Fueled Homogeneous Charge Compression Ignition Research Articles

Effects of hydrogen and EGR on energy efficiency improvement with ultra low emissions in a common rail direct injection compression ignition engine fueled with dimethyl ether (DME) under HCCI mode

This study deals with enhancing the energy efficiency with ultra-low emissions and extending the operating range (maximum load limit) of dimethyl ether (DME) fueled homogeneous charge compression ignition (HCCI) engine using hydrogen and exhaust gas recirculation (EGR). In the neat DME mode, the possible maximum load limit with controlled auto-ignition (CAI) was found as 24% (BMEP of 1.67 bar). Beyond 24% load, the knocking was observed with an advanced combustion phase, and shortened combustion duration resulted in uncontrolled auto-ignition (UAI) combustion. The addition of EGR extended the maximum load limit to 52% (BMEP of 3.62 bar) (60% EGR). Near-zero levels of NOx, zero smoke, and marginal CO and HC emissions reduction were observed with the optimized EGR rate (35%). The hydrogen fuel addition along with DME at an optimized EGR rate resulted in combustion phase retardation with the elimination of the low-temperature reaction (LTR) region. The energy efficiency (EE) and indicated thermal efficiency (ITE) increased along with zero smoke emission, ultra-low NOx, CO, and HC, and lower CO2 emissions till 12% of hydrogen energy share (HES). Thus, the combined strategy of EGR and hydrogen could effectively extend the operating range with ultra-low emissions levels.

Investigation on novel natural gas fueled homogeneous charge compression ignition engine based combined power and cooling system

A significant part of energy of fuel supplied is lost in internal combustion engines in the form of atmospheric discharge of engine exhaust gases which are considered as a big source of engine inefficiency and formation of pollutant emissions. To address this issue, a bottoming cycle combining the transcritical CO2 (T-CO2) refrigeration cycle and the supercritical CO2 (sCO2) power cycle is employed, aiming to produce cooling for food preservation by utilizing the exhaust heat of homogeneous charge compression ignition (HCCI) engine powering the refrigerated truck. The operative variables and their effect on thermal and exergetic efficiency of HCCI engine and the combined system are investigated. At the base case operative conditions, the thermal and exergy efficiencies of natural gas fueled HCCI engine are improved significantly from 48.69% to 61.28% and from 41.14% to 42.79%, respectively, after employing the sCO2 powered T-CO2 refrigeration cycle. Promotion of equivalence ratio from 0.3 to 0.9 enhances the thermal and exergy efficiencies of HCCI engine from 47.44% to 49.54% and from 40.14% to 42.12%, respectively. Increasing of engine speed from 1400 r.p.m to 2200 r.p.m provides marginal improvement in HCCI engine efficiencies but the efficiencies of combined cycle are significantly improved from 57.67% to 65.18% and from 40.64% to 45.06%, respectively. Finally, exergy analysis applied to determine the sources of non-idealities within the system revealed that out 361 kW (100%) fuel exergy supplied to the system, HCCI engine destroys 93.31 kW (25.85%), catalytic convertor destroys15.49 kW (4.29%), and the in-cylinder heat transfer losses and system exhaust losses are found as 35.72 kW (9.91%) and 16.61 kW (4.61%), respectively.

Experimental study of homogeneous charge compression ignition combustion in a light-duty diesel engine fueled with isopropanol–gasoline blends

Homogeneous charge compression ignition (HCCI) is a high-efficiency, ultra-low emission generating combustion technique that can potentially phase out conventional diesel combustion (CDC). Due to wide misfire and knocking limits, a limited load range impedes its commercial success. The present work addresses HCCI limitations using isopropanol–gasoline blends in a port fuel injected light-duty diesel engine. A cetane booster additive, 2-ethylhexyl nitrate (2-EHN), at 5vol.% was mixed with the test fuels to broaden the HCCI lower load limits. The tested fuels include biofuel isopropanol that replaced non-renewable gasoline in 20% increments to achieve higher loads during HCCI. The results show a substantial increment in HCCI operating load range (24%–86%) with test fuels over diesel HCCI (20%–38%). The characteristics of HCCI combustion in the modified test engine were benchmarked with CDC in the unmodified production engine. The significant benefits of HCCI over CDC were the concomitant reduction of indicated specific energy consumption (ISEC), oxides of nitrogen (NOx), and soot emissions, especially at higher loads. For instance, at 80% load, the ISEC, soot, and NOx were decreased by 5%, 99%, and 77%, respectively, for 60% isopropanol/35% gasoline/5% 2-EHN fueled HCCI than CDC. The exergy analysis was conducted to gain insight into irreversibility sources in thermodynamic processes during HCCI and CDC. The second law efficiency of HCCI improved with increased isopropanol content in the test fuels at a specific load. Overall, the present work shows that isopropanol–gasoline blends are viable alternatives to diesel to operate the HCCI engine that meets the desired emission and performance targets.

