"Clean" Type Heat Flux Meter

Brajuskovic, Branislav; Afgan, Naim

doi:10.1615/ihtc9.2950

Cited by 2 publications

(1 citation statement)

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“…In addition, hemispherical radiative flux measurements provide information that is not biased by the non-homogeneous distribution of particle number density in the combustion chamber, 121 unlike the narrow angle measurement, which may vary wildly with directions [27]. While a number of studies have reported measurement of hemispherical radiation in various combustion chambers [3,4,12,28,29], and other studies have tried to design and improve probes for hemispherical radiative measurement [30][31][32], few studies have discussed how to distinguish flame radiation from the incident radiation that is received by these hemispherical radiative measurement probes. 127…”

Section: Introduction 51mentioning

confidence: 99%

An approach to estimating flame radiation in combustion chambers containing suspended-particles

Yang

Adeosun

Kumfer

et al. 2017

Fuel

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Thermal radiation often plays a key role in heat transfer between flames and the surrounding environment. Therefore, reliable measurement of flame radiation is indispensable in the study of combustion. While the measurement of radiative flux from flames is straightforward in an open environment, it is challenging to do so in a confined chamber, due to the influence of the walls. Radiation emitted by the walls and the reflection of flame radiation off the walls can interfere with measurements of flame radiation. For wall surfaces that are at high temperature or highly reflective, the error in the flame radiation measurement can be significant. In this paper, a theoretical analysis was carried out to study the contribution of wall emission and wall reflection to the incident radiation measured by radiometers. The results reveal that for a typical lab-scale air-fired flame, the contribution of wall emission and wall reflection to the measured incident radiation can be as high as 55% for a refractory-lined wall and 40% for a water-cooled wall. A convenient approach is proposed to distinguish flame radiation from the measured incident radiation. The approach is based on measurements of surface incident radiation and net radiative heat flux through the wall. The approach can be applied to optically thin systems (most labscale and some pilot-scale atmospheric pressure combustion systems) and optically dense systems (typically pressurized large-scale combustion systems). CFD simulations were 41 also performed for two coal-fired combustors, one which represents optically thin and the 42 other optically thick systems, to validate the theoretical model and the approach to 43 estimating flame radiation. Good agreement was observed between CFD results and the 44 3 theoretical model results, and the proposed approach to estimation of flame radiation was 45 found to have reasonable accuracy. 46

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