scholarly journals Heat of Combustion as the Key Fire Characteristics of Electrical Cables

2019 ◽  
Vol 27 (44) ◽  
pp. 29-39
Author(s):  
Jozef Martinka ◽  
Peter Rantuch ◽  
Martina Hladová ◽  
Janka Sulová ◽  
Aleš Nečas ◽  
...  
Keyword(s):  
Aluminium Hydroxide ◽  
Heat Of Combustion ◽  
Inorganic Filler ◽  
Outer Sheath ◽  
Effective Heat ◽  
Cross Section Area ◽  
Significant Difference ◽  
Effective Heat Of Combustion ◽  
Fire Characteristics ◽  
Electrical Cables

Abstract This scientific study deals with investigation of the heat of combustion and effective heat of combustion of selected electrical cables. Two different electrical cables for rated voltage of 0.6/1 kV were investigated. Both cables were power three-core with cross-section area of each core of 1.5 mm2. The cores of both cables were made of a bar cooper wire. Insulations of conductors of both cables were made of silane cross-linked polyethylene without any inorganic filler, while the bedding and outer sheath were made of polyethylene-based copolymer (the beddings were filled with two fillers - aluminium hydroxide and calcium carbonate, while the outer sheath were filled only with aluminium hydroxide). Reaction to fire class of both cables was B2ca, s1, d0, a1. The main difference in the investigated cables was that the core of one of them was wrapped in a glass mica tape (this cable showed circuit integrity maintenance under fire conditions during 180 minutes). The heat of combustion and effective heat of combustion were determined by the oxygen bomb calorimeter according to the ISO 1716:2018 standard. The highest effective heat of combustion showed the insulation of wires (for both cables 42.47 ± 0.03 MJ/kg), lower value showed outer sheath (interval form13.61 to 15.26 MJ/kg) and the lowest value was determined for bedding (interval from 4.69 to 6.39 MJ/kg). The effective heath of combustion per unit of length of both investigated cables lies in the interval from 1.37 to 1.38 MJ/m. Therefore, there is no significant difference in effective heats of combustion of the electrical cables investigated.

Effective Heat of Combustion for Flaming Combustion of Mediterranean Forest Fuels

2010 ◽  
Vol 47 (2) ◽  
pp. 461-474 ◽  
Author(s):  
J. Madrigal ◽  
M. Guijarro ◽  
C. Hernando ◽  
C. Díez ◽  
E. Marino
Keyword(s):  
Heat Of Combustion ◽  
Mediterranean Forest ◽  
Forest Fuels ◽  
Effective Heat ◽  
Flaming Combustion ◽  
Effective Heat Of Combustion

scholarly journals Fire Risk of Halogen-Free Electrical Cable

2018 ◽  
Vol 26 (42) ◽  
pp. 21-27
Author(s):  
Jozef Martinka ◽  
Peter Rantuch ◽  
Igor Wachter ◽  
Karol Balog
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fire Risk ◽  
Heat Of Combustion ◽  
Total Heat Release ◽  
Electrical Cable ◽  
Effective Heat ◽  
Effective Heat Of Combustion ◽  
Halogen Free

Abstract This paper deals with the fire risk of a selected halogen-free electrical cable. The research was objected to a three-core power electric cable for a fixed installation CHKE J3x1.5 (cross section of each copper core was 1.5 mm2) with a declared class of reaction to fire B2ca, s1, d1, a1. The electrical cable was manufactured and supplied by VUKI, a. s., Slovakia. The fire risk of the electric cable was evaluated based on the heat release rate, total heat release, smoke release rate, total smoke release and effective heat of combustion. These parameters were measured using a cone calorimeter at 50 kW m−2 (specimens and cone emitter were placed horizontally during the test). The measured electrical cable showed a maximum heat release rate of nearly 150 kW m−2, a maximum average heat emission rate of almost 100 kW m−2, a total heat release of almost 130 MJ m−2, a maximum smoke release rate of almost 2.5 s−1, a total smoke release of more than 800 m2 m−2, an effective heat of combustion (cable as a whole) of nearly 9 MJ kg−1 and an effective heat of emission (polymeric parts of the cable) of 26.5 MJ kg−1.

