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Kamel Hooman - One of the best experts on this subject based on the ideXlab platform.
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A review of particulate fouling and challenges of Metal Foam heat exchangers
2015Co-Authors: S. A. Fadhilah, Mohammad Reza Malayeri, Kamel HoomanAbstract:In recent years, open-cell Metal Foam has gained attention for utilization as Exhaust Gas Recirculation (EGR) coolers due to its large surface area and porous structure. Theoretically, the porous Foam structure would has better transfer heat through conduction and convection processes. However, the exhaust gases that enter the cooler would carry particulate matter (PM) which may deposit within the Foam structure. The existing fouling studies cannot explain the underlying mechanisms of particulate deposition thoroughly within the Foam structure. This study reviews the present approaches to investigate fouling in the Metal Foam structured EGR coolers, as well as the fouled Metal Foam heat exchanger from other applications. In addition, this study also includes the challenges that lie ahead for implementing the Metal Foam heat exchangers in the industries. INTRODUCTION Metal Foam Microstructural & Thermo-physical Properties The Metal Foams have been used in the biomedical industry because of their bio-compatibility, in the automotive, aerospace, ship, and railway industries for their light-weight, crash energy absorption, and noise control properties, besides being proposed for heat exchanger industries due to its highly conductive and porous structure (Banhart, 2001). The Metal Foams are classified into two main categories: (1) open-cell or closed-cell structure and (2) cell arrangement stochastic or periodic (Han et al., 2012; T’Joen et al., 2010). The open-cell Metal Foam consists of interconnected cells like dodecahedron shape which allow fluids to flow and the closed-cell Metal Foam has individual enclosure within the material. The dodecahedron shape is usually modeled as a cubit unit cell in numerical or mathematical studies (Bhattacharya et al., 2002; Odabaee et al., 2013). Figure 1 shows the open-cell and closed-cell Metal Foams. The open-cell Metal Foam has been classified based on porosity and pore density– pore per inch (PPI) and it has superior surface area density and thermal performance (Bhattacharya et al., 2002; Ghosh, 2009; Odabaee et al., 2013). Fig 1. (a) 10 PPI open-cell Metal Foam (b) Closed-cell Metal Foam The high relative density offers high thermal conductivity, while the porous structure offers high convective heat transfer by thermal dispersion and permeability (T’Joen et al., 2010). The permeability increases with porosity and pore diameter, but solely porosity influences the effective thermal conductivity significantly (Bhattacharya et al., 2002; Muley, Kiser, Sunden, & Shah, 2012). However, the convective heat transfer within porous structure is more dominant than conduction as its thermal conductivity is one order of magnitude lower than their parent material (Han et al., 2012). By increasing the porosity, the ligament diameter could be decreased (Bhattacharya et al., 2002), which consequently affects the conduction and the overall heat transfer coefficient significantly (Ghosh, 2009). Besides, the ligaments show similar concepts of corrugated fins or vortex generators which increase the heat transfer rate by imposing higher mixing flow, especially, at high Reynolds numbers (Re) (Ashtiani Abdi et al., 2014; De Schampheleire et al., 2013). The ligament diameter and interfacial velocity influenced the values of Reynolds number (De Schampheleire et al., 2013). The open-cell Metal Foam heat exchangers show advantages as follows (De Schampheleire et al., 2013; Han et al., 2012; T’Joen et al., 2010): Light weight as composed about 90% of air. Large specific surface area i.e. 500 to 10,000 m/m High gas permeability and thermal conductivity. Proceedings of International Conference on Heat Exchanger Fouling and Cleaning 2015 (Peer-reviewed) June 07 12, 2015, Enfield (Dublin), Ireland Editors: M.R. Malayeri, H. Muller-Steinhagen and A.P. Watkinson Published online www.heatexchanger-fouling.com
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particle size distribution effects on preferential deposition areas in Metal Foam wrapped tube bundle
Science & Engineering Faculty, 2014Co-Authors: Emilie Sauret, Kamel HoomanAbstract:This paper presents a numerical model for understanding particle transport and deposition in Metal Foam heat exchangers. Two-dimensional steady and unsteady numerical simulations of a standard single row Metal Foam-wrapped tube bundle are performed for different particle size distributions, i.e. uniform and normal distributions. Effects of different particle sizes and fluid inlet velocities on the overall particle transport inside and outside the Foam layer are also investigated. It was noted that the simplification made in the previously-published numerical works in the literature, e.g. uniform particle deposition in the Foam, is not necessarily accurate at least for the cases considered here. The results highlight the preferential particle deposition areas both along the tube walls and inside the Foam using a developed particle deposition likelihood matrix. This likelihood matrix is developed based on three criteria being particle local velocity, time spent in the Foam, and volume fraction. It was noted that the particles tend to deposit near both front and rear stagnation points. The former is explained by the higher momentum and direct exposure of the particles to the Foam while the latter only accommodate small particles which can be entrained in the recirculation region formed behind the Foam-wrapped tubes.
