Engine Performance Deterioration Research Articles

Experimental investigation of performance and emissions of a VCR diesel engine fuelled with n-butanol diesel blends under varying engine parameters.

The continuous rise in the cost of fossil fuels as well as in environmental pollution has attracted research in the area of clean alternative fuels for improving the performance and emissions of internal combustion (IC) engines. In the present work, n-butanol is treated as a bio-fuel and investigations have been made to evaluate the feasibility of replacing diesel with a suitable n-butanol-diesel blend. In the current research, an experimental investigation was carried out on a variable compression ratio CI engine with n-butanol-diesel blends (10-25% by volume) to determine the optimum blending ratio and optimum operating parameters of the engine for reduced emissions. The best results of performance and emissions were observed for 20% n-butanol-diesel blend (B20) at a higher compression ratio as compared to diesel while keeping the other parameters unchanged. The observed deterioration in engine performance was within tolerable limits. The reductions in smoke, nitrogen oxides (NO x ), and carbon monoxide (CO) were observed up to 56.52, 17.19, and 30.43%, respectively, for B20 in comparison to diesel at rated power. However, carbon dioxide (CO2) and hydrocarbons (HC) were found to be higher by 17.58 and 15.78%, respectively, for B20. It is concluded that n-butanol-diesel blend would be a potential fuel to control emissions from diesel engines. Graphical abstract ᅟ.

Life Assessment of a Sea-Recoverable Small Turbojet Engine Designated for UAV Application

A small turbojet engine is subjected to sea recovery trials for assessment of its life. The engine operates at very high rotor speeds and its integrity needs to be maintained while delivering the required performance for different flight missions. The UAV is launched from ground stations or from ship decks with the help of booster rockets and is recovered over sea. The engine should be capable of reuse after injection of saline water and sand from the sea. Therefore, life assessment of the engine and its components plays an important role while qualifying the engine for the UAV application. Simulated sea dunking tests of the full-scale engine was carried out followed by tear-down examination to assess the extent of corrosion and damage in its components and deterioration in engine performance if any. These tests were found very useful in setting the life from safety and reliable point of view. The engine is cleared for field trials where they would experience real operating conditions and service environment. This paper highlights the sea recovery tests of the engine and the basis on which the life is assessed. Also the paper covers the engine refurbishment procedure which is a practice to refit the engine after every sea recovery.

Industrial Gas Turbine Health and Performance Assessment With Field Data

The paper presents a thorough analysis of the historical data and results acquired over a period of two years through an on-line real-time monitoring system installed at a combined heat and power (CHP) plant. For gas turbine health and performance assessment, a gas path analysis tool based on the adaptive modeling method is integrated into the system. An engine adapted model built through a semi-automated method is part of a procedure which includes a steam/water cycle simulation module and an economic module used for power plant performance and economic assessment. The adaptive modeling diagnostic method allowed for accurate health assessment during base and part load operation identifying and quantifying compressor recoverable deterioration and the root cause of an engine performance shift. Next, the performance and economic assessment procedure was applied for quantifying the economic benefit accrued by implementing daily on-line washing and for evaluating the financial gains if the off-line washings time intervals are optimized based on actual engine performance deterioration rates. The results demonstrate that this approach allows continuous health and performance monitoring at full and part load operation enhancing decision making capabilities and adding to the information that can be acquired through traditional analysis methods based on heat balance and base load correction curves.

Effect of split injection in mitigation of pollutant formation from a CI engine: a numerical study

Compression ignitions with diesel fuel find wide applications ranging from light duty to heavy duty. Diesel engines exhibit higher fuel conversion efficiency when compared to its counterpart-spark ignited engines. However, diesels pose the challenges of high NOx and soot emissions. Pollution-related issues are hampering the engine development processes. Experimental studies demand expensive hardware and researchers are resorting to computational investigation in optimizing engine performance parameters. Exhaust gas recirculation has been widely adopted to lower NOx emissions. Of late, split or multiple-injection strategy has been explored by many to precisely control the fuel injected per cycle and also to mitigate emissions. The present paper deals with the development of a single-zone phenomenological model for the combustion process for both in conventional and in a split injection diesel engine. The model considers a numerical solution of the energy equation while considering the effects of heat loss and temporally varying mixture-averaged values of gas constant. Pre-injection and main injection were modelled using physics-based models for fuel injection, ignition delay, premixed and diffusion heat release rates. The present study also emphasizes on pollutant formation of diesel engine under different operating conditions such as fuel injection timings, ambient conditions and EGR. EGR levels have been varied from 0 to 20 % where as two different multiple-injection levels are incorporated to examine the efficacy of the techniques adopted. It is observed that very low NOx levels are achieved with 20 % EGR with deterioration in engine performance, whereas with split injection NOx levels could be reduced without much loss in engine performance. The present analysis realized in a trade-off between NOx emissions and piston work. It is concluded that engine with split-injection strategy incorporated with electronic controls could be a better option for mitigating harmful engine emissions.

