Effect of Diesel Injection Timing on Peak Pressure Rise Rate and Combustion Stability in RCCI Engine

2018 ◽  
Author(s):  
Mohit Raj Saxena ◽  
Rakesh Kumar Maurya
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
Combustion Stability ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Diesel Injection ◽  
Rise Rate

Post Injection Strategy for the Reduction of the Peak Pressure Rise Rate of Neat N-Butanol Combustion

2015 ◽  
Author(s):  
Marko Jeftić ◽  
Ming Zheng
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
Injection Timing ◽  
Post Injection ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Compression Ignition Engine ◽  
Pressure Rise Rate ◽  
Injection Duration ◽  
Rise Rate

Enhanced premixed combustion of neat butanol in a compression ignition engine can have challenges with regards to the peak pressure rise rate and the peak in-cylinder pressure. It was proposed to utilize a butanol post injection to reduce the peak pressure rise rate and the peak in-cylinder pressure while maintaining a constant engine load. Post injection timing and duration sweeps were carried out with neat n-butanol in a compression ignition engine. The post injection timing sweep results indicated that the use of an early butanol post injection reduced the peak pressure rise rate and the peak in-cylinder pressure and it was observed that there was an optimal post injection timing range for the maximum reduction of these parameters. The results also showed that an early post injection of butanol increased the nitrogen oxide emissions and an FTIR analysis revealed that late post injections increased the emissions of unburned butanol. The post injection duration sweep indicated that the peak pressure rise rate was significantly reduced by increasing the post injection duration at constant load conditions. There was also a reduction in the peak in-cylinder pressure. Measurements with a hydrogen mass spectrometer showed that there was an increased presence of hydrogen in the exhaust gas when the post injection duration was increased but the total yield of hydrogen was relatively low. It was observed that the coefficient of variation for the indicated mean effective pressure was significantly increased and that the indicated thermal efficiency was reduced when the post injection duration was increased. The results also showed that there were increased nitrogen oxide, carbon monoxide, and total hydrocarbon emissions for larger post injections. Although the use of a post injection resulted in emission and thermal efficiency penalties at medium load conditions, the results demonstrated that the post injection strategy successfully reduced the peak pressure rise rate and this characteristic can be potentially useful for higher load applications where the peak pressure rise rate is of greater concern.

Investigation of Design Parameters in Partially Premixed Compression Ignition Combustion Using Adaptive Injection Strategies

2009 ◽  
Author(s):  
Sage L. Kokjohn ◽  
Rolf D. Reitz
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
Injection Pressure ◽  
Air Entrainment ◽  
Premixed Combustion ◽  
Design Parameters ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Wall Impingement

Premixed combustion strategies have been shown to yield very low NOx and soot emissions, while maintaining diesel-like efficiency; however, several issues must be addressed before they can gain widespread acceptance. This paper provides guidelines for solving problems with premixed combustion strategies, viz.: lack of combustion phasing control, excessive pressure rise rate, and spray wall impingement due to early injections. Cooled EGR and a multiple injection concept is used to control combustion phasing and reduce the peak pressure rise rate. To address spray-wall impingement, an Adaptive Injection Strategy (AIS) is employed. This strategy uses two injection pulses at different injection pressures to prepare an optimal in-cylinder mixture. The first injection is early in the cycle and utilizes a low injection pressure to minimize spray-wall impingement and create a well mixed charge. The second injection is near TDC and uses a high injection pressure in order to promote air entrainment and droplet dispersion. This study uses a multi-dimensional CFD code coupled with detailed chemistry, the KIVA-CHEMKIN code, to investigate the effects of several influential design parameters and identify emissions and performance tradeoffs. The combustion process considered is at a light load operating condition (nominal IMEP of 5.5 bar and high speed, 2000 rev/min). The parameters studied were: first and second pulse injection pressure and timing, IVC timing, EGR rate, fuel split, swirl ratio, and spray targeting. The investigation showed that the use of low pressure injections early in the cycle allows improved flexibility in fuel quantity and injection timing. An improved solution was found with near zero NOx and soot, a net ISFC of only 175 g/kW-hr, and a peak pressure rise rate of ∼8 bar/deg.