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on the electrical and thermal contact resistance of Metal Foam
International Journal of Heat and Mass Transfer, 2014Co-Authors: Thomas Fiedler, N White, Mahidzal Dahari, Kamel HoomanAbstract:Abstract This paper addresses the electrical and thermal contact resistance in Metal Foam–graphite assemblies considered for use in next generation air-cooled fuel cells as replacements of currently available water-cooled ones. Their successful application requires minimization of thermal and electrical contact resistance between components. The current study investigates the evolution of both resistances with increasing compressive force between Metallic Foam and graphite plates. Reducing these contact resistances through compressive force instead of brazing significantly reduces the manufacturing cost. Our results show that both electrical and thermal resistances monotonically decrease with increasing compressive force when moving from no compressive force to a slight one about 100 N (corresponding to a compressive stress of 0.01 MPa). Interestingly, compared with the thermal contact resistance, the electrical contact resistance shows more sensitivity to compressive force within this range of force. Furthermore, it has been noted that increases in compressive force beyond 300 N (i.e. 0.03 MPa) decrease the resistances only marginally. Electrical contact resistance was found to govern the total resistance of the Metal Foam–graphite assembly since electric bulk resistances are several orders of magnitude lower. Similar observations are made for thermal resistance where the minimum contact resistance exceeds the thermal resistance of the Foam in our experiments.
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particle deposition effects on heat transfer from a Metal Foam wrapped tube bundle
International Journal of Numerical Methods for Heat & Fluid Flow, 2013Co-Authors: Mostafa Odabaee, Michel De Paepe, Peter De Jaeger, Christophe Tjoen, Kamel HoomanAbstract:Purpose - The purpose of this paper is to clarify the relationship between dust deposition effects on the thermohydraulic performance of a Metal Foam heat exchanger. Design/methodology/approach - The paper uses finite volume approximation to solve the two-dimensional volume-averaged form of governing equations through and around a Metal Foam-covered tube bundle. Modified porosity, permeability, and form drag coefficient for a dusty Foam layer are obtained through the application of a thermal resistance network model. Findings - The paper provides novel data to predict the fouling effects on the performance of Foam-wrapped tube bundles as air-cooled heat exchangers. It is observed that depending on the deposited layer thickness, the increased pressure drop and heat transfer deterioration can be very significant. Originality/value - This paper fulfils an identified need to study fouling effects on thermohydraulic performance of a Foam heat exchanger.
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Metal Foam heat exchangers for heat transfer augmentation from a tube bank
Applied Thermal Engineering, 2012Co-Authors: Mostafa Odabaee, Kamel HoomanAbstract:A numerical study has been conducted to examine the heat transfer from a Metal Foam-wrapped tube bundle. Effects of key parameters, including the free stream velocity, longitudinal and transversal tube pitch, Metal Foam thickness and characteristics of the Foam (such as porosity, permeability, and form drag coefficient) on heat and fluid flow are examined. It can be observed that the performance of the Metal Foam heat exchangers, measured in terms of area goodness factor, can noticeably be better than that of the conventional design of finned-tube heat exchangers. It is also found that even a very thin layer of Metal Foam, when wrapped around a bare tube bundle, can significantly improve the area goodness factor. Finally, it is shown that while friction factor is more sensitive to the Metal Foam permeability than its porosity, the converse is true when it comes to the Colburn factor.
