Modeling Intermittent Drying of Wood under Rapidly Varying Temperature and Humidity Conditions with the Lumped Reaction Engineering Approach (L-REA)

For improving product quality and minimizing energy consumption during drying, intermittent drying is often recommended. The mathematical models that are used to describe intermittent drying are usually transport phenomena based, complex models. In this study, the lumped reaction engineering approach (L-REA) is implemented to model wood drying under rapid periodically changed drying air temperature and humidity with high number of cycles of intermittency. The equilibrium activation energy (ΔE _v,b ), an important parameter for REA approach, is evaluated according to the corresponding drying air temperature and humidity in each drying section. The results of modeling suggest the L-REA works well with the experimental data. The simplicity of the L-REA is obvious and is hoped to be used in an industrial setting more readily. The L-REA can be used for sustainable processing in industries to assist in energy audit and management.     

Heat and Mass Transfer in Unsaturated Porous Cake with Heated Walls

The mineral granules in the industrial drying units such as rotary dryer or fluidized dryer or the membrane in the PEMFC experience transient multiphase heat and mass transfer with transient heating mode. In particular, the transport process within mineral granules in the dryer is difficult to model owing to effects of complicated granule-granule collision and granule-heated surface. This article presents a comprehensive model consisting of continuity and heat and mass balances of three phases in an unsteady state. Numerical results revealed the flow patterns and temperature distributions of gas and liquid phases in mineral granule over time. The thermal response of the heated medium will be very different under low and high mixing intensities. The development of a recirculation liquid zone to balance the yielded capillary suction gradient enhances local evaporation and vapor accumulation rates, thus determining the overall evaporation rate form medium.     

THE MYSTERIES OF TECHNOLOGY TRANSFER. LUCK VERSUS GOOD PLANNING

Technology transfer is the art of turning elegant science or technology into a paying proposition. It requires good planning and a lot of hard work, but even these cannot guarantee success. Some examples of paper drying technologies that have enjoyed varying degrees of success have been used as a basis for discussion of some of the barriers to technology transfer and how they might be overcome.     

Influence of Oil Load and Maltodextrin Concentration on Properties of Tuna Oil Microcapsules Encapsulated in Two-Layer Membrane

The two layers of tuna oil-in-water emulsions containing different oil loads (5–10 wt%) and maltodextrin concentrations (10–20 wt%) were stabilized by a lecithin–chitosan membrane. The liquid emulsions were then spray dried at an inlet air temperature of 180 ± 2°C and an outlet air temperature of 85 ± 5°C. The characteristics of liquid emulsion (creaming and mean droplet size) and spray-dried microcapsules (moisture content, water activity, color, morphology, glass transition temperature, and encapsulation efficiency) were measured. The results suggest that two-layer oil-in-water emulsions are an effective system to produce high oil-loaded microcapsules, which may lead to its wide application for use in food products.     

Production of Microencapsulated Crawfish (Procambarus clarkii) Astaxanthin in Oil by Spray Drying Technology

In this study, an emulsion prepared with flaxseed oil containing crawfish astaxanthin, sodium caseinate, lactose, and water was spray dried to produce microencapsulated flaxseed oil containing crawfish astaxanthin powder (MCA). Production rate and energy used to produce MCA were estimated. Physicochemical properties and storage stability of MCA were determined. The energy required to spray dry the microencapsulated flaxseed oil containing astaxanthin was 2.36 × 10⁴ kJ/kg of emulsion. The microencapsulation efficiency for MCA was 86.06%, which indicated that more oil was encapsulated than on the particles’ surfaces. The particle size of MCA ranged from 6 to 100 µm. The astaxanthin concentration in MCA was 13.76 μg/g powder and alpha-linolenic acid (ALA) was the predominant fatty acid (53%) in MCA. Degradation of astaxanthin in MCA followed first-order reaction kinetics and could be well described by the Arrhenius equation. The astaxanthin in MCA was more stable when the powder was stored at 5°C than at 25 or 40°C.     

MODELING SIMULATION AND CONTROL OF THE WOOD DRYING PROCESS Part 1. A Set of PDE's as an Internal Model

Abstract

The internal model proposed is a nonlinear system of a few partial differential equations. The boundary conditions for the differential equations are specified at the lumber board entrance and between the wood and air. The initial conditions are calibrated by solving the static model and by the technical experiment. In conclusion, it can be said that the consistency of the model with experimental results seems to be reasonably good and can be used for process simulation and control