Performance of Dual Fuel Engine Running on Jojoba Oil as Pilot Fuel and CNG or LPG

2007 ◽  
Author(s):  
Mohamed Y. E. Selim ◽  
M. S. Radwan ◽  
H. E. Saleh
Keyword(s):  
Methyl Ester ◽  
Natural Gas ◽  
Pressure Rise ◽  
Combustion Noise ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Pilot Fuel

The use of Jojoba Methyl Ester as a pilot fuel was investigated for almost the first time as a way to improve the performance of dual fuel engine running on natural gas or LPG at part load. The dual fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or liquefied petroleum gas (LPG) as the main fuel and Jojoba Methyl Ester as a pilot fuel. Diesel fuel was used as a reference fuel for the dual fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic data of 100 engine cycle in terms of maximum pressure and its pressure rise rate. The tests examined the following engine parameters: gaseous fuel type, engine speed and load, pilot fuel injection timing, pilot fuel mass and compression ratio. Results showed that using the Jojoba fuel with its improved properties has improved the dual fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.

Combustion parameter evaluation of diesel engine via vibration acceleration signal

2021 ◽  
pp. 146808742110308
Author(s):  
Pan Zhang ◽  
Wenzhi Gao ◽  
Yong Li ◽  
Zhaoyi Wei
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
Peak Position ◽  
Maximum Pressure ◽  
Cylinder Pressure ◽  
Combustion Control ◽  
Pressure Rise Rate ◽  
Acceleration Signal ◽  
Rise Rate ◽  
Start Of Combustion

Efficient combustion control has increasingly become a quality requirement for automobile manufacturers because of its impact on pollutant and greenhouse gas emissions. In view of this, the management system development of modern internal combustion engines is mainly aimed at combustion control. The real-time detection of in-cylinder pressure characteristic parameters has a considerable significance on the closed-loop combustion control of the internal combustion engine. This paper presents a detection method in which the start of combustion, peak pressure, maximum pressure rise rate, and phase of maximum pressure rise rate are identified through vibration acceleration signal. In order to analyze the relationship between vibration and in-cylinder pressure signal, experimental data are acquired in a diesel engine by implementing various injection strategies and engine operating conditions (speed and load). The results show that the start of combustion can be detected by analyzing its relationship with the peak position of the filtered vibration signal, and the phase of the maximum pressure rise rate can be identified by examining its relationship with the zero-cross position that is adjacent to the right of the peak position. Moreover, the filtered vibration signals are also truncated in the same length and utilized as inputs for algorithms to detect the peak pressure and the maximum pressure rise rate. The algorithms are mainly performed on data compression (or feature extraction) and target regression. Major algorithms, such as one-dimensional convolutional neural network, compression sensing, wavelet decomposition, multilayer perceptron, and support vector machine, are tested. Various experimental results verify that for the test engine the phase detection accuracy of the start of combustion and maximum pressure rise rate is less than 1.7°CA for a 95% prediction interval width. For the detection of the peak pressure and maximum pressure rise rate, the normalized error threshold is set as 0.05, then the accuracies can be not less than 95%.

Fuel efficiency analysis and peak pressure rise rate improvement for neat n-butanol injection strategies

2016 ◽  
Vol 231 (1) ◽  
pp. 50-65 ◽  
Author(s):  
Marko Jeftić ◽  
Zhenyi Yang ◽  
Graham T Reader ◽  
Ming Zheng
Keyword(s):  
Carbon Monoxide ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Single Shot ◽  
Pilot Injection ◽  
Post Injection ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Main Injection ◽  
Injection Strategies

