Tadeusz Kudra

Sticky Region in Drying—Definition and Identification

Abstract A device has been developed, to characterize the stickiness of materials prone to shearing that is based on torque measurement during intermittent stirring. Experiments were carried out, using materials of various origin, and over a range of moisture contents that span the pasty to free-flowing powder consistencies. To reflect the complex nature of stickiness, often noted by researchers during the drying of slurries and pastes, the concept is proposed, of a stickiness region, adjacent to the stickiness curve. Referring to the two-dimensional visualization of a drying process with evolving moisture content and material temperature, possible trajectories are suggested, to deal with the stickiness problem. #The copyright is held by

Uniformity Issue in Microwave Drying

Microwave drying is an advanced drying technique in which heat is generated inside the material due to transformation of high-frequency electromagnetic energy so the liquid moisture is intensively evaporated and transported toward the material surface. However, an inherent problem in microwave drying is nonuniform heat generation, which leads to uneven drying. In this article, the factors causing nonuniform microwave heating were identified, and feasible approaches to solving the nonuniformity problem were analyzed in terms of improving the uniformity of the electromagnetic field distribution and random or organized dislocation of the processed material in virtually nonuniform microwave field. The R&D trends in microwave drying toward reducing uneven heating were pointed out and discussed.

INTERMITTENT DRYING OF CARROT IN A VIBRATED FLUID BED: EFFECT ON PRODUCT QUALITY

ABSTRACT Drying of diced carrot was studied experimentally in a laboratory batch-type vibrofluidized bed dryer (VFB) The kinetics of the degradation reaction of P-carotene chosen as the dominant quality index were determined for various time-temperature conditions. Relationships were obtained for instantaneous concentration of β-carotene, and for the degradation rate constant as a function of moisture content and material temperature. It was shown that the best quality product is obtained when carrot is dried in a VFB dryer down to the critical moisture content, than conditioned (tempered) in a single layer exposed to ambient air, and then finish dried to the final moisture content in a VFB dryer.

COMPUTER AIDED DRYING TECHNOLOGIES

A great progress has been done in computer software and hardware, which obviously broaden the application of computers to drying technologies. This paper provides the state-of-the art in computer-aided tools for drying environment. The following applications of computers are identified and discussed in depth: mathematical modeling and simulation for process calculation and equipment design (microscale approach– at the level of a single drop or particle, and macroscale approach– at the level of a dryer or drying system); process control; modeling tools; software packages; artificial intelligence systems; databases and information transfer.

Dynamic Characteristics of Solids Transportation in Rotary Dryers

Abstract An original method was proposed for the determination of the mean residence time in a continuous dryer, based on the step-change in the solids feed rate. The method has been validated through experiments performed in a pilot-scale rotary dryer. The effect of the solids flow rate, gas flow rate, dryer rotation speed, and dryer slope was quantified. Several design correlations to predict the residence time in rotary dryers were critically evaluated, and a new, more accurate correlation was derived. #The copyright is held by

PERFORMANCE CHARACTERISTICS OF THE VIBRATED FLUID BED OF INERT PARTICLES FOR DRYING OF LIQUID FEEDS

Experimental studies are presented on drying of soybean milk in a vibrated fluidized bed of inert particles. The effects of inlet air temperature, superficial air velocity, static bed height, and the feed rate on the bed pressure drop, product hold-up and the convective heat transfer coefficient are discussed. The thermal efficiency of the dryer as well as some basic characteristics for the vibrated fluid bed of glass beads and Teflon pellets are given and compared to the ones for conventional fluid beds. A regression equation for the volumetric heat transfer coefficient is provided.

EFFECT OF A TEMPERING PERIOD ON DRYING OF CARROT IN A VffiRO-FLUlDIZED BED

ABSTRACT Drying of diced carrot in a vibrofluidized bed was studied experimentally for various air temperatures, bed heights and size of the cubes. Effect of a tempering period that mav be implemented into ¦ drying cycle was examined with respect to drying kinetics and energy consumption. Although two stage drying with a tempering period increases the overall drying time, it shortens the drying time in a VFB dryer thus reduces energy consumption

On the 85th Birthday of Professor Czeslaw Strumillo

It is our privilege and great pleasure to honor Professor Czeslaw Strumillo, from Lodz Technical University in Poland, on his 85th birthday. The exceptional personality of Prof. Strumillo is widely acclaimed by his students, colleagues, and co-workers. His name is recognized worldwide for his invited lectures and notable scientific contributions to drying techniques and technology in numerous publications, conference presentations, and books he co-authored or contributed, among them the books Drying: Principles, Applications and Design (1986) and Thermal Processing of Biomaterials (1998), and chapters in Handbook of Industrial Drying (all four editions). In Poland, Prof. Strumillo is appreciated as the originator of in-depth studies on drying theory and practice. At his mother university, he established and headed the drying research group recognized for years as a leader in drying field in Poland and other European countries. He initiated regular meetings of drying researchers and practitioners. In 1972, these meetings turned into a series of biannual events known as the Polish Drying Symposium, which currently attracts a number of foreign participants. Professor Strumiłło was honored as the first recipient of the A. S. Mujumdar Medal for Outstanding Contribution to Drying R&D and Mentorship of Drying Researchers in 2007 at the Asia-Pacific Drying Conference in Hong Kong. On behalf of all his colleagues and co-workers, we would like to take this opportunity to wish Prof. Strumillo fruitful activity as Professor Emeritus and many happy and healthy years to come.

