Study of Pulse Spray, Heat Release, Emissions and Efficiencies in a Compound Diesel HCCI Combustion Engine

2004 ◽  
Author(s):  
Wanhua Su ◽  
Xiaoyu Zhang ◽  
Tiejian Lin ◽  
Yiqiang Pei ◽  
Hua Zhao
Keyword(s):  
Heat Release ◽  
Combustion Engine ◽  
Combustion Efficiency ◽  
Diffusion Combustion ◽  
Injection Timing ◽  
Nox Emissions ◽  
Injection Process ◽  
Hcci Combustion ◽  
Air Mixing ◽  
Combustion Technology

A compound diesel HCCI combustion technology has been developed based on the combustion strategies of combination of controlled premixed charge compression ignition (CPCCI) through multi-injections and lean diffusion combustion (LDC) organized by a mixing enhanced combustion chamber. The purpose of this paper is to investigate the fuel spray evolution during multi-injections, heat release mode, thermo-efficiency and exhaust emissions from the compound combustion. In this work, the STAR-CD based, multidimensional modeling is employed to improve the understanding and assist the optimization of the multiple injection process. The parameters explored include the effects of injection timing, dwell time, and the pulse width. Insight generated from these studies provides guidelines on designing an injection profile for optimization of fuel-air mixing. By comparison of different heat release modes of conventional diesel combustion, the pure HCCI combustion and the compound HCCI combustion, the engine heat release can be summarized as forward concentrated mode (FC mode), post concentrated mode (PC mode) and dispersed mode (DS mode). The FC mode gives the highest thermo-efficiency but with highest NOx emissions. The PC mode gets lower NOx emissions but with the drawback of lower thermo-efficiency and higher soot emissions. The DS mode is a flexible heat release mode created by the compound HCCI combustion. A typical DS mode reveals two equivalent peaks of heat release. The first peak represents the CPCCI combustion and the later peak represents the lean diffusion combustion. The thermo-efficiency in a DS mode can reach approximately as high as that in FC mode, while NOx and soot emission can be reduced simultaneously and remarkably. The combustion efficiency and the heat loss in different combustion mode are also discussed.

The NOx and N2O Emission Characteristics of an HCCI Engine Operated With N-Heptane

2007 ◽  
Author(s):  
Hailin Li ◽  
W. Stuart Neill ◽  
Hongsheng Guo ◽  
Wally Chippior
Keyword(s):  
N2o Emission ◽  
Combustion Efficiency ◽  
N2o Emissions ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Incomplete Combustion ◽  
Hcci Combustion ◽  
Wide Range ◽  
Combustion Phase

This paper presents the NOx and N2O emission characteristics of a Cooperative Fuel Research (CFR) engine modified to operate in Homogeneous Charge Compression Ignition (HCCI) combustion mode using an air-assist port fuel injector. The single-cylinder engine was fuelled with n-heptane for these experiments. The parameters examined include intake air temperature and pressure, air/fuel ratio, compression ratio, and exhaust gas recirculation (EGR) rate. The parameters were varied in order to change the combustion phasing from advanced (knocking) to retarded (incomplete combustion) conditions. NOx emissions were less than 5 ppm for a fairly wide range of combustion phases, except when knocking or incomplete combustion occurred, and were largely unaffected by the parameter varied when the combustion phase was within the acceptable range. It was also found that NOx emissions increased significantly when retarded and incomplete combustion was observed even though lower combustion temperatures were expected. The increased N2O and unburned hydrocarbon (THC) emissions usually observed with retarded combustion phasing, as well as the deteriorated combustion efficiency, may contribute to this unexpected increase in NOx emissions. It was also shown that N2O emissions were extremely low (less than 0.5 ppm) except when incomplete combustion was observed.

scholarly journals Fuel Economy of a Multimode Combustion Engine With Three-Way Catalytic Converter

