Second Paper: Instantaneous Heat Transfer Rates to the Cylinder Head Surface of a Small Compression-Ignition Engine

1970 ◽  
Vol 185 (1) ◽  
pp. 976-987 ◽  
Author(s):  
W. J. D. Annand ◽  
T. H. Ma
Keyword(s):  
Heat Transfer ◽  
Cylinder Head ◽  
Time Derivative ◽  
Working Fluid ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Local Conditions ◽  
Transfer Rates ◽  
Head Surface ◽  
Thin Film Thermocouple

Measurements of instantaneous heat transfer rates from the working fluid to the cylinder head of a small open-chamber, four-stroke, compression-ignition engine have been made at five points on the surface, using a new form of thin-film thermocouple. These observations demonstrate that flux magnitude and the form of flux variation during the cycle depend greatly on local conditions. Some of the observed phenomena are explained qualitatively. Finally, some results are presented of an analysis of fluxes averaged over all five locations, in terms of the bulk mean properties of the working fluid. It is shown that some compensation for the non-steady nature of the situation may be given by adding to the usual type of quasi-steady relation a term involving the time derivative of the bulk mean temperature.

scholarly journals Stress analysis of the cylinder block of a small compression ignition engine

2019 ◽  
Vol 179 (4) ◽  
pp. 259-263
Author(s):  
Jerzy WAWRZYCZEK ◽  
Tomasz KNEFEL
Keyword(s):  
Stress Analysis ◽  
Cylinder Head ◽  
Engine Block ◽  
Cylinder Block ◽  
Small Displacement ◽  
Compression Ignition ◽  
Main Bearing ◽  
Compression Ignition Engine ◽  
Combustion Pressure

The work contains calculations to determine the deformation and stress in the block of a currently produced small displacement compression ignition engine. It is also an attempt to introduce some modifications to reduce the mass of the calculated component. In the first step, based on measurements, the model of the engine block was developed. The Autodesk Inventor 2016 software was used. Two additional components were also designed to provide the block closure: a simplified cylinder head and an integrated main bearing support. All elements were imported to the Siemens NX 12 program. The calculations were carried out for different cylinders and different values of the combustion pressure. An attempt was made to introduce some modifications to reduce the weight of the calculated element.

Optimization of piston bowl and valve system in compression ignition engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers for high efficiency

2019 ◽  
pp. 146808741986538
Author(s):  
Bowen Li ◽  
Haoye Liu ◽  
Linjun Yu ◽  
Zhi Wang ◽  
Jianxin Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Compression Ignition Engine ◽  
Valve System ◽  
Percentage Points ◽  
Polyoxymethylene Dimethyl Ethers ◽  
Variable Valve

Polyoxymethylene dimethyl ethers, with excellent volatility and oxygen content of up to 49%, have great potential to improve engine performance and emission characteristics. In this study, experiments were carried out in a single-cylinder engine fueled with gasoline/diesel/polyoxymethylene dimethyl ethers blend fuel using multiple premixed compression ignition combustion mode along with engine optimization to exploit the high-efficiency potential. The thermal efficiency was increased by 9.4 percentage points after transforming the combustion mode from conventional diesel mode to gasoline/diesel/polyoxymethylene dimethyl ethers multiple premixed compression ignition mode. A fully variable valve system and a redesigned low-heat-transfer piston were used to further improve the thermal efficiency. The low-heat-transfer piston had a 15% lower area–volume ratio compared with the original ω-type piston. By replacing the original ω-type piston with the low-heat-transfer piston, the heat transfer loss was reduced by 2.29 percentage points and thus indicated thermal efficiency could be increased by 2.37 percentage points, which was up to 50.03%. On the basis of the low-heat-transfer piston, indicated thermal efficiency could be further increased to 51.09% with the application of fully variable valve system due to the longer ignition delay and more premixed combustion. At the same time, NOX emissions could be controlled below 0.4 g/kW·h using high exhaust gas recirculation ratio, which equaled the NOX emission limit of Euro VI standard. Although soot emissions could be increased due to weak turbulence and insufficient intake charge using the low-heat-transfer piston and fully variable valve system, it was still lower than those of the original diesel engines.

