Temperature Measurement Method of Flame Image Fusion with Different Exposures

Abstract

Fixed exposure will lead to underexposure or overexposure of collected flame radiation images using CCD, which has a great influence on the temperature measuring accuracy. A temperature measurement method was proposed by image fusion with multi-exposure, which can eliminate the influence of insufficient underexposure and overexposure. The approach was first to acquire a group of flame radiation images during different exposures. Then a partial region with good exposure effect in each radiation image was obtained by segmentation, with which the complete flame image can be spliced together. An experimental system was built to calibrate the temperature measurement parameters by two-color pyrometry through a blackbody furnace. The relation between exposure time and monochromatic gray level, as well as the relation between the temperature and temperature measurement coefficient were obtained. A candle flame was selected as the measuring object and the complete and accurate flame temperature distribution was acquired following our proposed method. The experimental results show that, compared with the temperature measurement using a single exposure time, our method can effectively avoid the measurement error caused by underexposure and overexposure, and improve the measurement accuracy.

Temperature Sensing in Space and Transparent Media: Advancements in Off-Axis Digital Holography and the Temperature Coefficient of Refractive Index

“…In Figure 9 (right), we observe a temperature profile with a local minimum at the center of the flame, flanked by two peaks of temperature. These experimental observations are in accordance with the reported measurements documented in [23,24,28,29,[46][47][48].…”

“…In our experimental investigation, as shown in Figures 6 and 9, we have observed patterns that support the aforementioned findings similar to those in [23,24,28,29,[46][47][48]. Specifically, in Figure 6 (right) and Figure 9 (right), we present our measured temperature profiles, where the peak temperature is located around the flame's center.…”

“…The temperature distribution of a candle flame is influenced by various parameters, including the type of oil wax and wick thickness [28,29]. Previous studies have reported peak temperatures ranging from 600 • C to 2000 • C for candle flames [23,24,28,29,[46][47][48]. Additionally, temperature profiles along the radial distance at different heights have shown variations in temperature.…”

Digital holography for temperature investigations in space and transparent media

“…The presence of two temperature peaks and a local minimum at the flame's center is an intriguing observation [12,17]. These experimental findings are consistent with the data reported and cited in [12,15,17,[21][22][23]. Given the maximum uncertainty of the laser source's wavelength at 0.1 nm, and considering the uncertainty of the phase change to be π/5, along with the factors L=7.4 mm and = 25π for the captured hologram, the resulting uncertainty in temperature measurement becomes 0.93°C [3].…”

Thermal Imaging Metrology Using High Dynamic Range Near-Infrared Photovoltaic-Mode Camera

“…There are countless other potential applications in high temperature manufacturing and the foundational industries. We note that stacking images with different exposure times can be used to increase the dynamic range, but this is sensitive to movement in the scene [ 7 , 8 ].…”