Engine tests were conducted to investigate the efficiency and the peak pressure rise rate performance of different fuel injection strategies for the direct injection of neat n-butanol in a compression ignition engine. Three different strategies were tested: a single-shot injection; a pilot injection; a post-injection. A single-shot injection timing sweep revealed that early injections had the highest indicated efficiency while late injections reduced the peak pressure rise rate at the cost of a slightly reduced thermal efficiency. Delayed single-shot injections also had increased emissions of nitrogen oxides, total hydrocarbon and carbon monoxide. Addition of a pilot injection had a negative effect on the peak pressure rise rate. Because of the low cetane number of butanol and the relatively lean and well-premixed air–fuel mixture, the pilot injection failed to autoignite and instead ignited simultaneously with the main injection. This resulted in slightly increased peak pressure rise rates and significantly increased unburned butanol hydrocarbon emissions. Conversely, the use of an early post-injection produced a noticeable engine power output and allowed the main injection to be shortened and the peak pressure rise rate to be substantially reduced. However, relatively early post-injections slightly reduced the indicated efficiency and increased the nitrogen oxide emissions and the carbon monoxide emissions compared with the single-shot injection strategy. These results recommended the use of a single-shot injection for low loads and medium loads owing to a superior thermal efficiency and suggested that the application of a post-injection may be more suited to high-load conditions because of the substantially reduced peak pressure rise rates.

Safe operation of dual-fuel engines using constrained stochastic control

2021 ◽  
pp. 146808742098510
Author(s):  
Carlos Guardiola ◽  
Benjamín Pla ◽  
Pau Bares ◽  
Alvin Barbier
Keyword(s):  
Pressure Rise ◽  
Maximum Amplitude ◽  
Dual Fuel ◽  
Injection Timing ◽  
Cylinder Pressure ◽  
Safe Operation ◽  
Pressure Oscillations ◽  
Engine Operation ◽  
Pressure Rise Rate ◽  
Rise Rate

Premixed combustion strategies have the potential to achieve high thermal efficiency and to lower the engine-out emissions such as NOx. However, the combustion is initiated at several kernels which create high pressure gradients inside the cylinder. Similarly to knock in spark ignition engines, these gradients might be responsible of important pressure oscillations with a harmful potential for the engine. This work aims to analyze the in-cylinder pressure oscillations in a dual-fuel combustion engine and to determine the feedback variables, control actuators, and control approach for a safe engine operation. Three combustion modes were examined: fully, highly, and partially premixed, and three indexes were analyzed to characterize the safe operation of the engine: the maximum pressure rise rate, the ringing intensity, and the maximum amplitude of pressure oscillations (MAPO). Results show that operation constraints exclusively based on indicators such as the pressure rise rate are not sufficient for a proper limitation of the in-cylinder pressure oscillations. This paper explores the use of a knock-like controller for maintaining the resonance index magnitude under a predefined limit where the gasoline fraction and the main injection timing were selected as control variables. The proposed strategy shows the ability to maintain the percentage of cycles exceeding the specified limit at a desired threshold at each combustion mode in all the cylinders.

Preliminary Investigation of Direct Injection Neat n-Butanol in a Diesel Engine

2013 ◽  
Author(s):  
Tadanori Yanai ◽  
Xiaoye Han ◽  
Graham T. Reader ◽  
Ming Zheng ◽  
Jimi Tjong
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Preliminary Investigation ◽  
Pressure Rise ◽  
Injection Pressure ◽  
Injection Timing ◽  
Boost Pressure ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Short Period

The characteristics of combustion, emissions, and thermal efficiency of a diesel engine with direct injection neat n-butanol were investigated. Tests were conducted on a single cylinder water-cooled four stroke direct injection diesel engine. The engine ran at a load of 6.5 ∼ 8.0 bar IMEP at 1500 rpm engine speed and the injection pressure was controlled to 900 bar. The intake boost pressure, injection timing and EGR rate were adjusted to investigate the engine performance. The test results showed that significantly longer ignition delays were possible when using butanol compared to diesel fuel. Butanol usage generally led to a rapid heat release in a short period, resulting in excessively high pressure rise rate. The pressure rise rate was reduced by retarding the injection timing. The butanol injection timing was limited by misfire and pressure rise rate. Thus, the ignition timing controllable window by injection timing was much narrower than that of diesel. The neat butanol combustion produced near zero soot and very low NOx emissions even at low EGR rate. The tests demonstrated that neat butanol had the potential to achieve ultra-low emissions. However, challenges related to reducing the pressure rise rate and improving the ignition controllability were identified.

