Driven by the goal of decreasing emissions and pollutants towards a more sustainable future, the automotive industry is undergoing a rapid transition towards battery-powered electric vehicles. This shift to sustainable transport is fast-paced, and new technical solutions are being offered on a regular basis to fulfil the future needs for electric vehicles, including battery-electric trucks. This continuously necessitates a fast development of the battery-electric truck, along with the cooling system. To validate the cooling system, Scania's preferred approaches are testing and 3D simulations. However, these approaches are time-consuming and cannot match the pace of the design or the development. This thesis addresses the implementation of using 1D Simulations (GT-Suite) to carry out coolant filling simulations as a more efficient approach by studying the filling of the battery cooling system in an electric truck and, later, validating the results obtained with a test rig. In this thesis, different cases were defined, each adding more complexity to the circuit, and the parameters studied were the filling times and the location of air traps. Finally, a case with a closed circuit and running a coolant pump was developed to study the possibilities of devising quicker deaeration techniques for the circuit. The work completed in this thesis may be used as an example of how filling simulations can be performed with GT-Suite. This thesis is a good starting point, exploring a vast potential in using 1D Simulations to simulate the coolant-air interaction in a cooling system. Nonetheless, the findings revealed that GT-Suite v2020 and v2021 lack a robust model to properly simulate the interaction of coolant and air in certain sections of the circuit. In addition, the simulation model failed to obtain a steady-state solution in some cases resulting in discrepancies between the results from the test rig and the simulations. In conclusion, it was found that 1D simulations are not an ideal way forward when individual components of the cooling circuit are being considered, for example, the cooling plates, but are much quicker and seem to be a promising method to get an overview on a system level. / Fordonsindustrin drivs av målet att minska utsläppen och föroreningarna mot en mer hållbar framtid och genomgår en snabb omställning mot batteridrivna elfordon. Övergången till hållbara transporter går snabbt och nya tekniska lösningar erbjuds regelbundet för att möta de framtida behoven av elfordon, inklusive batteridrivna lastbilar. Detta kräver kontinuerligt en snabb utveckling av den batteri-elektriska lastbilen, tillsammans med kylsystemet. För att validera kylsystemet är Scanias föredragna metoder testning och 3D-simuleringar. Dessa tillvägagångssätt är dock tidskrävande och kan inte matcha takten i designen eller utvecklingen. Denna avhandling behandlar implementeringen av att använda 1D-simuleringar (GT-Suite) för att utföra kylvätskefyllningssimuleringar som ett effektivare tillvägagångssätt genom att studera fyllningen av batterikylsystemet i en elektrisk lastbil och senare validera resultaten som erhållits med en testrigg. I denna avhandling definierades olika fall, var och en lägga till mer komplexitet till kretsen, och de undersökta parametrarna var påfyllningstiderna och platsen för luftfällor. Slutligen utvecklades ett fall med en sluten krets och kör en kylvätskepump för att studera möjligheterna att utforma snabbare deaerationstekniker för kretsen. Arbetet i denna avhandling kan användas som ett exempel på hur fyllningssimuleringar kan utföras med GT-Suite. Denna avhandling är en bra utgångspunkt och utforskar en enorm potential i att använda 1D-simuleringar för att simulera kylvätske-luftinteraktionen i ett kylsystem. Resultaten visade dock att GT-Suite v2020 och v2021 saknar en robust modell för att korrekt simulera interaktionen mellan kylvätska och luft i vissa delar av kretsen. Dessutom kunde simuleringsmodellen inte få en steady state-lösning i vissa fall vilket resulterade i skillnader mellan resultaten från testriggen och simuleringarna. Sammanfattningsvis konstaterades det att 1D-simuleringar inte är en idealisk väg framåt när enskilda komponenter i kylkretsen övervägs, till exempel kylplattorna, men är mycket snabbare och verkar vara en lovande metod för att få en översikt på systemnivå.