Application of waste heat in a novel trigeneration system integrated with an HCCI engine for power, heat and hydrogen production

In the current study, biomass was employed as the primary fuel in a multigenerational system to produce power, heat, and hydrogen. Biomass gasification unit, dual fuel homogeneous charge compression ignition (HCCI) engine, Rankine cycle, and waste heat recovery units are the main components of the developed system. The engine exhaust gas contains waste heat which can be utilized for biomass gasification. Hydrogen is the main output of the system whose specific fraction is introduced to the Heptane fueled HCCI engine. The results of the gasification unit and HCCI engine are in good agreement with the experimental reports in the literature. The cold gas and hydrogen efficiencies of the biomass gasification unit were 73% and 34%, respectively. Furthermore, the use of hydrogen as an additional fuel to the heptane-fueled HCCI engine improved the performance of the engine. Except for NOx, other emissions showed a decline. Results indicated that energy efficiency exceeded 57%, while the energy efficiency of the HCCI engine is 38%. Moreover, the exergy efficiency increased from 29% in the single HCCI engine to 47% in the proposed system.

Investigation of a Combined Refrigeration and Air Conditioning System Based on Two-Phase Ejector Driven by Exhaust Gases of Natural Gas Fueled Homogeneous Charge Compression Ignition Engine

Abstract A natural gas-fueled homogeneous charge compression ignition (HCCI) engine is coupled to an exhaust gas operated turbine driven two-phase ejector cycle to generate power and cooling energy, simultaneously. By establishing a thermodynamic model, the simulation of the proposed system and its parametric analyses are conducted. Energetic and exergetic investigations are carried out to study the role of equivalence ratio, engine speed, condenser temperature, refrigeration evaporator temperature, air-conditioning evaporator temperature, and ejector nozzle efficiency on the thermodynamic performance parameters of the combined cycle. The analysis of two-phase ejector cooling cycle using three working fluids including R717, R290, and R600a is conducted. Results reveal that the thermal efficiency of HCCI engine is increased from 47.44% to 49.94%, and for the R600a operated combined cycle it is increased from 60.05% to 63.26% when the equivalence ratio is promoted from 0.3 to 0.6. Distribution of fuel exergy results show that out of 100% exergy input, in case of R717 operated combined cycle, 139.79 kW (38.72%) is the total exergy output, and 164.21 kW (45.49%) and 57 kW (15.79%) are the values for exergy destruction and exergy losses. It is further shown that change in refrigerant minorly influence the percentages of exergy distribution.

Characterization of ringing intensity in a hydrogen-fueled HCCI engine

Homogeneous charge compression ignition (HCCI) is a promising alternative combustion strategy having higher thermal efficiency while maintaining the NOx and soot emissions below the current emissions mandates. The HCCI combustion engine has typically lower operating load range in comparison to conventional engines. The HCCI combustion is constrained by various operational limits such as combustion instability limit, combustion noise limits, emission limits and peak cylinder pressure limit. High load limit of HCCI combustion is typically limited by very high heat release rate, which leads to ringing operation. Intense ringing operation leads to very high combustion noise, and heavy ringing operation can also damage the engine parts. Thus, it is important to investigate the characteristics of ringing intensity (RI) in HCCI engine. Hydrogen fueled HCCI engine combines the potential advantages of alternative fuel as well as the alternative combustion strategy. This study presents the RI characterization and prediction using chemical kinetics and artificial neural network (ANN) for hydrogen-HCCI operation. In the first part of the study, the effect of equivalence ratio (φ), inlet temperature (Tivc), and engine speed on ringing intensity is investigated using chemical kinetics model. Based on ringing operation characteristics of hydrogen HCCI engine, ANN model is used to predict the ringing intensity (RI) for different engine operating conditions (i.e., φ Tivc, engine speed) and different combustion parameters. The result indicates that RI increases with advanced combustion phasing (CA50), higher inlet temperature, and equivalence ratio. To control the ringing operation, the CA50 position needs to be retarded by optimizing the Tivc and φ. Maximum engine operating range is found for lower engine speed (i.e., 1000 rpm) and reduces with increase in the engine speed. The results showed that the RI is strongly correlated to the CA50 position with a correlation coefficient of 0.99 at constant inlet temperature. The ANN results also show that ANN model predicts RI with sufficient accuracy. The ANN model predicts RI with engine operating conditions as well as combustion parameters with a correlation coefficient of 0.97 and 0.95 respectively.

