High-frequency wall heat flux measurement during wall impingement of a diffusion flame

The efficiency of internal combustion engines is limited by heat losses to the wall of the combustion chamber. A precise characterization of wall heat flux is therefore needed to optimize engine parameters. However, the existing measurements of wall heat fluxes have significant limitations; time resolution is often higher than the timescales of the physical phenomena of flame–wall interaction. Furthermore, few studies have investigated diesel flame conditions (as opposed to propagation flames). In this study, the heat flux generated by a diffusion flame impinging on a wall was measured with thin-junction thermocouple, with a time resolution of the whole acquisition chain better than 0.1 ms. The effects of variations in ambient gas temperature, injection pressure and injector–wall distance were investigated. Diesel spray impingement on the wall is shown to cause strong gas–wall thermal exchange, with convection coefficients of 6–12 kW/m2/K. Those results suggest the necessity of close-wall aerodynamic measurements to link macroscopic characteristics of the spray (injection pressure, impingement geometry) to turbulence values.

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Combustor Wall Surface Temperature and Heat Flux Measurement Using a Fiber-Coupled Long Wave Infrared Hyperspectral Sensor

10.1115/gt2021-58961 ◽

2021 ◽

Author(s):

Aravind Chandh ◽

Oleksandr Bibik ◽

Subodh Adhikari ◽

David Wu ◽

Tim Lieuwen ◽

...

Keyword(s):

Heat Flux ◽

Surface Temperature ◽

Flux Measurement ◽

Heat Fluxes ◽

Long Wavelength ◽

Combustion Gases ◽

Acoustic Perturbation ◽

Accuracy And Precision ◽

Long Wavelength Infrared

Abstract In this paper, we discuss the development of a non-intrusive surface temperature sensor based on long-wavelength infrared (LWIR) hyperspectral technology. The LWIR detection enables to minimize optical interferences from hot combustion gases (emission mostly within UV-MWIR region). Utilization of hyperspectral detection allows to further improve temperature measurement accuracy and precision. The developed sensor with fiber coupling provides the required flexibility to be maneuvered around/through combustor hardware. The LWIR fiber probe is fully protected by the custom-designed water-cooled probe housing. This device is designed to sustain temperature of 2400 K at pressure of 50 bar, which enables long-term optical diagnostics inside the practical high-pressure combustion facilities where extreme thermal acoustic perturbation and intense heat fluxes are present. The housing featured a diamond window to selectively measure spectra in the LWIR region to get accurate surface temperature exclusively of the combustor wall. The probe was installed into a RQL style combustor to get surface temperature of both hot and cold side of the combustor wall. Further, pointwise heat flux estimates across the combustion liner wall was derived using the temperature measurements.

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Investigation of the Turbulent Near Wall Flame Behavior for a Sidewall Quenching Burner by Means of a Large Eddy Simulation and Tabulated Chemistry

Fluids ◽

10.3390/fluids3030065 ◽

2018 ◽

Vol 3 (3) ◽

pp. 65 ◽

Cited By ~ 1

Author(s):

Arne Heinrich ◽

Guido Kuenne ◽

Sebastian Ganter ◽

Christian Hasse ◽

Johannes Janicka

Keyword(s):

Heat Flux ◽

Large Eddy Simulation ◽

Gas Turbines ◽

Internal Combustion Engines ◽

Heat Fluxes ◽

Maximum Heat ◽

Eddy Simulation ◽

Tabulated Chemistry ◽

Large Eddy ◽

Near Wall

Combustion will play a major part in fulfilling the world’s energy demand in the next 20 years. Therefore, it is necessary to understand the fundamentals of the flame–wall interaction (FWI), which takes place in internal combustion engines or gas turbines. The FWI can increase heat losses, increase pollutant formations and lowers efficiencies. In this work, a Large Eddy Simulation combined with a tabulated chemistry approach is used to investigate the transient near wall behavior of a turbulent premixed stoichiometric methane flame. This sidewall quenching configuration is based on an experimental burner with non-homogeneous turbulence and an actively cooled wall. The burner was used in a previous study for validation purposes. The transient behavior of the movement of the flame tip is analyzed by categorizing it into three different scenarios: an upstream, a downstream and a jump-like upstream movement. The distributions of the wall heat flux, the quenching distance or the detachment of the maximum heat flux and the quenching point are strongly dependent on this movement. The highest heat fluxes appear mostly at the jump-like movement because the flame behaves locally like a head-on quenching flame.

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Study on wall heat flux measurement using thin film RTD and two internal thermocouples

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2020.j05225 ◽

2020 ◽

Vol 2020 (0) ◽

pp. J05225

Author(s):

Makoto KAMATA ◽

Yoshiaki TOMOTO ◽

Osamu NAKABEPPU

Keyword(s):

Thin Film ◽

Heat Flux ◽

Flux Measurement ◽

Wall Heat Flux ◽

Heat Flux Measurement

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Effect of Compression and Expansion on Instantaneous Heat Transfer in Reciprocating Internal Combustion Engines

Proceedings of the Institution of Mechanical Engineers Part A Power and Process Engineering ◽

10.1243/pime_proc_1987_201_022_02 ◽

1987 ◽

Vol 201 (3) ◽

pp. 175-186 ◽

Cited By ~ 39

Author(s):

B Lawton

Keyword(s):

Heat Flux ◽

Internal Combustion Engines ◽

Fast Response ◽

Gas Temperature ◽

Maximum Heat ◽

Simple Modification ◽

Maximum Heat Flux ◽

Volumetric Rate ◽

Compression And Expansion ◽

Surface Thermocouple

Instantaneous heat flux at the surface of a cylinder head in a motored diesel engine has been measured, at various speeds, using a fast-response surface thermocouple. Heat flux during compression was found to be much larger than heat flux during expansion, the maximum heat flux occurred about 8° before top dead centre and there was a significant heat flux even when gas temperature and wall temperature were equal. During expansion, heat flowed from the surface to the gas even though the bulk gas temperature was greater than the surface temperature. These effects are predicted by solutions of the equation of thermal energy and are shown to be related to the volumetric rate of compression or expansion. A simple modification of Annand's equation gives good results and is recommended for general cycle calculations.

