Characterization of the thermal degradation and heat of combustion of Pinus halepensis needles treated with ammonium-polyphosphate-based retardants

  • A. Àgueda
  • S. Liodakis
  • E. Pastor
  • E. PlanasEmail author


The thermal degradation behavior of P. halepensis needles treated with two ammonium-polyphosphate-based commercial retardants was studied using thermal analysis (DTG) under nitrogen atmosphere. Moreover, for the same experimental material, the heat of combustion of the volatiles was estimated based on the difference between the heat of combustion of the fuel and the heat contribution of the charred residue left after pyrolysis. The heat of combustion of the volatiles was exponentially related to the retardant concentration of the samples. In the range of retardant concentrations from 10 to 20% w/w the mean reduction percentage of the heat of combustion of the volatiles, with respect to untreated samples, was 18%.


Bomb calorimeter Char Forest fires Heat of combustion Long-term retardants Thermal analysis Volatiles 

List of symbols


Ammonium polyphosphate


Differential thermogravimetry


DTG peak decomposition rate (103 s−1)


Effective heat of combustion (MJ kg−1 fuel consumed)


Fire-Trol 931


Fire-Trol 934


Heat of combustion (MJ kg−1)


High heat of combustion (MJ kg−1)


Heat yield (MJ kg−1)


Heat of combustion released per kg of oxygen consumed (13.1 MJ kg−1)

\( \Updelta h_{{dsp\;{\rm H_{2}O}}} \)

Heat of desorption of bound water in the fuel (MJ kg−1)

\( \Updelta h_{{v\;{\rm H_{2}O}}}\)

Latent heat of vaporization of water at 100 °C (MJ kg−1)


Low heat of combustion (MJ kg−1)

\({\dot{m}}_{\rm {O_{2},\infty }} \)

Oxygen mass flow at ambient conditions (kg s−1)

\( {\dot{m}}_{\rm{O_{2}}} \)

Instaneous oxygen mass flow (kg s−1)


Pinus halepensis


Heat rate (kW)


Heat loss due to incomplete combustion (MJ kg−1)


Heat loss due to radiation losses (MJ kg−1)


Percentage of residual mass at 550 °C to initial mass at 150 °C (% w/w)


DTG peak temperature (°C)


Char yield (% w/w)


Percentage of hydrogen (% w/w)


Retardant concentration (% w/w)


Moisture content on a dry basis (% w/w)



Charred residue







1, 2, 3

Peak number in DTG graphs



Three of the authors (A. Àgueda, E. Pastor and E. Planas) would like to acknowledge the Spanish Ministry of Education and Science for supporting this research under the project AGL2005-07269. These authors are also very grateful to M. Pérez, who performed with patience TG/DTG experiments. A. Àgueda also received financial support from the Department of Education and Universities of the Autonomous Government of Catalonia and the European Social Fund.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2009

Authors and Affiliations

  1. 1.Centre d’Estudis del Risc Tecnològic (CERTEC)Universitat Politècnica de CatalunyaBarcelona, CataloniaSpain
  2. 2.Laboratory of Inorganic and Analytical Chemistry, Department of Chemical EngineeringNational Technical University of Athens (NTUA)AthensGreece

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