scholarly journals Fire Behavior of Thermally Thin Materials in Cone Calorimeter

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1297
Author(s):  
Marouane El El Gazi ◽  
Rodolphe Sonnier ◽  
Stéphane Giraud ◽  
Marcos Batistella ◽  
Shantanu Basak ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Cone Calorimeter ◽  
Fire Hazard ◽  
Heat Of Combustion ◽  
Sample Weight ◽  
Effective Heat ◽  
Effective Heat Of Combustion

In this study, a representative set of thermally thin materials including various lignocellulosic and synthetic fabrics, dense wood, and polypropylene sheets were tested using a cone calorimeter at different heat fluxes. Time-to-ignition, critical heat flux, and peak of heat release rate (pHRR) were the main parameters considered. It appears that the flammability is firstly monitored by the sample weight. Especially, while the burning rate of thermally-thin materials does never reach a steady state in cone calorimeter, their pHRR appears to be mainly driven by the fire load (i.e., the product of sample weight and effective heat of combustion) with no or negligible influence of textile structure. A simple phenomenological model was proposed to calculate the pHRR taking into account only three parameters, namely heat flux, sample weight, and effective heat of combustion. The model allows predicting easily the peak of heat release rate, which is often considered as the main single property informing about the fire hazard. It also allows drawing some conclusions about the flame retardant strategies to reduce the pHRR.

A review of thermal properties of timber and char at elevated temperatures

2021 ◽  
pp. 1420326X2110355
Author(s):  
Long Shi ◽  
Michael Y. L. Chew
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Fire Risk ◽  
Empirical Models ◽  
Heat Of Combustion ◽  
Effective Heat ◽  
Effective Heat Of Combustion

Timber is one of the most frequently adopted combustible materials in the built environment. The thermal properties are the determining factors for assessing the fire risk in a building. The main thermal properties of timber and their char are reviewed, especially those temperature-dependent and moisture-dependent properties, including kinetic properties, ignition properties, thermal conductivity, specific heat capacity, effective heat of combustion and thermal diffusivity. The study has collected and summarized various thermal properties data and empirical models of hardwood and softwood with different mass percentages in cellulose, hemicellulose and lignin, as temperature increases. The average ignition temperature and effective heat of combustion of softwood are about 12.9% and 9.5% higher than those of hardwood, respectively. From most of the previous models, the thermal conductivity of timber char increases as temperature rises. Cellulose with a high density shows a higher thermal conductivity, but its impacts on the specific heat capacity are limited. Models to predict the main thermal properties of the hardwood, softwood and char are recommended. The collected data, together with those empirical models, can provide useful data resources and tools for the related fire risk assessments.

scholarly journals Impact of Water Content on Energy Potential and Combustion Characteristics of Methanol and Ethanol Fuels

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3491 ◽  
Author(s):  
Jozef Martinka ◽  
Peter Rantuch ◽  
Igor Wachter
Keyword(s):  
Water Content ◽  
Fire Risk ◽  
Combustion Characteristics ◽  
Flash Point ◽  
Heat Of Combustion ◽  
Combustion Characteristic ◽  
Energy Potential ◽  
Effective Heat ◽  
Effective Heat Of Combustion ◽  
The Impact

Methanol and ethanol are among the most important biofuels and raw materials used to produce biorenewable fuels. These fuels are used with varying water contents. Nevertheless, the exact impact of the water content of these fuels on the energy potential and combustion characteristics is still unknown. Besides that, there are two noticeable risks (environmental impact of combustion and fire risk) associated with their production, processing, and utilization. Likewise, impact of the water content of these fuels on fire risk and the impact of their combustion on the environment is also unknown. The best indicator of energy potential is the effective heat of combustion, and the best combustion characteristic and indicator of the impact of the combustion of alcohols on the environment is the carbon monoxide (CO) yield, whereas the fire risk of liquid fuels is quantified by the flash point and maximum heat release rate (mHRR). The dependency of flash point on the water content was determined via the Pensky-Martens apparatus and the dependencies of the effective heat of combustion, CO yield, and mHRR on the water content were determined via the cone calorimeter. With increased water content, the flash points of both methanol and ethanol exponentially increased and the both effective heat of combustion and mHRR almost linearly decreased. In the range of water content from 0 to 60%, the CO yield of both methanol and ethanol was practically independent of the water content.