Numerical study of engine parameters on combustion and performance characteristics in an n-heptane fueled HCCI engine

Homogeneous charge compression ignition (HCCI) is an alternative combustion concept which offers significant benefits in terms of its high efficiency. However, the operational range using HCCI combustion in terms of speed and load is restricted due to the absence of the direct control of the onset of ignition and the heat release rate. In this work, a zero-dimensional single-zone numerical simulation with reduced fuel chemistry was developed and used to investigate the effect of various engine parameters on combustion and performance characteristics in an HCCI engine fueled with n-heptane. The simulations show good agreement while comparing the results with the published experimental results and capture important combustion phase trends as engine parameters are varied with a minimum percentage of error which is less than 6%. The combustion phase was advanced and the combustion duration was shortened with the increase of intake air temperature and the decrease of the engine speed. The maximum load was successfully increased with increasing the intake air pressure. The highest load in this work was 11.27bar in IMEPg at the condition of 200kPa in intake air pressure and 333K in intake air temperature.

Using detailed chemical kinetics 3D-CFD model to investigate combustion phase of a CNG-HCCI engine according to control strategy requirements

Homogeneous Charge Compression Ignition (HCCI) method decline soot and NOx emission by offering high thermal efficiency in order of diesel engine. However, controlling HCCI combustion phenomena is known as the significant setback for its development. Control-oriented models use CA5, CA10, CA50 and CA90 as the most important dependent variables. Start of combustion (SOC), for instance, has already been traced via pressure rise versus crank angle. In fact, these simplifications have been progressed to reach real-time response as the main nature of controlling target. In this study, a 3D CFD model coupled with detailed chemical kinetics has been modified to devise a brief relation between these controlling parameters and what really happens in combustion chamber. The model has been validated with experimental results in four distinct conditions. To detect combustion phase, hydroxyl radical (OH) has been suggested as an indicator among all other chemical species due to its significant role in CNG combustion. Various sets of simulations have come up with noticeable findings that CA50 in CNG fueled HCCI engine equals crank angles when OH concentration and pressure rise rate reach their peaks. This result represents OH as a potential robust parameter in HCCI engine control even though this relation is not established well in weak combustion region rather than high heat release rate (HHR) cases. Finally, IMEP and BSFC, as the most important performance parameters of an engine have studied versus CA50 and OH concentration variation. The comparison proved good agreement between these two terms except in near-TDC combustion cases.

Experimental investigation on the effect of charge temperature on ethanol fueled HCCI combustion engine

In this investigation, an attempt has been made to study by varying the charge temperature on the ethanol fueled Homogeneous charge compression ignition (HCCI) combustion engine. Ethanol was injected into the intake manifold by using port fuel injection technique while the intake air was heated for achieving stable HCCI operation. The effect of intake air temperature on the combustion, performance, and emissions of the ethanol HCCI operation was compared with the standard diesel operation and presented. The results indicate that the intake air temperature has a significant impact on in-cylinder pressure, ringing intensity, combustion efficiency, thermal efficiency and emissions. At 170°C, the maximum value of combustion efficiency and brake thermal efficiency of ethanol are found to be 98.2% and 43%, respectively. The NO emission is found to be below 11 ppm while the smoke emission is negligible. However, the UHC and CO emissions are higher for the HCCI operation.

