Papers by C. Pérez-segarra
Applied Thermal Engineering, 2002
A detailed one-dimensional steady and transient numerical simulation of the thermal and¯uid-dynam... more A detailed one-dimensional steady and transient numerical simulation of the thermal and¯uid-dynamic behaviour of capillary tube expansion devices working with pure and mixed refrigerants has been developed. The discretised governing equations are coupled using an implicit step by step method. A special treatment has been implemented in order to consider transitions (subcooled liquid region, metastable liquid region, metastable two-phase region and equilibrium two-phase region). All the¯ow variables (enthalpy, temperatures, pressures, vapour quality, velocities, heat¯uxes, etc.) together with the thermophysical properties are evaluated at each point of the grid in which the domain is discretised. The numerical model allows analysis of aspects such as geometry, type of¯uid (pure substances and mixtures), critical or non-critical¯ow conditions, metastable regions, adiabatic or non-adiabatic capillary tubes and transient aspects. Comparison of the numerical simulation with experimental data presented in the technical literature will be shown in part II of the present article.
Solar energy, 2004
The aim of this work is to show the current computational possibilities of three-dimensional comp... more The aim of this work is to show the current computational possibilities of three-dimensional computational fluid dynamics (CFD) simulations, using loosely coupled parallel computers (Beowulf clusters) in the virtual prototyping of thermal storage tanks. The transient thermal behaviour of a storage tank forming part of a thermosyphon solar heating system is simulated numerically. The influence of the inlet mass flow rate on the degree of thermal stratification during an unloading process is analysed. Special attention is given to the validation of the assumed mathematical model, the verification of the numerical solutions, and the post-processing tasks carried out in order to quantify the level of thermal stratification. The computational possibilities and limitations of this kind of detailed numerical experiments are pointed out.
Journal of Physics: Conference Series, 2012
View the article online for updates and enhancements. You may also like Dynamic dose assessment b... more View the article online for updates and enhancements. You may also like Dynamic dose assessment by Large Eddy Simulation of the near-range atmospheric dispersion Lieven Vervecken, Johan Camps and Johan Meyers-Flow in complex terrain-a Large Eddy Simulation comparison study J. Berg, N. Troldborg, R. Menke et al.-Mean air velocity correction for thermal comfort calculation: assessment of velocity-to-speed conversion procedures using Large Eddy Simulation data Nikolay G Ivanov and Marina A Zasimova
... 31.2 del Reial Decret Legislatiu 1/1996, de 12 d'abril, pel qual s'aprova el Text Ref... more ... 31.2 del Reial Decret Legislatiu 1/1996, de 12 d'abril, pel qual s'aprova el Text Refós de la Llei de Propietat Intel·lectual, http://bibliotecnica.upc.es/sepi/legislacio.asp). Per a qualsevol ús que es vulgui fer diferent al permès, dirigiu-vos a: [email protected]. Valid XHTML 1.0! ...
This work presents the implementation and validation of a numerical model that simulates the ther... more This work presents the implementation and validation of a numerical model that simulates the thermal and fluiddynamic phenomena inside capillary tubes. The algorithm is based on a two-phase flow model where the governing equations (continuity, momentum, energy and entropy) are integrated over the discretized fluid domain and solved by means of a step-by-step scheme. The numerical procedure considers four different transitional regions (subcooled liquid region, metastable liquid region, metastable two-phase flow region and equilibrium two-phase flow region), allows the prediction of both critical and non-critical flow conditions, and evaluates the heat exchanged between the capillary tube and the compressor suction line. The model predictions have been compared against experimental data sets including adiabatic and non-adiabatic conditions. In addition, a parametric study on capillary tubes used in household refrigerators and working with isobutane has been carried out (different geometric conditions were considered).
A complete and advanced numerical simulation model of the thermal and fluid-dynamic performance o... more A complete and advanced numerical simulation model of the thermal and fluid-dynamic performance of hermetic reciprocating compressors has been developed and is used in the optimization Electrolux compressor design. During the last few years several global experimental validations have been carried out. A detailed instrumentation of a commercial reciprocating compressor for household refrigerators has been developed to determine the average temperature distribution on the surface and the gas at different strategic points in all the compressor zones. This work is focussed on presenting a parametric study of a concrete commercial hermetic reciprocating compressor by means of the numerical simulation model, together with a detailed experimental comparison. The objective is to demonstrate how both global and detailed experimental comparison confirms the possibilities offered by these models.
