Hannes KöhlerTechnische Universität Dresden | TUD · Institute of Natural Materials Technology
Hannes Köhler
Doctor of Engineering
About
46
Publications
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Introduction
Description, Evaluation and Modelling of Cleaning Processes
Additional affiliations
July 2010 - present
Publications
Publications (46)
Die Reinigung von Maschinen und Anlagen ist ein komplexer Prozessschritt in der Lebensmittelindustrie. Gegenwärtig erfolgt die Auslegung von Reinigungsprozessen in der Regel erfahrungsbasiert oder nach empirischen Regeln. Der alternative Lösungsansatz einer Reinigungssimulation bietet das Potential einerseits Einblicke in die relevanten Mechanismen...
Cleaning simulation: possibilities and challenges
Insight into the current state of research at TU Dresden
Knowledge of the cleaning mechanism is necessary to choose a suitable model for a cleaning simulation. In the present work, an existing classification scheme for cleaning mechanisms is considered. Altough this framework is quite promising, the generation of training data constitutes a bottleneck, since the labeling was done manually and very roughl...
In this contribution the authors investigate how flushing of chocolate using a follow‐up chocolate in a straight horizontal pipe is affected by temperature. The authors investigate a non‐uniform distribution of temperature across the considered domain. This is done using two cases, where the first exhibits a wall temperature deviating from the norm...
Consumer safety and product quality are of high priority in the food industry. Strongly adhering deposits are formed in processing equipment such as plate heat exchangers, which demand large quantities of water, chemicals, energy and time for cleaning. This study presents an approach to characterize soil properties and to link them to the cleaning...
Predicting the cleaning time required to remove a thin layer of soil is a challenging task and subject of current research. One approach to tackle this problem is the decomposition into physical sub-problems which are modelled separately and the subsequent synthesis of these models. In this paper, an existing model for adhesive detachment is extend...
To clean highly viscous fluids from pipework, flushing processes are used. The cleaning
time for a pair of fluids, one being flushed and one used for flushing the other out, is
typically estimated by using expensive experiments or costly fully resolved numerical
simulations. In this work the authors propose a new approach to determine an accurate
a...
Cleaning is an important process step in the food industry, especially to avoid contamination during increasingly frequent product changes. The equipment is cleaned almost daily causing high ecological and economic expenses. Predicting the cleaning time required to remove a thin soil layer for given operating conditions can prevent the use of unnee...
For the design of cleaning processes in general and for the parameterization of process models in particular, it is necessary to determine cleaning-relevant material properties of the soils and their change depending on cleaning fluid and soaking time. The dominant cleaning mechanism depends on the balance of cohesive strength within the soil and t...
Predicting the cleaning time required to remove a thin layer of soil is a challenging task and subject of current research. One approach to tackle this problem is the description of physical sub-problems and the subsequent synthesis of these models. In this paper, an existing model for adhesive detachment is extended for the prediction of the clean...
Consumer safety and product quality are of high priority in the food industry. Strongly adhering deposits are formed in processing equipment such as plate heat exchangers, which demand large quantities of water, chemicals, energy and time for cleaning. This study presents an approach to characterize soil properties and to link them to the cleaning...
Cleaning is an important process step in the food industry, especially to avoid contamination during increasingly frequent product changes. The equipment is cleaned almost daily causing high ecological and economic expenses. Predicting the cleaning time required to remove a thin soil layer can prevent the use of unneeded resources. The authors rece...
The removal of film-like deposits is a challenge in many fields of production. For environmental and economic reasons, the cleaning processes need to be optimized. An optimization by means of computational fluid dynamics seems to be beneficial, but is subject to some restrictions, especially in industrial context. General modeling ideas, a subdivis...
The removal of film-like soils is a challenge in many fields of production for consumer goods. For ecological and economic reasons, these cleaning processes have to be optimized. A model for the prediction of the cleaning times of adhesively detaching soils is presented. It is formulated as a boundary condition for CFD simulations, which reduces th...
Closed production lines are often cleaned by oversized Cleaning in place (CIP) procedures designed according to worst-case scenarios. This study presents an inline sensor system for monitoring the local cleaning process of swellable food soils based on the inverted piezo electrical effect. The sensor uses quartz crystals to detect soil layers on it...
Due to the increasing awareness of both environmental and consumer protection as well as the advancing individualisation of consumer goods, the food industry continuously faces new challenges. An increasing product variety and simultaneously decreasing batch sizes demand for frequent product changes and, consequently, a large number of cleaning pro...
The cleaning behaviour of a pre-wetted soil is studied experimentally and modelled numerically for the prototypical case of plane channel flow. One of the channel walls is soiled with a food-based model soil containing luminescent tracer particles to perform space- and time-resolved investigations of the cleaning process. Pre-wetting is applied for...
The removal of film-like deposits is a challenge in many fields of production. For environmental and economic reasons, the cleaning processes need to be optimised. An optimisation by means of computational fluid dynamics seems to be beneficial, but is subject to some restrictions, especially in industrial context. General modelling ideas, a subdivi...
The removal of film-like deposits is a challenge in many fields of production. For environmental and economic reasons, the cleaning processes need to be optimised. An optimisation by means of computational fluid dynamics seems to be beneficial, but is subject to some restrictions, especially in industrial context. General modelling ideas, a subdivi...
Using a new test setup, the results for the mechanical impact force and pressure of water jets of a nozzle in tubular form with different nozzle diameters (3,4 mm), gauge pressures (1…6 bar) and stand-off distances (0.5…5 m) are presented. It is shown that the stand-off distance and thus the jet break-up has a significant influence on the mechanica...