Experimental and numerical analysis of the performance and exhaust gas emissions of a biogas/n-heptane fueled HCCI engine

The use of highly reactive fuel as an ignition promoter enables operation of biogas fueled homogeneous charge compression ignition (HCCI) engine at low intake temperatures with practical control of combustion phasing. In order to gain some insight into this operation mode the influence of addition of n-heptane on combustion, performance, emissions and control of combustion phasing of a biogas fueled HCCI engine is experimentally researched and presented in this paper. Additionally, the performance analysis of the practical engine solution for such operation is estimated by using the numerical simulation of entire engine. The results showed that the introduction of highly reactive fuel results with a significant change in operating conditions and with a change in optimum combustion phasing. The addition of n-heptane resulted in lower nitrogen oxides and increased carbon monoxide emissions, while the unburned hydrocarbons emissions were strongly influenced by combustion phasing and at optimal conditions are lowered compared to pure biogas operation. The results also showed a practical operation range for strategies that use equivalence ratio as a control of load. Simulation results showed that the difference in performance between pure biogas and n-heptane/biogas operation is even greater when the practical engine solution is taken into account.

Spark‐assisted HCCI engine using hydrous methanol as a fuel: an ANN approach

AbstractThe main purpose of the experiment is to investigate the performance and emission characteristics of a hydrous methanol (85% methanol and 15% water) fueled homogeneous charge compression ignition (HCCI) engine through various spark timings (SPT) (32°, 34°, 36°, 38° and 40° before Top Dead Centre). In this study a spark plug is used for assisting auto‐ignition. Experimental investigation reveals that the brake thermal efficiency (BTE) of an HCCI engine increases when the SPT is increased and a maximum BTE of 28.5% was obtained for 40°SPT. Emission analysis reveals a significant decrease in nitrogen oxides (NOx) as there are slightly higher emissions of hydrocarbon (HC) and carbon monoxide (CO). An artificial neural network (ANN) was developed with brake mean effective pressure (BMEP), SPT, and energy share as the input data and BTE, NOx, HC, CO, and rate of pressure rise as output data. In this prediction technique, about 80% of experimental data obtained were used in training and 20% of data were used to test the model developed. The performance in the developed ANN models was compared with experimental data, and statistically evaluated; they are seen to have good agreement. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Effect of hydrogen peroxide addition to methane fueled homogeneous charge compression ignition engines through numerical simulations

The effect of the direct injection of hydrogen peroxide into a port-injected methane fueled homogeneous charge compression ignition engine was investigated numerically. The injection of aqueous hydrogen peroxide was implemented as a means of combustion phasing control. A single-cylinder homogeneous charge compression ignition engine (2.43 L Caterpillar) was modeled using the Cantera 2.0 flame code toolkit, the GRI-Mech 3.0 chemical reaction mechanism, and a single-zone slider-crank engine model. Start of injection timing and the amount of injected hydrogen peroxide were manipulated to achieve desired combustion phasing under a wide range of intake temperatures. As the concentration of hydrogen peroxide is increased, the combustion phasing is advanced up to 22° for the conditions investigated in this study. This advancing effect is most pronounced at small concentrations (<10 g H2O2/kg CH4) and early injection timings (start of injection < 25° before top dead center). The model suggests hydrogen peroxide can be introduced as a means of combustion phasing control while maintaining the low emissions and peak in-cylinder pressures inherent in homogeneous charge compression ignition engines.

Investigations on the effects of intake temperature and charge dilution in a hydrogen fueled HCCI engine

This work was aimed at improving the performance and extending the load range of hydrogen fueled homogeneous charge compression ignition (HCCI) engine through charge temperature regulation and addition of carbon dioxide in order to control the combustion phasing. Intake charge temperature and equivalence ratio were varied from 130 °C to 80 °C and 0.19 to 0.3 respectively. In the neat hydrogen mode it was possible to operate the engine only until a brake mean effective pressure (BMEP) of 2.2 bar. Higher charge temperatures lead to knocking and advanced combustion. At any equivalence ratio the lowest possible charge temperature is the one that leads to the highest thermal efficiency. Addition of carbon dioxide retarded the combustion process and improved the thermal efficiency and also extended the load range to a BMEP of 3.1 bar. Efficiencies of hydrogen HCCI mode were higher than the conventional diesel mode with negligible level of NO emissions.