2014 ◽  
Vol 137 (5) ◽  
Author(s):  
Sandro P. Nüesch ◽  
Anna G. Stefanopoulou ◽  
Li Jiang ◽  
Jeff Sterniak
Keyword(s):  
Fuel Economy ◽  
Combustion Engine ◽  
Catalytic Converter ◽  
Combustion Efficiency ◽  
Oxygen Storage ◽  
Nox Emissions ◽  
Combustion Mode ◽  
Mode Switch ◽  
Drive Cycle ◽  
The Impact

Highly diluted, low temperature homogeneous charge compression ignition (HCCI) combustion leads to ultralow levels of engine-out NOx emissions. A standard drive cycle, however, would require switches between HCCI and spark-ignited (SI) combustion modes. In this paper we quantify the efficiency benefits of such a multimode combustion engine, when emission constraints are to be met with a three-way catalytic converter (TWC). The TWC needs unoccupied oxygen storage sites in order to achieve acceptable performance. The lean exhaust gas during HCCI operation, however, fills the oxygen storage and leads to a drop in NOx conversion efficiency. If levels of tailpipe NOx become unacceptable, a mode switch to a fuel rich combustion mode is necessary in order to deplete the oxygen storage and restore TWC efficiency. The resulting lean-rich cycling leads to a penalty in fuel economy. Another form of penalty originates from the lower combustion efficiency during a combustion mode switch itself. In order to evaluate the impact on fuel economy of those penalties, a finite state model for combustion mode switches is combined with a longitudinal vehicle model and a phenomenological TWC model, focused on oxygen storage. The aftertreatment model is calibrated using combustion mode switch experiments from lean HCCI to rich spark-assisted HCCI (SA-HCCI) and back. Fuel and emission maps acquired in steady-state experiments are used. Different depletion strategies are compared in terms of their influence on drive cycle fuel economy and NOx emissions. It is shown that even an aggressive lean-rich cycling strategy will marginally satisfy the cumulated tailpipe NOx emission standards under warmed-up conditions. More notably, the cycling leads to substantial fuel penalties that negate most of HCCI's efficiency benefits.

Influence of Swirl and Primary Zone Airflow Rate on the Emissions and Performance of a Liquid-Fueled Gas Turbine Combustor

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Parneeth Lokini ◽  
Dinesh Kumar Roshan ◽  
Abhijit Kushari
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Combustible Mixture ◽  
Airflow Rate ◽  
Nox Emissions ◽  
Swirl Number ◽  
Primary Zone ◽  
Air Mixing ◽  
Efficient Combustion ◽  
And Performance

This paper presents the results of an experimental study on the influence of swirl number (S) and primary zone airflow rate on the temperature, emission indices of the pollutants, and combustion efficiency in an atmospheric pressure liquid-fueled gas turbine (GT) combustor, equipped with a swirling jet air blast atomizer and operated with Jet A1 fuel. Experiments were conducted at three primary zone air flow rates and three swirl numbers (0.49, 0.86, and 1.32). For all the cases, it was found that the NOx emissions were very low (< 2 g/kg of fuel). At all the swirl numbers, an increase in primary zone airflow led to a nonmonotonous variation in CO while minimally affecting the NOx emissions. However, increase in the swirl number generated relatively higher NOx and lower CO owing to higher temperature resulting from efficient combustion caused by a superior fuel–air mixing. Also, the unburnt hydrocarbons (UHC) was quite high at S = 0.49 because of the unmixedness of fuel and air, and zero at S = 0.86 and 1.32. The combustion efficiency was very low (around 60%) at S = 0.49 while almost 100% at S = 0.86 and 1.32. The study conducted demonstrates a significant dependence of emissions and GT performance on the swirl number governed by the convective time scales and the residence time of the combustible mixture in the combustion zone.