To simulate cleaning processes is of constantly growing importance with regard to optimising the cleaning efficiency in food production lines. This requires suitable parameters to describe the cleaning behaviour of different soils. Therefore, a method was developed to determine the normal and shear stress, which are necessary to remove a swollen so...
A physical-numerical simulation model for the cleaning of swellable soils by diffusive dissolution or cohesive separation of small soil particles, which was developed targeting a low computational effort, is presented and validated. The flow calculation, based on the Reynolds averaged Navier Stokes equations (RANS), and the calculation of the soil...
Method for investigation, modelling and optimisation of cleaning processes with coherent liquid jet
Kurzfassung Ein im Hinblick auf geringen Berechnungsaufwand entwickeltes, physikalisch-numerisches Simulationsmodell für Reinigungsvorgänge durch diffusives Auflösen oder kohäsives Trennen kleiner Verschmutzungsteilchen wird vorgestellt und validiert. Die Strömungs-berechnung auf Grundlage der Reynolds-gemittelten Navier Stokes Gleichungen (RANS) u...
The cleaning behaviour of a pre-wetted soil is studied experimentally and modelled numerically for the prototypical case of plane channel flow. One of the channel walls is soiled with a food-based model soil containing luminescent tracer particles to perform space-and time-resolved investigations of the cleaning process. Pre-wetting is applied for...
The cleaning behavior of a soil with physical properties that depend on the wetting time is studied experimentally via the local phosphorescence detection method and simulated numerically in fully developed plane channel flow for Reynolds numbers up to 30,000. A computationally inexpensive general cleaning model is proposed, adopting an existing re...
To meet consumer safety and high product quality there is a need of reliable cleaning processes in the food industry. To keep competitive position it is necessary to control costs of those cleaning in place (CIP) processes e.g. Expenses for fresh and waste water, detergents and to minimize downtime of the production facilities. The removal of food...
The cleaning behavior of a soil with physical properties that depend on the wetting time is studied experimentally via the local phosphorescence detection method and simulated numerically in fully developed plane channel flow for Reynolds numbers up to 30000. A computationally inexpensive general cleaning model is proposed adopting an existing remo...
The removal of layers of a model food soil (dried Xanthan gum containing fluorescent ZnS particles) by a vertical water jet impinging normally on to the plate, generated by a solid stream nozzle which moves across the plate was reported by K?hler et al. (2014). Their experiments investigated nozzle pressures from 0.5-2.0 barg; nozzle diameters from...
Für die Entwicklung eines praxistauglichen Vorhersagemodells für die Strahlreinigung wird ein Ansatz motiviert, welcher auf der Zerlegung in abhängig vom Anwendungsfall parametrierbare Teilprozesse beruht. Als Ausgangspunkt der Modellierung dient eine reduzierte Konfiguration: der senkrecht auf eine glatte Verschmutzung auftreffende, kohärente isot...
This article summarises recent progress on the wetting and cleaning of tank walls by liquid jets. New models give good agreement with experimental data.
Cleaning of process equipment is a necessity in the pharmaceutical and food industry. Recently, the efficiency of these cleaning processes has come more into focus due to increasing economical and ecological demands. Different approaches to assess cleaning processes in terms of their cleaning effectiveness, cleaning efficiency, cleaning rate and cl...
Die Reduzierung des Ressourcenaufwandes für Reinigungen in der Lebensmittelproduktion ist ökonomisch und ökologisch sinnvoll. Deshalb wird hier durch die Identifikation relevanter Verfahrensparameter das Potenzial der pulsierenden Spritzreinigung zur Steigerung der zeitbezogenen Reinigungseffizienz aufgezeigt. Der Einfluss der Frequenz sowie der re...
The cleaning action of coherent liquid jets impinging (a) vertically downwards on horizontal plates, and (b) horizontally on vertical plates, was investigated using three soft-solid model soil layers: (i) PVA glue on glass and polymethylmethacrylate (Perspex) substrates; (ii) Xanthan gum on stainless steel; and (iii) petroleum jelly on glass. The l...
Cleaning with a pulsating liquid jet
Efficient cleaning is a considerable challenge in various industrial fields. Laboratory scale cleaning tests are an approach to investigate the influences of operating parameters on the cleaning result and to assess the required efforts. In this paper an impinging jet cleaning process was studied. The test setup and evaluation method enables the me...
The spatially resolved measurement of the soil layer thickness on surfaces is a precondition for quantitative cleanability tests of 3D parts which are important for the investigation, optimization and validation of spray cleaning systems. In this paper a photogrammetric analysis method is investigated which uses the luminescence intensity as an amo...
For the production of high-quality food products regular and effective cleaning of processing machines is
essential. Although spray cleaning is common standard in food processing industry a detailed explanation of
aspects important to describe cleaning processes is still missing. The objective of this work was to study the
influence of surface roug...
The use of optical systems is an approach to monitor the cleaning progress. But so far a constant thickness of the soil layer is a precondition for quantitative evaluation of cleaning effects. Our results give rise to the hypothesis that a constant soil thickness is not necessary, since the thickness might be calculated from the measured light inte...
Mit optischen Systemen können Reinigungsvorgänge
überwacht werden. Eine Voraussetzung für die quantitative
Erfassung ist bisher eine konstante Schichtdicke der Verschmutzung.
Die hier vorgestellten Ergebnisse geben Anlass
zu der Hypothese, dass die Schichtdicke von fluoreszierenden
Verschmutzungen anhand der gemessenen Emissionsintensität
ermittelt...
Regular and effective cleaning of food processing machines is essential to guarantee high food quality. Cleaning times in dairy industry make up about 15-40% of the total production time.
Research results presented prior to this work show the influence of machine surface properties on cleaning efforts and the potential to reduce the cleaning effort...