Real-Time Control of Maximum Heat Release Rate and Its Influence on Emission Dispersions in Diesel Engines

Unexpected combustions dispersion due to variations in fuel quality, production tolerance, and aging of components results in the deterioration of engine performance and increases harmful emissions. Many researchers have studied real-time combustion monitoring and control to maintain performance even under undesirable or abnormal conditions. They have reported that the reduction of combustion dispersion is promising for the decrease of emissions dispersion. In this study, we control the maximum heat release (HR) to compensate for combustion dispersion and compared the relationship between before and after control. The maximum rate of heat release (ROHRmax) is an important parameter and is highly related to engine performance and emission level. The control experiments were carried out using a diesel engine at 1500 rpm and brake mean effective pressure (BMEP) of 400 kPa, while the engine parameters were varied. The varied parameters were fuel rail pressure, swirl valve, pilot injection timing, and duration. The experimental results showed that control of the ROHRmax has the potential for the reduction of the dispersions of particulate matter (PM) emission and combustion noise even in unexpected combustion environments.

Real-time start of a combustion detection algorithm using initial heat release for direct injection diesel engines

The start of combustion (SOC) in a compression ignition engine may not be consistent due to the engine operating conditions of each engine cycle. This is true even if fuel is injected at a consistent time. Variable factors include humidity, temperature, fuel quality, exhaust gas recirculation (EGR) rate, and boost pressure. These variations in SOC cause an increase in harmful emissions as well as deterioration of engine performance; therefore, SOC has to be detected and controlled. In this study, we present a simplified heat release (HR) equation to detect SOC for real-time closed-loop combustion control in a compression ignition engine. The proposed method extracts SOC using an initial heat release (IHR) equation that is a modified heat release equation. The detected SOC using IHR reveals a close correlation with one percent of heat release at various engine operating conditions such as main injection timing, injected fuel quantity, fuel-rail pressure, and EGR rate changes. In addition, the SOC detected from the proposed method shows great potential for real-time applications as it reduces of the amount of cylinder pressure data by 50.2% and computational load by 55.2%. Finally, SOC was well controlled in real-time with the estimated SOC despite engine operating condition changes.

Injection strategy for simultaneous reduction of NOx and soot emissions using two-stage injection in DME fueled engine

The ultimate purpose of this study is the reduction of exhaust emissions from a dimethyl ether (DME) fueled diesel engine without deterioration of engine performance, such as indicated mean effective pressure (IMEP) and indicated specific fuel consumption (ISFC). In this study, we applied multiple injection strategies to achieve the research goal. In a comparison between diesel and DME single injection combustion, the IMEP in both fuels was similar around the top dead center (TDC) injection condition (this is the typical injection timing). However, the nitrogen oxide (NOx) emission in DME was higher than that in diesel. The single injection combustion in DME and diesel was compared on the basis of the same energy input condition. When the injection timing was advanced in order to reduce the DME NOx emission, the IMEP in DME decreased below the diesel level. Therefore, multiple injection strategies, including pilot injection, split injection, and advanced+post injection, were applied in this study. In the experimental results, the pilot injection strategy with advanced main injection (2nd injection) resulted in the lowest NOx, HC, and CO emissions. In the case of soot emission, DME itself has soot free combustion, and emitted an ignorable amount of soot. Moreover, the pilot injection strategy showed the highest IMEP level and the lowest ISFC level in the test conditions.

