Drying Of Biomaterials Research Articles

Pulsed electric field pre-treatment efficiency analysis in processes of biomaterials drying

The transition to an efficient economy and efficient production requires building the foundations for the development of energy efficient technologies and the drying of biomaterials to convert them into useful products. The purpose of this work is to analyze the effectiveness of pretreatment with a pulsed electric field (PEF) in the process of convective drying of biomaterials. The PEF was processed with electric field strength of 2, 4 and 6 kV/cm, the number of pulses 500, with a pulse duration of 50 ?s. Based on the electrical conductivity data of the biomaterial, the index of the disintegration 56% was determined before and after the PEF treatment, which confirms the existence of an electroporation mechanism of the material structure. The drying process is presented with a description of various mathematical models. PEF pre-treatment with the parameters of electric field strength 4 and 6 kV / cm and the number of impulses 500 allowed to reduce the drying time by 13.8% for the value E = 0.02. Total time spent on the drying process reduced by 20-25 minutes. It should be noted that the total energy spent on PEF pre-treatment (<150 W / kg) compared with the energy spent on the drying process is incommensurably small. Statistical analysis of the considered mathematical models showed good convergence of most models with experimental data. The considered technology of pretreatment of PEF can ensure the effective processing of biomaterials in the required amount to obtain high-quality and safe products. Obtained data of the kinetics process can be used to the mathematical model of the drying process design with the use of preliminary treatment processing.

Investigation of the Parameters Governing the Performance of Jet Impingement Quick Food Freezing and Cooling Systems – A Review

Jet Impingement Technology (JIT) is a heat transfer enhancement technique. Available literature soundly confirm its wide applications in the cooling of combustion chambers, critical parts of turbines, glass technology, electronic components, drying of paper and textile materials, drying of biomaterials and food preservation. The technology has interesting fluid dynamics and heat transfer properties. Its relative simplicity and low cost, abundance of air, generation of high heat transfer and faster freezing rates have made it a subject of extensive investigations. Several investigations on jet impingement quick food freezing and cooling systems which range from visualization, experimental, computational simulations and or numerical analysis, factorial and mathematical models have been studied. This paper reviews the governing parameters of the jet impingement quick food freezing and cooling systems.

Analysis of Energy Consumption in Drying Process of Biomaterials Using a Combined Unsymmetrical Double-Feed Microwave and Vacuum System (CUMV)—Case Study: Tea Leaves

An energy analysis of drying of biomaterials (tea leaves) was conducted on a combined unsymmetrical double-feed microwave and vacuum system (CUMV) to optimize the operating conditions and quality of the products. Tea leaves were dried from an initial moisture content of 172 to 7% (db). An energy consumption model based on the first law of thermodynamics was developed to evaluate energy efficiency. The influences of microwave power, vacuum pressure, and microwave operation modes on energy consumption were investigated in detail. The results showed that energy consumption as well as energy efficiency were strongly dependent on vacuum pressure and microwave power. Energy consumption and color parameters of the tea leaves were compared at different drying conditions. In particular, the experiments were carried out at different microwave powers (800 and 1,600 W) at a frequency of 2,450 MHz and different vacuum pressures (535 and 385 torr) to investigate the effects of these factors on the microwave–vacuum drying.

