Implementation Challenges and Solutions for Homogeneous Charge Compression Ignition Combustion in Diesel Engines

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Usman Asad ◽  
Ming Zheng ◽  
David S.-K. Ting ◽  
Jimi Tjong
Keyword(s):  
High Pressure ◽  
Diesel Engines ◽  
Homogeneous Charge Compression Ignition ◽  
Performance Metrics ◽  
Pressure Rise ◽  
Injection Pressure ◽  
Combustion Stability ◽  
Compression Ignition ◽  
Hcci Combustion ◽  
Homogeneous Charge

Homogeneous charge compression ignition (HCCI) combustion in diesel engines can provide cleaner operation with ultralow NOx and soot emissions. While HCCI combustion has generated significant attention in the last decade, however, till date, it has seen very limited application in production diesel engines. HCCI combustion is typically characterized by earlier than top-dead-center (pre-TDC) phasing, very high-pressure rise rates, short combustion durations, and minimal control over the timing of the combustion event. To offset the high reactivity of the diesel fuel, large amounts of exhaust gas recirculation (EGR) (30–60%) are usually applied to postpone the initiation of combustion, shift the combustion toward TDC, and alleviate to some extent, the high-pressure rise rates and the reduced energy efficiency. In this work, a detailed analysis of HCCI combustion has been carried out on a high-compression ratio (CR), single-cylinder diesel engine. The effects of intake boost, EGR quantity/temperature, engine speed, injection scheduling, and injection pressure on the operability limits have been empirically determined and correlated with the combustion stability, emissions, and performance metrics. The empirical investigation is extended to assess the suitability of common alternate fuels (n-butanol, gasoline, and ethanol) for HCCI combustion. On the basis of the analysis, the significant challenges affecting the real-world application of HCCI are identified, their effects on the engine performance quantified, and possible solutions to overcome these challenges explored through both theoretical and empirical investigations. This paper intends to provide a comprehensive summary of the implementation issues affecting HCCI combustion in diesel engines.

Implementation Challenges and Solutions for Homogenous Charge Compression Ignition Combustion in Diesel Engines

2014 ◽  
Author(s):  
Usman Asad ◽  
Ming Zheng ◽  
David Ting ◽  
Jimi Tjong
Keyword(s):  
High Pressure ◽  
Diesel Engines ◽  
Performance Metrics ◽  
Pressure Rise ◽  
Engine Performance ◽  
Injection Pressure ◽  
Combustion Stability ◽  
Compression Ignition ◽  
Hcci Combustion ◽  
Homogenous Charge Compression Ignition

Homogenous charge compression ignition (HCCI) combustion in diesel engines can provide for cleaner operation with ultra-low NOx and soot emissions. While HCCI combustion has generated significant attention in the last decade, however, to date, it has seen very limited application in production diesel engines. HCCI combustion is typically characterized by earlier than top-dead-center (pre-TDC) phasing, very high pressure rise rates, short combustion durations and minimal control over the timing of the combustion event. To offset the high reactivity of the diesel fuel, large amounts of EGR (30 to 60%) are usually applied to postpone the initiation of combustion, shift the combustion towards TDC and alleviate to some extent, the high pressure rise rates and the reduced energy efficiency. In this work, a detailed analysis of HCCI combustion has been carried out on a high-compression ratio, single-cylinder diesel engine. The effects of intake boost, EGR quantity/temperature, engine speed, injection scheduling and injection pressure on the operability limits have been empirically determined and correlated with the combustion stability, emissions and performance metrics. The empirical investigation is extended to assess the suitability of common alternate fuels (n-butanol, gasoline and ethanol) for HCCI combustion. On the basis of the analysis, the significant challenges affecting the real-world application of HCCI are identified, their effects on the engine performance quantified and possible solutions to overcome these challenges explored through both theoretical and empirical investigations. This paper intends to provide a comprehensive summary of the implementation issues affecting HCCI combustion in diesel engines.

