Numerical investigation of radiative heat transfer in internal combustion engines

2019 ◽  
Vol 235 ◽  
pp. 147-163 ◽  
Author(s):  
Zongyu Yue ◽  
Rolf D. Reitz
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Radiative Heat Transfer ◽  
Internal Combustion Engines ◽  
Radiative Heat ◽  
Internal Combustion ◽  
Combustion Engines

Maximum efficiencies for internal combustion engines: Thermodynamic limitations

2017 ◽  
Vol 19 (10) ◽  
pp. 1005-1023 ◽  
Author(s):  
Jerald A Caton
Keyword(s):  
Heat Transfer ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Pressure Rise ◽  
Internal Combustion ◽  
Thermodynamic Evaluation ◽  
Combustion Engines ◽  
Automotive Engine ◽  
Specific Heats ◽  
Cycle Simulation

The thermodynamic limitation for the maximum efficiencies of internal combustion engines is an important consideration for the design and development of future engines. Knowing these limits helps direct resources to those areas with the most potential for improvements. Using an engine cycle simulation which includes the first and second laws of thermodynamics, this study has determined the fundamental thermodynamics that are responsible for these limits. This work has considered an automotive engine and has quantified the maximum efficiencies starting with the most ideal conditions. These ideal conditions included no heat losses, no mechanical friction, lean operation, and short burn durations. Then, each of these idealizations is removed in a step-by-step fashion until a configuration that represents current engines is obtained. During this process, a systematic thermodynamic evaluation was completed to determine the fundamental reasons for the limitations of the maximum efficiencies. For the most ideal assumptions, for compression ratios of 20 and 30, the thermal efficiencies were 62.5% and 66.9%, respectively. These limits are largely a result of the combustion irreversibilities. As each of the idealizations is relaxed, the thermal efficiencies continue to decrease. High compression ratios are identified as an important aspect for high-efficiency engines. Cylinder heat transfer was found to be one of the largest impediments to high efficiency. Reducing cylinder heat transfer, however, is difficult and may not result in much direct increases of piston work due to decreases of the ratio of specific heats. Throughout this work, the importance of high values of the ratio of specific heats was identified as important for achieving high thermal efficiencies. Depending on the selection of constraints, different values may be given for the maximum thermal efficiency. These constraints include the allowed values for compression ratio, heat transfer, friction, stoichiometry, cylinder pressure, and pressure rise rate.

Radiative Heat Transfer and Fluorescence Measurements in Laminar Prevaporized Canola Methyl Ester/Diesel Blend Flames

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
V. Singh ◽  
R. N. Parthasarathy ◽  
S. R. Gollahalli
Keyword(s):  
Heat Transfer ◽  
Methyl Ester ◽  
Radiative Heat Transfer ◽  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Radiative Heat ◽  
Concentration Field ◽  
Gaseous Species ◽  
Flame Radiation ◽  
Fluorescence Measurements

Biofuels, such as canola methyl ester (CME), continue to receive considerable attention for their potential use as alternatives to petroleum diesel fuel. The studies on the application of biofuels in internal combustion engines, in general, have shown a considerable reduction in carbon monoxide (CO), soot, and radiative heat emissions, and a small increase in NOx emissions. Radiative heat transfer from flames, which is important in applications such as gas turbines and glass-manufacturing furnaces, has received little attention. The objective of this investigation was to document radiative heat transfer and radical and gas concentration measurements to understand the dominant mechanism of heat transfer in CME/diesel blend flames. In order to isolate the fuel chemical effects on the combustion characteristics of fuels, laminar flames of prevaporized liquid fuels were studied at injector-exit equivalence ratios of 1.2, 2, 3, and 7. Measurements of radiative heat transfer and flame structure including OH and CH radical concentration field were completed. While the peak temperatures in the various blend flames were comparable at the same equivalence ratio, the total flame radiation decreased with the increase in CME concentration in the fuel. Estimates of radiation from gaseous species and soot indicated that about 27–30% of the radiation was from gases, and the rest from soot. The gaseous species contribution to the flame radiation increased slightly with the biofuel content in the blend.

Thermophysical Properties of Working Substance and Heat Transfer in a Hydrogen Combustion Engine

2003 ◽  
Author(s):  
T. Shudo ◽  
H. Oka
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Heat Loss ◽  
Thermophysical Properties ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Spark Ignition ◽  
Hydrogen Combustion ◽  
Spark Ignition Engine ◽  
Combustion Engines

Hydrogen is a clean alternative to fossil fuels for internal combustion engines and can be easily used in spark-ignition engines. However, the characteristics of the engines fueled with hydrogen are largely different from those with conventional hydrocarbon fuels. A higher burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a higher degree of constant volume and a larger heat transfer from the burning gas to the combustion chamber wall of the engines. Because of the large heat loss, the thermal efficiency of an engine fueled with hydrogen is sometimes lower than that with hydrocarbons. Therefore, the analysis and the reduction of the heat loss are crucial for the efficient utilization of hydrogen in internal combustion engines. The empirical correlations to describe the total heat transferred from the burning gas to the combustion chamber walls are often used to calculate the heat loss in internal combustion engines. However, the previous research by one of the authors has shown that the widely used heat transfer correlations cannot be properly applied to the hydrogen combustion even with adjusting the constants in them. For this background, this research analyzes the relationship between characteristics of thermophysical properties of working substance and heat transfer to the wall in a spark-ignition engine fueled with hydrogen.

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