Browsing by Subject "Drying"

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ACHEMA 2022: Innovationen und Trends in der Trocknungstechnik
(2023) Ruprecht, Nora Alina; Frank, Jennifer; Raiber, Tobias V.; Teichmann, Heike; Gschwind, Peter; Kohlus, Reinhard
In diesem Beitrag werden die Highlights der auf der ACHEMA 2022 ausgestellten Neuerungen zusammengefasst und es wird über die beobachteten Trends berichtet. Neben neuen Anlagen in einzelnen Trocknungsbereichen wurden die Schritte der Firmen in den Bereichen der Schwerpunktthemen Digitalisierung und Nachhaltigkeit näher betrachtet.
Experimental analysis and CFD-based modeling of grain bulk drying dynamics
(2021) Ramaj, Iris; Schock, Steffen; Müller, Joachim
Drying is of great importance in the postharvest processing of agricultural commodities. It refers to the removal of the surplus moisture responsible for biochemical, microbiological, and other moisture-related deteriorative reactions, thereby ensuring quality preservation. However, drying is an intricate process comprising simultaneous heat and moisture transfers, which depends on product and drying air conditions. Therefore, drying practices are oftentimes misused, resulting in serious degradation of product quality. For this reason, modeling can be used to provide a deeper understanding of air-product interactions and to gain insights into drying process. Thus, this study focused on developing a CFD systematic approach to model the drying dynamics of wheat bulk (Pionier A, DSV AG) under controlled conditions. Within the model framework, a porous medium approach with tailored user-defined functions was utilized to represent the grain bulk characteristics. The drying experiments were performed using a high-precision and automated through-flow laboratory dryer. A coherent set of drying air temperatures T = 10 - 50°C, relative humidity RH = 20 - 60% and airflow velocity v = 0.15 - 1.00 ms-1 were employed for model validation. Afterwards, the validated computational model was used to predict the drying performance at T = 40°C, RH = 40% and v = 0.15 ms-1, where the simulated temperature and moisture content agreed very well with the experimental results (R2 ≥ 0.98 and MAPE ≤ 14.93%). The proposed model proved to be an efficient tool capable of simulating temperature and moisture dynamics inside the grain bulk with high spatial and temporal resolution, providing rapid and in-depth information compared to laborious physical experiments. In conclusion, the CFD-based approach has demonstrated a great potential for simulating drying processes. Its capabilities should be further assessed across various drying technologies, operating conditions, and agricultural commodities.
Improvement of the drying performance of pre-cooked beans (Phaseolus vulgaris) through ultrasonic-assisted hulling
(2022) Ramaj, Iris; Schock, Steffen; Ayetigbo, Oluwatoyin; Ntwali, Janvier; Müller, Joachim
Beans are among the most versatile and widely consumed staple foods worldwide. They are highly nutritious and contain high levels of dietary fibers, complex carbohydrates, proteins, essential vitamins, and minerals that are indispensable to human wellbeing. Due to their given importance, the development of processing methods for hard-to-cook beans for the preparation of instant end-products is of great interest, especially in developing countries. Thus, this study focused on investigating the influence of ultrasonic-assisted dehulling on the drying behaviour of pre-cooked beans as a viable alternative to the present drying approaches. Red kidney beans (Phaseolus vulgaris), unhulled (UHB) and dehulled via ultrasonication (HB/UT), were used for the experimental analysis. The cooking time of beans was determined based on sensory evaluation, with 50 and 25 min proving to be optimal for UHB and HB/UT, respectively. Afterwards, the pre-cooked samples were dried in a high-precision through-flow laboratory dryer (HPD-TF3+) at 30, 50, and 70° C with an air velocity of 0.20 ms-1 and specific humidity of 10 g kg-1. Results revealed a faster moisture transfer of the HB/UT beans compared to UHB beans at p < 0.05, which was attributed to the lower resistance to moisture diffusion induced by the hull removal. Henceforth, a reduction of drying time up to 73.3% was ascertained experimentally. A generalised semi-empirical model was developed from the analysis of the drying data, which was capable of predicting the drying behaviour of beans with R2 ≥ 0.990 and MAPE ≤ 10.0%. In terms of colour, UHB and HB/UT beans differed significantly at p < 0.05 for redness a*, yellowness b*, hue angle H*, and chroma c* across all drying conditions, while no significant differences were observed for luminosity L*. Microstructural analysis revealed comparable structures after drying at 30 and 50° C, with beans exhibiting an intact cellular structure. Temperatures of 70° C, on the other hand, degraded the cellular integrity of beans by breaking down the cell wall boundaries, especially in HB/UT beans. In conclusion, ultrasonic-assisted hulling has demonstrated a great potential for improving the drying performance of beans, thereby making it a viable alternative for practical applications.
