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Juergen Brandner - One of the best experts on this subject based on the ideXlab platform.
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Numerical and experimental investigation of a wire-net Compact Heat Exchanger performance for high-temperature applications
Applied Thermal Engineering, 2019Co-Authors: Jojomon Joseph, Michel Delanaye, Rabia Nacereddine, Andres Giraldo, Mehdi Rouabah, Jan Korvink, Juergen BrandnerAbstract:The objective of this paper is to have a detailed investigation of the microchannel performance of a complex wire-net Compact Heat Exchanger and investigate its collector performance experimentally for a micro combined Heat and power system. Localised turbulence can enhance Heat Exchanger performance. Besides, this will increase the pressure losses also. Shifting the Reynolds critical to smaller Reynolds number by using perturbators will control the pressure losses and enhance the microchannel thermal efficiency. In this paper, we consider microchannels with wire-net perturbators. The wire-net micro Heat Exchanger is assembled as a stack of counterflow flow passages with optimised thickness separated by thin foils. A metallic wire-net mesh is inserted in the flow passages to provide the required stiffness and enhance the microchannel efficiency. A parametric study was conducted on various Heat Exchanger parameters to optimise the Heat Exchanger size, thermal effectiveness and pressure losses for a micro-CHP system. Besides, a detailed investigation of the wire-net flow physics was made using a higher-order Reynolds stress turbulence model to obtain the full velocity gradient tensor. This could detail the effect of anisotropic flow physics in the isotropic wire-net microchannels. Lambda 2 criteria was implemented to investigate the flow mixing of the centrally convected non-disturbed mass flow. Furthermore, the analysis of the turbulence production terms provided a deeper insight into flow attachment and detachment near the wire-net intersections. The Heat Exchanger was experimentally tested, and it was found that the collector pressure losses are not su ciently low as compared to the microchannel pressure losses. The microchannel conjugate Heat transfer thermal e↵ectiveness is in good agreement with the overall experimental efficiency.
Jean-pierre Leclerc - One of the best experts on this subject based on the ideXlab platform.
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CFD and experimental investigation of the gas-liquid flow in the distributor of a Compact Heat Exchanger
Chemical Engineering Research and Design, 2014Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:High performance of Compact Heat Exchangers is conditioned by correct fluid distribution. This is especially true for gas-liquid Heat Exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels. The present study deals with the simulation and experimental investigation of the two-phase distribution and flow regimes in a distributor located at the bottom of the cold flow pilot plant of a vertical Compact Heat Exchanger. Air and water are the working fluids, and the range of superficial velocities inside the distributor is 0.9-8.8m s(-1) and 0.35-0.8 ms(-1), for air and water respectively. Three-dimensional Volume Of Fluid (VOF) simulations are performed and compared to experimental distributions, pressure drops, and visualizations.
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CFD and experimental investigation of the gas–liquid flow in the distributor of a Compact Heat Exchanger
Chemical Engineering Research and Design, 2014Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:Abstract High performance of Compact Heat Exchangers is conditioned by correct fluid distribution. This is especially true for gas–liquid Heat Exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels. The present study deals with the simulation and experimental investigation of the two-phase distribution and flow regimes in a distributor located at the bottom of the cold flow pilot plant of a vertical Compact Heat Exchanger. Air and water are the working fluids, and the range of superficial velocities inside the distributor is 0.9–8.8 m s −1 and 0.35–0.8 m s −1 , for air and water respectively. Three-dimensional Volume Of Fluid (VOF) simulations are performed and compared to experimental distributions, pressure drops, and visualizations.
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Single phase pressure drop and two-phase distribution in an offset strip fin Compact Heat Exchanger
Applied Thermal Engineering, 2012Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:Experiments have been conducted in a Compact Heat Exchanger with two-phase inlet conditions and vertical upflow in order to study the flow behavior. The test section consists of an offset strip fin Heat Exchanger with a rectangular cross-section (dimensions: 1 m x 1 m x 7.13 mm). The distributor was designed to optimize two-phase flow distribution. In a preliminary step, pressure drop of single phase flow in offset strip fins is needed to assess the quality of the distribution in the single phase case. For that, pressure drop of single phase flow has been measured in the experimental loop. Pressure drop has also been analysed numerically via CFD simulations. For low Reynolds numbers, numerical results show good agreement with experimental measurements. In a second step, the two-phase flow distribution at the outlet was characterized using air and water as working fluids and for different operating conditions. This characterization consists of the measurement of gas and liquid flow rates in different zones evenly distributed at the outlet. We observed that high air flow rates led to a more homogenous distribution.
