Tag Archives: drying

xxx J.L. Paes, B.C. Vargas, J.P.B. Cunha, D.S.C. Silva, G.A.S. Ferraz, M.R.S. Braz, P.F.P. Ferraz, L. Conti and G. Rossi
Thermal performance of a solar hybrid dryer for Conilon coffee (Coffea canephora)
Abstract |
Full text PDF (978 KB)

Thermal performance of a solar hybrid dryer for Conilon coffee (Coffea canephora)

J.L. Paes¹*, B.C. Vargas¹, J.P.B. Cunha¹, D.S.C. Silva¹, G.A.S. Ferraz², M.R.S. Braz¹, P.F.P. Ferraz², L. Conti³ and G. Rossi³

¹Rural Federal University of Rio de Janeiro, Engineering Department, Campus Seropédica, ZIP Code BR23890000, Seropédica, Rio de Janeiro, Brazil
²Federal University of Lavras, Agricultural Engineering Department, ZIP Code BR37200000, Lavras, Minas Gerais, Brazil
³University of Florence, Department of Agricultural, Food, Environment and Forestry (DAGRI), Via San Bonaventura, 13, IT50145, Florence, Italy *Correspondence: juliana.lobop@gmail.com

Abstract:

The study was aimed at design and development of an energy efficient hybrid solar dryer suitable for drying of organic Conilon coffee placed in the town of Seropédica, Rio de Janeiro, Brazil. The energy efficiency and the drying efficiency were the evaluation criteria for thermal performance of the hybrid solar dryer during the coffee drying. Temperature and relative humidity (RH) of the drying and ambient air, solar radiation intensity and coffee weight loss were monitored during the drying process. The process occurred over six consecutive days; the drying time was from 07:00 to 17:00 h, totalling 120 h of operation with an intermittent period (at night) of 14 h. During intermittence, the exhaust system kept off and solar collector and drying chamber sealed. The effective drying period took 60 h, with temperature and RH, respectively, of 38.3 °C and 60.6% outlet of the solar collector, 32.7 °C and 72.2% outlet drying chamber and 27.8 °C and 74.5% ambient air. The maximum temperature in the solar collector and drying chamber reached 54 and 47.7 °C, respectively, with an ambient air temperature of 32 °C at 12:00 h. These values showing temperature increase 22.2 °C in solar collector and 10 ºC drying chamber. The mean variation for the reduction in RH between the drying air inside the solar collector and the ambient air was 28%, while in the chamber obtained in a range of 10.5% at 13:00 h. The solar collector and dryer chamber efficiency were 29.1 and 40.8%, respectively, while the overall dryer efficiency 39.7%.

Key words:

, , ,




360-375 V. Bulgakov, I. Holovach, S. Kiurchev, S. Pascuzzi, M. Arak, F. Santoro, A.S. Anifantis and J. Olt
The theory of vibrational wave movement in drying grain mixture
Abstract |

The theory of vibrational wave movement in drying grain mixture

V. Bulgakov¹, I. Holovach¹, S. Kiurchev², S. Pascuzzi³, M. Arak⁴, F. Santoro³, A.S. Anifantis³ and J. Olt⁴*

¹National University of Life and Environmental Sciences of Ukraine, 15 Heroyiv Oborony Str., Kyiv UA 03041, Ukraine
²Dmytro Motornyi Tavria State Agrotechnological University, 18B Khmelnytsky Ave, UA 72310, Melitopol, Zaporozhye Region, Ukraine
³University of Bari Aldo Moro, Department of Agricultural and Environmental Science, Via Amendola, 165/A, IT70125 Bari, Italy
⁴Estonian University of Life Sciences, Institute of Technology, 56 Kreutzwaldi Str., EE51006 Tartu, Estonia
*Correspondence: jyri.olt@emu.ee

Abstract:

This paper outlines a theory that involves the vibrational wave transportation of bulk grain during the course of passing that grain under an infrared radiation source, in a working thermal radiation drying chamber, and using a vibrational wave transporter belt that has been developed by the authors of this paper. The main outstanding feature of the proposed design is the presence of mechanical off-centre vibration drives which generate the vibration in the working rollers at a preset amplitude and frequency, thereby generating a mechanical wave on the surface of the flexible transporter belt which ensures the movement of bulk grain along the processing zone which itself is being subjected to infrared radiation. A calculation method was developed for the oscillation system that is used in conjunction with the vibrational transportation of the grain mass, in order to be able to determine the forces that may be present in the vibrational system and to prepare the differential calculations for the movement of the vibrational drive’s actuators, utilising for this purpose Type II Lagrange equations. The solving of the aforementioned integral equations on a PC yielded a number of graphical dependencies in terms of kinetic and dynamic parameters for the vibrational system described above; the analysis of those dependencies provided a rational structural, along with kinetic and dynamic indicators. According to the results that were taken from theoretical and experimental studies on the functioning of the developed infrared grain dryer combined with a vibrational exciter, stable movement for its working roller takes place if the angular velocity of a drive shaft is changed within the range of between 50–80 rads–1, whereas the amplitude of the indicated oscillations falls within the range of 3.0–4.0 mm. It has been discovered that a rational speed when transporting soy seeds during infrared drying falls between the range of between 0.15–0.60 cm s-1, whereas the amplitude of the indicated oscillations falls within the range of 3.0–4.0 mm. An increase of this parameter within the stated limits increases the time that it takes to achieve the stage in which a constant drying soy speed is reached by more than 2.5 times (from 205 seconds to 520 seconds), stabilising the figure at a level of 520 seconds, which makes it possible to recommend a range of transport speeds of between 0.15–0.40 cm s–1 under infrared radiation for the seeds in order to achieve the required moisture content with a single pass of the produce on the wave transporter.
With that in mind, the power consumption levels for the vibrational exciter do not exceed 50W, while the angular velocity of the drive shaft’s rotation falls within the range of between 100–120 rads–1. The results of the experimental study that has been conducted indicated that a rational transportation speed for the soy seeds on the wave transporter under infrared radiation is between 0.15–0.40 cm s–1.

Key words:

, , , , ,




1301-1311 A. Aboltins, T. Rubina and J. Palabinskis
Shrinkage effect on diffusion coefficient during carrot drying
Abstract |
Full text PDF (824 KB)

Shrinkage effect on diffusion coefficient during carrot drying

A. Aboltins¹, T. Rubina²* and J. Palabinskis¹

¹Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Agricultural Machinery, J.Cakstes Blv 5, LV-3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Information Technologies, Department of Computer Systems, Liela 2, LV-3001 Jelgava, Latvia
*Correspondence: tatjana.rubina@llu.lv

Abstract:

Many studies have been previously carried out on the carrot drying and the undergoing processes. The developed mathematical models provide an opportunity to gain an understanding of this complex process and its dynamics. But they are simplified and based on a number of assumptions, including calculation of diffusion coefficient values. In one of the previous studies, the authors of this study determined that the diffusion coefficient is linearly dependent on the moisture concentration with the assumption that the sample’s geometric shape does not change. The aim of this study is to determine the dependence of the diffusion coefficient on the moisture concentration taking into account the change in sample thickness during the drying experiment. The experiments were carried out with carrot slices of three different thicknesses: 5 mm, 10 mm and 15 mm thickness on the film infrared dryer at temperature 40 °C. During the experiments, measurements of the weight and thickness of the slices were performed. Using the experimental data the average thickness and diffusion coefficient of slices was calculated depending on the moisture concentration. Obtained results show that thickness depends linearly on the moisture concentration. Using experimental data and obtained average values of samples thickness, the values of diffusion coefficient was calculated. The results indicate that diffusion coefficient value depend linearly on moisture concentration. Their values are close and tend to zero when the concentration decreases if the thickness changes are taken into account during the experiment.