Influence of wet extrudates from pumpkin seed proteins on drying, texture, and appearance of dry-cured hybrid sausages
(2022) Ebert, Sandra; Jungblut, Florence; Herrmann, Kurt; Maier, Barbara; Terjung, Nino; Gibis, Monika; Weiss, Jochen
Hybrid meat products represent a promising, more sustainable alternative to all-meat formulations. However, differences among plant- and animal-based proteins may alter traditional handling and final product properties. In this study, pork meat was partially replaced with texturized pumpkin seed proteins at 12.5, 25, 37.5, and 50% to obtain dry-cured hybrid meat sausages and their ripening (acidification, drying) during 21 days and final product properties (texture, sensory) were characterized and compared to a control (all-meat formulation). The drying behavior and distribution of moisture and free water of hybrids with extrudate contents of 12.5 and 25% were comparable to the sample made with meat and no significant ( p > 0.05) differences in proximate composition were found. In contrast, higher meat replacement levels resulted in distinct changes of compositional and textural attributes i.e. chewiness was decreasing by up to 70%. Results suggested 25% of extrudates as an important threshold in manufacture of hybrid dry-cured sausages due to alterations in their ability to bind or release water. Results may be used to understand the influence of alternative texturized proteins in hybrid formulations and help product developers to understand related process and product relevant changes.
Modelling of air resistance during drying of wood-chips
(2011) Müller, Joachim; Karaj, S.; Barfuss, Isabel; Schalk, J.; Reisinger, G.; Pude, R.
The objective of this study was to investigate the parameters that affect the drying process of wood chips at low air flow conditions. This objective was determined by measuring the air pressure resistance being produced by wood chips by examining different variables such as: air flow rate, air velocity, wood chip size, bulk density, bulk height and porosity. The air flow resistance was measured inside a 3 meter high cylindrical air duct constructed at University of Hohenheim. Physical properties of two different Spruce wood chip fractions were analyzed and their characteristics were considered on fitting the model expression. The analysed model expresses the physical behaviour of air flow resistance. Statistical analyses show high correlation of air speed versus air flow resistance. The model could be used for determination of drying conditions with low air mass flow. The height of bulk density according air mass flow generated or the necessary air mass flow needed for transporting air through the bulk height.
Untersuchungen und Verbesserungen der Querstromtrocknung von Getreide
(1980) Kuppinger, Heinz; Kutzbach, Heinz Dieter
Das Querstromtrocknungsverfahren findet weit verbreitete Anwendung zur Getreidetrocknung. Allerdings hat dieses Trocknungsverfahren den Nachteil der geringen Trocknungsleistung, des hohen Wärmebedarfs und der ungleichmäßigen Trocknung der Körnerschüttung.. Ziel der vorliegenden Arbeit war es daher, zu untersuchen, inwieweit durch eine Variation der das Trocknungsverhalten beeinflussenden Trocknungsparameter und durch eine Modifikation des Querstromverfahrens Verbesserungen der Querstromtrocknung zu erreichen sind.