Heat Release Rate and Effective Heat of Combustion Measurements: A Comparative Study of Thermal and Oxygen Consumption Techniques

1995 ◽  
Vol 13 (6) ◽  
pp. 482-499 ◽  
Author(s):  
Fatima Moussan ◽  
Jean-Louis Delfau ◽  
Christian Vovelle ◽  
Christian Pham Van Cang ◽  
Gérard Bosseboeuf
Keyword(s):  
Oxygen Consumption ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Radiant Heat ◽  
Heat Of Combustion ◽  
Second Step ◽  
Thermal Method ◽  
Effective Heat ◽  
Effective Heat Of Combustion

A new calorimeter especially built for the measurement of the heat release rate and effective heat of combustion of composite materials is pre sented. Two procedures can be used to obtain these data: the first one is based on the direct measurement of the convective and radiant heat liberated by the flame, the second involves oxygen consumption measurement. Preliminary ex periments were carried out with a gas burner to calibrate and check the inertia of the thermal method. In a second step, measurements were performed on PMMA and PVC samples. The results obtained with both methods are very similar and in agreement with literature values.

Effective heat of combustion for flaming combustion of conifers

2006 ◽  
Vol 36 (3) ◽  
pp. 659-663 ◽  
Author(s):  
Vytenis Babrauskas
Keyword(s):  
Moisture Content ◽  
Forest Fire ◽  
Fire Hazard ◽  
Douglas Fir ◽  
Wood Products ◽  
Experimental Results ◽  
Heat Of Combustion ◽  
Benchmark Testing ◽  
Effective Heat ◽  
Effective Heat Of Combustion

The heat of combustion of burning trees is often used in forest-fire hazard modeling to relate mass-loss results to the heat produced; therefore reliable values are needed. Experimental results for the effective heat of combustion of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees are presented as a function of moisture content. It is also shown that during a forest fire, the effective heat of combustion does not correspond to the oxygen-bomb-test value. Instead, the value will always be lower, since the heat of combustion of char is higher than that of the pyrolysate vapors, and char mostly remains unburned during a forest fire. These are the first and only experimental results obtained from testing of actual trees. But results from benchmark testing and studies on wood products by other investigators are broadly consistent with our findings. It is further shown that moisture content has a major effect on the effective heat of combustion. A quantitative expression for the effective heat of combustion, as a function of moisture content, is obtained. Benchmark testing by earlier researchers established that generally there is only a slight species effect on the heat of combustion; therefore the present Douglas-fir results can be applied in more general forest-fire modeling.

scholarly journals Effects of Feedstock and Catalyst Concentration on Biodiesel Production

2012 ◽  
pp. 23-32
Author(s):  
Norzita Ngadi ◽  
Hajar Alias ◽  
Siti Aktar Ishak
Keyword(s):  
Catalyst Concentration ◽  
Heat Of Combustion ◽  
Biodiesel Production ◽  
Soap Content ◽  
Soybean Oils ◽  
Used Oil ◽  
Significant Difference ◽  
Percentage Yield ◽  
Transesterification Method

In this study, production of biodiesel from new and used palm and soybean oils was carried out using a transesterification method. The effect of catalyst amount used towards the percentage yield, soap content and heat of combustion of the biodiesel produced was investigated. The soap content and heat combustion of the biodiesel were determined using titration (AOCS Cc-95) and heat calorimeter bomb (ASTM D240-09), respectively. The results showed that catalyst concentration of 0.5 w/w% gave the best result in terms of yield of biodiesel produced from both palm and soybean oils. However, the quality of biodiesel (i.e. soap content and heat of combustion) produced from palm and soybean oils behaved differently towards catalyst concentration. Overall, both oils (palm and soybean), either new or used oil apparently showed no significant difference in term of yield or qualities of biodiesel produced. This indicates that the used oil has high potential as an economical and practical future source of biodiesel.

scholarly journals The influence of mineral carriers on the simultaneous active and passive immunization of guinea-pigs against tetanus

1965 ◽  
Vol 63 (2) ◽  
pp. 243-262 ◽  
Author(s):  
A. J. Fulthorpe
Keyword(s):  
Calcium Phosphate ◽  
Tetanus Toxoid ◽  
Aluminium Hydroxide ◽  
Guinea Pigs ◽  
Calcium Salt ◽  
Primary Response ◽  
Tissue Response ◽  
Aluminium Phosphate ◽  
Tetanus Antitoxin ◽  
Significant Difference