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Experimental distribution of phases and pressure drop in a two-phase offset strip fin type Compact Heat Exchanger
International Journal of Multiphase Flow, 2011Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:TUniform distribution of fluids is crucial to obtain high performance in Compact Heat Exchangers. Maldistribution has been studied by many authors, especially for parallel channels Heat Exchangers. But theoretical models and experimental studies for predicting flow maldistribution in offset strip fins Exchangers are scarce. Offset strip fins, besides their higher thermal hydraulic performances, favour lateral distribution due to their geometry. In this work, an experimental investigation has been carried out for this type of Heat Exchanger. The experimental set-up consists in a flat vertical Compact Heat Exchanger (1 m x 1 m area and 7.13 mm thickness) equipped with offset strip fins with a hydraulic diameter of 1.397 mm. Air and water are the working fluids. The flow rates of each phase in seven zones regularly distributed at the outlet have been measured as well as the pressures at the inlet, the outlet and two intermediate positions. These measurements were completed with visualisations using a high-speed camera. First, the single-phase flow has been investigated. A correlation for friction factor has been derived from experiments covering laminar, transition and turbulent regimes. CFD simulations of the single-phase flow have been performed. The numerical results were compared with the determined correlation and with correlations available in the literature. In single-phase flow, a uniform distribution was experimentally observed. Then, the two-phase hydrodynamics was characterised. A flow regime map was established and the influences of phases inlet directions (co-current and counter-current inlets of the phases) and of superficial velocities on the distribution were studied. The gas superficial velocity has more effect on the distribution than the liquid one. Comparison between pressure drop profiles and flow rate distribution profiles shows that information about pressure drop can provide information about phase distribution. It must be noticed that the nonuniform distribution of phases can entail the coexistence of several flow regimes in the Heat Exchanger.
Jojomon Joseph - One of the best experts on this subject based on the ideXlab platform.
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Advanced Numerical Methodology to Analyze High-Temperature Wire-Net Compact Heat Exchangers For a Micro-Combined Heat and Power System Application
Heat Transfer Engineering, 2019Co-Authors: Jojomon Joseph, Michel Delanaye, Rabia Nacereddine, Jan Korvink, Juergen J. BrandnerAbstract:AbstractThe objective of this paper is to predict Compact Heat Exchanger (CHE) performance for a miniaturized combined Heat and power system by a detailed modeling of the complex microchannels and ...
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Numerical and experimental investigation of a wire-net Compact Heat Exchanger performance for high-temperature applications
Applied Thermal Engineering, 2019Co-Authors: Jojomon Joseph, Michel Delanaye, Rabia Nacereddine, Andres Giraldo, Mehdi Rouabah, Jan Korvink, Juergen BrandnerAbstract:The objective of this paper is to have a detailed investigation of the microchannel performance of a complex wire-net Compact Heat Exchanger and investigate its collector performance experimentally for a micro combined Heat and power system. Localised turbulence can enhance Heat Exchanger performance. Besides, this will increase the pressure losses also. Shifting the Reynolds critical to smaller Reynolds number by using perturbators will control the pressure losses and enhance the microchannel thermal efficiency. In this paper, we consider microchannels with wire-net perturbators. The wire-net micro Heat Exchanger is assembled as a stack of counterflow flow passages with optimised thickness separated by thin foils. A metallic wire-net mesh is inserted in the flow passages to provide the required stiffness and enhance the microchannel efficiency. A parametric study was conducted on various Heat Exchanger parameters to optimise the Heat Exchanger size, thermal effectiveness and pressure losses for a micro-CHP system. Besides, a detailed investigation of the wire-net flow physics was made using a higher-order Reynolds stress turbulence model to obtain the full velocity gradient tensor. This could detail the effect of anisotropic flow physics in the isotropic wire-net microchannels. Lambda 2 criteria was implemented to investigate the flow mixing of the centrally convected non-disturbed mass flow. Furthermore, the analysis of the turbulence production terms provided a deeper insight into flow attachment and detachment near the wire-net intersections. The Heat Exchanger was experimentally tested, and it was found that the collector pressure losses are not su ciently low as compared to the microchannel pressure losses. The microchannel conjugate Heat transfer thermal e↵ectiveness is in good agreement with the overall experimental efficiency.
Selma Ben Saad - One of the best experts on this subject based on the ideXlab platform.
