Exploring Strategies for Reducing High Intake Temperature Requirements and Allowing Optimal Operational Conditions in a Biogas Fueled HCCI Engine for Power Generation

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Iván D. Bedoya ◽  
Samveg Saxena ◽  
Francisco J. Cadavid ◽  
Robert W. Dibble
Keyword(s):  
Power Generation ◽  
Power Output ◽  
Numerical Results ◽  
Inlet Temperature ◽  
Zone Model ◽  
Nox Emissions ◽  
Efficient Operation ◽  
Operational Conditions ◽  
Hcci Engines ◽  
Temperature Requirements

This paper evaluates strategies for reducing the intake temperature requirement for igniting biogas in homogeneous charge compression ignition (HCCI) engines. The HCCI combustion is a promising technology for stationary power generation using renewable fuels in combustion engines. Combustion of biogas in HCCI engines allows high thermal efficiency similar to diesel engines, with low net CO2 and low NOx emissions. However, in order to ensure the occurrence of autoignition in purely biogas fueled HCCI engines, a high inlet temperature is needed. This paper presents experimental and numerical results. First, the experimental analysis on a 4 cylinder, 1.9 L Volkswagen TDI diesel engine running with biogas in the HCCI mode shows high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%) and NOx emissions below the 2010 US limit (0.27 g/kWh). Stable HCCI operation is experimentally demonstrated with a biogas composition of 60% CH4 and 40% CO2 on a volumetric basis, inlet pressures of 2–2.2 bar (absolute), and inlet temperatures of 200–210 °C for equivalence ratios between 0.19–0.29. At lower equivalence ratios, slight changes in the inlet pressure and temperature caused large changes in cycle-to-cycle variations, while at higher equivalence ratios these same small pressure and temperature variations caused large changes to the ringing intensity. Second, numerical simulations have been carried out to evaluate the effectiveness of high boost pressures and high compression ratios for reducing the inlet temperature requirements while attaining safe operation and high power output. The one zone model in Chemkin was used to evaluate the ignition timing and peak cylinder pressures with variations in temperatures at intake valve close (IVC) from 373 to 473 K. In-cylinder temperature profiles between IVC and ignition were computed using Fluent 6.3 and fed into the multizone model in Chemkin to study combustion parameters. According to the numerical results, the use of both higher boost pressures and higher compression ratios permit lower inlet temperatures within the safe limits experimentally observed and allow higher power output. However, the range of inlet temperatures allowing safe and efficient operation using these strategies is very narrow, and precise inlet temperature control is needed to ensure the best results.

Exploring Strategies for Reducing High Intake Temperature Requirements and Allowing Optimal Operational Conditions in a Biogas Fueled HCCI Engine for Power Generation

2011 ◽  
Author(s):  
Iva´n D. Bedoya ◽  
Samveg Saxena ◽  
Francisco J. Cadavid ◽  
Robert W. Dibble
Keyword(s):  
Power Generation ◽  
Power Output ◽  
Numerical Results ◽  
Inlet Temperature ◽  
Zone Model ◽  
Nox Emissions ◽  
Efficient Operation ◽  
Operational Conditions ◽  
Hcci Engines ◽  
Temperature Requirements

This paper evaluates strategies for reducing the intake temperature requirement for igniting biogas in HCCI engines. HCCI combustion is a promising technology for stationary power generation using renewable fuels in combustion engines. Combustion of biogas in HCCI engines allows high thermal efficiency similar to Diesel engines, with low net CO2 and low NOx emissions. However, in order to ensure the occurrence of autoignition in purely biogas fueled HCCI engines, a high inlet temperature is needed. This paper presents experimental and numerical results. First, experimental analysis on a 4 cylinder, 1.9 L Volkswagen TDI Diesel engine running with biogas in HCCI mode shows high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%) and NOx emissions below the 2010 US limit (0.27g/kWh). Stable HCCI operation is experimentally demonstrated with a biogas composition of 60% CH4 and 40% CO2 on a volumetric basis, inlet pressures of 2–2.2 bar (absolute) and inlet temperatures of 200–210°C for equivalence ratios between 0.19–0.29. At lower equivalence ratios, slight changes in inlet pressure and temperature caused large changes in cycle-to-cycle variations while at higher equivalence ratios these same small pressure and temperature variations caused large changes to ringing intensity. Second, numerical simulations have been carried out to evaluate the effectiveness of high boost pressures and high compression ratios for reducing the inlet temperature requirements while attaining safe operation and high power output. The one zone model in Chemkin was used to evaluate the ignition timing and peak cylinder pressures with variations in temperatures at IVC from 373 to 473 K. In-cylinder temperature profiles between IVC and ignition were computed using Fluent 6.3 and fed into the multi-zone model in Chemkin to study combustion parameters. According to the numerical results, the use of both higher boost pressures and higher compression ratios permit lower inlet temperatures within the safe limits experimentally observed and allow higher power output. However, the range of inlet temperatures allowing safe and efficient operation using these strategies is very narrow, and precise inlet temperature control is needed to ensure the best results.