Phase change material thermal storage for biofuel preheating in micro trigeneration application: A numerical study

A biofuel micro trigeneration prototype has been developed to utilise local energy crop oils as fuel in rural areas and developing countries. Straight plant oils (SPOs) only leave behind very little carbon footprint during its simply production process compared to commercial biodiesels in refineries, but the high viscosity of SPOs causes difficulties at engine cold starts, which further results in poor fuel atomisation, compromised engine performance and fast engine deterioration. In this study, a phase change material (PCM) thermal storage is designed to recover and store engine exhaust heat to preheat SPOs at cold starts. High temperature commercial paraffin is selected as the PCM to meet the optimal preheating temperature range of 70–90°C, in terms of the SPO property study. A numerical model of the PCM thermal storage is developed and validated by references. The PCM melting and solidification processes with the consideration of natural convection in liquid zone are simulated in ANSYS-FLUENT to verify the feasibility of the PCM thermal storage as a part of the self-contained biofuel micro trigeneration prototype.

Erosion Testing of Thermal Barrier Coatings in a High Enthalpy Wind Tunnel

One of the major problems facing the users of aircraft engines and stationary gas turbines in dusty and dirty environments is erosion, causing engine performance deterioration. Thermal barrier coatings (TBCs) are often applied on metal engine components as combustor heat shields or tiles as well as turbine blades allowing enhanced operating temperatures and resulting in increased thermal efficiency of the turbine and also reduced fuel consumption and gaseous emission. Erosive attack by airborne dust or fly ash, coarse particles causes coating degradation resulting in lifting issues of engine components. In the present study, an erosion test facility was used to simulate the mechanisms of coating degradation expected in gas turbines in a more realistic way closer to real engine conditions. A loading situation combining thermal gradient cycling and erosive media was used. The experiments have been performed with an arc heated plasma wind tunnel (PWT total enthalpy up to 20 MJ/kg), which is available at the Institute for Thermodynamics at the University of the Federal Armed Forces in Munich, Germany. The experimental setup and the integration of the air jet erosion test rig into the existing PWT will be elucidated. Different plasma sprayed TBC materials, including the standard TBC material yttria-stabilized zirconia (YSZ), were investigated regarding their erosion resistance. For validation and verification, samples of nickel-based Mar-M 247 and INCO 718 alloys have been used.

G0710406 脂肪酸および脂肪酸メチルエステルを添加した軽油のデポジット生成特性([G071-04]エンジンシステム部門一般セッション(4):「燃焼と反応」)

It is well known that bio-diesel fuel produces much deposit on engine components compared with diesel fuel (DF). Deposit accumulated in combustion chamber causes engine troubles and deterioration of engine performance and pollutant emissions. Therefore, it is important to elucidate the mechanism of deposit formation to maintain the performance for a long time. However, it is very difficult to perform the deposition test using actual engine. In this study, single fuel droplet was dripped on a hot surface repeatedly and evaporation deposit formed on it were analyzed. Test fuels were DF, DF to which 10wt% oleic acid was added (DFO10) and DF to which 10wt% methyl oleate was added (DFMO10). As a result, the mass of deposit formed from DFO10 were more than that formed from pure DF under the low surface temperature condition. However, under high surface temperature condition, DFO10 formed less deposit than pure DF. The mass of deposit formed from DFMO10 were less than that formed from pure DF both under the low and high surface temperature conditions.

선박용 디젤기관의 열화성능 예측에 관한 연구

Abstract: The higher energy efficiency for ship and the lower pollution for global environment are re-quired strictly. However the performance of marine diesel engine is gradually deteriorated with time. And also the operation condition is varied with sea conditions. Hence the optimization for operating con-dition of marine engines is needed for energy saving and environment kindly. In this paper, it was attempted to investigate the influence of aging for marine diesel engine. The dete-rioration of engine performance is assessed by the calculation results of the simulation program for two-stroke marine diesel engine developed by author which was reported before. And three parameters for deterioration of engine performance were considered such as lower efficiency of turbocharger by fouling, increase of blow-by gas due to wear of cylinder liner and getting worse of combustion by poor injection. By the results, it was shown that the influence of engine performance by aging was relatively not so small - 10.4 bar low in Pmax and 3.2% decrease in Pmi.

