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Smoothed Particle Hydrodynamics (SPH) is a mesh-free particle method that has been widely used over the past decade to model complex flows. The method has mainly been used to investigate problems related to hydrodynamics and maritime engineering, in which heat transfer does not play a key role. In this article, the heat-conduction equation is implemented in the open-source code DualSPHysics, based on the SPH technique, and applied to different study cases, including conduction in still water in a cavity, laminar water flow between two infinite parallel plates and tube bank heat exchanger. The thermal solutions obtained from SPH are benchmarked with the solutions from Finite Volume Method (FVM) and validated using available analytical solutions. DualSPHysics results are in good agreement with FVM and analytical models, and demonstrate the potential of the meshless approach for industrial applications involving heat transfer.

Liquid sloshing inside a partially filled tank has a great impact on the fragile internal tank coating and also on the stability of carrier ships. Several studies highlighted the challenges encountered due to the sloshing and proposed anti-sloshing tank structures. However, sloshing of liquefied natural gas fuel in high pressure vessels during transportation still remain a challenge. In the present numerical study we consider a downscaled 2D geometry to investigate the sloshing. Non-dimensional numbers are used to downscale the geometry. The purpose is to understand the flow structures and validate the downscaling approach based on the similarity scale laws. In the present work, Computational Fluid Dynamics (CFD) based on the Reynolds Averaged Navier-Stokes equations (RANS) with the Volume of Fluid (VOF) method in one hand and the Smooth Particle Hydrodynamics (SPH) method in the other hand, are used to simulate the downscaled model. The results from both methods are compared and validated using experimental data. A full scale model have also been simulated using SPH to verify the applicability of the scaling laws. The SPH model shows the capability to efficiently capture the sloshing phenomena. The VOF and SPH provide similar results in terms of flow dynamics, pressure and forces. The overall numerical results agree with the measurements and show that SPH can be an efficient tool to be used in modelling sloshing phenomena, compared to the RANS-VOF approach which is expensive in terms of CPU time. However, features like turbulence need to be further investigated. 

Thermal management of the rotating electrical machines is a very challenging area which needs appropriate solutions for each machine and operating condition. The heat is generated by the electromagnetic losses and the mechanical friction during the rotation. Computational Fluid Dynamics (CFD) is used in this study to predict and analyze the thermal performance of a rotating electrical machine where high speed rotation is coupled with small flow gaps. The investigation presented in this paper is based on a geometry used for model assessment and verification purposes. However, the approach outlined and the observations made are transferrable to other geometries. ANSYS Fluent has been used to perform CFD simulation where both the air velocity field and the temperature distribution are obtained. The results are qualitatively highly interesting to understand the thermal behavior within an electrical machine operations. The results show a periodic temperature distribution on the stator surface with similar periodic pattern for the heat transfer coefficient on the rotor surface. The simulated average heat transfer coefficient at the rotor surface is compared with the correlations from published literature with an overall good agreement.

More than half of all electrical energy is consumed by motors and generators in an industrialized country. About 5-25% of this energy is lost and converted to heat. This heat produced by the losses has adverse effect on the lifetime and performance of a machine. A machine has to be operated at a given temperature to achieve maximum efficiency, therefore heat transfer study of machines is of special interest to rotating machines manufacturers. In this paper we investigate the heat transfer in the air-gap between the rotor and the stator of a simplified induction motor using Computational Fluid Dynamics. We consider three different air-gap widths and rotation speeds to explore the change in air-gap heat transfer when changing the air-gap width and the rotation speed. The simulated average heat transfer coefficients for all the models are in good agreement with the correlations from published literature. The Taylor-Couette vortical flow pattern is observed in the air-gap in our simulation results for the models with large air-gaps. The numerical results show that the presence of Taylor-Couette vortices in the air-gap enhance the heat transfer. The heat transfer coefficient increases with the increase in the rotation speed and decreases with the decrease in the air-gap width. 

