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Emissivity/temperature study: Measured blackbody at varying set points across a range of emissivities
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Coal temperatures affect the burn properties of cigarettes. Thermal imaging was used to determine the average maximum surface coal temperatures during smolder of cigarettes of different tobacco types. The thermal imaging camera was calibrated against a reference blackbody. An emissivity correction was necessary since the set point temperatures of t...
Context in source publication
Context 1
... blackbody data were collected across a range of 300 (550-850 C) and five emissivities (0.99-0.60). The measured temperatures of the reference blackbody decreased with increasing emissivities at each set point temperature of the reference blackbody ( Figure 1). Across an emissivity span ranging from 0.99 to 0.80, the temperature values moved 4.5% or less from the set point. ...
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Citations
... Temperatures of between 500-700°C are established at the tip of the cigarette and raise to above 850°C when air is drawn into the burning cone [69]. The high temperatures, heat released, rapid rise in temperature and visible glowing upon puffing clearly evidence the overall exothermic nature of the smoldering combustion process [69][70][71][72]. The temperature onset of the combustion of tobacco samples, characterized by a rapid oxidation reaction (as evidenced by a rapid loss in weight with a simultaneous large exothermic release of heat) has been reported to occur above 400°C when investigated by thermogravimetric analysis coupled to differential scanning calorimetry [21,25]. ...
An experimental investigation of the thermal processes taking place in the tobacco substrate of a recently developed multicomponent electrically heated tobacco product (EHTP) that is part of an electrically heated tobacco system (EHTS – also referred to as the Tobacco Heating System 2.2) was carried out. Temperature profiles in the tobacco substrate of the EHTP were characterized using thermocouples positioned at different distances from the heater surface. The average maximum temperature of the tobacco measured 0.2 mm from the heater’s surface was < 260 °C, well below the temperature required for the self-sustaining smoldering combustion of the tobacco substrate to occur. The chemical composition of the aerosol generated from the EHTP when the EHTS was operated under oxidative and non-oxidative atmospheres was investigated. The aerosol derived from the controlled heating of the tobacco substrate is comprised principally of water, nicotine and glycerol that are evaporated from the tobacco substrate. No significant change in aerosol composition and in the amounts of CO, NO and NOx were detected when comparing the aerosol formed under non-oxidative (where combustion processes cannot occur) and oxidative atmospheres.
... The thermal emissivity of the cigarette burning zone during smoulder is 0.87-0.88 (Lyman et al. 2003), which is somewhat less than would be expected from a char produced from a biomass fuel. This may be because the surface of the burnt tobacco rod is usually covered with a layer of cigarette paper that is rich in calcium carbonate and its residual decomposition product (Zheng et al. 2006). ...
A burning cigarette is a known cause of fire when mishandled. Studies into cigarette ignition propensity intensified after the US Cigarette Fire Safety Act of 1984. Extensive research has investigated the thermal properties of a smouldering cigarette, mostly away from any object of thermal contact or interference. To understand fire ignition, the thermophysics of cigarette’s burning tip has also been examined with and without a contact substrate. In either free or contact smouldering cases, oxygen diffusion through the cigarette wrapping paper has been found to be an important parameter controlling the rate of burn and the energy released. Research by the US National Institute of Standards and Technology led to a standardized test method to determine cigarette ignition propensity, and eventually regulations enforcing Reduced Ignition Propensity (RIP) cigarettes have been passed in all US states and other countries. Among the physical parameters of a burning cigarette related to its thermal energy release, circumferential bands applied to the cigarette wrapping paper that reduce air permeability or diffusivity during smouldering have become the main approach to produce commercial RIP cigarettes. Studies have been performed to ensure that RIP cigarettes have equivalent or lower mainstream smoke yields and biological activities as compared with their conventional non-RIP equivalents. The effects of the paper band properties (width, gap between the bands, type as well as the amount of the material applied) have been studied systematically to establish a manufacturability window. Studies on human smoking behaviour confirmed that RIP cigarettes matched closely their predecessors. The bands, as intended, alter the combustion temperatures during cigarette smouldering within the band. Further research into the interaction of RIP cigarettes with different types of commercial upholstery fabrics and materials should help to understand its mechanism of action in support of emerging post-implementation fire statistics.
... Both the emissivity of substrate (ε pap ) and cigarette (ε cig ) were taken as 0.9 (32). According to (15), the convection of heat to the ambient can be calculated as [12] amb c p amb h T T , with [13] h h he ...
SUMMARY A numerical model based on the finite element method has been constructed to simulate the ignition propensity (IP) tests. The objective of this mathematical model was to quantify the influence of different characteristics of the cellulosic substrate on the results of the IP-tests. The creation and validation of the model included the following steps: (I) formulation of the model based on experimental thermodynamic characteristics of the cellulosic substrate; (ii) calibration of the model according to cone calorimeter tests; (iii) validation of the model through mass loss and temperature profiling during IP-testing. Once the model was validated, the influence of each isolated parameter of the cellulosic substrate was quantified via a parametric study. The results revealed that the substrate heat capacity, the cigarette temperature and the pyrolysis activation energy are the most influencing parameters on the thermodynamic response of the substrates, while other parameters like heat of the pyrolysis reaction, density and roughness of the substrate showed little influence. Also the results indicated that the thermodynamic mechanisms involved in the pyrolysis and combustion of the cellulosic substrate are complex and show low repeatability which might impair the reliability of the IP-tests.