Xiao-lu Gong - One of the best experts on this subject based on the ideXlab platform.
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Numerical analysis on the energy storage efficiency of phase change material embedded in finned Metal Foam with graded porosity
Applied Thermal Engineering, 2017Co-Authors: Chuan Zhang, Xiao-lu GongAbstract:The Metal Foam/phase change material (PCM) composite is a promising material in the thermal energy storage system. In the present study, a modified structure of Metal Foam, finned Metal Foam with graded porosity (FFGP), is proposed to further accelerate the melting process of the composite. The finite volume method and two equations model are applied in the modeling of FFGP. The average power of energy storage is defined to evaluate the energy storage efficiency of the composite. The effects of the structural parameters of FFGP on the average power of energy storage are investigated, including thickness of Metal fin, porosity gradient of Metal Foam and pore per inch (PPI). The results indicate that FFGP structure could reduce the total melting time and enhance greatly the energy storage performance. This is because the Metal fin changes the melting sequence of PCM and the gradient Metal Foam contributes to the heat transfer between the heat source and the composite. Besides, the value of PPI has a great impact on natural convection in the composite. Through combining the proper Metal fin, gradient Metal Foam and PPI, the FFGP structure with the good performance could be obtained.
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Numerical analysis and comparison of the thermal performance enhancement methods for Metal Foam/phase change material composite
Applied Thermal Engineering, 2016Co-Authors: Chuan Zhang, Xiao-lu GongAbstract:Three methods to further enhance thermal performance of the Metal Foam/phase change material (PCM) composite are investigated and compared. These three methods include changing the pores per inch (PPI) of Metal Foam, modifying the shape of the cold wall and using the discrete heat sources. In this study, the composite consists of two materials: aluminum Foam with 90% porosity as Metal Foam and paraffin wax as PCM. The numerical model based on finite volume method is developed, and the non-equilibrium equation is applied to study the melting process of the paraffin embedded in aluminum Foam. The heat loss, the liquid average velocity and the efficiency of latent heat storage are analyzed and discussed. The results show that adopting the aluminum Foam with high PPI value or modifying the shape of the cold wall could improve the thermal response of composite. Besides, the discrete heat sources could lead to a large average velocity in the liquid region. Combining the advantages of these methods, an optimization method is also proposed, which could improve the efficiency to 83.32% comparing with the pure paraffin.
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Thermo-Mechanical Behavior Analysis of Pressure Infiltration Casting Process for Manufacturing Open-Cell Metal Foam
Advanced Materials Research, 2013Co-Authors: Jian Fei Wang, Xiao-lu GongAbstract:Pressure infiltration casting technique is widely used to manufacture open-cell Metal Foam and it has been well performed in manufacture practice in our research group. In the present study, an attempt is made to highlight the influence of the infiltration casting process on the physical structure of Metal Foam. According to the production practice, several parameters: the pressure difference, the temperature condition, the particle size and the mould dimension, need to be well considered. A 2D model coupling porous zone and multiphase is created with a fixed grid. The cooling and solidifying process of molten Metal are as well carried out with enthalpy method. Reasonable convergence rules are used to proceed high quality calculations. This work provides excellent experimental and numerical comprehension of pressure infiltration casing process to manufacture open-cell Metal Foam. These understandings can well guide and optimize the product manufacture, the physical structure and the mechanical behaviors of open-cell Metal Foams within their industrial application.