Losses in an electric motor amount to between 4–24% of the total electrical power, and are converted to heat. The maximum hot spot temperature is one of the design constraints of thermal and electrical performance. Several studies have explored flow and thermal characteristics inside the air-gap between two concentric rotating cylinders such as those found in electric motors, however the transient flow and thermal effects still remain a challenge. This study uses Computational Fluid Dynamics to predict the thermal behaviour of a machine rotating at the kind of speed usually encountered in motors. The Reynolds Averaged Navier-Stokes model together with the realizable k-ε turbulence model are used to perform transient simulations. Velocity profiles and temperature distribution inside the air-gap are obtained and validated. The transient flow features and their impact on thermal performance are discussed. The numerical results show turbulent Taylor vortices inside the air-gap that lead to a periodic temperature distribution. When compared to correlations from published literature, the simulated average heat transfer coefficient at the rotor surface shows overall good agreement. The transient effects introduce local impacts like oscillations to the Taylor-Couette vortices. These flow oscillations result in oscillations of the hotspots. However, this transient oscillatory behaviour does not show any additional impact on the global thermal performance.

Runout Table (ROT) cooling is one of the most important factors for controlling quality of hot rolled steel. ROT cooling uses large quantities of water to cool the steel plate. Optimizing heat transfer in the ROT would reduce the amount of water used, which will lower the amount of energy needed for pumping, filtering, storage and use of water. Optimization will therefore result in a direct energy saving as well as increasing the product quality.

This study investigates heat transfer by turbulent water jets impinging on a hot flat steel plate at temperatures below the boiling point in order to understand convection heat transfer phenomena. This is an important stage that precedes the boiling and addresses the applicability of the heat transfer correlations available in the literature.

A single axisymmetric jet and a pair of interacting jets are simulated using Computational Fluid Dynamics (CFD). The Reynolds Averaged Navier Stokes (RANS) model under steady and transient conditions and the k–ɛ turbulence model are used in both 2D axisymmetric and 3D simulations. We investigate the influence of the water flow rate on the jet cooling characteristics and develop a correlation for the radial position of the maximum Nusselt number based on numerical results.

Two sets of boundary conditions – constant temperature and constant heat flux – are applied at the surface of the steel plate and evaluated. The single jet numerical results compare favourably with published data based on measurements and analytical models. The thermal performance of a two-jet system was found to be no better than a single jet because the jets were too far from each other to generate any additional thermal interaction.

The manufacturing sector is one of the biggest energy consumers. The iron and steel markets in China are growing very fast. Several studies have been performed to evaluate the Chinese steel sector in terms of energy savings and CO₂ emissions. The results of the studies showed that the major energy savings expected within 2020 and 2030 timeframe will be from industrial furnaces in steel mills. For the Swedish steel industry, it is important to be very efficient in order to remain competitive. The hot rolling process in the steel industry is a long process, where big slabs are heated in a furnace above the recrystallization temperature to roll the metal into a thin sheet and then the sheet is cooled at the Runout table using water. The amount of energy used during the process directly influences the price of the products. Moreover, the government policy on energy usage and CO₂ emissions, the competitive market and the water scarcity, demand an optimal process operation to reduce energy consumption and greenhouse gas emission. Computer simulation is the best and most convenient way to approximate real-world processes; therefore, there is a need to have a real-time online simulation tool for process optimisation, decision support and diagnostics in different industries.

Computational fluid dynamics (CFD) is a robust tool for simulating almost any kind of real-world process related to fluid flow, heat transfer and combustion. However, simulating real-world processes in real-time using CFD is very challenging due to the complexity involved in the physical phenomena studied. In this thesis, CFD simulations have been performed in small scale to understand the physics and perceive the complexity involved in the heating process of steel slabs and the cooling process of the steel sheets at hot rolling steel industries. The results from the simulations are successfully validated using experimental and theoretical results published in open literature. Past experience suggests using mesh-based commercial CFD solvers for simulating industrial processes, only if accurate and detail results are desired. However, the computational performance of these solvers shows limitations from a real-time perspective and indicates the need for alternative CFD methods and solvers. In the literature review performed as part of the first stage of this work, we have identified different alternative methods which can be used to perform CFD simulations in real-time or near real-time for large industrial processes. The thesis discusses the limitations of different types of CFD methods and points out the difficulties and challenges in utilising these methods for simulating large industrial processes. Our preliminary simulation work brings light towards the goal of multi-phase multi-physics real-time simulations.

