# Kinetic Models of Wood Biomass Drying in Hot Airflow Systems  
[PERSON]  
1 Departamento de Production Vegetal, Universitat Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain; [EMAIL_ADDRESS] (I.G.V. ); slococor@upvcs (I.L.C. )1 Departamento de Ingenieria Rural y Agroalimentaria, Universitat Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain2 Departamento de Ingenieria Rural y Agroalimentaria,into charcoal. The ground material can be used for the production of pellets or briquettes. Although there are probably experiments on drying small particles, it is usual to carry out drying on chipped or crushed material, with a particle size greater than 3 cm. Obviously the small particle size increases the mass transfer surface, but the handling of these particles is more difficult. After particle size reduction, several drying methods are available. Common methods include the following:  
* Air drying: This is the most commonly used method. It involves the use of air to evaporate moisture from the material. The air stream can be forced or natural. The air absorbs the water particles by diffusion and convection [4]. * Vacuum drying: A reduced negative pressure on the surface is used to accelerate the evaporation process. This pressure influences the diffusion of particles inside the pores of the biomass and thus increases the rate of mass transfer [5]. * Radiation drying: In this process, radiant energy is absorbed by the material, which causes the water to evaporate. Electromagnetic radiation can come from various sources, such as electric radiators, infrared lamps, microwaves, or other sources of radiant energy [6]. When the radiation reaches the wet material, some of the energy is absorbed and converted into heat. This heat causes the water to evaporate, allowing it to escape from the material in the form of steam. Radiation drying can be selective, as different materials have different absorption capacities, which affects the speed and efficiency of the drying process. For example, the material may be transparent to microwaves, which will interact exclusively on water molecules, where the heat of evaporation is generated [7]. * Freeze-drying: This involves freezing the material and then removing the water by sublimation under vacuum conditions. The duration of the process varies according to the method used, the type of material, porosity, and the required moisture level. During the drying process, it is important to control several parameters such as particle size, temperature, relative humidity, air velocity, and vacuum pressure if applicable. It is important to note that the drying process can be critical in the energy balance of biofuel production. Energy efficiency is an important consideration during the design and implementation of industrial drying systems [8]. This is why mathematical modelling for the prediction of process time and quality becomes a scientific challenge that needs to be worked on. Several works suggest that further research should focus on obtaining models adaptable to different species and environmental conditions to improve the applicability of empirical studies. This need parallels the findings observed in the study of [PERSON] et al. (2015) [9] where it was demonstrated that environmental factors significantly influence dust generation in vibrated cohesive powders. On the other hand, drying is also a process widely used in the agri-food and pharmaceutical industry, for example, for drying foodstuffs or wood, and it is for this reason that in-depth knowledge of it becomes necessary in order to optimise it. Thus, the technical difficulties of predictive modelling of drying processes have led to the development of empirical curves, which, although they allow the results of the process to be obtained with relative simplicity [10; 11], only allow their application in the conditions given at the time and place of the experimentation, thus not being able to transport the process to other conditions and obtain the same results.