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An analytical stress-strain model for open-cell Metal Foam
Journal of Porous Media, 2012Co-Authors: Xiao-lu GongAbstract:The main objective of the present investigation is to develop an analytical stress-strain model to quantitatively describe the stress-strain behavior of open-cell Metal Foam. Based on solid mechanics, an analytical stress-strain model is developed. This new stress-strain model involves two main parameters: relative density and plastic Poisson's ratio. As a key characteristic of Metal Foam, relative density directly takes effect on the uniaxial stress-strain behavior of Metal Foam and the uniaxial stress of Metal Foam increases with increasing relative density. Plastic Poisson's ratio is measured as a function of uniaxial compressive plastic strain and its value is neither 0 nor 0.5. Corresponding uniaxial compression tests of Metal Foams were conducted and numerical simulations were also carried out. The results indicate that this analytical stress-strain model of Metal Foam is in good agreement with both the experimental validations and the numerical simulations. This work provides useful information for understanding the deformation mechanism of open-cell Metal Foam.
Mostafa Odabaee - One of the best experts on this subject based on the ideXlab platform.
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particle deposition effects on heat transfer from a Metal Foam wrapped tube bundle
International Journal of Numerical Methods for Heat & Fluid Flow, 2013Co-Authors: Mostafa Odabaee, Michel De Paepe, Peter De Jaeger, Christophe Tjoen, Kamel HoomanAbstract:Purpose - The purpose of this paper is to clarify the relationship between dust deposition effects on the thermohydraulic performance of a Metal Foam heat exchanger. Design/methodology/approach - The paper uses finite volume approximation to solve the two-dimensional volume-averaged form of governing equations through and around a Metal Foam-covered tube bundle. Modified porosity, permeability, and form drag coefficient for a dusty Foam layer are obtained through the application of a thermal resistance network model. Findings - The paper provides novel data to predict the fouling effects on the performance of Foam-wrapped tube bundles as air-cooled heat exchangers. It is observed that depending on the deposited layer thickness, the increased pressure drop and heat transfer deterioration can be very significant. Originality/value - This paper fulfils an identified need to study fouling effects on thermohydraulic performance of a Foam heat exchanger.
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Metal Foam heat exchangers for heat transfer augmentation from a tube bank
Applied Thermal Engineering, 2012Co-Authors: Mostafa Odabaee, Kamel HoomanAbstract:A numerical study has been conducted to examine the heat transfer from a Metal Foam-wrapped tube bundle. Effects of key parameters, including the free stream velocity, longitudinal and transversal tube pitch, Metal Foam thickness and characteristics of the Foam (such as porosity, permeability, and form drag coefficient) on heat and fluid flow are examined. It can be observed that the performance of the Metal Foam heat exchangers, measured in terms of area goodness factor, can noticeably be better than that of the conventional design of finned-tube heat exchangers. It is also found that even a very thin layer of Metal Foam, when wrapped around a bare tube bundle, can significantly improve the area goodness factor. Finally, it is shown that while friction factor is more sensitive to the Metal Foam permeability than its porosity, the converse is true when it comes to the Colburn factor.
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Metal Foam heat exchangers for heat transfer augmentation from a cylinder in cross flow
Transport in Porous Media, 2011Co-Authors: Mostafa Odabaee, Kamel Hooman, Halim GurgenciAbstract:A numerical study has been conducted to examine the heat transfer from a Metal Foam-wrapped solid cylinder in cross-flow. Effects of the key parameters including the free stream velocity and characteristics of Metal Foam such as porosity, permeability, and form drag coefficient on heat and fluid flow are examined. Being a determining factor in pressure drop and heat transfer increment, the porous layer thickness is changed systematically to observe that there is an optimum layer thickness beyond which the heat transfer does not improve while the pressure drop continues to increase. This has been verified by the application of Bejan’s Intersection of Asymptotes method. Results have been compared to those of a finned-tube heat exchanger to observe much higher heat transfer rate with reasonable excess pressure drop leading to a higher area goodness factor for Metal Foam-wrapped cylinder.
Christophe Tjoen - One of the best experts on this subject based on the ideXlab platform.