A numerical simulation of a liquid overfeed system working with pure refrigerants in steady state... more A numerical simulation of a liquid overfeed system working with pure refrigerants in steady state conditions has been performed. The global algorithm is based on the sequential resolution of the different elements of the system (compressor, evaporator, condenser, ...). For each element, a simplified mathematical model based on global balances of mass, momentum and energy is used. For the evaporator and condenser, specially tailored lumped parameter models have been developed based on an advanced detailed simulation model. In this way, global heat transfer coefficient (U) and the flow configuration factor (F) have been obtained. The behaviour of two refrigerant working fluids, ammonia and Rl34a, has been compared for a specified system and for different working conditions.
An advanced numerical simulation of the thermal and fluid-dynamic behaviour of hermetic reciproca... more An advanced numerical simulation of the thermal and fluid-dynamic behaviour of hermetic reciprocating compressors has been developed and recently improved to be used in the whole compressor domain. The domain is divided into fluid and solid control volumes. The fluid flow modelation is based on the full integration of the onedimensional and transient governing equations of the flow (continuity, momentum and energy) in all the fluid compressor zones. The solid thermal behaviour is based on heat global balances at each solid component The oil heat transfer is taken into account as global heat balance. The hermetic compressor model also carries out at each time-step the force balances in the connecting rod and crankshaft mechanism. The simulation incorporates a new multidimensional model for the valve dynamics, which is able to use spring valves. Finally, the program evaluates the thermodynamic and transport properties for different refrigerant fluids and mixtures using local co111ditions. This present work is focussed on showing the news explained above and present a parametric study together with an experimental comparison based on the study, using a small hermetic refrigeration compressor as an example. The idea is to demonstrate the advantage that the complete compressor simulation offers, and emphasises the points that Fgrzs Gas force to the cylinder q Vale plate participation factors v Poisson's ratio
Chemical Engineering Science, 2011
8th European Congress on Computational Methods in Applied Sciences and Engineering
8th European Congress on Computational Methods in Applied Sciences and Engineering
14th WCCM-ECCOMAS Congress, 2021
In this work, a numerical framework aimed at simulating high-viscous and viscoelastic liquid inje... more In this work, a numerical framework aimed at simulating high-viscous and viscoelastic liquid injection processes is presented. The study of fluid i njection w ith v iscoelastic p roperties, s uch as synthetic polymers, is of great importance in several industrial sectors, such as metallurgy, automotive, food and pharmaceutical products, ink jets and 3D printers. In this work, a Geometrical Volume-of-Fluid (VOF) method is used to represent the interface, while finite-volume d iscretizations o f Navier-Stokes equations on collocated unstructured meshes are solved through a fractional step method. Viscoelastic constitutive models are used to resolve the non-Newtonian behaviours. The employed implementations allow integrating different types of constitutive equations and stabilization approaches. The test case proposed in the current work consist of the simulation of the discharge of a polymeric jet from an upper nozzle into an air-containing cavity with solid bottom. The behavior of the fluids under analysis is validated by observing the onset of fluid-buckling s tructures. This phenomenon consists in the appearance of toroidal oscillation (as coiling and folding patterns) after the jet hits the solid surface and begins to accumulate. First, low-Reynolds number (Re<1.0) Newtonian Jets are analyzed, with the objective of validating the appearance of buckling as a function of Re number, and comparing the results with reference works. Finally, the potentialities of the proposed numerical methods are shown by simulating buckling phenomena in viscoelastic Jets described with the Oldroyd-B constitutive model.
