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Energy Release Rates
Published in Björn Karlsson, James G. Quintiere, Nils Johansson, Björn Karlsson, Enclosure Fire Dynamics, 2022
Björn Karlsson, James G. Quintiere
Heat of combustion: The effective heat of combustion (sometimes called the chemical heat of combustion) can be estimated from Eq. (3.2) if both the energy release rate and the mass loss rate have been measured as described above. It is important to distinguish between the effective heat of combustion, ∆Heff, and the complete heat of combustion, ∆Hc. The complete heat of combustion can be measured in a device called the bomb calorimeter, where the sample is completely combusted under high pressure in pure oxygen, leaving almost no residue and releasing almost all of its potential energy. This is not representative of real fires, where typically only 70%–80% of the mass is converted to volatiles that burn almost completely, leaving some char or residue. Additionally, some of the volatiles do not combust completely, leaving some combustible components such as CO, soot, and unburnt hydrocarbons in the products of combustion.
Ignitable and Explosive Atmospheric Hazards
Published in Neil McManus, Safety and Health in Confined Spaces, 2018
Combustion produces heat. Heat of combustion is the energy released during the reactions that constitute combustion. Heat released during combustion is essential to sustaining the combustion reaction. Heat activates molecules of both fuel and oxidizer by raising their internal energy. For combustion to be self-sustaining, the rate of production of activated molecules must exceed the rate of decay back to the unexcited state (Meyer 1989). Once ignition has occurred, combustion will continue until one of the following has occurred: • All available fuel or oxidant has been consumedThe flame is extinguished by coolingThe number of reactive species has been reduced by some means below sustaining levels (Drysdale 1991).
Air Sampling
Published in Martin B., S.Z., of Industrial Hygiene, 2018
Gases and vapors have certain thermal properties that can be exploited in their analysis. Of the instruments available for industrial hygiene applications, one of two thermal properties, heat of combustion or thermal conductivity, is measured. Heat of combustion refers to the heat released by the complete combustion of a unit mass of combustible material. It is a measure of the maximum amount of heat that can be released by a certain mass of a combustible chemical. Table 4.7 lists the heats of combustion for some selected chemicals.
Investigation on the performance, emission and combustion pattern of research diesel engine fueled with higher alcohol and pongamia biodiesel blends
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Devaraj Rangabashiam, Jayaprakash V, Ganesan S, Christopher D
The variation in heat release rate for the O10PBD90, PBD, O20PBD20, and diesel is shown in Figure 9. Diesel exhibit highest heat release rate among test fuels. The possible reason for the higher heat release rate for diesel is due to its higher calorific value. Fuel with higher calorific value produces more quantity of heat during combustion (Radhakrishnan, 2017). By adding 10 and 20 vol% of octanol to PBD observe a considerable increase in heat release rate. This is due to improved combustion, reduced delay period and higher heat release rate (Kim and Choi, 2010). Further, the HRR rises for PBD with an increase in the content of octanol. This is due to lower viscosity of octanol in PBD, which in turn increases the air and fuel mixing, accelerates the combustion, and releases the maximum HRR. This result matches to the many kinds of literature (Rajesh et al. 2016; Saravanan et al. 2017; Harmiwati and Rahmad, 2015) that reported similar HRR variation of diesel engine powered by biodiesel, diesel, and alcohol mixture (Giakoumis et al., 2012).
Cashew nut husk and babassu coconut husk residues: evaluation of their energetic properties
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Antônia Mabrysa Torres Gadelha, Francisca Diva Lima Almeida, Ronaldy Araújo Silva, Jackson Queiroz Malveira, Ada Amélia Sanders Lopes, Maria Alexsandra De Sousa Rios
The heating values of raw materials and their blends are presented in Table 4. The energy content of the fuel is determined by its heat of combustion. This property depends on the biomass constituents and moisture content of materials (Poddar et al. 2014). All samples had high heating values (17.36–17.79 MJ/kg) compare to other fuels used in energy production such as wheat straw (16.4 MJ/kg) (Nanda et al. 2013), cereal straw (17.3 MJ/kg) (McKendry 2002), wood biomass (17.6 MJ/kg) and oat (17.2 MJ/kg) (Magdziarz and Wilk 2013). It is noted that although the CNH had shown relatively low moisture content, it showed the lowest high heating value as well. In other cases, biomasses with low moisture content possess high gross heat of combustion such as shown by Deshannavar et al. (Machado et al. 2018) studying rice husk residues.
Development of a test method to determine the effectiveness of UVC systems on commercial cooking effluent (RP-1614)
Published in Science and Technology for the Built Environment, 2020
Meng Kong, J. Zhang, K. Han, B. Guo, Z. Liu
The flammability of the deposition is a function of the composition of it. In this project, it refers to the heat of combustion released by a unit mass of the deposition. Generally, the heat of combustion of the organic compounds is determined by the energy released by breaking weaker bonds (i.e., C-H) and creating stronger bonds (i.e., C-O, H-O). Therefore, theoretically, after the UVC system, the flammability of the deposition should be reduced. However, Table 9 shows that the flammability of the depositions was not always reduced. The possible explanation is that the content of the food varied between cases and the oxidation of the deposition was far less than significant.