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particle deposition effects on heat transfer from a Metal Foam wrapped tube bundle
International Journal of Numerical Methods for Heat & Fluid Flow, 2013Co-Authors: Mostafa Odabaee, Michel De Paepe, Peter De Jaeger, Christophe Tjoen, Kamel HoomanAbstract:Purpose - The purpose of this paper is to clarify the relationship between dust deposition effects on the thermohydraulic performance of a Metal Foam heat exchanger. Design/methodology/approach - The paper uses finite volume approximation to solve the two-dimensional volume-averaged form of governing equations through and around a Metal Foam-covered tube bundle. Modified porosity, permeability, and form drag coefficient for a dusty Foam layer are obtained through the application of a thermal resistance network model. Findings - The paper provides novel data to predict the fouling effects on the performance of Foam-wrapped tube bundles as air-cooled heat exchangers. It is observed that depending on the deposited layer thickness, the increased pressure drop and heat transfer deterioration can be very significant. Originality/value - This paper fulfils an identified need to study fouling effects on thermohydraulic performance of a Foam heat exchanger.
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thermo hydraulic study of a single row heat exchanger consisting of Metal Foam covered round tubes
International Journal of Heat and Mass Transfer, 2010Co-Authors: Christophe Tjoen, Henk Huisseune, P De Jaeger, S Van Herzeele, N Vorst, M. De PaepeAbstract:Abstract Open cell Metal Foam is a novel engineering material that offers an interesting combination of material properties from a heat exchanger point of view such as a high specific surface area, tortuous flow paths for flow mixing and low weight. A new heat exchanger design with Metal Foams is studied in this work, aimed at low airside pressure drop. It consists of a single row of aluminum tubes covered with thin layers (4–8 mm) of Metal Foam. Through wind tunnel testing the impact of various parameters on the thermo-hydraulic performance was considered, including the Reynolds number, the tube spacing, the Foam height and the type of Foam. The results indicated that providing a good Metallic bonding between the Foam and the tubes can be achieved, Metal Foam covered tubes with a small tube spacing, small Foam heights and made of Foam with a high specific surface area potentially offer strong benefits at higher air velocities (>4 m/s) compared to helically finned tubes. The bonding was done by conductive epoxy glue and was found to have a strong impact on the final results, showing a strong need for a cost-effective and efficient brazing process to connect Metal Foams to the tube surfaces.
C Y Zhao - One of the best experts on this subject based on the ideXlab platform.
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thermal analysis on Metal Foam filled heat exchangers part i Metal Foam filled pipes
International Journal of Heat and Mass Transfer, 2006Co-Authors: W W Lu, C Y Zhao, S A TassouAbstract:This paper presents an analytical study of the forced convection heat transfer characteristics in high porosity open-cell Metal-Foam filled pipes. The Brinkman-extended Darcy momentum model and two-equation heat transfer model for porous media were employed. Based on the analytical solutions, the velocity and temperature distributions in Metal-Foam filled pipes were obtained. The effects of the microstructure of Metal Foams on overall heat transfer were examined. The results show that the pore size and porosity of Metal-Foams play important roles on overall heat transfer performance. The use of Metal-Foam can dramatically enhance the heat transfer but at the expense of higher pressure drop.
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thermal analysis on Metal Foam filled heat exchangers part ii tube heat exchangers
International Journal of Heat and Mass Transfer, 2006Co-Authors: C Y Zhao, S A TassouAbstract:The forced convection heat transfer characteristics in high porosity open-cell Metal-Foam filled tube heat exchangers are analysed in this paper. The Brinkman-extended Darcy momentum model and two-equation heat transfer model for porous media are employed for the analysis of the heat transfer performance. The morphological effects of Metal Foams on overall heat transfer are examined. The optimal Foam-area ratio for a Metal-Foam filled counter-flow tube-in-tube heat exchanger is predicted. The study shows that the thermal performance of a Metal-Foam heat exchanger can be superior to that of conventional finned tube heat exchangers.