Guinea-pigs given two doses of 2–25 Lf of fluid tetanus toxoid at 28 days interval had very satisfactory antitoxin titres 10 days after the second dose of toxoid (g.m. 28–2 units/ml.). Similar groups of animals given 150 units of horse tetanus antitoxin simultaneously with the first dose of toxoid responded very badly (g.m. < 0·016).Interference by passive antitoxin occurred even when the antitoxin was given as late as 4 days after the first dose of toxoid.Interference by passively administered antitoxin was minimal when aluminium hydroxide-adsorbed toxoid was used. It was necessary to increase the dose of antitoxin from 150 to 2400 units before significant interference occurred.The route of administration of antitoxin did not significantly affect the results except when the antitoxin was given intravenously.When guinea-pigs were immunized and bled at regular intervals it was found that with both fluid and aluminium hydroxide-adsorbed preparations, titratable antitoxin was present on the 14th day. The increase in titre thereafter was more rapid with the adsorbed preparation, but after a second dose of toxoid there was no significant difference in titre.Passively administered antitoxin virtually abolished the active response to fluid toxoid, but with aluminium hydroxide-adsorbed preparations the primary response was not abolished but reduced and delayed and there was much individual variation.Horse serum-sensitive guinea-pigs given adsorbed toxoid with simultaneous passive horse antitoxin gave a better primary response to the toxoid than did unsensitive animals.The effectiveness of adsorbed tetanus toxoid in the simultaneous immunization procedure was directly related to the concentration of aluminium hydroxide or phosphate used: this concentration was critical and amounts below a certain level were ineffective. Calcium phosphate used as an adsorbent was unsatisfactory in this way, although it was an excellent adsorbent.Investigation of the adsorbent characteristics of aluminium hydroxide and phosphate and of calcium phosphate, showed that the calcium salt on a molar basis was the most effective and that aluminium phosphate was the least effective.Elution of toxoid from centrifuged precipitates of the three types of adsorbent showed that only 5% of toxoid was removed from the aluminium hydroxide, 13–18% from the calcium phosphate and 31–33% from the aluminium phosphate preparation when incubated with normal serum at 37° C.Aluminium hydroxide adsorption in vitro interfered with the ability of antitoxin to combine with toxoid and to a lesser extent calcium phosphate had the same effect; aluminium phosphate, however, did not appear to interfere at all in this wayHistological observations on the tissue response to aluminium phosphate and calcium phosphate indicated that the typical alum granuloma produced by aluminium phosphate was not produced by the calcium salt.

scholarly journals Effect of Dentin Preparation Mode on the Bond Strength Between Human Dentin and Different Resin Cements

2018 ◽  
Vol 29 (3) ◽  
pp. 268-274 ◽  
Author(s):  
Lara Almeida Cyrillo Cerqueira ◽  
Ana Rosa Costa ◽  
Ana Maria Spohr ◽  
Eduardo Miyashita ◽  
Benito André Silveira Miranzi ◽  
...  
Keyword(s):  
Bond Strength ◽  
Resin Composite ◽  
Testing Machine ◽  
Resin Cement ◽  
Hybrid Layer ◽  
Resin Cements ◽  
Diamond Bur ◽  
Cross Section Area ◽  
Significant Difference ◽  
Preparation Mode

Abstract The aim was to evaluate the influence of different dentin preparation mode in the smear layer characteristics (SL), hybrid layer (HL), and microtensile bond strength (µTBS) to dentin with two resin cements. The occlusal dentin of 120 third molars was exposed. The teeth were divided into 4 groups (n=30) according to the dentin preparation mode: 1- fine grain diamond bur; 2- coarse grain diamond bur; 3- multi laminate carbide steel bur; and, 4- ultrasonic CV Dentus diamond bur. Each treated dentin group was divided into 2 sub-groups (n=15) according to the resin cement: (1) RelyX U200 and (2) RelyX ARC. Resin composite blocks were cemented on dentin. After storage at 37o C for 24 h, beams with a cross section area of 1.0 mm2 were obtained, and tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Two additional teeth for each sub-group were prepared to analyze the SL and HL on a scanning electron microscopy. According to Kruskal-Wallis test and Dunn tests, there was no significant difference in µTBS among the rotary instruments within each resin cement group. RelyX ARC obtained higher µTBS values compared to RelyX U200 (p<0.05). RelyX ARC formed evident HL, which was not observed for RelyX U200. The dentin mode preparation did not influence the µTBS of the resin cements. The SL was different for all instruments. The cementing agent is more determinant in the hybrid layer formation and bond strength to dentin than the instruments applied on dentin.

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