Study of diesel-fuelled homogeneous charge compression ignition combustion by in-cylinder early fuel injection and negative valve overlap

2005 ◽  
Vol 219 (10) ◽  
pp. 1193-1201 ◽  
Author(s):  
L Shi ◽  
K Deng ◽  
Y Cui
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Ignition Time ◽  
Combustion Stability ◽  
Inlet Temperature ◽  
Compression Ignition ◽  
Engine Load ◽  
Hcci Combustion ◽  
Negative Valve Overlap ◽  
Valve Overlap ◽  
Homogeneous Charge

This paper presents a scheme to achieve diesel-fuelled homogeneous charge compression ignition (HCCI) combustion, which is to inject diesel fuel directly into the cylinder at near intake top dead centre and adjust the valve overlap to obtain a higher internal exhaust gas recirculation (EGR) in the cylinder. The effects of the engine load, speed, inlet temperature, external EGR, and internal EGR on HCCI combustion and emission were studied. The combustion stability of HCCI combustion was also studied by statistics analysis. The results show the following: when the engine load or inlet temperature increases, which results in a higher in-cylinder temperature, the start of combustion (SOC) is advanced; the ignition time of HCCI relative to the engine crank angle is retarded when the engine speed increases; inert gases contained in the EGR can slow the chemical reaction rate, which can delay the auto ignition time; for the diesel-fuelled HCCI, increasing the negative valve overlap (NVO) makes the SOC advanced and makes the combustion stability better at low loads and worse at high loads. The emission results show that the nitrogen oxides (NOx) and smoke emissions are very low, and a large NVO can decrease the smoke emission but not benefit the NOx emission at high loads for diesel-fuelled HCCI combustion.

Residual-effected homogeneous charge compression ignition at a low compression ratio using exhaust reinduction

2003 ◽  
Vol 4 (3) ◽  
pp. 163-177 ◽  
Author(s):  
P. A. Caton ◽  
A. J. Simon ◽  
J. C. Gerdes ◽  
C. F. Edwards
Keyword(s):  
Compression Ratio ◽  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Single Digit ◽  
Hcci Combustion ◽  
Actuation System ◽  
Order Of Magnitude ◽  
No Emissions ◽  
Homogeneous Charge

Studies have been conducted to assess the performance of homogeneous charge compression ignition (HCCI) combustion initiated by exhaust reinduction from the previous engine cycle. Reinduction is achieved using a fully flexible electrohydraulic variable-valve actuation system. In this way, HCCI is implemented at low compression ratio without throttling the intake or exhaust, and without preheating the intake charge. By using late exhaust valve closing and late intake valve opening strategies, steady HCCI combustion was achieved over a range of engine conditions. By varying the timing of both valve events, control can be exerted over both work output (load) and combustion phasing. In comparison with throttled spark ignition (SI) operation on the same engine, HCCI achieved 25–55 per cent of the peak SI indicated work, and did so at uniformly higher thermal efficiency. This was accompanied by a two order of magnitude reduction in NO emissions. In fact, single-digit (ppm) NO emissions were realized under many load conditions. In contrast, hydrocarbon emissions proved to be significantly higher in HCCI combustion under almost all conditions. Varying the equivalence ratio showed a wider equivalence ratio tolerance at low loads for HCCI.

Characterizing the cyclic variability of ignition timing in a homogeneous charge compression ignition engine fuelled with n-heptane/iso-octane blend fuels

2008 ◽  
Vol 9 (5) ◽  
pp. 361-397 ◽  
Author(s):  
M Shahbakhti ◽  
C R Koch
Keyword(s):  
Equivalence Ratio ◽  
Homogeneous Charge Compression Ignition ◽  
Coolant Temperature ◽  
Cyclic Variation ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Compression Ignition Engine ◽  
Hcci Combustion ◽  
Cyclic Variations ◽  
Homogeneous Charge