Spouted and fluidised bed drying of biomaterials

Spouted and fluidised bed drying of biomaterials

Microwave-Vacuum Drying of Flax Fiber for Biocomposite Production

Flaxfiber is one of the important bastfiber available in North America which has low density and good mechanical propertiesfor reinforcing various polymers to develop industrial biocomposite. But the hydrophilic nature of the fiber leads to poor adhesion between the fiber and the polymer matrices which, in turn, leads to poor dimensional stability. To enhance the adhesion between polymer matrix andfiber, chemical treatments of the fiber are necessary. After these treatments, the fiber needs to be uniformly dried to minimum moisture content for better compounding offlax in polymer matrices. Drying by conventional dryers at higher temperature usually results in overall quality loss due to surface drying, and it is also time consuming and energy intensive. In recent years, the microwave has been effectively used for enhancing bulk drying of biomaterials especially when coupled with vaccum. Such a volumetric heat transfer mechanism coupled with drying in vacuum provides an ideal low-temperature drying technique resulting in better organoleptic quality. In this study, the drying characteristics offlax fiber were studied under microwave-vacuum condition. The drying experiments were conducted in Enwave® Microwave-vacuum dryer using three different process variables viz., microwave power (750 W and 375 W), vacuum level (25, 10, and 0 in Hg) and time of drying (0 to 14 mins). In order to select the appropriate drying curve equation, the drying data was fitted in three different models viz., Page model, single exponential model and approximation of diffusion model.

Determination of Air Flow Pattern During Solar Drying of Fruits Using a Low Range Air Speed Sensor

The solar drying is an attractive drying method in a sense of low temperature dehydration process which is useful for the dry product quality and energy saving including the environmental issues. Moreover, it can be applied in small scale (family size farms) which is in accordance with the distributed resource approach of the sustainable development. In the course of the recent research numerous drying experiments were elaborated with the solar drying of biomaterials, mainly with fruits. Beside the measurements, the modelling of the drying process was also investigated. Special attempt was carried out developing a low range air speed sensor (for measuring natural ventilation during the solar drying process) which can be used with a usual data logging system. After choosing the working principle a one dimensional prototype of the sensor was developed and constructed. Based on the measurements the optimal setting of the sensor was determined. Additionally, the set-up of a two-dimensional sensor prototype is also presented, along with its first measurement results.

A New Laboratory Dryer for Analysing the Deterioration Kinetics of Biomaterials

Convective drying is a cost saving presewtion technique for the production of bulk products. However, heat senstive bioprodusts may be damaged by convective drying. This paper presents the conception of a convective laboratory dryer with particular features for a simple and rapid examnination of deterioration processes during the drying of biomaterials. The drayer is described and results are given concerning the preservation of microorganisms for environmental applications. The results show that deterioration of the gram-negative bacteria Pseodomonas putida during drying is mainly caused by dehydration. Membrane damage is one of the dehydration deterioration mechanisms. Drying temperatures below 40°C ensure that thermal death of P. putida is neglegible.

The Application of Heat Pump in Drying of Biomaterials

ABSTRACT The UN estimates that 6.4 billion people will be living on Earth by the year 2000. As a consequence, dried biomaterials demand will rise and equipments will have to be built or redesigned to accomadate changes. The design and innovations on industrial dryers require fundamental knowledge conceived in laboratory units. The new heat pump dryer operates at a wide relative humidity and the air temperature is adjustable from –20 to 100'C. Above and belw freezing point drying modes are done in the same plant which allows the control of biomaterial properties. The technique consists of two stages, unbound weakly held water removal by freeze drying. and tightly bound moisture desorption by medium temperature drying. The fluidized and shelf heat pump dryers have the required features to dry heat sensitive biomaterials. The dryers were built and extensive research on biomaterials has been conducted at The Norwegian Institute of Technology. Many emeriments were done on effect of heat pump drying conditions ...

Modeling Simultaneous Heat and Mass Transfer in an Isotropic Sphere-A Finite Element Approach

ABSTRACT Afmite-element formulation is used to obtain numerical solutions to the simultaneous moisture and heat diffusion equations describing the moisture removal and heat intake process for an isotropic sphere. The model is used to solve a sample problem of drying a soybean kernel. The distribution and gradients of temperature and moisture dveloped inside the kernel during the drying process are established. The predicted drying curve for the soybean model compared favorably with experimental results in the literature. This technique is very powerful in explaining the complicated coupled phenomena of heat and mass transfer in general, and drying of biomaterials in particular.