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

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Iván D. Bedoya ◽  
Samveg Saxena ◽  
Francisco J. Cadavid ◽  
Robert W. Dibble
Keyword(s):  
Numerical Analysis ◽  
Power Output ◽  
Numerical Results ◽  
Combustion Stability ◽  
Absolute Pressure ◽  
Nox Emissions ◽  
Model Simulations ◽  
Hcci Engine ◽  
Hcci Combustion ◽  
Hcci Engines

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.

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

2011 ◽  
Author(s):  
Iva´n D. Bedoya ◽  
Samveg Saxena ◽  
Francisco J. Cadavid ◽  
Robert W. Dibble
Keyword(s):  
Numerical Model ◽  
Power Output ◽  
Internal Combustion Engines ◽  
Numerical Results ◽  
Experimental Results ◽  
Combustion Stability ◽  
Absolute Pressure ◽  
Nox Emissions ◽  
Hcci Engine ◽  
Hcci Engines

This study investigates the effects of biogas composition on combustion stability for a purely biogas fueled 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 validate a numerical model, and second the model is used to investigate how biogas composition impacts combustion stability. In the first part of the study, experimental analysis of a 4 cylinder, 1.9 L Volkswagen TDI Diesel engine running with biogas in HCCI mode has shown high gross indicated mean effective pressure (close to 8 bar), high gross indicated efficiency (close to 45%) and ultra-low 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. A numerical model is validated against these experimental results. In the second part of the study, the 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 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 ultra low NOx emissions achieved for all tested compositions.

A Study on Low NOx Combustion in LBG-Fueled 1500°C-Class Gas Turbine

1996 ◽  
Vol 118 (3) ◽  
pp. 534-540 ◽  
Author(s):  
T. Nakata ◽  
M. Sato ◽  
T. Ninomiya ◽  
T. Hasegawa
Keyword(s):  
Power Generation ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Combustion Process ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Gas Temperature

Developing integrated coal gasification combined-cycle systems ensures cost-effective and environmentally sound options for supplying future power generation needs. The reduction of NOx emissions and increasing the inlet temperature of gas turbines are the most significant issues in gas turbine development in Integrated Coal Gasification Combined Cycle (IGCC) power generation systems. The coal gasified fuel, which is produced in a coal gasifier of an air-blown entrained-flow type has a calorific value as low as 1/10 of natural gas. Furthermore, the fuel gas contains ammonia when a gas cleaning system is a hot type, and ammonia will be converted to nitrogen oxides in the combustion process of a gas turbine. This study is performed in a 1500°C-class gas turbine combustor firing low-Btu coal-gasified fuel in IGCC systems. An advanced rich-lean combustor of 150-MW class gas turbine was designed to hold stable combustion burning low-Btu gas and to reduce fuel NOx emissions from the ammonia in the fuel. The main fuel and the combustion air are supplied into a fuel-rich combustion chamber with strong swirl flow and make fuel-rich flame to decompose ammonia into intermediate reactants such as NHi and HCN. The secondary air is mixed with primary combustion gas dilatorily to suppress the oxidization of ammonia reactants in fuel-lean combustion chamber and to promote a reducing process to nitrogen. By testing under atmospheric pressure conditions, the authors have obtained a very significant result through investigating the effect of combustor exit gas temperature on combustion characteristics. Since we have ascertained the excellent performance of the tested combustor through our extensive investigation, we wish to report on the results.