Jet emerging from an annular nozzle and impinging onto cylindrical cavity: Effect of jet velocity on flow structure and heat transfer rates

2008 ◽  
Vol 222 (6) ◽  
pp. 1021-1031 ◽  
Author(s):  
S Z Shuja ◽  
B S Yilbas ◽  
S M A Khan
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Cylindrical Cavity ◽  
Substrate Material ◽  
Working Fluid ◽  
Cavity Surface ◽  
Annular Nozzle ◽  
Transfer Rates ◽  
Jet Velocity

In laser gas assisting processes, nozzles are used to accelerate the impinging gas and attain a proper flow structure to improve the quality of the end product. In this study, the jet emerging from an annular nozzle and impinging onto a cylindrical cavity is considered. The effects of jet velocity at nozzle exit onto the flow structure in the region of the cavity and heat transfer rates from the cavity surface are examined. To resemble the laser-produced cavity, the cavity wall temperature is kept elevated (almost the melting temperature of the substrate material). Reynolds stress turbulence model is exploited to account for the turbulence. In the simulations, four jet velocities, two outer angles of the annular nozzle, and two depths of the cylindrical cavity are employed while air is used for the working fluid. It is found that jet velocity has a significant effect on the heat transfer rates and skin friction, which is more pronounced with increasing cavity depths.

Heat Transfer in Compression-Ignition Engines: First Paper: Heat Transfer in a Quiescent Chamber Diesel Engine

1970 ◽  
Vol 185 (1) ◽  
pp. 963-975 ◽  
Author(s):  
N. D. Whitehouse
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Realistic Model ◽  
Compression Ignition ◽  
Usual Model ◽  
Mean Values ◽  
Transfer Rates ◽  
Compression Ignition Engines ◽  
Instantaneous Values ◽  
The Mean

Instantaneous and mean values of heat transfer at various positions in the combustion chamber were obtained, by means of surface thermocouples, for different loads and speeds and compared with those obtained theoretically from synthesized cycle calculations. The results show that the usual model of homogeneity in the cylinder is inadequate for heat transfer calculations. Peak rates of heat transfer when in the vicinity of a fuel spray were comparatively little dependent upon load or speed. At the periphery of the combustion chamber the mean heat transfer rates were appreciably lower than to the cylinder head and piston and the rapid rise in instantaneous values occurred appreciably later. The results all suggest the need for a more realistic model based upon the geometry and penetration of the fuel sprays.

Experimental and Numerical Study of Evaporative Heat Transfer From Ten- Micro Microchannels

2006 ◽  
Author(s):  
Hoki Lee ◽  
T. A. Quy ◽  
C. D. Richards ◽  
D. F. Bahr ◽  
R. F. Richards
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Latent Heat ◽  
Numerical Study ◽  
Electrical Power ◽  
Three Dimensional ◽  
Working Fluid ◽  
Silicon Membrane ◽  
Transfer Rates ◽  
Evaporative Heat Transfer

Experimental and numerical results are presented for evaporative heat transfer from ten-micron square open-top channels. The radial channels are fabricated in epoxy photoresist on a two micron thick silicon membrane. The working fluid is pumped by capillary forces from a reservoir at the edge of the silicon membrane into the channels where it evaporates. The electrical power dissipated in a thin-film heater in the center of the membrane, the conduction heat transfer rate radially out of the membrane, and the rate of evaporation of the working fluid are measured. A three-dimensional finite difference, time-domain integration is used to predict sensible and latent heat transfer rates. Only 5-10% of the energy dissipated as heat in the thin film heater is carried away as latent heat by the evaporating working fluid. Computed temperatures and heat transfer rates are shown to match the experimental results.