The aim of this work is to delve into the turbulent flow of viscoplastic-type non-Newtonian fluid... more The aim of this work is to delve into the turbulent flow of viscoplastic-type non-Newtonian fluids through specific and essential numerical aspects for them. Specifically, the numerical problems introduced by the transpose diffusive term which are associated with the velocity field discontinuity and the artificial viscous diffusion will be addressed from the beginning. The objective is to gain insight into the underlying physics of this class of non-Newtonian fluid flows.
J. Muela, J. Ventosa-Molina, O. Lehmkuhl, C.D. Pérez-Segarra and A. Oliva 1 Centre Tecnològic de ... more J. Muela, J. Ventosa-Molina, O. Lehmkuhl, C.D. Pérez-Segarra and A. Oliva 1 Centre Tecnològic de Transferència de Calor (CTTC), Universitat Politècnica de Catalunya (UPC), ETSEIAT, Colom 11, 08222, Terrassa, Barcelona, Spain. E-mail: [email protected]. URL: http://www.cttc.upc.edu/ 2 Termo Fluids S.L., Avinguda Jaquard, 97 1-E, 08222, Terrassa, Barcelona, Spain. E-mail: [email protected]. URL: http://www.termofluids.com/
Proceedings of the Sixth International Symposium On Turbulence, Heat and Mass Transfer, 2009
Flow around cylindrical structures is of relevance for many practical applications. Knowledge of ... more Flow around cylindrical structures is of relevance for many practical applications. Knowledge of flow-related unsteady loading of such structures is crucial for hydro - and aerodynamic control and design. Recenty, the increase in computer power has allowed detailed numerical studies of this flow at high Reynolds numbers [1]. In order to obtain deeper knowledge of this kind of flow, several symmetry-preserving regularization simulations [2] and a DNS have been performed at ReD = 3900 (ReD = UrefD/v). These are the first published studies with symmetry-preserving regularization models for this flow.
The ACABMA (Air-Cooled water-LiBr ABsorption cooling Machine of low capacity for Air- conditionin... more The ACABMA (Air-Cooled water-LiBr ABsorption cooling Machine of low capacity for Air- conditioning) project is a Craft-Joule Project within the framework of the Non Nuclear Energy Programme Joule III coordinated by the Centre Tecnològic de Transferència de Calor (CTTC). The basic objective of this project is the development of a new air-cooled absorption cooling machine for air-conditioning, in the low power sector market. Making use of water-LiBr technology together with the air-cooling feature, it is possible to reach a better relationship between quality (in terms of performance, ecology, etc.) and price of such absorption machines, than the ones existing on the market. Air- cooling instead of water cooling saves installation costs specially in small systems and removes the demand for cooling water (an important aspect in Southern-European countries), thus increasing the possible application range. The main interest for the SME proposers is to take advantage of the increasing coo...
This work is aimed at presenting numerical predictions regarding unsteady natural convection in a... more This work is aimed at presenting numerical predictions regarding unsteady natural convection in a rectangular cavity. The flow in the buoyancy-driven cavity o f 7 : 1 aspect ratio is numerically analyzed for water (P r = 3.77) which is exposed to hot and cold vertical plates with periodic temperatures. The results are obtained for three different variable Rayle igh numbers sets whose maximum values are 1.58·10 5 , 1.58·10 8 , and 1.58·10 11 . Outcome of the numerical experiment is of interest as it permits to estimate the unsteady heat transfer in a rectangular parell elepiped tank of an integrated solar collector [1]. Numerous correlations of the Nusselt number have been reported in the literature regarding laminar and turbulent natural convection flow in vertical cavities for s teady state situations [2,3], which cannot necessarily predict the transient heat transfer rate with accu racy. This work allows to check the capability of the steady state correlations to provide reasonable pred ictions for transient situations. Two-dimensional Navier-Stokes equations together with the energy equation assuming constant thermophysical properties, Newtonian fluid behaviour, and Bous sinesq approximation, have been solved by means of finite-volume techniques on structured grids usi ng a staggered arrangement [4]. Diffusive terms are evaluated by central differences, while convective terms are discretized by using high-order SMART scheme [5]. Second order fully implicit time integration has been applied [6] and the resulting system of algebraic equations is solved employing a pressure-based SIMPLE-like algorithm [7].
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Papers by C. Pérez-segarra