Effects of Heat Release Mode on Emissions and Efficiencies of a Compound Diesel Homogeneous Charge Compression Ignition Combustion Engine

2005 ◽  
Vol 128 (2) ◽  
pp. 446-454 ◽  
Author(s):  
Wanhua Su ◽  
Xiaoyu Zhang ◽  
Tiejian Lin ◽  
Yiqiang Pei ◽  
Hua Zhao
Keyword(s):  
Heat Release ◽  
Thermal Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Experimental Comparison ◽  
Injection Timing ◽  
Compression Ignition ◽  
Multiple Injection ◽  
Hcci Combustion ◽  
Flexible Mode ◽  
Homogeneous Charge

A compound diesel homogeneous charge compression ignition (HCCI) combustion system has been developed based on the combined combustion strategies of multiple injection strategy and a mixing enhanced combustion chamber design. In this work, a STAR-CD based, multidimensional modeling is conducted to understand and optimize the multiple injection processes. The parameters explored included injection timing, dwell time, and pulse width. Insight generated from this study provides guidelines on designing the multipulse injection rate pattern for optimization of fuel-air mixing. Various heat release modes created by different injection strategies are investigated by experimental comparison of combustion efficiency, heat loss, and thermal efficiency. It is demonstrated that the process of fuel evaporation and mixing are strongly influenced by pulse injection parameters. Through control of the parameters, the stratification and autoignition of the premixed mixture, and the heat release mode can be controlled. The dispersed mode of heat release created only by the compound diesel HCCI combustion is a flexible mode in combustion control. The thermal efficiency with this mode can reach approximately to as high as that of conventional diesel combustion, while the NOx and smoke emissions can be reduced simultaneously and remarkably.

Experimental and Simulation Study of Fuel Injection Timing, Pressure and EGR for Lower Exhaust Emissions From Diesel HCCI Combustion

2009 ◽  
Author(s):  
S. Juttu ◽  
S. S. Thipse ◽  
N. V. Marathe ◽  
M. K. Gajendra Babu
Keyword(s):  
Simulation Study ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Emissions ◽  
Injection Timing ◽  
Nox Emissions ◽  
Hcci Combustion ◽  
Fuel Injection Timing ◽  
Start Of Injection ◽  
Wide Range

The objective of this work is to study the effect of different control parameters viz. EGR, fuel injection pressure and start of injection timing on exhaust emissions from diesel fueled HCCI combustion concept. A 4-cylinder LCV engine has been selected for experiments and FIRE 3D CFD software was used for simulation study. The basic idea of the simulation study is to find the suitable EGR ratio to run the engine on HCCI combustion mode so as to avoid any damage to the engine during testing. From simulation study, it was observed that the minimum EGR required for running the engine at 5.6 bar BMEP @ 2500 rpm in HCCI mode is approximately 45%. The trends of simulation results viz. soot and NOx emissions are closely following the experiments. The experiments were conducted at different loads at 2500 rpm and EGR varied from 0% to 60%. With increased EGR ratio, soot bump was observed at 50%, 75% and 100%. The BTE dropped to 24.5% from 33.5%. The effect of fuel injection pressures (750bar, 1000bar and 1500bar) were studied to improve the BTE and to control soot bump over a wide range injection timings EGR ratio. Detailed experiments were conducted at 2.8 bar BMEP @ 2500 rpm to study simultaneous reduction of NOx, SOOT, UHC and CO emissions from diesel HCCI combustion. At injection pressure (1500 bar), advanced fuel injection timing and high EGR ratio, the soot CO and THC emissions were reduced significantly without penalty on NOx emissions. The BTE was improved from 24.5% to 31% against 33.5% of convention diesel combustion.

scholarly journals Investigation Into Reactivity Separation Between Direct Injected and Premixed Fuels in RCCI Combustion Mode

2019 ◽  
Author(s):  
Ziming Yan ◽  
Brian Gainey ◽  
Deivanayagam Hariharan ◽  
Benjamin Lawler
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Efficiency ◽  
High Reactivity ◽  
Injection System ◽  
Injection Timing ◽  
Nox Emissions ◽  
Light Duty ◽  
Primary Reference

