Dulong’s formula

Ultimate analysis-an analysis to determine the amounts of basic feed constituents. These constituents are moisture, oxygen, carbon, hydro- gen, sulfur, nitrogen, and ash. In addition, it is typical to determine chloride and other elements that may contribute to air emissions or ash- disposal problems. Once the ultimate analysis has been completed, Dulong s formula can be used to estimate the heating value of the sludge, Dulong s formula is ... 

For accurate heat values of solid and liquid fuels calorimeter determinations are required. However, approximate heat values may be determined for most cools if the ultimate chemical analysis is known. Dulong s formula gives reasonably accurate results (within 2 to 3%) for most coals and is often used as a routine check of values determined by calorimeter ... 

Dulong s Formula and the Choice of Biomass Derived Fuel Form... 

Feedstock Characteristics. Feedstock characteristics are presented in Table I. Results of the metal analysis will be considered in Phase II of the project. Calorific values were approximated using Dulong s formula and not actually measured. The oat straw had a lower ash content than the stover and a correspondingly higher calorific value. Calorific values, calculated on a dry basis and including the latent heat of water vapour in the products of combustion (high heat value), were 17.9 MJ/kg for the straw and 16.0 MJ/kg for the stover. 

High heat value approximated using Dulong s formula... 

The value of coal expressed in calories evolved in its combustion can be ascertained either by calculation or by actual determination in a calorimeter. The chief constituents of coal which in combustion evolve heat are carbon and hydrogen. Those which absorb it during combustion are moisture and the inorganic matter which remains in the form of ash. Dulong s formula for calculating the number of calories (V) evolved by the combustion of 1 kg. of coal is—... 

Using Dulong s formula, calculate the Gross and Net calorific value of the coal. 

In 1818 he mentions Dulong s (see p. 199) and Berzelius s results and confirmed Dulong s discovery of hypophosphorous acid, but thought his phosphatic (hypophosphoric) acid a mixture. Davy by taking the proportional numbers or equivalents of oxygen as 15 and phosphorus 45 obtained what correspond with the formulae hypophosphorous acid P + 0, phosphorous acid P + 2O, and phosphoric acid P + 4O, all incorrect. He was unable to find the composition of liquid chloride of phosphorus (PCI3) by synthesis but from 13 6 gr. decomposed by water he obtained 43 gr. of silver chloride (correct 42 6) 3 gr. of phosphorus required about 20 (should be 17I) gr. of chlorine to form the sublimate (PCI5). Most of the experiments were made by Faraday. 

The relationship between the high and low heating values of a fuel having the empirical chemical formula is given by Dulong s equations. Note that the negative sign indi-... 

The values of C, H, S, and O can be taken from the fuel or flue-gas analysis. If the heating value of a fuel is known and the C and S are known, the approximate value of the net H can be determined from the Dulong formula. A general relation between the gross heating and net heating values is... 

If we knew the numerical value of the constant a in formula (7), this expression could be employed to calculate the value of dO/dt for any given value of 0. To evaluate a, substitute the observed values of V and 6 in (7) and take the mean of the different results so obtained. Thus, a = 0 031. The third column shows the velocities of cooling calculated on the assumption that Newton s law is true. The agreement between the experimental and theoretical results is very poor. Hence it is necessary to seek a second approximation to the true law. With this object, Dulong and Petit have proposed... 

Petit and Dulong suggested that their law might apply to compounds but made no attempt to verify this. It was first extended to solid compounds by Franz Ernst Neumann, professor of physics and mineralogy in Konigsberg, who from results with carbonates, sulphides, and oxides, concluded that the amounts of chemically similar compounds expressed by their formulae possess equal specific heats , by which he understood molecular heats, i.e. sp. ht. xmol. wt. Avogadro arrived at a similar conclusion, but his results were not very accurate and were criticised by Regnault, who confirmed Neumann s law for compounds de mSme composition atomique et de constitution chimique semblable . 

Dulong Pierre-Louis (1785-1838) Fr. chem., research on refractive indices and specific heats of gases, co-formulated Dulong-Petit s law, devised empirical formula for the heat Earnest Charles Mansfield (1941-) US chem., expert in geoscience and minerals (book Thermal analysis of clays 1984) Einstein Albert (1879-1955) Ger. phys., originator of theories of relativity, laws of motion and rest, simultaneity and... 

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