Computational Study to Identify Feasible Operating Space for a Mixed Mode Combustion Strategy—A Pathway for Premixed Compression Ignition High Load Operation

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Mixed Mode ◽  
Pressure Rise ◽  
High Load ◽  
Cfd Modeling ◽  
Injection Timing ◽  
Compression Ignition ◽  
Fuel Mass ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Operating Space

A mixed mode combustion strategy with a premixed compression ignition (PCI) combustion event and a mixing controlled load extension injection was investigated in the current study. Computational fluid dynamics (CFD) modeling was used to perform a full factorial design of experiments (DOE) to study the effects of premixed fuel fraction, load extension injection timing, and exhaust gas recirculation (EGR). The goal of the study was to identify a feasible operating space and demonstrate a pathway to enable high-load operation with the mixed mode combustion strategy. The gross-indicated efficiency (GIE) increased with premix fraction, but the maximum premix fraction was constrained by pressure rise rate which confined the feasible operating space to a premix fuel mass range of 70–80%. Injecting part of the premixed fuel as a stratified injection relieved the pressure rise rate constraint considerably through in-cylinder equivalence ratio stratification. This allowed operation with premix fuel mass of 70% and higher and EGR rates less than 40% which resulted in improved GIE of the late cycle injection cases. It was also identified that by targeting the fuel from the stratified injection into the squish region, there is improved oxygen availability in the bowl for the load extension injection, which resulted in reduced soot emissions. This allowed the load extension injection to be brought closer to top dead center while meeting the soot constraint, which further improved the GIE. Finally, the results from the study were used to demonstrate high-load operation at 20 bar and 1300 rev/min.

Postinjection Strategy for the Reduction of the Peak Pressure Rise Rate of Neat n-Butanol Combustion

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Marko Jeftić ◽  
Ming Zheng
Keyword(s):  
Nitrogen Oxide ◽  
Thermal Efficiency ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Compression Ignition Engine ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Load Conditions

Enhanced premixed combustion of neat butanol in a compression ignition engine can have challenges with regards to the peak pressure rise rate (PRR) and the peak in-cylinder pressure. It was proposed to utilize a butanol postinjection to reduce the peak PRR and the peak in-cylinder pressure while maintaining a constant engine load. Postinjection timing and duration sweeps were carried out with neat n-butanol in a compression ignition engine. The postinjection timing sweep results indicated that the use of an early butanol postinjection reduced the peak PRR and the peak in-cylinder pressure and it was observed that there was an optimal postinjection timing range for the maximum reduction of these parameters. The results also showed that an early postinjection of butanol increased the nitrogen oxide emissions, and a Fourier transform infrared spectroscopy (FTIR) analysis revealed that late postinjections increased the emissions of unburned butanol. The postinjection duration sweep indicated that the peak PRR was significantly reduced by increasing the postinjection duration at constant load conditions. There was also a reduction in the peak in-cylinder pressure. Measurements with a hydrogen mass spectrometer showed that there was an increased presence of hydrogen in the exhaust gas when the postinjection duration was increased but the total yield of hydrogen was relatively low. It was observed that the coefficient of variation for the indicated mean effective pressure was significantly increased and that the indicated thermal efficiency was reduced when the postinjection duration was increased. The results also showed that there were increased nitrogen oxide, carbon monoxide, and total hydrocarbon (THC) emissions for larger postinjections. Although the use of a postinjection resulted in emission and thermal efficiency penalties at medium load conditions, the results demonstrated that the postinjection strategy successfully reduced the peak PRR, and this characteristic can be potentially useful for higher load applications where the peak PRR is of greater concern.

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