Experimental Investigations of Particulate Size and Number Distribution in an Ethanol and Methanol Fueled HCCI Engine

Alcohols (ethanol and methanol) are being widely considered as alternative fuels for automotive applications. At the same time, homogeneous charge compression ignition (HCCI) engine has attracted global attention due to its potential of providing high engine efficiency and ultralow exhaust emissions. Environmental legislation is becoming increasingly stringent, sharply focusing on particulate matter (PM) emissions. Recent emission norms consider limiting PM number concentrations in addition to PM mass. Therefore, present study is conducted to experimentally investigate the effects of engine operating parameters on the PM size–number distribution in a HCCI engine fueled with gasoline, ethanol, and methanol. The experiments were conducted on a modified four-cylinder diesel engine, with one cylinder modified to operate in HCCI mode. Port fuel injection was used for preparing homogeneous charge in the HCCI cylinder. Intake air preheating was used to enable auto-ignition of fuel–air mixture. Engine exhaust particle sizer (EEPS) was used for measuring size–number distribution of soot particles emitted by the HCCI engine cylinder under varying engine operating conditions. Experiments were conducted at 1200 and 2400 rpm by varying intake air temperature and air–fuel ratio for gasoline, ethanol, and methanol. In this paper, the effect of engine operating parameters on PM size–number distribution, count mean diameter (CMD), and total PM numbers is investigated. The experimental data show that the PM number emissions from gasoline, ethanol, and methanol in HCCI cannot be neglected and particle numbers increase for relatively richer mixtures and higher intake air temperatures.

Combustion and Emission Characterization of n-Butanol Fueled HCCI Engine

Biofuels are attracting global attention as alternate transportation fuels due to advantages of their being produced from locally available renewable resources, lower pollution potential, and biodegradable nature. Butanol is fast emerging as one of the competitive biofuels for use in transportation engines. Homogeneous charge compression ignition (HCCI) engines have shown great potential for higher engine efficiency and ultralow NOx and particulate matter (PM) emissions. This experimental study is therefore carried out to combine the advantages of biofuels and HCCI engines, both. Detailed performance, combustion, and emission characteristics of n-butanol fueled HCCI engine are investigated experimentally. The study is conducted on a four cylinder diesel engine, whose one cylinder was modified to operate in HCCI combustion mode. Port fuel injection technique was used for homogeneous charge preparation in the intake manifold. Auto-ignition of fuel in the engine cylinder was achieved by intake air preheating. In-cylinder pressure-crank angle data acquisition with subsequent heat release analyses and exhaust emission measurements were done for combustion and emission characterization. In this paper, the effect of intake air temperature and air–fuel ratio on the combustion parameters, thermal and combustion efficiency, ringing intensity (RI), and emissions from n-butanol fueled HCCI engine were analyzed and discussed comprehensively. Empirical correlations were derived to fit the experimental data for various combustion parameters.

Analysis of benefits of using internal exhaust gas recirculation in biogas-fueled HCCI engines

This paper describes a numerical study that analyzed the influence of combustion products (CP) concentration on the combustion characteristics (combustion timing and combustion duration) of a biogas fueled homogeneous charge compression ignition (HCCI) engine and the possibility of reducing the high intake temperature requirement necessary for igniting biogas in a HCCI engine by using internal exhaust gas recirculation (EGR) enabled by negative valve overlap (NVO). An engine model created in AVL Boost, and validated against experimental engine data, was used in this study. The results show, somewhat counter-intuitively, that when CP concentrations are increased the required intake temperature for maintaining the same combustion timing must be increased. When greater NVO is used to increase the in-cylinder CP concentration, the in-cylinder temperature does increase, but the chemical dilution influence of CP almost entirely counteracts this thermal effect. Additionally, it has been observed that with larger fractions of CP some instability of combustion in the calculation was obtained which indicates that the increase of internal EGR might produce some combustion instability.

Experimental investigations of performance, combustion and emission characteristics of ethanol and methanol fueled HCCI engine

Homogeneous charge compression ignition (HCCI) engines have potential to provide both diesel like efficiencies and very low NOx and particulate matter (PM) emissions. There is growing global interest in using alternative biofuels in order to reduce the reliance on conventional fossil fuels. Therefore this experimental study was carried out to investigate performance, combustion and emission characteristics of HCCI engine fueled with ethanol and methanol and compare it with baseline gasoline fuel. The experiments were conducted on a modified four-cylinder four-stroke engine at different engine speeds using port fuel injection technique for preparing homogeneous charge. To achieve auto-ignition of air–fuel mixture in the combustion chamber, intake air pre-heater was used. In-cylinder pressure data acquisition with subsequent heat release analysis and exhaust emission measurements were done for combustion and emission diagnostics. In this paper, effect of intake air temperature and air–fuel ratio on combustion parameters, thermal efficiency, combustion efficiency, ringing intensity and emissions in HCCI engine is analyzed and discussed. Results show that methanol and ethanol are good replacements to gasoline in HCCI combustion mode.

