Presentation on theme: "simulation of transient heat transfer in 2D free-form objects"— Presentation transcript:
1simulation of transient heat transfer in 2D free-form objects PHYSIBEL
2IntroductionThe Physibel program BISTRA allows simulations of transient heat transfer in 2D free-form objects. This slide show highlightshow to solve a 2D transient problem using BISTRA (with RADCON option)useful application examples - ground heat losses and frost insulation - fire engineering – steel-concrete floor - fire engineering – window frame - harmonic analysis of walls - temperature of heated & unheated rooms - thermal effect of solar radiation on façades
3Solving a 2D transient heat transfer problem using BISTRA 1. Problem definition The analysis of a fictitious problem shows the powerful performances of BISTRA.
4Solving a 2D transient heat transfer problem using BISTRA 1. Problem definition Materials with non-linear thermal properties, phase change materials (PCM) and an argon filled gas layer bounded by a low emissivity surface occur.
5Solving a 2D transient heat transfer problem using BISTRA 1. Problem definition The water temperature in the tubes rises and a heat is released at the PCM border Non-linear convection and radiation occur.
6Solving a 2D transient heat transfer problem using BISTRA 2. Problem implementation: BISTRA program interface > windowsbitmapcoloursmeasuresborderline bc’sfunctions
72. BISTRA program interface bitmap window each colour corresponds to a material or to a boundary conditionautomatic filling of line drawingdrawing and fill tools available for modifying the bitmap as in BISCO
82. BISTRA program interface colours window colour used in bitmapmaterial – boundary condition typespecific standard rule, for example used to calculate the equivalent thermal conductivitythermal conductivitysurface IR emissivitytemperature (global, air, radiant)constant or temperature dependent functiondensityconstant or time functionspecific heatconstant or temperature dependent functionheat sourceglobal or convective surface coefficientstandard rule coefficientsconstant or time function
9parameter or file defined functions 2. BISTRA program interfacefunctions windowfunction graph viewparameter or file defined functions
10size for automatic triangulation 2. BISTRA program interfacemeasures window0.5 msize for automatic triangulation
11calculation parameters 2. BISTRA program interfacecalculation parametersstart-up calculation duration allows transient start conditionmultiple iteration cycles for non-linear problemsboth linear and non-linear radiation model with automatic view factor calculationrecalculation of temperature dependent quantities at each time step
17BISTRA application example 1 ground heat losses and frost insulation BISTRA allows transient thermal simulations according to EN ISO Thermal performance of buildings - Heat transfer via the ground - Calculation methodsEN ISO Thermal performance of buildings - Thermal design of foundations to avoid frost heave
20BISTRA application example 2 fire engineering – steel-concrete floor BISTRA allows fire engineering simulations according to the EUROCODES for structural calculations. A fire curve (typically ISO 834) is assumed at one side of the construction. The simulation of the heat transfer by radiation, convection and conduction allows predicting the temperature evolution in the construction. Temperature dependent material properties (steel, concrete, ...) are considered.
42BISTRA application example 6 thermal effect of solar radiation on façades For a south façade (double glazing, aluminium frame, opaque insulation panel) in Brussels the temperature distribution is calculated, taking into account the solar radiation transmitted through the glazing and absorbed in the façade.
54… about 3D …The Physibel program VOLTRA allows simulations of transient heat transfer in 3D objects described with rectangular blocks. VOLTRA has the same basic simulation performances as BISTRA. BISTRA data can be imported ! The bitmap pixels are treated as small rectangular blocks. Further information can be found on:
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