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CFD and experimental investigation of the gas-liquid flow in the distributor of a Compact Heat Exchanger
Chemical Engineering Research and Design, 2014Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:High performance of Compact Heat Exchangers is conditioned by correct fluid distribution. This is especially true for gas-liquid Heat Exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels. The present study deals with the simulation and experimental investigation of the two-phase distribution and flow regimes in a distributor located at the bottom of the cold flow pilot plant of a vertical Compact Heat Exchanger. Air and water are the working fluids, and the range of superficial velocities inside the distributor is 0.9-8.8m s(-1) and 0.35-0.8 ms(-1), for air and water respectively. Three-dimensional Volume Of Fluid (VOF) simulations are performed and compared to experimental distributions, pressure drops, and visualizations.
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Single phase pressure drop and two-phase distribution in an offset strip fin Compact Heat Exchanger
Applied Thermal Engineering, 2012Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:Experiments have been conducted in a Compact Heat Exchanger with two-phase inlet conditions and vertical upflow in order to study the flow behavior. The test section consists of an offset strip fin Heat Exchanger with a rectangular cross-section (dimensions: 1 m x 1 m x 7.13 mm). The distributor was designed to optimize two-phase flow distribution. In a preliminary step, pressure drop of single phase flow in offset strip fins is needed to assess the quality of the distribution in the single phase case. For that, pressure drop of single phase flow has been measured in the experimental loop. Pressure drop has also been analysed numerically via CFD simulations. For low Reynolds numbers, numerical results show good agreement with experimental measurements. In a second step, the two-phase flow distribution at the outlet was characterized using air and water as working fluids and for different operating conditions. This characterization consists of the measurement of gas and liquid flow rates in different zones evenly distributed at the outlet. We observed that high air flow rates led to a more homogenous distribution.
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Experimental distribution of phases and pressure drop in a two-phase offset strip fin type Compact Heat Exchanger
International Journal of Multiphase Flow, 2011Co-Authors: Selma Ben Saad, Patrice Clement, Jean-francois Fourmigue, Caroline Gentric, Jean-pierre LeclercAbstract:TUniform distribution of fluids is crucial to obtain high performance in Compact Heat Exchangers. Maldistribution has been studied by many authors, especially for parallel channels Heat Exchangers. But theoretical models and experimental studies for predicting flow maldistribution in offset strip fins Exchangers are scarce. Offset strip fins, besides their higher thermal hydraulic performances, favour lateral distribution due to their geometry. In this work, an experimental investigation has been carried out for this type of Heat Exchanger. The experimental set-up consists in a flat vertical Compact Heat Exchanger (1 m x 1 m area and 7.13 mm thickness) equipped with offset strip fins with a hydraulic diameter of 1.397 mm. Air and water are the working fluids. The flow rates of each phase in seven zones regularly distributed at the outlet have been measured as well as the pressures at the inlet, the outlet and two intermediate positions. These measurements were completed with visualisations using a high-speed camera. First, the single-phase flow has been investigated. A correlation for friction factor has been derived from experiments covering laminar, transition and turbulent regimes. CFD simulations of the single-phase flow have been performed. The numerical results were compared with the determined correlation and with correlations available in the literature. In single-phase flow, a uniform distribution was experimentally observed. Then, the two-phase hydrodynamics was characterised. A flow regime map was established and the influences of phases inlet directions (co-current and counter-current inlets of the phases) and of superficial velocities on the distribution were studied. The gas superficial velocity has more effect on the distribution than the liquid one. Comparison between pressure drop profiles and flow rate distribution profiles shows that information about pressure drop can provide information about phase distribution. It must be noticed that the nonuniform distribution of phases can entail the coexistence of several flow regimes in the Heat Exchanger.
Anica Trp - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical study of the Compact Heat Exchanger with different microchannel shapes
International Journal of Refrigeration-revue Internationale Du Froid, 2015Co-Authors: Vladimir Glazar, Bernard Frankovic, Anica TrpAbstract:Experimental and numerical analysis of Heat transfer and fluid flow in the Compact Heat Exchanger has been done in this paper. In an open circuit wind tunnel, developed on purpose for this investigation, the measurement of working media temperatures and mass flow rates for Heat Exchanger with microchannel coil has been accomplished. In accordance with the Heat Exchangers used for experiments, numerical 3D simulation of adequate geometry shapes has been done. With utilization of air/water side numerical simulation, more detailed results have been achieved in relation to the simulation that assumes constant temperature or constant Heat flux on the pipe wall. Good agreement between experimentally measured and numerically calculated results has been accomplished. The influence of different microchannel shapes on Heat transfer effectiveness and pressure drop has been studied numerically. Comparison of results has been made accompanied by the discussion and final conclusions.