Key words:

, , ,




723-727 P. Heřmánek, A. Rybka and I. Honzík
Determination of moisture ratio in parts of the hop cone during the drying process in belt dryer
Abstract |
Full text PDF (707 KB)

Determination of moisture ratio in parts of the hop cone during the drying process in belt dryer

P. Heřmánek*, A. Rybka and I. Honzík

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ165 00 Praha 6 - Suchdol, Czech Republic
*Correspondence: hermanek@tf.czu.cz

Abstract:

The paper deals with monitoring the moisture content of hop cones and their parts (strigs and bracts) in PCHB 750 hop belt dryer. When drying hop cones, the critical point is the sufficient drying of the strig. These are therefore dried to a moisture content of 6 to 8%. This exact moisture provides a sufficient guarantee ensuring that the strig is dried up. On the other hand, bracts are dried up to such a level which makes pressing the hops impossible. Therefore, after drying, the bracts are remoistened. This is called hops conditioning. After conditioning the moisture content of hops is optimal, ranging between 8 and 11%. There is no doubt that drying or any further moistening does not benefit the hop cone.
During the experiment, the moisture content was determined regarding the whole hop cones as well as the bracts and strigs separately, the samples of which had been taken from the hops prior to entering the dryer, from different parts of belts in the dryer and subsequently before and after the conditioning. The moisture content was determined by means of Mettler HE53 moisture analyzer. After the bracts and strigs had been dried, we calculated their weight ratio which was approx. 90% of bracts and 10% of strigs. Based on this ratio the weighted average was calculated which corresponds to the moisture content of the whole hop cone.
The measured values indicate that the average moisture content of hops below 10% was already at the beginning of the third belt of the dryer. The hops had been unnecessarily overdried along the whole third belt. Another output refers to the moisture ratio of hop cones, bracts and strigs in different parts of the dryer. The obtained values will serve as a basis for the follow-up design of a device for monitoring the dryer parameters and its visualisation.

Key words:

, , , , , ,




349-356 V. Bulgakov, V. Bandura, M. Arak and J. Olt
Intensification of rapeseed drying process through the use of infrared emitters
Abstract |
Full text PDF (635 KB)

Intensification of rapeseed drying process through the use of infrared emitters

V. Bulgakov¹, V. Bandura², M. Arak³ and J. Olt³*

¹National University of Life and Environmental Sciences of Ukraine, 15, Heroyiv Oborony street, UA03041 Kyiv, Ukraine
²Vinnytsia National Agrarian University of Ukraine, Soniachna street 3, UA21008 Vinnytsia, Ukraine
³Estonian University of Life Sciences, Kreutzwaldi 56, EE51014 Tartu, Estonia; *Correspondence: jyri.olt@emu.ee

Abstract:

The theoretical basis of the agricultural material drying techniques has been formed in the world for two and a half centuries. Nevertheless, despite the multitude of studies well presented in the literature, the industry still lacks universally recognized methods of design calculation for the majority of drying problems. Presumably, this is due to the fact that the dehydration of foodstuffs is one of the most energy-intensive and complicated work processes. In the process of thermal treatment during the drying, the physical state of the water in the treated item changes, the properties of the item itself are altered.
Recently, the drying of foodstuffs by means of infrared (IR) radiation has been gaining ever wider acceptance. At the same time, the technologies for dehydrating foodstuffs and materials are now far ahead of the theory of drying. Not only the classical literature on the drying problems, but even special studies on the subject cannot provide any specific recommendations for the design of installations with the electro-magnetic principle of energy input. Whereas that is exactly the type of installations that are now actively making headway, while offering serious challenges in their modelling. For that reason, experimenting has until now been the only reliable way of their studying. Despite the available extensive scientific literature on the drying, including works on IR units, the practical issues of engineering IR driers have not been tackled. All the existing studies consider solely particular cases. This study discusses the process of drying the fixed bed of rapeseeds with the use of the electromagnetic infrared emitter. The energy intensity of the process and the optimum thickness of the product bed are determined. The aim of the paper is to examine the effect that the operating condition parameters (energy input intensity, temperature, grain bed thickness) have on the drying kinetics and the energy characteristics of the process. The methods of research are based on the thermophysical analysis of the material’s structure. The experimental studies were carried out with the use of monitoring and measuring equipment, up-to-date methods and instruments, including solutions developed by the authors. The analytical treatment was performed with the use of the software packages: MathCAD, Excel. The sample testing and examination took place in the laboratory and the methods were in compliance with the applicable standards. A comprehensive experimental investigation of the effect that the operating parameters (specific load and power) have on the rape seed IR-drying kinetics had been accomplished.

