Methods in S.I. Engine Modelling: Auto-calibration of Combustion and Heat Transfer Models, and Exergy Analysis

A second law analysis has been developed for an evaporative atomized spray in a uniform parallel stream of hot gas. Using a discrete droplet evaporation model, an equation for entropy balance of a drop has been formulated to determine numerically the entropy generation histories of the evaporative spray. For the exergy analysis of the process, the rate of heat transfer and that of associated irreversibilities for complete evaporation of the spray have been calculated. A second law efficiency (ηII), defined as the ratio of the total exergy transferred to the sum of the total exergy transferred and exergy destroyed, is finally evaluated for various values of pertinent input parameters, namely, the initial Reynolds number (Rei = 2ρgVixi/μg) and the ratio of ambient to initial drop temperature (Θ∞′/Θi′).

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Heat transfer models for two-component media with interfacial jump

Applicable Analysis ◽

10.1080/00036811.2015.1124421 ◽

2015 ◽

Vol 96 (2) ◽

pp. 247-260 ◽

Cited By ~ 3

Author(s):

I. Gruais ◽

D. Poliševski

Keyword(s):

Heat Transfer ◽

Two Component ◽

Transfer Models

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Analysis of Roll Gap Heat Transfers in Hot Steel Strip Rolling through Roll Temperature Sensors and Heat Transfer Models

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.504-506.1043 ◽

2012 ◽

Vol 504-506 ◽

pp. 1043-1048 ◽

Cited By ~ 12

Author(s):

Nicolas Legrand ◽

Nathalie Labbe ◽

Daniel Weisz-Patrault ◽

Alain Ehrlacher ◽

Tomasz Luks ◽

...

Keyword(s):

Heat Transfer ◽

Steel Strip ◽

Temperature Sensors ◽

Strip Rolling ◽

Strip Surface ◽

Roll Temperature ◽

Heat Transfers ◽

Roll Gap ◽

Roll Bite ◽

Transfer Models

This paper presents an analysis of roll bite heat transfers during hot steel strip rolling. Two types of temperature sensors (drilled sensor /slot sensor) implemented near roll surface and heat transfer models are used to identify in the roll bite interfacial heat flux, temperature and Heat Transfer Coefficient HTCroll-bite during pilot rolling tests. It is shown that: - the slot type sensor is much more efficient than the drilled type sensor to capture correctly fast roll temperature changes in the bite during hot rolling but life’s duration of the slot sensor is shorter. - average HTCroll-bite, identified with roll sensors temperature signals is within the range 15-26 kW/m2/K: the higher the strip reduction is, the higher the HTCroll-bite is. - scale thickness at strip surface tends to decrease heat transfers from strip to roll in the roll bite. - HTCroll-bite appears not uniform along the roll-strip contact, in contrast to usual assumptions made in existing models - Heat dissipated by friction at roll-strip interface and its partitioning through roll and strip respectively seems over-estimated in the existing thermal roll gap model [1]. Modeling of interfacial friction heat dissipation should be reviewed and verified. The above results show the interest of roll temperature sensors to determine accurately roll bite heat transfers and evaluate more precisely the corresponding roll thermal fatigue degradation.

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A Comparative Evaluation of Advanced Combined Cycle Alternatives

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2906544 ◽

1991 ◽

Vol 113 (2) ◽

pp. 190-197 ◽

Cited By ~ 43

Author(s):

O. Bolland

Keyword(s):

Heat Transfer ◽

Steam Turbine ◽

Comparative Evaluation ◽

Exergy Analysis ◽

Combined Cycle ◽

Heat Transfer Area ◽

Turbine Condenser ◽

Pressure Cycle ◽

Steam Turbine Condenser ◽

Exergy Balance

This paper presents a comparison of measures to improve the efficiency of combined gas and steam turbine cycles. A typical modern dual pressure combined cycle has been chosen as a reference. Several alternative arrangements to improve the efficiency are considered. These comprise the dual pressure reheat cycle, the triple pressure cycle, the triple pressure reheat cycle, the dual pressure supercritical reheat cycle, and the triple pressure supercritical reheat cycle. The effect of supplementary firing is also considered for some cases. The different alternatives are compared with respect to efficiency, required heat transfer area, and stack temperature. A full exergy analysis is given to explain the performance differences for the cycle alternatives. The exergy balance shows a detailed breakdown of all system losses for the HRSG, steam turbine, condenser, and piping.

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