential resonances. The most important adiabatic coefficients were carried out and used to calculate the heat release rate.

Development of a modified diesel engine cycle

This paper presents an investigation of a novel type of diesel engine cycle, an approximate constant pressure cycle. The prototype engine is called the diesel engine with oil cushioned piston (DEOCP). In contrast to conventional engines, the DEOCP has a variable cylinder volume which is controlled automatically by the engine's cylinder pressure. The variable cylinder pressure is achieved by inserting a hydraulic cylinder into the engine's piston rod. The engine cylinder pressure is thus self-controlled and an ideal constant pressure cycle can theoretically be achieved. Computer simulations and engine tests have shown that the DEOCP distinguishes itself with high cycle efficiency, improved low-load performance and good starting ability. A detailed theoretical analysis and test results are presented in the paper, as well as a discussion of existing problems and possible further developments. Development of the diesel engine with oil cushioned piston could break the limit of cycle efficiency of conventional engines, hence opening a new avenue for diesel engine development.