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A Modified Directional Flame Thermometer: Development, Calibration, and Uncertainty Quantification

Journal of Verification Validation and Uncertainty Quantification ◽

10.1115/1.4046657 ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

J. M. Cabrera ◽

R. D. Moser ◽

O. A. Ezekoye

Keyword(s):

Heat Flux ◽

Thermal Model ◽

Flux Measurement ◽

Heat Fluxes ◽

Harsh Environments ◽

Unknown Parameters ◽

Fire Scenarios ◽

Flux Measurements ◽

Measurement Devices ◽

Free Parameters

Abstract The directional flame thermometer (DFT) is a robust device used to measure heat fluxes in harsh environments such as fire scenarios but is large when compared to other standard heat flux measurement devices. To better understand the uncertainties associated with heat flux measurements in these environments, a Bayesian framework is utilized to propagate uncertainties of both known and unknown parameters describing the thermal model of a modified, smaller DFT. Construction of the modified DFT is described along with a derivation of the thermal model used to predict the incident heat flux to its sensing surface. Parameters of the model are calibrated to data collected using a Schmidt–Boelter (SB) gauge with an accuracy of ±3% at incident heat fluxes of 5 kW/m2, 10 kW/m2, and 15 kW/m2. Markov Chain Monte Carlo simulations were used to obtain posterior distributions for the free parameters of the thermal model as well as the modeling uncertainty. The parameter calibration process produced values for the free parameters that were similar to those presented in the literature with relative uncertainties at 5 kW/m2, 10 kW/m2, and 15 kW/m2 of 17%, 9%, and 7%, respectively. The derived model produced root-mean-squared errors between the prediction and SB gauge output of 0.37, 0.77, and 1.13 kW/m2 for the 5, 10, and 15 kW/m2 cases, respectively, compared to 0.53, 1.12, and 1.66 kW/m2 for the energy storage method (ESM) described in ASTM E3057.

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Active Heating/Cooling Requirements for Divers in Water at Varying Temperatures

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 3 ◽

10.1115/ht2007-32226 ◽

2007 ◽

Author(s):

Erik R. Bardy ◽

Joseph C. Mollendorf ◽

David R. Pendergast

Keyword(s):

Heat Flux ◽

Human Subject ◽

Heat Fluxes ◽

Body Temperatures ◽

Thermal Exchange ◽

Thermal Limits ◽

Body Regions ◽

Temperature Heat ◽

The Subject ◽

Skin Temperatures

The active heating/cooling requirements to thermally sustain a human subject submerged in 10, 20, 30 and 40 °C water was measured using a system that circulated water through a zoned tubesuit garment. Water at 30 °C was circulated through the garment at a flow rate of about 0.5 L/min to each of six body regions and the outlet temperatures were measured. In addition, skin and core temperature, heat flux, and oxygen consumption was measured. The subject wore either a 6.5 mm or a 3 mm foam neoprene wetsuit. Body temperatures and heat fluxes reached steady state after 30–90 minutes and the immersions lasted 2–4 hours and core and skin temperatures remained within set thermal limits. In both wetsuits there was a linear correlation between the thermal exchange of the tubesuit and water temperature. While in the 6.5 mm wetsuit −214 to 242 W of heating (−) or cooling (+) was necessary in 10 to 40 °C water, respectively. While wearing the 3 mm wetsuit −462 to 342 W was necessary in 10 to 40 °C water, respectively. It was therefore concluded that a subject can be kept in thermal balance and comfort in 10–40 °C water with active heating/cooling.

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F212 Wall heat flux measurement in premixed combustion by MEMS sensor

The Proceedings of the Thermal Engineering Conference ◽

10.1299/jsmeted.2015._f212-1_ ◽

2015 ◽

Vol 2015 (0) ◽

pp. _F212-1_-_F212-2_

Author(s):

Osamu NAKABEPPU ◽

Keisuke NAGASAKA ◽

Tomohiro TSUCHIYA ◽

Yuto NAKAMURA

Keyword(s):

Heat Flux ◽

Flux Measurement ◽

Premixed Combustion ◽

Wall Heat Flux ◽

Heat Flux Measurement ◽

Mems Sensor

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Heat transfer and critical heat flux for two-phase immersion cooling of an inverter power module

Journal of Physics Conference Series ◽

10.1088/1742-6596/2116/1/012007 ◽

2021 ◽

Vol 2116 (1) ◽

pp. 012007

Author(s):

I T’ Jollyn ◽

J Nonneman ◽

M De Paepe

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Critical Heat Flux ◽

Pool Boiling ◽

Flux Measurement ◽

Base Plate ◽

Heat Fluxes ◽

Power Module ◽

Two Phase ◽

Heat Flux Measurement

Abstract Heat transfer and critical heat flux measurement are reported for pool boiling cooling of the base plate of an inverter power module. Novec 649 is used as refrigerant. Heat fluxes up to 14.6 W/cm2 were applied with refrigerant saturation temperatures of 36 °C, 41 °C and 46 °C. The measured boiling curves are comparable to those reported for similar refrigerants. The critical heat fluxes range from 12.1 W/cm2 to 14.6 W/cm2, which corresponds within 10% to the correlation of Zuber. The critical heat flux is significantly lower than the highest heat fluxes expected from the power module, indicating that methods to increase the critical heat flux are needed to enable two-phase power module cooling.

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