The cyclic variations of homogeneous charge compression ignition (HCCI) ignition timing is studied for a range of charge properties by varying the equivalence ratio, intake temperature, intake pressure, exhaust gas recirculation (EGR) rate, engine speed, and coolant temperature. Characterization of cyclic variations of ignition timing in HCCI at over 430 operating points on two single-cylinder engines for five different blends of primary reference fuel (PRF), (iso-octane and n-heptane) is performed. Three distinct patterns of cyclic variation for the start of combustion (SOC), combustion peak pressure ( Pmax), and indicated mean effective pressure (i.m.e.p.) are observed. These patterns are normal cyclic variations, periodic cyclic variations, and cyclic variations with weak/misfired ignitions. Results also show that the position of SOC plays an important role in cyclic variations of HCCI combustion with less variation observed when SOC occurs immediately after top dead centre (TDC). Higher levels of cyclic variations are observed in the main (second) stage of HCCI combustion compared with that of the first stage for the PRF fuels studied. The sensitivity of SOC to different charge properties varies. Cyclic variation of SOC increases with an increase in the EGR rate, but it decreases with an increase in equivalence ratio, intake temperature, and coolant temperature.

Active valvetrain for homogeneous charge compression ignition

2005 ◽  
Vol 6 (4) ◽  
pp. 377-397 ◽  
Author(s):  
N Milovanovic ◽  
J G W Turner ◽  
S A Kenchington ◽  
G Pitcher ◽  
D W Blundell
Keyword(s):  
Homogeneous Charge Compression Ignition ◽  
Cold Start ◽  
Smooth Transition ◽  
Engine Management System ◽  
Compression Ignition ◽  
Load Range ◽  
Hcci Combustion ◽  
Particulate Matter Emissions ◽  
Mode Transitions ◽  
Homogeneous Charge

Homogeneous charge compression ignition (HCCI), also known as controlled autoignition (CAI) or the premixed charge compression ignition (PCCI) engine concept, has the potential to be highly efficient and to produce low NOx, carbon dioxide, and particulate matter emissions. However, it experiences problems with cold start in a gasoline HCCI engine, running at idle and at high loads, which, together with controlling the combustion over the entire speed/load range, limits its practical application. A way to overcome these problems is to operate the engine in ‘hybrid mode’, where the engine operates in HCCI mode at low, medium, and cruising loads and can switch to or from spark ignition (SI) or diesel (CI) mode for a cold start, idle, and higher loads. Such an engine will have frequent changes in engine load and speeds and therefore frequent transitions between HCCI and SI combustion modes. The valvetrain and engine management system (EMS) have to provide a successful control of HCCI mode and a fast and smooth transition keeping all relevant engine parameters within an acceptable range. Consequently, this leads to high demands on the valvetrain and therefore a need for a very high degree of flexibility. The aim of this paper is to present the potential of a fully variable valvetrain (FVVT) system, the Lotus active valvetrain (AVT™), for controlling HCCI combustion and enabling fast and smooth mode transitions in a HCCI/SI engine fuelled with commercially available gasoline (95 RON) and in a HCCI/DI engine fuelled with diesel (50 CN) fuel.

Comparing Cetane Number Measurement Methods

2020 ◽  
Author(s):  
Riley C. Abel ◽  
Jon Luecke ◽  
Matthew A. Ratcliff ◽  
Bradley T. Zigler
Keyword(s):  
High Pressure ◽  
Diesel Engines ◽  
Ignition Delay ◽  
High Efficiency ◽  
Performance Metrics ◽  
Fuel Injection ◽  
Cetane Number ◽  
Compression Ignition ◽  
Fuel Performance ◽  
Compression Type

