Determination of mechanical properties for wood pellets used in DEM simulations
Eutiquio Gallego 1  
,   José María Fuentes 1  
,   Ángel Ruiz 2  
,   Gonzalo Hernández-Rodrigo 2  
,   Pedro Aguado 2  
,   Francisco Ayuga 1  
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BIPREE Research Group, ETSIAAB, Technical University of Madrid, Avda. Puerta de Hierro 2, 28040 Madrid, Spain
Department of Engineering and Agricultural Sciences, University of Leon, Avda. de Portugal, 41, 24071 Leon, Spain
Eutiquio Gallego   

Ingeniería Agroforestal., Universidad Politecnica de Madrid, ETSIAAB. Avda. Puerta de Hierro 2-4, 28040, Madrid, Spain
Final revision date: 2020-11-10
Acceptance date: 2020-11-18
Publication date: 2020-12-16
Int. Agrophys. 2020, 34(4): 485–494
Wood pellets are increasingly being used to produce energy as a part of the decarbonization process of the economy, but their handling is associated with several problems, which usually requires that the equipment used has to be modified and improved. The discrete element method is a numerical technique suitable for simulating individual particles and handling systems. This paper focuses on the determination of the mechanical and physical parameters for wood pellet particles which are required to develop a discrete element method model to improve handling and transport systems. This study reports the experimentally determined values for wood pellet particles with respect to particle density, modulus of elasticity, particle – particle and particle – wall coefficients of restitution, and particle – particle and particle – wall coefficients of friction. Following the previous findings by other researchers with large samples of bulk material, it has been found that the modulus of elasticity for individual wood pellets depends on the water content, and the particle – wall coefficient of restitution depends on the impact velocity.
Aarseth K.A., 2004. Attrition of feed pellets during pneumatic conveying: the influence of velocity and bend radius. Biosystems Eng., 89(2), 197-213.
ASAE S368.4, 2006. Compression Test of Food Materials of Convex Shape. American Society of Agricultural and Biological Engineers (ASABE).
Bedford A. and Fowler W., 2008. Engineering mechanics statics & dynamics. Prentice Hall.
Deng T., Alzahrani A., and Bradley M., 2019. Influences of environmental humidity on physical properties and attrition of wood pellets. Fuel Processing Technol., 185, 126-138.
Dyjakon A. and Noszczyk T., 2019. The influence of freezing temperature storage on the mechanical durability of commercial pellets from biomass. Energies, 12, 2627.
European Commission, 2019. Report from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions on the implementation of the Circular Economy Action Plan. European Commission, Brussels.
Frodeson S., Henriksson G., and Berghel J., 2019. Effects of moisture content during densification of biomass pellets, focusing on polysaccharide substances. Biomass Bioenergy, 122, 322-330.
Gilvari H., de Jong W., and Schott D.L., 2020. Breakage behavior of biomass pellets: an experimental and numerical study. Computational Particle Mechanics.
González-Montellano C., Fuentes J.M., Ayuga-Téllez E., and Ayuga F., 2012. Determination of the mechanical properties of maize grains and olives required for use in DEM simulations. J. Food Eng., 111(4), 553-562.
Graham S., Eastwick C., Snape C., and Quick W., 2017. Mechanical degradation of biomass wood pellets during long term stockpile storage. Fuel Proc. Technol., 160, 143 -151.
Hastie D.B., 2013. Experimental measurement of the coefficient of restitution of irregular shaped particles impacting on horizontal surfaces. Chemical Engineering Science, 101, 828-836.
Hlosta J., Žurovec D., Rozbroj J., Ramírez-Gómez A., Nečas J., and Zegzulka J., 2018. Experimental dete.rmination of particle-particle restitution coefficient via double pendulum method. Chemical Eng. Res. Design, 135, 222-233.
Hlosta J., Jezerská L., Rozbroj J., Žurovec D., Nečas J., and Zegzulka J., 2020a. DEM investigation of the influence of particulate properties and operating conditions on the mixing process in rotary drums: Part 1 Determination of the DEM Parameters and Calibration Process. Processes, 8, 222.