A Study on Practical Use of Cellulosic Liquefaction Fuel in Diesel Fuel

The cellulosic liquefaction fuel (CLF) was made from woods by the direct liquefaction process. Coconuts-oil Methyl Ester (CME) of 5 wt.% was used to mix CLF and diesel fuel, because CLF was not completely mixed with diesel fuel. To clarify a desirable CLF fraction for the diesel engine, CLF was divided into two fractions by the distillation: 200 to 250 °C (CLF1) and 250 to 300 °C (CLF2). The weight mixing ratio of CLF in blended fuel was varied until 20 wt.% to analyze ignition characteristics and performance of diesel fuel-CLF-CME blends. The brake thermal efficiency of both CLF mixed fuel was almost equal to diesel fuel, however high NOx was emitted at a high load. This is because the combustion gas temperature was increased by a rapid combustion pressure rise. The smoke concentration of CLF mixed fuel was lower than that of diesel fuel. When CLF1 or CLF2 is mixed with diesel fuel by using 5 wt% of CME and the weight mixing ratio of CLF is up to 20 wt%, CLF mixed fuels have almost no influence on engine performance. For both CLF1 and CLF2 mixed fuel, it is possible to operate diesel engine without any remarkable deterioration of engine performance. When 5 wt.% CLF was mixed to diesel fuel with CME, diesel engine could be continuously operating for 8 hours without any deterioration. The ignition timing of CLF1 mixed fuel was slightly earlier than that of CLF2 at any mixing ratios, therefore CLF1 was suitable for diesel engine.

Optimizations of turboprop engines using the non-dominated sorting genetic algorithm

This article presents a Pareto approach to design for the optimal performance of four configurations of turboprop engines matching the power requirements of a class of propeller-driven aircrafts. In these bi-objective optimizations of the thermal cycle parameters, the power-specific fuel consumption is minimized and the specific power is maximized while maintaining the power levels and limiting the temperature of the power turbine blades. For this purpose, a multi-objective evolutionary optimization algorithm called non-dominated sorting genetic algorithm is used. To avoid engine performance deterioration and constraint violation at extreme operating conditions, the objective functions and constraints are evaluated at both design and off-design conditions. The trade-off surfaces representing the sets of alternative solutions are obtained based on the Pareto optimality. By considering additional subjective criteria, three design points are proposed for each engine configuration.

Long-term operation of a small biogas/diesel dual-fuel engine for on-farm electricity generation

Biogas from anaerobic digestion of animal manure waste can be used as a renewable energy source for on-farm power generation. In this study, biogas was used in a single-cylinder, direct-injection, compression ignition engine, which has been modified to operate under dual-fuel condition to generate electricity. The primary fuel is biogas, which is ignited by a pilot diesel liquid injection. Long-term engine operation up to 2000 h was carried out. Performance in terms of output power, specific fuel consumption and thermal efficiency was evaluated over a fixed load and a range of engine speeds, and compared against a conventional diesel engine for the first 50 h of operation. Engine components were weighed, inspected visually and given rating for wear, at the start and after 2000 h of operation. Results indicated that short-term performance between conventional diesel and dual-fuel operations was comparable. Biogas/diesel dual-fuel engine was observed to operate successfully with biogas substitution rate at above 90% by mass. Long-term fuel economy was not found to be adversely affected by running time, and the engine was able to maintain 1.45 kW output of electricity throughout the period. Thin layers of carbon deposits were found to build up on the piston, combustion chamber wall, the intake port and exhaust valve stems. Minor surface wear was evident but not significant enough to cause deterioration in engine performance. Overall, the dual-fuel engine appeared to perform well and have great potential for useful on-farm energy utilisation.

Study on biogas premixed charge diesel dual fuelled engine

This paper presents an experimental investigation of a small IDI biogas premixed charge diesel dual fuelled CI engine used in agricultural applications. Engine performance, diesel fuel substitution, energy consumption and long term use have been concerned. The attained results show that biogas–diesel dual fuelling of this engine revealed almost no deterioration in engine performance but lower energy conversion efficiency which was offset by the reduced fuel cost of biogas over diesel. The long term use of this engine with biogas–diesel dual fuelling is feasible with some considerations.