Tillverkningsindustrin är en av de största energikonsumenterna.  Järn och stålindustrin i Kina växer väldigt fort. Flera studier har genomförts för att utvärdera den kinesiska stålindustrisektorn vad gäller energieffektivisering och utsläpp av CO₂. Resultaten av studierna visade att de stora energibesparingarna som kan genomföras mellan 2020 – 2030 kommer från industriella ugnar i stålverken. För den svenska stålindustrin är det viktigt att vara mycket effektiv för att bibehålla konkurrenskraft. Varmvalsningsprocessen i stålindustrin är en lång process, där stora skivor hettas upp i en ugn över den temperatur där materialet rekristalliseras och metallen valsas sedan i tunna skivor. Skivorna kyls sedan på utrullningsbordet med vatten. Energimängden som används under processen påverkar direkt priset på produkterna. Dessutom kräver stränga statliga bestämmelser, en konkurrenskraftig marknad och bristen på vatten optimala processförhållanden för att reducera energikonsumtionen och utsläppen av klimatgaser. Datasimulering är det bästa och mest pålitliga verktyget att approximera en verkliga processer. Det finns därför ett behov att ha ett online simuleringsverktyg för processoptimering, beslutsstöd och diagnostik i olika industrier.

CFD-simulering (Computational fluid dynamics) är ett robust simuleringsverktyg för nästan alla typer av verkliga processer relaterade till vätskeflöde, värmeöverföring och förbränning. Dock är simulering av verkliga processer med CFD mycket utmanande på grund av komplexiteten i de fysikaliska fenomenen som ska studeras.  I den här avhandlingen har CFD-simulering använts i liten skala för att förstå fysikaliska egenskaper och komplexiteten i värmningsprocesser av stålskivor och kylningsprocessen av de tunna stålplåtarna vid varmvalsningsprocessen i stålindustrin. Resultaten från simuleringarna är framgångsrikt validerade från experimentella och teoretiska resultat publicerade i litteraturen. Tidigare erfarenheter föreslår nätverksbaserade kommersiella CFD verktyg för att simulera industriella processer om korrekta och detaljerade resultat ska fås. Dock är prestandan för dessa verktyg begränsade ur ett verklighetsperspektiv och indikerar behovet av alternativa CFD-metoder och verktyg. Det första steget i detta arbete var att genomföra en litteraturgenomgång av tidigare studier. Vi identifierade då alternativa metoder som skulle kunna användas för att genomföra CFD-simulering i realtid och i nära realtid för stora industriella processer. Avhandlingen diskuterar begränsningar av olika CFD-metoder och synliggör svårigheter och utmaning i att utnyttja dessa metoder för att simulera stora industriella processer. Vårt preliminära simuleringsarbete är ett litet steg på vägen i målet att producera flerfasiga och multifysikaliska realtidssimuleringar.

Engineering advanced methods for example Computational Fluid Dynamics (CFD) are heavily used to solve, design and model complex industrial applications. They provide high accuracy however, the simulation time is too long and this limit its generalized use dramatically as for control purposes. CFD tools and methods are often used to analyze the energy distribution and management in different industrial processes like hot rolling industries, furnaces and boilers as well as a number of areas where mixing and thermal management are of importance. Huge amounts of energy are often fed into such processes. A small amount of optimization can provide a very large energy saving. It is now an urgent need to have a tool like real-time CFD to analyze, control and optimize on-line various industrial processes. This tool or method can contribute to build efficient and sustainable energy systems. The scope of this work is to find alternative simulation techniques that can also address industrial applications and provide solutions within a decent accuracy and resolution. In this paper we provide a literature review of those methods that can be categorized as mesh based, mesh free and hybrid that are capable of providing appropriate results in some key areas of interest. As a next step one of these methods will be implemented and coupled to CFD simulation of cooling impinging jets used to control the heat transfer and temperature behavior of a hot flat surface in a hot rolling process where thermal energy and cooling water are used with excess. (C) 2015 The Authors. Published by Elsevier Ltd.

One of the most important steps to control the quality in steel hot rolling is the Runout Table (ROT) Cooling. In this investigation, the heat transfer of water jets impinging on a hot flat steel plate was studied under temperatures below the boiling point to understand the convection heat transfer phenomena which is a major step preceding the boiling. Single axisymmetric jet and a pair of interacting jets are simulated using Computational Fluid Dynamics (CFD). The RANS model under steady and transient conditions as well as the k-Ɛ turbulence model are used for both 2D axisymmetric and 3D simulations. The water flow rate influence on the jets cooling characteristics is investigated.Two sets of boundary conditions, constant temperature and constant heat flux were applied at the surface of the steel plate and evaluated. The single jet numerical results are successfully compared to published data based on measurements and analytical models. The two jets thermal performance was found to be unaffected because the jets are too far from each other to generate any additional thermal interaction.