Calorific potential

Abbreviations AT, temperature rise Am, mass loss tt, duration of flaming PCS, gross calorific potential FIGRA, ... 

The heat released in the course of complete combustion of a unit mass sample is the calorific potential of the material. Complete combustion implies that the total carbon, sulphur and hydrogen content of the material is converted into CO2, SO2 and H2O, respectively. 

Gross calorific potential is the enthalpy released by combustion of unit mass of a material provided that both the material before combustion and the combustion products after combustion are at about room temperature. Two variants of gross calorific potential exist as the combustion can proceed either at constant pressure or constant volume. 

Net calorific potential is the gross calorific potential reduced by the latent heat of vaporisation released when water is condensed in the system after combustion, including that from the combustion of hydrogen content of the material, that from the moisture content of the material, and the possible water of crystallization present in the material. 

The heat of combustion or calorific potential of solids (or liquids) is measured by a water jacket calorimeters with a kind of calorimeter bomb (Fig. 3.33). The water... 

The net calorific potential (2net) is calculated as the difference between the gross calorific potential (Q ) and the latent heat of vaporization of the condensed water (q) ... 

In Europe, gross heat of complete combustion (gross calorific potential, PCS), measured by following the ISO 1716 standard test method is used for the classification of reaction to fire performance for constmction products (prEN 13501-1) [42] ... 

A bomb calorimetric method is used to measure calorific potential of materials. Similar tests are described in DIN 51900, NF M03-005 and in Italian regulations. This type of test is often used in conjunction with flammability test methods to determine classifications of materials for legislation (for example, in French Building Regulations, only materials with a calorific value of less than 2500 kj kg , as determined in NF M03-005, can be considered for MO, the highest classification). 

There is an important feedback factor which cannot be properly evaluated at this time. It concerns future municipal investment in a specific waste control system. This could result in legislation controlling the input of important potential waste materials to the municipality. For example large capital investment in a heat/energy recovery system based on incineration might induce legislative restrictions on low calorific materials like metals and glass. 

Calorific values, calorimetric values and calorimetric potentials of NC and proplnts 2 C9—CIO... 

Phase 2. Transformation of calorific to chemical energy. Part of the heat released in the 1st phase is consumed in the chemical decompn of the next immediate layer of expl and thus releases the potential energy of that layer. The remainder of the calorific energy will be spent in the acceleration and reinforcement of the chem action. A considerable amt of kinetic energy is developed at this stage... 

Calorific Values, Calorimetric Values and Calorimetric Potentials of Nitrocelluloses and Propellants, Taylor et al (Ref 2,p 580), define the calorific value as the heat evolved (in calories per gram) when a substance is exploded in a special calorimetric bomb capable of withstanding high pressure... 

Calorimetric Value is defined by Comer(Ref 3) as the value which is obtained by measuring the heat evolved when a propellant is burned in a bomb calorimeter contg an insert atmosphere. The temps are near 300° K. This value can also be calcd as shown in Ref 3,pp 127--8 Calorimetric Potential, Apparant (Potentiel calorimetrique, apparent in Fr). Tavernier (Ref 4,p 234) defines it as the quantity of heat evolved on the decompn of a proplnt, provided it does not do any exterior work (which means under const vol) and if the gases evolved in reaction are cooled (which means that the water is liquid). This value is, accdg to Tavernier, identical with the English value called "Calorific Value . A similar value was called by DePauw (Ref 1) "die Characteristik einer Substanz ... 

Analyses and calorific values are determined on a mineral-matter-free basis by the Parr formulas (ASTM D-388), with corrections for pyrite and other mineral matter. The amount of pyrite is taken to be that equivalent to the total sulfur of the coal, which despite the potential error has been found to correlate well in studies of mineral matter. The remaining mineral matter is taken to be 1.08 times the weight of the corresponding (iron-oxide-free) ash ... 

Isothermal chemistry in fuel cells. Barclay (2002) wrote a paper which is seminal to this book, and may be downloaded from the author s listed web site. The text and calculations of this paper are reiterated, and paraphrased, extensively in this introduction. Its equations are used in Appendix A. The paper, via an equilibrium diagram, draws attention to isothermal oxidation. The single equilibrium diagram brings out the fact that a fuel cell and an electrolyser which are the thermodynamic inverse of each other need, relative to existing devices, additional components (concentration cells and semi-permeable membranes), so as to operate at reversible equilibrium, and avoid irreversible diffusion as a gas transport mechanism. The equilibrium fuel cell then turns out to be much more efficient than a normal fuel cell. It has a greatly increased Nernst potential difference. In addition the basis of calculation of efficiency obviously cannot be the calorific value of the... 

The thermodynamic basis of the calculation of the maximum possible work potential or chemical exergy of reversible and irreversible chemical reactions is explained and discussed. Combustion is asserted to be fundamentally irreversible. It is a nonequilibrium uncontrollable chain reaction with hot branches, in a cool milieu, and a limited work output proportional to Carnot efficiency x calorific value (Barclay, 2002). 

Table 19.1 lists the calorific values of some common polymers and compares them with some conventional fuels. As illustrated in the table, the calorific values of these plastics are very similar to those of liquid fuels. Thus, there is a potential for recycling of these waste plastics as liquid fuels. 

In this work, special attention was paid to minimising the potential residues from PET recycling. Some works have been published on active carbons from granulated non-used PET [4], but none concerning the use of plastic wastes. The advantage of the pyrolysis of post-consumer PET is that all the products obtained present interesting applications (i.e., chemical products, gases with calorific value and a solid that can be used as an active carbon), as a result of which residual wastes can be minimised considerably. The aim of this work was to obtain valuable active carbons from the solid residue from PET pyrolysis. 

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