Hydraulic tanks have a variety of different tasks. The have to store the volume of oil needed for asymmetric actors in the system as well as to supply the system with preconditioned oil. This includes the deaeration as air contamination is affecting the overall system performance. The separation of the air in the tank is being realized mainly by passive methods, improving the guidance of the air and oil flow. The use of CFD models to improve the design of hydraulic tank is recently often discussed. In this paper, a design method for hydraulic tanks using CFD is presented and discussed. First the different requirements on a hydraulic tank are described as well as the motivation changing the tank designs. Additionally, a quick overview on different calculation models for the behavior of air in oil as well as the capabilities of CFD to reproduce them is given. After this the methodology of tank design applying CFD is presented. The method is then used in an example.

Abstract The objective of this thesis was to determine the effects of design, operational and furnish quality parameters on pressure screen and hydrocyclone performance. The general contradictory interrelationships between capacity and selectivity in pressure screening and cleaning are commonly recognized, but deep understanding of the effects of design, operational and furnish quality parameters on the state of operation is missing. As separation selectivity is closely dependent on thickening and pulp passage, an operation curve for separation was applied and its application further developed to examine the parameters affecting pressure screen and hydrocyclone separation. New information was found on the geometry of the screen plate, furnish quality parameters in pressure screen fibre fractionation, and the hydrocyclone separation of fibres, sand and gases. The capacity increases achieved by changes in the wire screen plate geometry were found to be achieved at the cost of separation selectivity in probability screening. The capacity of the screen plate was affected by the flow on the screen plate and through it. The hydraulic resistance both in the forward and reverse flow directions was found to be of great importance for the capacity of the screen plate. Previously unreported knowledge was found regarding the effects of wire width, height and shape. Pressure screening capacity was found to decrease with increasing fibre length, fibre network strength and flocculation. Pressure screen fibre fractionation selectivity was increased by broadening of the fibre length distribution of the feed furnish. The furnish properties also affected the separation selectivity of fibres, sand and gases in the hydrocyclone. An increase in fibre network strength reduced the separation selectivity of the hydrocyclone separation of fibres and sand. Any increase in the specific surface area, and especially in the amount of fines, was found to make gas removal more challenging. It was concluded that a broader range of the specific surface distribution can increase the selectivity of fibre fractionation in the hydrocyclone. Knowledge of the general effects of design, operational and furnish quality parameters on the performance of pressure screen and hydrocyclone separation was deepened as a result of this work, which provides a framework for studying these effects further in pursuit of the general objective of maximizing capacity and selectivity while minimizing energy and investment costs.

Abstract A pulp suspension consists of water, fibres, fines, fillers and chemicals, but air or other gases are also present in practically all pulping processes either in dissolved form or as bubbles. Dissolved gases seldom disturb the processes, but they are readily converted to gaseous form when conditions change. The gas bubbles affect the properties of the pulp suspension, reduce the accuracy of certain measurements, interfere with the runability of the papermachine and detract from the quality of the end-product. Gases are removed from the process by either mechanical or chemical means, resulting in increased investments and operational costs. The aim of this work was to study the behaviour of gas in pulp and papermaking processes with laboratory, pilot-scale and mill-scale experiments. Five main areas of the research can be identified: 1. Occurrence of gases in pulp and paper mill processes, 2. Dissolution, precipitation and hold-up of gases in the pulp suspension and mill water, 3. Effects of gases on certain consistency measurements, centrifugal pumping and operation of the hydrocyclone. 4. Measurement of the gas content of the pulp suspension by compression, radiometric, microwave and sonar methods and 5. Removal of gases with a centrifugal pump equipped with vacuum pump or hydrocyclone equipped light reject removal. The results show that the dissolution and precipitation of gas is strongly dependent on the pulp and water properties. Dissolved and colloidal material reduces the solubility potential of gas, but also accelerates the precipitation of dissolved gases in gaseous form. The hold-up of precipitated gas bubbles was found to be much more pronounced in hydrophobic mechanical pulps than in lignin-free chemical pulps. The accuracy of consistency measurements was affected by free gas in the pulp suspension, requiring special attention when assessing the results. The operation of pressure screens and hydrocyclones was affected only at high volumes of free gas in the feed suspension. According to the experiments, a reliable gas content measurement can be achieved by in-line radiometric, microwave or sonar methods, and also by the off-line compression method if a representative sample is obtained. A centrifugal pump equipped with a gas removing unit is designed mainly to ensure undisturbed pumping, whereas its gas removal efficiency remains quite low, especially with small bubbles and at a low gas content. The gas removal efficiency of a hydrocyclone equipped with light reject removal is good, but decreases with small precipitated bubbles. These results offer new information of the behaviour of the gas in pulp suspensions and white water and underline the importance of the bubble generation mechanism in this context.