Key words:

, , , ,




713–719 P. Heřmánek, A. Rybka and I. Honzík
Experimental chamber dryer for drying hops at low temperatures
Abstract |
Full text PDF (390 KB)

Experimental chamber dryer for drying hops at low temperatures

P. Heřmánek*, A. Rybka and I. Honzík

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ165 00 Praha 6 – Suchdol, Czech Republic
*Correspondence: hermanek@tf.czu.cz

Abstract:

Hop drying takes a significant part in growers’ costs of the final product processing. The current drying technology is based on drying at the drying air temperature of 55–60 °C for 6–9 hours to the final moisture content of about 10%. However, the process results in irreversible transformations and losses of, inter alia, heat labile substances contained in hops.
The experimental chamber dryer was tested at harvest in 2016. Assays hop drying were carried out at a temperature of the drying medium 40 °C. The research results in the form of an experimental new experimental chamber dryer will be used for testing of drying technologies at lower temperatures of the drying medium.
This is what will enable to preserve the quality of aroma as well as other characteristics of the components contained in hops.

Key words:

, ,




202-211 Xu Ma, R.H. Driscoll and G. Srzednicki
Development of in-store dryer model for corn for varying inlet conditions
Abstract |
Full text PDF (657 KB)

Development of in-store dryer model for corn for varying inlet conditions

Xu Ma, R.H. Driscoll and G. Srzednicki*

UNSW Australia, School of Chemical Engineering, Sydney NSW 2032 Australia;
*Correspondence: g.srzednicki@unsw.edu.au

Abstract:

Many thin layer drying models have been developed for constant inlet conditions. During deep bed drying, drying air conditions vary with position in the bed and also vary with time, so models developed for thin layers under constant conditions are not valid for deep bed drying analysis. A new thin layer drying rate model (called the two-layer model) is presented which allows for varying air conditions. The model was applied to corn by retro-fitting the model to Page’s mode as fitted by Li and Morey (1984). The model was then incorporated into a deep bed simulation, and the results compared with pilot plant drying data. During drying experiments, constant air conditions and varying air conditions were both tested. For constant conditions, all models gave reasonable agreement, but for varying drying conditions, the diffusion model showed an ability to respond better to changes.

Key words:

, , , ,




267-274 A. Aboltins and J. Palabinskis
New types of air heating solar collectors and their use in drying agricultural products
Abstract |
Full text PDF (568 KB)

New types of air heating solar collectors and their use in drying agricultural products

A. Aboltins* and J. Palabinskis

Institute of Agricultural Machinery, Latvia University of Agriculture, Cakstesblvd. ⁵, Jelgava, LV – ³00¹, Latvia;
*Correspondence: aivars.aboltins@inbox.lv

Abstract:

The  aim  of  this  research  was  to  make  new  types  of  air  heating  solar  collection  foragricultural production drying and check their operation. In ²0¹¹ and ²0¹² were obtained twoLatvian Republic Patents for air heating solar collectors. One for an autonomous, compact air-heating solar collector, the other one for a cylindrical crop production drying device with solarcollector  that  can  be  used  for  drying  products.  So  there  are  two  different  types  of  dryingfacilities with solar collectors using sun-warmed air: cylindrical crop production drying device,and  autonomous,  compact  crop  production  drying  facility.  Cylindrical  facility  is  tested  fordrying  ¹⁹.⁵%  wet  wheat.  Autonomous,  compact  crop  production  drying  facility  is  tested  forfresh  carrots  and  apples  ⁵–¹0 mm  slices  drying,  using  ambient  air,  heated  with  the  solarcollector.  For  experimental  results  on  carrot  and  apple  slices  the  layers  of  humidity  andtemperature  changes  in  the  drying  process  are  given.  Grain  temperature  distribution  in  wetwheat layers during drying with heated ambient air depending from sun radiation is given.

Key words:

, ,




529-532 A. Pasila
Changes, challenges and opportunities in the wood energy supply chain
Abstract |
Full text PDF (136 KB)

Changes, challenges and opportunities in the wood energy supply chain

A. Pasila

Seinäjoki University of Applied Sciences, School of Agriculture and Forestry,Ilmajoentie ⁵²⁵, ⁶0⁸00 Ilmajoki, Finland;
e-mail: antti.pasila@seamk.fi

Abstract:

One of the biggest challenges in using bioenergy has been the problem of logistics;that is how, in many cases, to process and transport these low density and bulky raw materials.Finnish  forestry  technology  is  advanced  and  the  same  machinery  which  is  used  in  timberharvesting is often used in energy wood harvesting.A  change  in  the  forest  industry  has  however  caused  some  new  expectations  concerning  thewood  energy  supply  chain.  One  of  the  basic  requirements  for  woodchips  is  low  moisturecontent. In the transportation of wood chips high moisture content, and therefore a high weight,may limit the carrying capacity of vehicles and roads. Also in syngas and charcoal productiondry raw material is needed to be able to control the combustion process.The reduction of moisture content under natural drying conditions means an extended storagetime. With Finnish climate conditions this normally means a storage period of at least one year.The  various  types  of  energy  wood:  stems,  whole  tree  harvested  stems,  logging  residues  orstumps are piled in storage sites and covered. The raw material is chipped or crushed at theseintermediate storage sites and after that transported to bio-refineries.In  the  measurement  of  the  energy  wood’s  quality  and  quantity  there  are  some  differencescompared  to  timber  measurements.  Normally  the  timber  measurements  are  based  on  solidvolume in cubic metres. The forest harvesters are equipped with on-line measurement systems.This  on-line  measurement  is  more  complicated  to  carry  out  in  the  case  of  energy  wood.Especially difficult are the volume measurements in whole tree and stump harvesting. A newmethod used in the measurement of energy wood is weight.

Key words:

, , , , ,




55-65 G. Pupinis
Grain drying by use of changeable air flow method
Abstract |
Full text PDF (217 KB)

Grain drying by use of changeable air flow method

G. Pupinis

Institute of Agricultural Engineering, Lithuanian University of Agriculture Raudondvaris,LT-51132 Kaunas, Lithuania; e-mail: pupinis@mei.lt

Abstract:

The article describes a new energy saving method for drying grain. The idea of the method is that once moisture released from grain decreases, air discharge going through the grain is reduced as well. ´Roland´ variety of barley with 25% and 30% moisture content was used in the trial. It was dried with a changeable air discharge in order to maintain absorption qualities. After the drying process has begun, air flow to the grain is reduced in the process of drying as the relative moisture content of air passing through decreases. It has been established that the optimum initial air discharge is 800 m3 (t h)-1. During grain drying air discharge is reduced and it can be described by equation0,0114969.85xye−=, R2 = 0.8088.The scheme for a designed and manufactured trial device is presented. Intensity of airdischarge and dynamics of moisture absorption in a layer of dried grain have been established.

Key words:

, , ,