Hlosta J., Jezerská L., Rozbroj J., Žurovec D., Nečas J., and Zegzulka J., 2020b. DEM Investigation of the influence of particulate properties and operating conditions on the mixing process in rotary drums: Part 2 – Process validation and experimental study. Processes, 8, 184.
ISO 18134-2, 2017. Solid biofuels – Determination of moisture content – Oven dry method – Part 2: Total moisture – Simplified method. International Organization for Standardization (ISO).
ISO 18847, 2016. Solid biofuels – Determination of particle density of pellets and briquettes. International Organization for Standardization (ISO).
Jägers J., Wirtz S., Scherer V., and Behr M., 2020. Experimental analysis of wood pellet degradation during pneumatic conveying processes. Powder Technol., 359, 282-291.
Jezerska L., Zegzulka J., Palkovska B., Kucerova R., and Zadrapa F., 2018. Pelletization of invasive Reynoutria Japonica with spruce sawdust for energy recovery. Wood Res., 63(6), 1045-1058.
Kocsis Z. and Csanády E., 2017. Investigation on the mechanics of wood pellet production from sawdust and chips. Progress report nº 6. Dep. Wood Engineering, University of West – Hungary.
Kruggel-Emden H. and Kacianauskas R., 2013. Discrete element analysis of experiments on mixing and bulk transport of wood pellets on a forward acting grate in discontinuous operation. Chemical Eng. Sci., 92, 105-117.
Molenda M., Stasiak M., Moya M., Ramirez A., Horabik J., and Ayuga F., 2006. Testing mechanical properties of food powders in two laboratories – degree of consistency of results. Int. Agrophysics, 20, 37-45.
Moya M., Ayuga F., Guaita M., and Aguado P., 2002. Mechanical properties of granular agricultural materials. Trans. ASAE, 45(5), 1569-1577.
O’Sullivan C., Bray J.D., and Riemer M., 2004. Examination of the response of regularly packed specimens of spherical particles using physical tests and discrete element simulations. J. Eng. Mechanics, 130(10), 1140-1150.
Oveisi E., Lau A., Sokhansanj S., Lim C.J., Bi X. T., Larsson S.H., and Melin S., 2013. Breakage behavior of wood pellets due to free fall. Powder Technol., 235, 493-499.
Ramírez-Gómez Á., Gallego E., Fuentes J.M., González-Montellano C., and Ayuga F., 2014. Values for particle-scale properties of biomass briquettes made from agroforestry residues. Particuology, 12, 100-106.
Rozbroj J., Zegzulka J., Necas J., and Jezerska, L., 2019. Discrete element method model optimization of cylindrical pellet size. Processes, 7(2), 101.
Saeed A., Farooq M., Andrews G., Phylaktoua H., and Gibbs B., 2019. Ignition sensitivity of different compositional wood pellets and particle size dependence. J. Environ.Manag., 232, 789-795.
Salehi H., Poletto M., Barletta D., and Larsson S., 2019. Predicting the silo discharge behavior of wood chips - A choice of method. Biomass Bioenergy, 120, 211-218.
Schott D., Tans R., Dafnomilis I., Hancock V., and Lodewijks G., 2016. Assessing a durability test for wood pellets by discrete element simulation. FME Trans., 44, 279-284.
Stasiak M., Molenda M., Bańda M., Wiącek J., Parafiniuk P., Lisowski A., Gancarz M., and Gondek E., 2019. Mechanical characteristics of pine biomass of different sizes. European J. Wood Wood Products, 77, 593-608.
Wojtkowski M., Pecen J., Horabik J., and Molenda M., 2010. Rapeseed impact against a flat surface: physical testing and DEM simulation with two contact models. Powder Technol., 198(1), 61-68.
Wong C., Daniel M., and Rongong J., 2009. Energy dissipation prediction of particle dampers. J. Sound and Vibration, 319(1-2), 91-118.
Wu M., Schott D., and Lodewijks G., 2011. Physical properties of solid biomass. Biomass Bioenergy, 35, 2093-2105.
Yazdanpanah F., Sokhansanj S., Lau A.K., Lim C.J., Bi X., Melin S., and Afzal M., 2010. Permeability of wood pellets in the presence of fines. Bioresource Technol., 101, 5565-5570.