Experimental study on liquefied petroleum gas fueled homogeneous charge compression ignition engine

EGR (Exhaust Gas Recirculation) is one of the most effective techniques currently available for reducing NOx emissions from compression ignition engines but its application to LPG (liquefied petroleum gas) fueled HCCI (Homogeneous Charge Compression ignition) engine is yet to be widely implemented. The objective of this research is to determine the effects of EGR on the combustion processes of HCCI-LPG engine. Butane and propane were used for the LPG fueled HCCI engines. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI-LPG engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders.

Numerical Analysis of Biogas Composition Effects on Combustion Parameters and Emissions in Biogas Fueled HCCI Engines for Power Generation

This study investigates the effects of biogas composition on combustion stability for a purely biogas fueled homogeneous charge compression ignition (HCCI) engine. Biogas is one of the most promising renewable fuels for combined heat and power systems driven by internal combustion engines. However, the high content of CO2 in biogas composition leads to low thermal efficiencies in spark ignited and dual fuel compression ignited engines. The study is divided into two parts: First experimental results on a biogas-fueled HCCI engine are used to illustrate the effects of intake conditions on combustion stability, and second a simulation methodology is used to investigate how biogas composition impacts combustion stability at constant intake conditions. Experimental analysis of a four cylinder, 1.9 L Volkswagen TDI diesel engine shows that biogas-HCCI combustion exhibits high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%), and ultralow NOx emissions below the US2010 limit (0.27 g/kWh). An inlet absolute pressure of 2 bar and inlet temperature of 473 K (200 °C) were required for allowing HCCI combustion with a biogas composition of 60% CH4 and 40% CO2 on a volumetric basis. However, slight changes in inlet pressure and temperature caused large changes in cycle-to-cycle variations at low equivalence ratios and large changes in ringing intensity at high equivalence ratios. Numerical analysis of biogas-HCCI combustion is carried out with a sequential methodology that includes one-zone model simulations, computational fluid dynamics (CFD) analysis, and 12-zones model simulations. Numerical results for varied biogas composition show that at high load limit, higher contents of CH4 in biogas composition allow advanced combustion and increased burning rates of the biogas air mixture. Higher contents of CO2 in biogas composition allow lowered ringing intensities with moderate decrease in the indicated efficiency and power output. NOx emissions are not highly affected by biogas composition, while CO and unburned hydrocarbons (HC) emissions tend to increase with higher contents of CO2. According with the numerical results, biogas composition is an effective strategy to control the onset of combustion and combustion phasing of HCCI engines running biogas, allowing more stabilized combustion at low equivalence ratios and safe operation at high equivalence ratios. The main advantages of using biogas-fueled HCCI engines in CHP systems are the low sensitivity of power output and indicated efficiency to biogas composition, as well as the ultralow NOx emissions achieved for all tested compositions.

Utilization of waste heat from a HCCI (homogeneous charge compression ignition) engine in a tri-generation system

The waste heat from exhaust gases and cooling water of Homogeneous charge compression ignition engines (HCCI) are utilized to drive an ammonia-water cogeneration cycle (AWCC) and some heating processes, respectively. The AWCC is a combination of the Rankine cycle and an absorption refrigeration cycle. Considering the chemical kinetic calculations, a single zone combustion model is developed to simulate the natural gas fueled HCCI engine. Also, the performance of AWCC is simulated using the Engineering Equation Solver software (EES). Through combining these two codes, a detailed thermodynamic analysis is performed for the proposed tri-generation system and the effects of some main parameters on the performances of both the AWCC and the tri-generation system are investigated in detail. The cycle performance is then optimized for the fuel energy saving ratio (FESR). The enhancement in the FESR could be up to 28.56%. Under optimized condition, the second law efficiency of proposed system is 5.19% higher than that of the HCCI engine while the reduction in CO2 emission is 4.067% as compared with the conventional separate thermodynamic systems. Moreover, the results indicate that the engine, in the tri-generation system and the absorber, in the bottoming cycle has the most contribution in exergy destruction.