Modelling the transient heat transfer in the ceramic combustion chamber walls of a low heat rejection diesel engine

Rakopoulos, C.D.; Mavropoulos, G. C.

doi:10.1504/ijvd.1999.001865

Cited by 20 publications

(19 citation statements)

References 22 publications

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“…By analysing the whole range of both experimental measurements it was concluded that the total duration of structural phase of the transient is estimated at 200 sec for variation "3", whereas it exceeds 300 sec in the case of variation "4". Similar values have been calculated theoretically by the author in the past using the simulation model for structural thermal field (Rakopoulos and Mavropoulos, 1999). Of special importance are the results of measurements presented in Figs 8b and 9b related to the "short-term scale" that is with reference to the instantaneous cyclic surface temperatures.…”

Section: Results Concerning Short-term Heat Transfer Phenomena In Comsupporting

confidence: 82%

“…A brief reference of the previous models was provided in subsections 2.2 and 2.3. Additional details are available in previous publications (Rakopoulos & Mavropoulos, 1996, 1999. Like any other classic FEM code, the thermal analysis program developed consists of the following three main stages: (a) preprocessing calculations; (b) main thermal analysis; and (c) postprocessing of the results.…”

Section: Simulation Process and Experimental Test Cases Consideredmentioning

confidence: 99%

“…This way the final solution is achieved when the heat balance equation between all components involved is satisfied. More details are provided in , 1999. For the postprocessing step one option is a 3d representation of the thermal field variables ( Fig.…”

Section: Simulation Process and Experimental Test Cases Consideredmentioning

confidence: 99%

“…Research efforts concerning conduction heat transfer in reciprocating internal combustion engines are aiming, among other, to the investigation of thermal loading at critical combustion chamber components (Keribar & Morel, 1987;Rakopoulos & Mavropoulos, 1996) with the target to improve their structural integrity and increase their factor of safety against fatigue phenomena. The application of ceramic materials in low heat rejection (LHR) engines (Rakopoulos & Mavropoulos, 1999) is also among the large amount of examples where engine conduction heat transfer is a dominant factor. At the same time, special engine cases like the air-cooled (Perez-Blanco, 2004;Wu et al, 2008) or HCCI ones demand a special treatment for a successful description of the heat transfer phenomena involved.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Unsteady Heat Conduction Phenomena in Internal Combustion Engine Chamber and Exhaust Manifold Surfaces

Mavropoulos¹

2011

Heat Transfer - Engineering Applications

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Section: Results Concerning Short-term Heat Transfer Phenomena In Comsupporting

confidence: 82%

Section: Simulation Process and Experimental Test Cases Consideredmentioning

confidence: 99%

Section: Simulation Process and Experimental Test Cases Consideredmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Unsteady Heat Conduction Phenomena in Internal Combustion Engine Chamber and Exhaust Manifold Surfaces

Mavropoulos¹

2011

Heat Transfer - Engineering Applications

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“…As regards steady-state operation, various studies have been reported for LHR engine operation by applying either first-, e.g. [2,[6][7][8][9][10][11], or second-law, e.g. [12][13][14][15][16] balances.…”

Section: Introductionmentioning

confidence: 99%

Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Rakopoulos¹,

Giakoumis²

2007

SAE Technical Paper Series

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During the last decades, a vivid interest in the low heat rejection (LHR) diesel engine has arisen. In a LHR engine, an increased level of temperatures inside the cylinder is achieved resulting from the insulation applied to the combustion chamber walls. The steady-state LHR engine operation has been studied so far by applying either first-or second-law balances. However, very few works have treated this subject during the very important transient operation, with the results limited to the engine speed response. For this purpose, an experimentally validated simulation code of the thermodynamic cycle of the engine during transient conditions is applied. This takes into account the transient operation of the fuel pump, the development of friction torque using a detailed per degree crank angle sub-model, while the equations for each cylinder are solved individually and sequentially. In this work, two common insulators of various thicknesses are considered for the engine in hand, viz. silicon nitride and plasma spray zirconia. The transient response of various engine (e.g. speed, volumetric efficiency, fuel pump rack position, brake mean effective pressure and specific fuel consumption) and turbocharger variables is depicted and analyzed, with the results compared to the non-insulated transientand the insulated steady-state operation. For a more indepth analysis of transient engine heat transfer, the interesting phenomenon of the short-term temperature (cyclic) oscillations in the combustion chamber walls during transients needs to be studied. To this aim, the thermodynamic model of the engine is appropriately coupled to a wall periodic heat conduction model, which uses the gas temperature variation as boundary condition throughout the engine cycle after being treated by Fourier analysis techniques. The evolution of many variables during the transient engine cycles, such as the amplitude of oscillation or gradient of temperature swing is thus illustrated. Moreover, the simulation code is expanded in a way to include the second-law balance, as this may prove an interesting alternative to the firstlaw analysis. It is revealed that after a ramp increase in load, the second-law values unlike the first-law ones are heavily impacted by the insulation scheme applied.Combustion and total engine irreversibilities decrease significantly (up to 24% for the cases examined) with increasing insulation. Unfortunately, this decrease is not transformed into an increase in piston work but rather increases the potential for extra work recovery owing to the higher availability content of the exhaust gas.

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Investigation of the temperature oscillations in the cylinder walls of a diesel engine with special reference to the limited cooled case

Rakopoulos

Antonopoulos

Rakopoulos

et al. 2004

Int. J. Energy Res.

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SUMMARYThis work investigates the interesting phenomenon of the temperature (cyclic) oscillations in the combustion chamber walls of a diesel engine. For this purpose, a comprehensive simulation code of the thermodynamic cycle of the engine is developed taking into account both the closed and the open parts of it. The energy and state equations are applied, with appropriate combustion, gas heat transfer, and mass exchange with the atmosphere sub-models, to yield cylinder pressure, local temperatures and heat release histories as well as various performance parameters of the engine. The model is appropriately coupled to a wall periodic conduction model, which uses the gas temperature variation as boundary condition throughout the engine cycle after being treated by Fourier analysis techniques. It is calibrated against measurements, at various load and speed conditions, from an experimental work carried out on a direct injection (DI), naturally aspirated, four-stroke, diesel engine located at the authors' laboratory, which has been reported in detail previously. After gaining confidence into the predictive capabilities of the model, it is used to investigate the phenomenon further, thus providing insight into many interesting aspects of transient engine heat transfer, as far as the influence that engine wall material properties have on the values of cyclic temperature swings. These swings can take prohibitive values causing high wall thermal fatigue, when materials of specific technological interest such as thermal insulators (ceramics) are used, and may lead to deterioration in engine performance.

show abstract

Modelling the transient heat transfer in the ceramic combustion chamber walls of a low heat rejection diesel engine

Cited by 20 publications

References 22 publications

Unsteady Heat Conduction Phenomena in Internal Combustion Engine Chamber and Exhaust Manifold Surfaces

Unsteady Heat Conduction Phenomena in Internal Combustion Engine Chamber and Exhaust Manifold Surfaces

Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Investigation of the temperature oscillations in the cylinder walls of a diesel engine with special reference to the limited cooled case

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