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A fast running numerical model based on the implementation of volume forces for prediction of pressure drop in a fin-tube heat exchanger
Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
2014 (English)In: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, no 24, 5822-5835 p.Article in journal (Refereed) Published
Abstract [en]

Numerical based design of geometrical structures is common whenstudying systems involving heat exchangers, a central component inseveral fields, such as industrial, vehicle and household systems. Thegeometrical structure of heat exchangers is generally comprised byclosely placed fins and tube bundles. The creation of a mesh grid for ageometrically compact heat exchanger will result in a dense structure,which is not feasible for personal computer usage. Hence, volume forceswere created based on Direct Numerical Simulations (DNS) on a FlowRepresentative Volume (FRV) of a tube fin heat exchanger in an internalduct system of a heat pump tumble dryer. A relation of the volumeaveraged velocity and the volume averaged force was established in twodifferent FRV-models with a finite element simulation in COMSOL. Thisrelation was subsequently used to create flow resistance coefficientsbased on volume averaged expressions of fluid velocity and volume forces.These flow resistance coefficients were implemented in two respectiveporous models, which represent the entire heat exchanger except theinterior arrangements of fins and tube bundles. Hence, the computationtime was reduced thanks to the absence of a dense mesh grid. Experimentalresults of the entire heat exchanger showed good agreement with thesecond porous model in terms of pressure drop and volume flow rate.

Place, publisher, year, edition, pages
Elsevier, 2014. no 24, 5822-5835 p.
Keyword [en]
CFD, Heat exchanger, Tumble dryer, Comsol MultiPhysics, Volume forces
National Category
Fluid Mechanics and Acoustics
Research subject
Environmental and Energy Systems
Identifiers
URN: urn:nbn:se:kau:diva-31951DOI: 10.1016/j.apm.2014.04.051ISI: 000346214000005OAI: oai:DiVA.org:kau-31951DiVA: diva2:713393
Available from: 2014-04-22 Created: 2014-04-22 Last updated: 2015-12-28Bibliographically approved
In thesis
1. Methods for Reducing the Complexity of Geometrical Structures Based on CFD Programming: Time Efficient Simulations Based on Volume Forces Coupled with Single and Two-phase Flow
Open this publication in new window or tab >>Methods for Reducing the Complexity of Geometrical Structures Based on CFD Programming: Time Efficient Simulations Based on Volume Forces Coupled with Single and Two-phase Flow
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Throughout recent years, computer based programs have been applied to solve and analyse industrial problems encountered global fields such as automobile design for reduction of CO2-gas, designing wind parks aimed at increasing power output etc. One of these developed programs is Computational Fluid Dynamics (CFD) which numerically solves complex flow behaviour based on computer power.

As there is an ongoing expansion of CFD usage in industry, certain issues need to be addressed as they are becoming more frequently encountered. The general demand for the simulation of larger control volumes and more advanced flow processes result in an extensive requirement of computer resources. Moreover, the implementation of commercial CFD codes in small-scaled industrial companies seems to generally be utilised as a black box based on the knowledge of fluid mechanic theory. Increased partnerships between industry and the academic world involving various CFD based design processes generally yield to a verbal communication interface, which is a crucial step in the process given the level of dependency between both sides.

Based on these notions, a method for establishing time efficient CFD-models with implementation of volume forces as sink terms in the momentum equation is presented. The internal structure, or parts of the structure, in the simulation domain is removed which reduces the geometrical complexity and along with it, computational demand.  These models are the basis of assessing the benefits of utilizing a numerical based design process in industry in which the CFD code is used as a communication tool for knowledge sharing with counterparts in different fields.

Abstract [en]

As there is an ongoing expansion of CFD usage in industry, certain issues need to be addressed as they are becoming more frequently encountered. The general demand for the simulation of larger control volumes and more advanced flow processes result in an extensive requirement of computer resources. Moreover, the implementation of commercial CFD codes in small-scaled industrial companies seems to generally be utilised as a black box based on the knowledge of fluid mechanic theory. Increased partnerships between industry and the academic world involving various CFD based design processes generally yield to a verbal communication interface, which is a crucial step in the process given the level of dependency between both sides.

Based on these notions, a method for establishing time efficient CFD-models with implementation of volume forces as sink terms in the momentum equation is presented. The internal structure, or parts of the structure, in the simulation domain is removed which reduces the geometrical complexity and along with it, computational demand.  These models are the basis of assessing the benefits of utilizing a numerical based design process in industry in which the CFD code is used as a communication tool for knowledge sharing with counterparts in different fields.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2014. 104 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2014:32
Keyword
Numerical design cycle, CFD, porous media, volume forces, heat exchanger, vacuum dewatering, time efficient simulations
National Category
Fluid Mechanics and Acoustics
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-31983 (URN)978-91-7063-565-6 (ISBN)
Public defence
2014-06-09, 9C 204, Universitetsgatan 2, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2014-05-19 Created: 2014-04-25 Last updated: 2016-10-06Bibliographically approved

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Rezk, KamalForsberg, Jan
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