Abstract Gas removal from the papermaking process is currently a standard practice, whereas purification of the internal water circulation has become common only recently. Both unit processes have progressed greatly during recent decades and new concepts are constantly being developed. The aim of this thesis was to analyse the efficiency and applicability of a channel flow design introduced by Metso for passive white water deaeration and to study the dynamics of passive bubbly gas removal. In addition, separation of the detrimental process water components by selective flotation during deaeration was studied to add further functionality to the channel flow design. Turbulent mixing at the flow discharge and the consequent air entrainment were seen to limit the gas separation efficiency. Also, the properties of different white waters notably affect their deaeration through viscous forces, the concentration of surface active components and bubble-particle interactions. Thus similar levels of gas separation cannot be achieved with all process waters. The analysis showed that the drag of small microbubbles is mostly caused by hydrophobic contamination and the dispersed particles that readily attach to the bubbles. Correlations were derived based on experimental data to provide new information on the drag force experienced by small bubbles in white waters. Chemically unaided flotation of white water in the channel flow was shown to be efficient in separating hydrophobic contaminants that have adverse effects on paper machine production and product quality. Both good reductions in contaminant content and high selectivity in their removal were achieved. Channel flow with an overflow can be considered well suited for the first stage of froth separation, while further treatment of the channel flow reject may consist of a secondary flotation or other process that enables the recirculation of fines and fillers. Although a certain level of losses of fines and fillers must be expected, substantial fraction of these solid components can be returned to the process stream. The proposed multifunctional process, channel flow deaeration and frothing of white water, was seen to be straightforward, economical and feasible while also providing benefits in terms of total process efficiency that are not delivered by any current process scheme. The experimental parameters presented here regarding bubble dynamics and flotation efficiency can be used to achieve better models of these processes.

Hydraulic tanks have a variety of different tasks. The have to store the volume of oil needed for asymmetric actors in the system as well as to supply the system with preconditioned oil. This includes the deaeration as air contamination is affecting the overall system performance. The separation of the air in the tank is being realized mainly by passive methods, improving the guidance of the air and oil flow. The use of CFD models to improve the design of hydraulic tank is recently often discussed. In this paper, a design method for hydraulic tanks using CFD is presented and discussed. First the different requirements on a hydraulic tank are described as well as the motivation changing the tank designs. Additionally, a quick overview on different calculation models for the behavior of air in oil as well as the capabilities of CFD to reproduce them is given. After this the methodology of tank design applying CFD is presented. The method is then used in an example.

This paper introduces the comprehensive approach of ARGO-HYTOS in developing and optimizing hydraulic tanks. Starting with a detailed analysis of the application, the tank design was optimized and an innovative deaerator was developed. In a first step, various Computational Fluid Dynamics (CFD) -based analyzing methods are presented, which are used to support the optimization process of tank development with regard to complex flow conditions and unexpected influences. The main topic of this paper is the introduction of an innovative labyrinth deaerator, causing coalescence of air bubbles, slower subsequent flow conditions and finally a better deaeration. A further focus is on a customized deaeration test rig, which is used to validate improved components and tank designs on the one hand and to learn more about the complex deaeration effects on the other hand. With this comprehensive optimization approach and the innovative, compact and patented labyrinth deaerator, the size of the tank and the amount of oil can be reduced to a minimum, without impairing air separation, but on the contrary, even improving the air separation behavior.