The modified Dulong equation can be used to calculate the Higher Heating Value HHV of biomass (IFRF. International Flame Research Foundation 2004; Heaven et al. 2011; Milledge and Heaven 2015):

 HHV (MJ  kg-1 dry fuel)="  (34.1C+102H+6.3N+19.1S- 9.85O)/100

where C, H, N, S and O are the amounts of carbon, hydrogen, nitrogen, sulphur and oxygen in the biomass expressed as %.

Heaven S, Milledge J, Zhang Y (2011) Comments on 'Anaerobic digestion of microalgae as a necessary step to make microalgal biodiesel sustainable' Biotechnol Adv 29: 164-167 doi:DOI: 10.1016/j.biotechadv.2010.10.005

IFRF. International Flame Research Foundation (2004) Online Combustion Handbook. Method from Combustion File 24.

Milledge JJ, Heaven S (2015) Energy Balance of Biogas Production from Microalgae: Development of an Energy and Mass Balance Model Current Biotechnology 4:554-567

Good Morning.

The fixed carbon content is derived from subtraction of volatile materials content and ash content of the fuel. The calorific value is a property calculated based on contents elemental analysis (C, H, O, N). In this direction, there is a positive relationship between the carbon content and calorific value. However, the ash content (that is inserted in the fixed carbon calculation) has a negative effect on the final calorific value.

Hello Shahabaldin Rezania,

there are other equations like the modified Dulong equation mentioned by mr. Milledge, like Boie's: HHV / MJ/kg = 34,834 c + 115,912 h + 10,467 s + 6,28 n - 10,802 o with small letters as mass fraction

[LaTeX: \begin{equation}

\frac{H_{o,wf}}{\rm {MJ}/{kg}} = 34,834\,c_{\rm wf} + 115,912\,h_{\rm wf} + 10,467\,s_{\rm wf} + 6,28\,n_{\rm wf} - 10,802\,o_{\rm wf}

\end{equation}]

[BibTeX: @Book{boie1957,author = {Boie, W}, title = {Vom Brennstoff zum Rauchgas}, publisher = {Teubner}, year = 1957}]

, or Reed's: HHV / btu/lb = 141 c + 615 h + 39,95 s - 10,2 n - (1 - a) (17,244 h/c) + 149 with small letters as mass fraction, a for ash.

, or, if only the carbon content is known, Tillman's: HHV / Btu/lb = 188 c - 718

, or the IGT-equation: HHV / btu/lb = 146,58c + 568,78 h + 29,45 - 6,58 a - 51,53 (o+n)

all: [BibTeX: @Book{reed1981,editor = {Reed, T. B.}, title = {Biomass gasification}, publisher = {Noyes Data Corporation}, year = 1981, subtitle = {Principles and technology}, address = {New Jersey, USA}, note = {Solar Energy Research Institute, Golden, Colorado},}]

There are further equations, e.g. by Antal, that rely on proximate analysis, but the results are not as good as those relying on full ultimate analysis.

One remark about ash content. If you use data from ultimate analysis you also have to do proximate analysis to evaluate at least water- and ash-content.

Hope it helps,

greetings Jörg Ho

There are several models that can be used to estimate the calorific value, and the choice depends on type of biomass, and author. A detailed review has been done by Vargas-Moreno et al. (2012).

J.M. Vargas-Morenoa, A.J. Callejón-Ferrea, J. Pérez-Alonsoa, B. Velázquez-Martí, A review of the mathematical models for predicting the heating value of biomass

materials, Renewable and Sustainable Energy Reviews 16 (2012) 3065– 3083

Dear Emmanuel Menya 

This references (Vargas-Moreno et al. (2012) is too interesting for me and thanks for your help

Special thanks to all the researchers for their valuable comments , 

Jörg Ho, Ananias Junior, John Milledge and Pushpa Jha  

Dear Rezania,

You are very much welcome.

Emmanuel

If you can read text in Portuguese, I suggest a reading in the attached file.

http://www.imedpub.com/articles/physical-and-combustion-properties-of-briquettes-produced-from-sawdust-of-three-hardwood-species-and-different-organic-binders.pdf