... To complement the gas-phase temperature measurements, peripheral solid-phase temperatures were also measured by an infrared thermal camera (G90, SATIR, China) at a recording frequency up to 25 Hz. Details of the test procedure was similar to that reported previously [16,17]. ...
An experimental study was conducted to examined the combustion behaviour of reduced ignition propensity (RIP) cigarettes during smouldering and puffing phases. The internal gas-phase temperature of the burning tip (or coal) was systematically measured by using arrays of fine thermocouples accurately inserted around the RIP band. Both temperature and temperature gradient contours at up to 10 Hz were digitally constructed. The results revealed for the first time that the RIP band caused a marked change in the temperature distribution patterns under puffing. The band was also able to suppress smouldering well ahead of the approaching coal. The temperature gradient contours demonstrated the changes in the extent combustion, mostly caused by modification to the air influx during puffing. The coal volume fractions at different temperatures were quantified and compared to a non-RIP control cigarette. Possible implications of the observations on RIP cigarettes ignition testing and smoke composition were discussed.
... According to Baker [2], when a cigarette is lit the tobacco temperature rises rapidly and a hot carbonaceous coal forms at the lit end of the cigarette. Peak puff temperatures of the coal can exceed 900°C during a 2-second puff [11,12]. At the end of a puff the coal temperature declines in-line with the reduction in air flow. ...
This short review summarises some fundamental aspects of cigarette combustion and smoke formation, including how cigarettes burn, how cigarette smoke is formed and the complex and reactive nature of it's composition. Particular emphasis has been placed on important factors which have to be controlled when generating, trapping and analyzing cigarette smoke. Examples are provided which demonstrate the sensitivity of cigarette smoke composition to the way it is produced and measured, a subject of particular importance for redox sensitive species such as free radicals and multiple valency-state metals. Recent regulatory interest in smoke constituent yields is summarized, as well as risk assessment approaches which have sought to identify the smoke constituents which make the greatest contribution to smoking related diseases. Limitations of these approaches are discussed, and a number of other aspects of cigarette smoke that have been suggested to contribute to the incidence of smoking related diseases are highlighted.
Knjiga obrađuje najnovija naučna saznanja iz oblasti tehnologije cigareta. Opisani su tehnološi procesi pripreme, izrade i pakovanja cigareta, kao i kontrole kvaliteta osnovnih i pomoćnih sirovina, proizvoda i repro materijala kroz navedene procese. Detaljno je opisano generisanje dima sa režimima pušenja, tehnike za sakupljanje dima, reaktivnost dima, i komponente cigaretnog dima kroz dvije osnovne faze dima – čestičnu i gasnu.
Detaljno su predstavljeni glavni parametri dizajna cigarete, koji utiču na produkciju dima i to: fizičke karakteristike svitka, cigaret papir, dizajn filtera, tip i količina duhana i duhanskih prerađevina u mješavini, i uticaj zeolita kao katalizatora.
Peripheral smoldering temperatures from six "low ignition propensity" (LIP) cigarettes were measured. The six cigarettes are identical except for their different pass rates under the 3-layer substrate test achieved by different band properties. The objective was to evaluate the peripheral combustion behaviors for improved fire-safety cigarette designs. The results showed that the bands were effective in inducing significant temperature reductions, which were greater for cigarettes with a higher 3-layer pass rate. A rapid temperature recovery was often observed before the burn line traversed the full band width. The temperature between the bands was unchanged. The rate of the temperature reduction was relatively constant.
A semi-empirical model was developed to use the radiant coal power of cigarettes in non-contact free smolder to predict the
percentage of cigarettes smoldering on 10 layers of filter paper from a sample set that would burn the entire length of the
tobacco rod. To develop the model the radiant coal power for cigarettes in non-contact free smolder was measured using infrared
imaging and the percentage of the same type of cigarettes smoldering on 10 layers of standard chemical filter paper that burned
the entire length of the tobacco rod was measured. From the experimental data, a characteristic coal power and an effective
extinguishment threshold were established for the cigarettes. The effective extinguishment threshold was plotted as a function
of the characteristic coal power for different cigarette designs, and the optimized Boltzmann model of the data allows the
percentage of cigarettes smoldering on 10 layers of filter paper that would burn the entire length of the tobacco rod to be
predicted by measuring the radiant coal power for the cigarettes in non-contact free smolder. The model was also used to predict
the percentage of cigarettes smoldering on 7 layers of filter paper that would burn the entire length of the tobacco rod.
The percentages predicted shows good agreement with the percentages measured for both 7 and 10 layers of filter paper.