Availability analysis on combustion of n-heptane and isooctane blends in a reactivity controlled compression ignition engine

2017 ◽  
Vol 232 (11) ◽  
pp. 1501-1515 ◽  
Author(s):  
Mostafa Mohebbi ◽  
Masoud Reyhanian ◽  
Iraj Ghofrani ◽  
Azhar Abdul Aziz ◽  
Vahid Hosseini
Keyword(s):  
Heat Transfer ◽  
Mass Fraction ◽  
Fossil Fuels ◽  
Utilization Efficiency ◽  
Second Law ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Reactivity Controlled Compression Ignition ◽  
Fuel Mass ◽  
Availability Analysis

Unfortunately, energy demands and destruction of the environment from uncontrolled manipulation of fossil fuels have increased. Climate change concerns have resulted in the rapid use of new, alternative combustion technologies. In this study, reactivity controlled compression ignition (RCCI) combustion, which can simply be exploited in internal combustion (IC) engines, is investigated. To introduce and identify extra insightful information, an exergy-based study was conducted to classify various irreversibility and loss sources. Multidimensional models were combined with the primary kinetics mechanism to investigate RCCI combustion, incorporating the second law of thermodynamics. The n-heptane, a highly reactive fuel, was supplied by direct injection into the cylinder, whereas premixed fuel was supplied through the intake port in an isooctane/ n-heptane RCCI engine. For five n-heptane increments (5%, 7.5%, 15%, 25%, and 40%) and six different exhaust gas recirculation (EGR) rates (0%, 10%, 20%, 30%, 40%, and 50%), accumulation of different exergy terms was calculated. The results show that as EGR introduction increases from 0% to 50%, the exergy destruction increases from 21.1% to 28.9%. Furthermore, the value of exhaust thermomechanical exergy decreases from 18.4% to 14.4% of the mixture fuel chemical exergy. Among the five different high reactive fuel mass regimes, the 40% n-heptane mass fraction has the major heat transfer exergy owing to its advanced CA50 that exerts a unique influence on cylinder charge temperature of heat transfer layer. The utilization efficiency of exhaust in RCCI is less affected by the variation of reactive fuel mass fraction by contrast; it will significantly influence heat transfer availability. This study revealed that with increasing reactive fuel ( n-heptane) from 7.5% to 40% the irreversibility decreased from 28.6% to 25.8% and the second law efficiency first increased from 43.2% to 44.6% at 15% n-heptane then decreased to 42.9% at 40% n-heptane.

Effect of Electric Fields on Two-Phase Impingement Heat Transfer

2007 ◽  
Author(s):  
Xin Feng ◽  
James E. Bryan
Keyword(s):  
Heat Transfer ◽  
Electric Fields ◽  
Capillary Flow ◽  
Heated Surface ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Two Phase ◽  
Transfer Rates ◽  
Impingement Heat Transfer

The effect of electric fields applied to two-phase impingement heat transfer is explored for the first time. The application of an electric field between a capillary and heated surface results in the ability to control the free boundary flow from discreet drops to jets to sprays. Through an experimental study, the impingement heat transfer was evaluated over a range of operating and geometrical parameters using subcooled ethanol as the working fluid. The ability to change the mode of impinging mass did change the surface heat transfer. The characteristics of the impinging mass on heat transfer was dependent on capillary flow rate, applied voltage, capillary to heated surface spacing, capillary geometry, and heat flux. Enhancement occurred primarily at low heat fluxes (below 30 W/cm2) under ramified spray conditions where the droplet momentum promoted thin films on the heated surface. Higher heat fluxes resulted in greater vapor momentum from the surface minimizing the effect of different modes. However, under ramified spray conditions less mass was impacting the heated surface showing that heat transfer rates at higher heat fluxes were achievable with less mass, resulting in greater evaporation efficiency.

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