Abstract This experimental study focuses on the effects of the reactivity separation between the port injected fuel and the direct injection fuel, the amount of external-cooled exhaust gas recirculation (EGR), and the direct injection timing of the high reactivity fuel on Reactivity Controlled Compression Ignition (RCCI) combustion. The experiments were conducted on a light-duty, single-cylinder diesel engine with a production GM/Isuzu engine head and piston and a retrofitted port fuel injection system. The global charge-mass equivalence ratio, ϕ′, was fixed at 0.32 throughout all of the experiments. To investigate the effects of the fuel reactivity separation, different Primary Reference Fuels (PRF) were port injected, with the PRF number varying from 50 to 90. To investigate the effects of EGR, an EGR range of 0 to 55% was used. To investigate the effects of the injection timing, an injection timing window of −65 to −45 degrees ATDC was chosen. The results indicate that there are several tradeoffs. First, decreasing the port injected fuel reactivity (increasing the PRF number) delays combustion phasing, decreases the combustion efficiency by up to 9%, increases the gross indicated thermal efficiency up to 22%, enhances the combustion sensitivity to the direct injection timing, and slightly increases the UHC, CO, and NOx emissions. Second, increasing the EGR percentage delays combustion phasing, lowers the peak heat release rate, and lowers the NOx emissions. The combustion efficiency first increases and then decreases with EGR percentage for high reactivity fuels (low PRF number), but only decreases for low reactivity fuels. Finally, delaying the injection timing advances combustion phasing and increases the combustion efficiency, but decreases the gross indicated thermal efficiency and increases the NOx emissions. Across all of the experiments, delays in CA50 increase the gross indicated thermal efficiency and decrease the combustion efficiency, which represents an inherent tradeoff for RCCI combustion on a light-duty engine.

scholarly journals Effect of EGR on Performances and Emissions of DI Diesel Engine Fueled with Waste Plastic Oil: CDF Approach

2021 ◽  
Vol 45 (3) ◽  
pp. 217-223
Author(s):  
Khatir Naima ◽  
Younes Menni ◽  
Mounir Alliche ◽  
Giulio Lorenzini ◽  
Hijaz Ahmad ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Release Rate ◽  
Injection Timing ◽  
Nox Emissions ◽  
Cylinder Pressure ◽  
Waste Plastic ◽  
Waste Plastic Oil ◽  
Di Diesel Engine ◽  
Fraction Increase

Recently, there is an increasing interest in the pyrolysis of waste plastic into usable fuel as a friendly environment method for waste plastic disposal. The existing literature from various studies stated that the major problem related to the use of WPO in diesel engines is the high NOx emissions level. This paper aims to remedy this problem by suggesting the best EGR percentage with the advanced optimum injection timing. Primary, 5 EGR percentage fractions are considered: 0%, 5%, 15%, 20% and 25% percent. The results showed that 25% is the best percentage regarding emissions. However, a significant reduction in mean in-cylinder pressure, temperature, and heat release rate was depicted with the EGR fraction increase. Injection timing is advanced to recoup the decrease in performance. The results showed that 25% of EGR and advanced injection timing by 5 degrees would be better for performances and emissions of DI diesel engine while running with waste plastic oil as an alternative fuel.

Low-Temperature Combustion Within a HSDI Diesel Engine Using Multiple-Injection Strategies

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Tiegang Fang ◽  
Robert E. Coverdill ◽  
Chia-Fon F. Lee ◽  
Robert A. White
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Injection Pressure ◽  
Diffusion Combustion ◽  
Injection Timing ◽  
Low Temperature Combustion ◽  
Conventional Combustion ◽  
Main Injection ◽  
Temperature Combustion ◽  
Injection Strategies

Low-temperature compression ignition combustion employing multiple-injection strategies in an optical high-speed direct injection diesel engine was investigated. Heat release characteristics were analyzed. The whole cycle combustion process was visualized by imaging the natural flame luminosity. The NOx emissions were measured in the exhaust pipe. The effects of the pilot injection timing, pilot fuel quantity, main injection timing, operating load, and injection pressure on the combustion and emissions were studied. Low-temperature combustion modes were achieved by using a small pilot injection with an injection timing much earlier than top dead center (TDC) followed by a main injection after TDC. The results were compared with conventional diesel (diffusion) combustion for comparison purposes. A premixed-combustion-dominated heat release rate pattern was seen for all the low-temperature combustion cases, while a typical diffusion flame combustion heat release rate was obtained for the conventional combustion case. A highly luminous flame was observed for the conventional combustion condition while a much less luminous flame was seen for the low-temperature combustion cases. For the higher-load and lower injection pressure cases, liquid fuel being injected into low-temperature premixed flame was observed for certain cases. Compared with the conventional diffusion combustion, simultaneous reductions in soot and NOx were obtained for the low-temperature combustion mode under similar operating loads. For high-load conditions, higher NOx emissions were obtained due to higher in-cylinder temperatures. However, compared with the conventional combustion case, a significant reduction in soot was achieved for the high-load conditions, which shows that increasing injection pressure greatly reduces soot emissions.