Abstract Cetane number is one of the most important fuel performance metrics for mixing controlled compression-ignition “diesel” engines, quantifying a fuel’s propensity for autoignition when injected into end-of-compression-type temperature and pressure conditions. The historical default and referee method on a Cooperative Fuel Research (CFR) engine configured with indirect fuel injection and variable compression ratio is cetane number (CN) rating. A subject fuel is evaluated against primary reference fuel blends, with heptamethylnonane defining a low-reactivity endpoint of CN = 15 and hexadecane defining a high-reactivity endpoint of CN = 100. While the CN scale covers the range from zero (0) to 100, typical testing is in the range of 30 to 65 CN. Alternatively, several constant-volume combustion chamber (CVCC)-based cetane rating devices have been developed to rate fuels with an equivalent derived cetane number (DCN) or indicated cetane number (ICN). These devices measure ignition delay for fuel injected into a fixed volume of high-temperature and high-pressure air to simulate end-of-compression-type conditions. In this study, a range of novel fuel compounds are evaluated across three CVCC methods: the Ignition Quality Tester (IQT), Fuel Ignition Tester (FIT), and Advanced Fuel Ignition Delay Analyzer (AFIDA). Resulting DCNs and ICNs are compared for fuels within the normal diesel fuel range of reactivity, as well as very high (∼100) and very low DCNs/ICNs (∼5). Distinct differences between results from various devices are discussed. This is important to consider because some new, high-efficiency advanced compression-ignition (CI) engine combustion strategies operate with more kinetically controlled distributed combustion as opposed to mixing controlled diffusion flames. These advanced combustion strategies may benefit from new fuel chemistries, but current rating methods of CN, DCN, and ICN may not fully describe their performance. In addition, recent evidence suggests ignition delay in modern on-road diesel engines with high-pressure common rail fuel injection systems may no longer directly correlate to traditional CN fuel ratings. Simulated end-of-compression conditions are compared for CN, DCN, and ICN and discussed in the context of modern diesel engines to provide additional insight. Results highlight the potential need for revised and/or multiple fuel test conditions to measure fuel performance for advanced CI strategies.

Development and experimental validation of a field programmable gate array–based in-cycle direct water injection control strategy for homogeneous charge compression ignition combustion stability

2019 ◽  
Vol 20 (10) ◽  
pp. 1101-1113 ◽  
Author(s):  
David Gordon ◽  
Christian Wouters ◽  
Maximilian Wick ◽  
Bastian Lehrheuer ◽  
Jakob Andert ◽  
...  
Keyword(s):  
Field Programmable Gate Array ◽  
Homogeneous Charge Compression Ignition ◽  
Water Injection ◽  
Combustion Stability ◽  
Compression Ignition ◽  
Field Programmable ◽  
Gate Array ◽  
Compression Ignition Combustion ◽  
Gas Recirculation ◽  
Homogeneous Charge

Homogeneous charge compression ignition is a part-load combustion method, which can significantly reduce oxides of nitrogen (NO x) emissions compared to current lean-burn spark ignition engines. The challenge with homogeneous charge compression ignition combustion is the high cyclic variation due to the lack of direct ignition control. A fully variable electromagnetic valve train provides the internal exhaust gas recirculation through negative valve overlap which is required to obtain the necessary thermal energy to enable homogeneous charge compression ignition. This also increases the cyclic coupling as residual gas and unburnt fuel is transferred between cycles through exhaust gas recirculation. To improve combustion stability, an experimentally validated feed-forward water injection controller is presented. Utilizing the low latency and rapid calculation rate of a field programmable gate array, a real-time calculation of residual fuel mass is implemented on a prototyping engine controller. Using this field programmable gate array–based calculation, it is possible to calculate the amount of fuel and the required control interaction during an engine cycle. This controller prevents early rapid combustion following a late combustion cycle using direct water injection to cool the cylinder charge and counter the additional thermal energy from any residual fuel that is transferred between cycles. By cooling the trapped cylinder mass, the upcoming combustion phasing can be delayed to the desired setpoint. The controller was tested at several operating points and showed an improvement in the combustion stability as shown by a reduction in the standard deviation of combustion phasing and indicated mean effective pressure.

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