유전자 알고리즘을 이용한 항공기용 가스터빈 엔진의 단일 결함 진단에 대한 연구

유전자 알고리즘은 자연선택과 유전법칙을 적용하여 최적해를 탐색하는 방법으로, 본 연구에서 항공기용 가스터빈 엔진의 결함 진단을 위한 학습 알고리즘으로 사용되었다. 성능 저하를 고려한 구성요소는 압축기, 가스발생기 터빈, 동력 터빈이며, 설계점에서 엔진의 단일 구성요소에 대하여 각각 성능 저하 예측을 수행한 후, 이를 바탕으로 결함 진단을 수행하였다. 학습데이터 수의 증가가 유전자 알고리즘을 이용한 성능 저하 예측 및 결함 진단에 미치는 영향을 분석하였으며, 결과적으로 결함치에 대한 RMS 오차율이 모두 3% 이내로 예측됨을 확인하였다. Genetic Algorithms(GA) which searches optimum solution using natural selection and the law of heredity has been applied to learning algorithms in order to estimate performance deterioration of the aircraft gas turbine engine. The compressor, gas generator turbine and power turbine are considered for engine performance deterioration and estimation for performance deterioration of a single component at design point was conducted. As a result of that, defect diagnostics has been conducted. The input criteria for the genetic algorithm to guarantee the high stability and reliability was discussed as increasing learning data sets. As a result, the accuracy of defect estimation and diagnostics were verified with its RMS error within 3%.

Effect of Rounding-off Nozzle Hole Inlet on Fuel Injection and Combustion Characteristics under High-Temperature and High-Pressure

Fuel injection pressure of diesel engines has been increased to improve engine performance and to reduce emission year by year. The higher injection pressure causes a cavitation and leads to erosion in the nozzle hole. Deformation of nozzle hole may result deterioration in engine performance, especially when using heavy fuel oil. It is noted that rounding-offof nozzle hole inlet proves to be effective to maintain the nozzle hole shape and the injection characteristics. In the present paper, from a fundamental viewpoint, measurement of ignition delays of diesel sprays from single hole injection nozzles with and without rounding-off hole inlet were conducted in a high-pressure combustion chamber. Further, fuel flow patterns in the nozzle hole were numerically simulated by three dimensional highly precision nozzle flow model.When ambient pressure and fuel injection quantity are relatively low, sprays from nozzle without rounding-off hole inlet do not ignite at low ambient temperature. On the other hand, there is no difference in ignition delay under high ambient temperature. In cases where an ambient pressure is high enough and a large amount of fuel is injected, ignition delays of nozzle with rounding-off and without rounding-off show almost the same values even at low ambient temperature. The computed results of numerical simulations show that cavitation level decreases significantly for all cases of rounding-off nozzles.

Axial Compressor Deterioration Caused by Saltwater Ingestion

Gas turbine performance deterioration can be a major economic factor. An example is within offshore installations where a degradation of gas turbine performance can mean a reduction of oil and gas production. This paper describes the test results from a series of accelerated deterioration tests on a General Electric J85-13 jet engine. The axial compressor was deteriorated by spraying atomized droplets of saltwater into the engine intake. The paper presents the overall engine performance deterioration as well as deteriorated stage characteristics. The results of laboratory analysis of the salt deposits are presented, providing insight into the increased surface roughness and the deposit thickness and distribution. The test data show good agreement with published stage characteristics and give valuable information regarding stage-by-stage performance deterioration.

3823 自動車燃料配管内における脈動解析手法の開発 : 実車モデルへの適用(J15-2 流体関連の騒音と振動(2)-管内流れ-,J15 流体関連の騒音と振動,2005年度年次大会)

It is known that the fuel pulsation caused by fuel pump or injectors is generated for a vehicle fuel line. This fuel pulsation caused noise and deterioration of engine performance. Therefore, estimating this pulsation in an early stage of development is hoped. So, we developed the fuel pulsation analysis method by using 1D fluid flow analysis software. Modeling of piping, fuel damper, pressure regulator, and injector that are main parts for fuel line and examinations of simple bench models have been described in the first report. In this study, the vehicle fuel line was constructed by using part models and influences of fuel injections were examined. Comparing the experimental results with the calculation results, the propriety of this method was confirmed.

109 自動車燃料配管内における脈動解析手法の開発

It is known that the fuel pulsation caused by fuel pump or injectors is generated for vehicle fuel line. This fuel pulsation caused noise and deterioration of engine performance. Therefore, estimating this pulsation in an early stage of development is hoped. So, we developed the fuel pulsation analysis method by using 1D fluid flow analysis software. Firstly, piping, fuel damper, pressure regulator, and injector that are main parts for fuel line were modeled. Secondly, simple bench models were constructed by using models of parts and calculated. Comparing the experimental results with the calculation results, the propriety of this method was confirmed.