Guest Editorial: Selected Papers from the XIII Polish Drying Symposium

It is our privilege and great honor to serve as Guest Editors for this special issue of Drying Technology, built on selected papers presented at the XIII Polish Drying Symposium (PDS) held in Kolobrzeg, Poland, on September 5–6, 2013. The symposium was organized in the frame of XXI Polish Conference on Chemical and Process Engineering (September 2–6), so the organizing committee for this conference dealt with all administrative and logistic issues, such as conference venue, registration, accommodation, etc., as well as printing the book of Abstracts. The electronic version of full papers forming the conference proceedings were published on CD (ISBN 978-83-7518-596-6). The Nestor of the Polish drying community, Professor Czeslaw Strumillo, stated in his Inaugural Lecture on ‘‘Preface and a Short History of Polish and International Drying Symposia’’ that

Guest Editorial: Special Issue to Commemorate 30 Years of Drying Technology

The purpose of this special issue is to celebrate the 30th anniversary of Drying Technology. We see the reasons for celebrating not primarily in the round number of years passed since the introduction of the journal in 1982, but mainly in its uniqueness, success, internationality, interdisciplinary character, and the ability to shape the research field and promote the transfer of science into practice. Uniqueness of the journal is self-evident, because there is simply no other scientific periodical exclusively dedicated to drying. Success and internationality are countable in terms of subscriptions, printed pages, bibliographic indices (for example, an impact factor of, presently, about 2), and the almost complete coverage of the globe by journal contributors. The promotion of the transfer of science into practice is difficult to measure, but those of us who work closely with industry know very well that Drying Technology is the first place to look at when confronted with real-world drying problems, and that many results published in the journal have found, directly or indirectly, their way to application. As to the formation of the research field, it is probably the most important goal and indication of real impact for any scientific journal. In the case of Drying Technology, it may be assessed by comparing drying research 30 years ago and nowadays. With a certain simplification, one can say that the main focus of drying research 30 years ago was on dryer scaling up. This means that scientists were mainly involved in investigating heat and mass transfer in gas-solid systems typical of drying applications in order to find out, how large a dryer needs to be to fulfill a given dewatering duty. Such investigations were very close to thermodynamics and transport phenomena, with glass, sand and inert porous particles as the most popular materials. Concerning the contemporary stand of drying research, it is reflected quite well in the contents of the present anniversary issue. We are very grateful to all our colleagues who have positively responded to our respective call by providing the excellent set of articles included in this issue. Some of these papers have review character, some others express opinions about achievements and future challenges in drying, many more report the results of current research work. In total, the ‘‘anniversary papers’’ indicate that transport phenomena in multiphase systems are still an important topic, as they were 30 years ago. However, the papers show also clearly that several additional themes and crucial issues have strongly and seriously moved in the focus of contemporary drying research, such as the preservation and augmentation of product quality, the formation and formulation of multifunctional particles by drying, reduction of the energy demand and environmental footprint of the process, and process intensification by novel equipment configurations. Modern drying technology uses—and produces—rather soft and highly structured biomaterials than stiff inorganic compounds such as glass ballotini. It applies—and sometimes develops— advanced computational and experimental techniques, in a genuinely interdisciplinary frame. The richness and power of this research portfolio make us confident that farewell is not in the center of our present celebration, but rather the perspective and promise of thrilling research, and of new, innovative results for the next 30 years to come. Behind this optimistic outlook are the preparatory effort and the founding act from the year 1982, which was mainly driven by Dr. Carl W. Hall—at that time in transition from a professorship at the Washington State University to the Directorate of Engineering of the National Science Foundation, both USA—and by Dr. Arun S. Mujumdar—in 1982 professor at McGill University in Montreal, Canada. The drying community has given a highly earned tribute to Professor Hall on the occasion of the 25th anniversary of this journal, with a special issue dedicated to him in 2007. Today we are paying the tribute to Professor Mujumdar, who took over after Professor Hall and successfully led Drying Technology to its renowned position as a drying community forum. The personal curriculum of Professor Mujumdar is so closely integrated with the journal’s history and development that the 30th anniversary of Drying Technology is without any doubt also his own anniversary. We were lucky and delighted to obtain a laudatio to his person, written by nobody less than Professor Czeslaw Strumillo from the Technical University of Lodz in Poland, another outstanding personality from our community. Drying Technology, 30: 1125–1126, 2012 Copyright # 2012 Taylor & Francis Group, LLC ISSN: 0737-3937 print=1532-2300 online DOI: 10.1080/07373937.2012.705563