International

Understanding optimal engine operating strategies for gasoline-fueled HCCI engines using crank-angle resolved exergy analysis

This study couples a crank-angle resolved exergy analysis methodology with a multi-zone chemical kinetic model of a gasoline-fueled HCCI engine to quantify exergy loss mechanisms and understand how the losses change with different HCCI engine operating conditions. The in-cylinder exergy loss mechanisms are identified as losses to combustion, heat loss, unburned species, and physical exergy lost to exhaust gases.

Highly flexible burner concept for research on combustion technologies with recirculation of hot combustion products

This paper reports the development and testing of a research coflow burner that generates laminar flames in a hot and diluted environment, which is adequate for studying the operating conditions found in practical combustors that use flue gas recirculation techniques. The burner has two flame zones; the first is an annular laminar premixed flat flame stabilized by a perforated plate, which generates a hot oxygen-rich flue gas mixture. The second is a non-premixed laminar flame, which uses the hot oxygen-rich flue gas mixture as an oxidizer.

Experimental evaluation of a 20 kW oxygen enhanced self-regenerative burner operated in flameless combustion mode

Results are presented on the effects of oxygen enrichment on the performance of a flameless combustion furnace equipped with a regenerative burner. Natural gas was used as fuel (∼97% CH4) and the oxygen concentration in the combustion air was varied from 21% to 35% (volumetric percent). The influence of oxygen enrichment on temperature and species profiles, pollutant emissions, thermal efficiency and regenerators effectiveness was quantified; measures were registered under steady state conditions for average wall temperatures of 880 °C.

Heat transfer model in recuperative compact heat exchanger type honeycomb: Experimental and numerical analysis

This paper presents a model to calculate the thermal performance of a heat recovery unit fabricated from an alumina honeycomb matrix and a methodology for the discretization of the energy equations necessary to develop a calculation algorithm for designing and sizing compact heat recovery units. Based on the results from the algorithm, a prototype heat recovery unit built from alumina honeycomb was tested. The device reached an efficiency of 84% and an air preheating temperature of 621 °C for an 8.19 kW power level.

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.

Understanding Loss Mechanisms and Identifying Areas of Improvement for HCCI Engines Using Detailed Exergy Analysis

This paper presents a detailed exergy analysis of homogeneous charge compression ignition (HCCI) engines, including a crank-angle resolved breakdown of mixture exergy and exergy destruction. Exergy analysis is applied to a multizone HCCI simulation including detailed chemical kinetics. The HCCI simulation is validated against engine experiments for ethanol-fueled operation. The exergy analysis quantifies the relative importance of different loss mechanisms within HCCI engines over a range of engine operating conditions.

Laminar burning velocity and interchangeability analysis of biogas/C3H8/H2 with normal and oxygen-enriched air

Numerical and experimental measurements of the laminar burning velocities of biogas (66% CH4 – 34% CO2) and a biogas/propane/hydrogen mixture (50% biogas – 40% C3H8 – 10% H2) were made with normal and oxygen-enriched air while varying the air/fuel ratio. GRI-Mech 3.0 and C1–C3 reaction mechanisms were used to perform numerical simulations. Schlieren images of laminar premixed flames were used to determine laminar burning velocities at 25 °C and 849 mbar. The mixture's laminar burning velocity was found to be higher to that of pure biogas due to the addition of propane and hydrogen.

Laminar burning velocity with oxygen-enriched air of syngas produced from biomass gasification

Several studies on the laminar burning velocity of syngas mixtures have been conducted by various researchers. However, in most of these studies, dry air was used as the oxidizer, whereas very few studies have been conducted on syngas combustion in oxygen – enriched air. In this work, a numerical and experimental study on the laminar burning velocity of a mixture of H2, CO and N2 (20:20:60 vol%) was performed using air enriched with oxygen as the oxidizer, varying the oxygen content from 21% up to 35% for different equivalence ratios.

Effects of oxygen enriched air on the operation and performance of a diesel-biogas dual fuel engine

The effect of oxygen enriched air was tested for a diesel-biogas dual fuel engine. The operation and performance characteristics, such as thermal efficiency, pollutant emissions and combustion parameters were determined. Experiments have been carried out with a stationary compression ignition (CI) engine coupled with a generator in dual mode using a typical biogas composition of 60 vol. %CH4 and 40% vol. %CO2. For every engine load evaluated, the oxygen concentration in the intake air engine was varied from 21% to 27% O2 v/v.

Experimental evaluation of strategies to increase the operating range of a biogas-fueled HCCI engine for power generation

In this research oxygen enrichment, gasoline pilot port injection, and delayed time of 50% cumulative heat release (CA50) are evaluated to expand the range for stable and safe combustion of a lean-burning biogas-fueled HCCI engine. A 4-cylinder 1.9 L Volkswagen TDI engine was modified to run in HCCI mode at 1800 rpm, and boost pressures and charge heating are used to promote autoignition of the biogas-in-air mixture at desired combustion timings. A typical biogas composition of 60% CH4 and 40% CO2 in a volumetric basis was simulated by controlling the CH4 and CO2 flow rates.

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