scholarly journals Impact of Power Output Curtailment Control of Photovoltaic Power Generation on Grid Frequency

2020 ◽  
Vol 53 (2) ◽  
pp. 12157-12162
Author(s):  
Takeyoshi Kato ◽  
Masaki Imanaka ◽  
Muneaki Kurimoto ◽  
Shigeyuki Sugimoto
Keyword(s):  
Power Generation ◽  
Power Output ◽  
Photovoltaic Power

scholarly journals Cu2Se-based thermoelectric cellular architectures for efficient and durable power generation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Seungjun Choo ◽  
Faizan Ejaz ◽  
Hyejin Ju ◽  
Fredrick Kim ◽  
Jungsoo Lee ◽  
...  
Keyword(s):  
Power Generation ◽  
3D Printing ◽  
Power Output ◽  
Waste Heat ◽  
Computational Simulation ◽  
Mechanical Stiffness ◽  
Higher Power ◽  
Printing Inks ◽  
Binder Free ◽  
Sustainable Power

AbstractThermoelectric power generation offers a promising way to recover waste heat. The geometrical design of thermoelectric legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular thermoelectric architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu2Se thermoelectric materials. We design the optimum aspect ratio of a cuboid thermoelectric leg to maximize the power output and extend this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based thermoelectric legs. Moreover, we develop organic binder-free Cu2Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se82− polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrate the superior power output and mechanical stiffness of the proposed cellular thermoelectric architectures to other designs, unveiling the importance of topological designs of thermoelectric legs toward higher power and longer durability.

scholarly journals Predicting the Performance of Solar Power Generation Using Deep Learning Methods

2021 ◽  
Vol 11 (15) ◽  
pp. 6887
Author(s):  
Chung-Hong Lee ◽  
Hsin-Chang Yang ◽  
Guan-Bo Ye
Keyword(s):  
Power Generation ◽  
Solar Energy ◽  
Power Output ◽  
Power Plants ◽  
Solar Power ◽  
Photovoltaic Cell ◽  
Power Prediction ◽  
Seasonal Characteristics ◽  
Variable Nature ◽  
Solar Power Plants

In recent years, many countries have provided promotion policies related to renewable energy in order to take advantage of the environmental factors of sufficient sunlight. However, the application of solar energy in the power grid also has disadvantages. The most obvious is the variability of power output, which will put pressure on the system. As more grid reserves are needed to compensate for fluctuations in power output, the variable nature of solar power may hinder further deployment. Besides, one of the main issues surrounding solar energy is the variability and unpredictability of sunlight. If it is cloudy or covered by clouds during the day, the photovoltaic cell cannot produce satisfactory electricity. How to collect relevant factors (variables) and data to make predictions so that the solar system can increase the power generation of solar power plants is an important topic that every solar supplier is constantly thinking about. The view is taken, therefore, in this work, we utilized the historical monitoring data collected by the ground-connected solar power plants to predict the power generation, using daily characteristics (24 h) to replace the usual seasonal characteristics (365 days) as the experimental basis. Further, we implemented daily numerical prediction of the whole-point power generation. The preliminary experimental evaluations demonstrate that our developed method is sensible, allowing for exploring the performance of solar power prediction.

A Critical Review of NOx Correlations for Gas Turbine Combustors

1975 ◽  
Author(s):  
D. A. Sullivan ◽  
P. A. Mas
Keyword(s):  
Experimental Data ◽  
Data Base ◽  
Gas Turbine ◽  
Critical Review ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Empirical Correlations ◽  
Gas Turbine Combustors ◽  
Semi Empirical ◽  
Adequate Data

The effect of inlet temperature, pressure, air flowrate and fuel-to-air ratio on NOx emissions from gas turbine combustors has received considerable attention in recent years. A number of semi-empirical and empirical correlations relating these variables to NOx emissions have appeared in the literature. They differ both in fundamental assumptions and in their predictions. In the present work, these simple NOx correlations are compared to each other and to experimental data. A review of existing experimental data shows that an adequate data base does not exist to evaluate properly the various NOx correlations. Recommendations are proposed to resolve this problem in the future.

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