Improvement of Heat Flux Measurement on Combustion Chamber of Spark Ignition Engine : Conditions of Thin Film Type of Heat Flux Sensor for Heat Flux Measurement of Engine(Thermal Engineering)

The measurement of thermal properties or internal or external boundary conditions requires temperature and heat flux data. Both information can be provided by heat flux sensors. The one consisting in measuring temperature at various locations within the wall and using inverse method to estimate wall temperature and heat flux is among those providing the lowest measurement bias for transient heat flux measurement. However, this very accurate sensor requires time consuming technical work for microthermocouples implementation and due to the welding, one cannot locate precisely the temperature measurement. The idea developed in this work is to replace the wire microthermocouples by thin film resistance temperature detectors deposited on polymer substrate in order to ease the fabrication and to increase the accuracy of heat flux sensor. As the deposited sensors are RTDs, a preliminary study is performed showing the effect of the metal as well as the processing conditions on the electrical resistivity and temperature coefficient of copper and aluminum thin film

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Heat Flux Measurement and Heat Flux Sensor

Heatmetry - Heat and Mass Transfer ◽

10.1007/978-3-030-40854-1_1 ◽

2020 ◽

pp. 1-17

Author(s):

Sergey Z. Sapozhnikov ◽

Vladimir Yu. Mityakov ◽

Andrey V. Mityakov

Keyword(s):

Heat Flux ◽

Flux Measurement ◽

Heat Flux Sensor ◽

Heat Flux Measurement ◽

Flux Sensor

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Unsteady in-cylinder heat transfer in a spark ignition engine: Experiments and modelling

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1243/0954407011528329 ◽

2001 ◽

Vol 215 (6) ◽

pp. 747-760 ◽

Cited By ~ 48

Author(s):

D J Oude Nijeweme ◽

J. B. W. Kok ◽

C. R. Stone ◽

L Wyszynski

Keyword(s):

Boundary Layer ◽

Heat Flux ◽

Combustion Chamber ◽

Energy Equation ◽

Spark Ignition ◽

Surface Heat ◽

Spark Ignition Engine ◽

Unexpected Result ◽

Reynolds Analogy ◽

Law Of The Wall

Instantaneous heat flux measurements have shown that, in the expansion stroke, heat can flow from the wall into the combustion chamber, even though the bulk gas temperature is higher than the wall temperature. This unexpected result has been explained by modelling of the unsteady flows and heat conduction within the gas side thermal boundary layer. This modelling has shown that these unsteady effects change the phasing of the heat flux, compared with that which would be predicted by a simple convective correlation based on the bulk gas properties. Twelve fast response thermocouples have been installed throughout the combustion chamber of a pent roof, four-valve, single-cylinder spark ignition engine. Instantaneous surface temperatures and the adjacent steady reference temperatures were measured, and the surface heat fluxes were calculated for motoring and firing at different speeds, throttle settings and ignition timings. To make comparisons with these measurements, the combustion system was modelled with computational fluid dynamics (CFD). This was found to give very poor agreement with the experimental measurements, so this led to a review of the assumptions used in boundary layer modelling. The discrepancies were attributed to assumptions in the law of the wall and Reynolds analogy, so instead the energy equation was solved within the boundary layer. The one-dimensional energy conservation equation has been linearized and normalized and solved in the gas side boundary layer for a motored case. The results have been used for a parametric study, and the individual terms of the energy equation are evaluated for their contribution to the surface heat flux. It was clearly shown that the cylinder pressure changes cause a phase shift of the heat flux forward in time.

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