Understanding the Effect of Wall Conditions and Engine Geometry on Thermal Stratification and HCCI Combustion

2014 ◽  
Author(s):  
Benjamin Lawler ◽  
Satyum Joshi ◽  
Joshua Lacey ◽  
Orgun Guralp ◽  
Paul Najt ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Heat Release ◽  
Wall Temperature ◽  
Compression Ratio ◽  
Thermal Stratification ◽  
Ceramic Coatings ◽  
Combustion Efficiency ◽  
Noticeable Effect ◽  
Hcci Engine ◽  
Hcci Combustion

Thermal stratification of the unburned charge in the cylinder has a profound effect on the burn characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine. Experimental data was collected in a single cylinder, gasoline-fueled, HCCI engine in order to determine the effects of combustion chamber geometry and wall conditions on thermal stratification and HCCI combustion. The study includes a wall temperature sweep and variations of piston top surface material, piston top geometry, and compression ratio. The data is processed with a traditional heat release routine, as well as a post-processing tool termed the Thermal Stratification Analysis, which calculates an unburned temperature distribution from heat release. For all of the sweeps, the 50% burned point was kept constant by varying the intake temperature. Keeping the combustion phasing constant ensures the separation of the effects of combustion phasing from the effects of wall conditions alone on HCCI and thermal stratification. The results for the wall temperature sweep show no changes to the burn characteristics once the combustion phasing has been matched with intake temperature. This result suggests that the effects of wall temperature on HCCI are mostly during the gas-exchange portion of the cycle. The ceramic coatings were able to very slightly decrease the thermal width, increase the burn rate, increase the combustion efficiency, and decrease the cumulative heat loss. The combustion efficiency increased with the lower surface area to volume ratio piston and the lower compression ratio. Lastly, the compression ratio comparison showed a noticeable effect on the temperature distribution due to the effect of pressure on ignition delay, and the variation of TDC temperature required to match combustion phasing.

scholarly journals The NOx and N2O Emission Characteristics of an HCCI Engine Operated With n-Heptane

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Hailin Li ◽  
W. Stuart Neill ◽  
Hongsheng Guo ◽  
Wally Chippior
Keyword(s):  
N2o Emission ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
N2o Emissions ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Incomplete Combustion ◽  
Hcci Combustion ◽  
Wide Range

This paper presents the oxides of nitrogen (NOx) and nitrous oxide (N2O) emission characteristics of a Cooperative Fuel Research (CFR) engine modified to operate in homogeneous charge compression ignition (HCCI) combustion mode. N-heptane was used as the fuel in this research. Several parameters were varied, including intake air temperature and pressure, air/fuel ratio (AFR), compression ratio (CR), and exhaust gas recirculation (EGR) rate, to alter the HCCI combustion phasing from an overly advanced condition where knocking occurred to an overly retarded condition where incomplete combustion occurred with excessive emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO). NOx emissions below 5 ppm were obtained over a fairly wide range of operating conditions, except when knocking or incomplete combustion occurred. The NOx emissions were relatively constant when the combustion phasing was within the acceptable range. NOx emissions increased substantially when the HCCI combustion phasing was retarded beyond the optimal phasing even though lower combustion temperatures were expected. The increased N2O and UHC emissions observed with retarded combustion phasing may contribute to this unexpected increase in NOx emissions. N2O emissions were generally less than 0.5 ppm; however, they increased substantially with excessively retarded and incomplete combustion. The highest measured N2O emissions were 1.7 ppm, which occurred when the combustion efficiency was approximately 70%.

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