Thermophysical properties of dilute acid slurries of cassava bagasse as a function of biomass loading, acid concentration, and temperature

Abstract

For suitable design of equipment and process optimization, the determination of thermophysical properties of the raw materials is necessary. Therefore, this work was aimed at determining and modeling the density, specific heat, thermal diffusivity, and thermal conductivity of acid slurries of cassava bagasse used during its conversion into bioethanol. Experimental measurements were carried out in slurries with different mass fractions of cassava bagasse (0.00 to 0.10) and phosphoric acid (0.00 to 0.10) at temperatures from 278.13 to 318.13 K. Results obtained show that density varied from 986.5 to 1,029.3 kg∙m−3, specific heat from 3,830.0 to 4,142.6 J∙kg−1∙K−1, thermal diffusivity from 0.9624 × 10−7 to 1.5249 × 10−7 m2∙s−1 and thermal conductivity from 0.3825 to 0.6212 W∙m−1∙K−1. While density increased with increasing solids and acid content at decreasing temperature, the thermal properties decreased at higher solids and acid content and increased when heating the slurries. The values were well‐fitted to polynomial models with good accuracy (R2 > 0.921 and MRE < 1.75%), allowing the application of the models to obtain reliable and ready‐to‐use data for cassava bagasse processing. Thus, the data reported in this study can be used for designing and managing momentum, heat and mass transfer processes for enhancing bioethanol production from cassava bagasse.

Explorative Study of Reactive Extrusion over Nixtamalization‐Maize Pericarp Residue: Effect on Dietary Fiber, Resistant Starch, and Nixtamalized Corn Flour Tortillas

“…Phosphoric acid has been used before to change the recalcitrant structure of cassava bagasse to a sustainable fiber substrate for bioethanol production. [ 34 ] According to other works, phosphoric acid with steam explosion hydrolyses hemicellulose until sugars monomers but does not affect cellulose. [ 23 ] There is also an observed effect on lignin to release starch and glucose.…”

Physical Properties and Molecular Interactions Applied to Food Processing and Formulation

“…On the other hand, there is some difficulty in changing samples with successive cleaning of the apparatus and in controlling the temperature of the sample and the overall calibration. For these reasons, electronic techniques involving the use of density meters have demonstrated accurate results, in addition to being easy to handle, even when dealing with suspensions [10,11]. More advanced techniques involve the collection of ultrasonic measurements using electrostatic transducers and signal processing to detect density variations in foods [12].…”

“…They consist of a specific apparatus that enables energy balancing when heat is provided to the sample inside the bottle [23]. In order to provide more accurate and rapid data, the use of a differential scanning calorimeter (DSC) has become increasingly popular [24], currently representing the most used method for estimation of specific values and their temperature dependence in different applications [11,25,26].…”

“…This property represents the correlation between the rate of heat conducted through the material and the rate of stored heat [11]. The most common techniques used to estimate thermal diffusivity of foods are based on food composition [21] or experimentally obtained values of specific heat capacity, thermal conductivity and density [37].…”