This paper studies the effectiveness of one commercial computational fluid dynamics (CFD) program for simulating combined natural convection and heat transfer in three dimensions for air-filled cavities similar to those found in the extruded frame sections of windows. The accuracy of the conjugate CFD simulations is evaluated by comparing results for surface temperature on the warm side of the specimens to results from experiments that use infrared (IR) thermography to map surface temperatures during steady-state thermal tests between ambient thermal chambers set at 0 °C and 20 °C. Validations using surface temperatures have been used in previous studies of two-dimensional simulations of glazing cavities with generally good results. Using the techniques presented and a noncontact infrared scanning radiometer we obtained surface temperature maps with a resolution of 0.1 °C and 3 mm and an estimated uncertainty of +/-0.5 °C and +/-3mm. Simulation results are compared to temperature line and contour plots for the warm side of the specimen. Six different cases were studied, including a simple square section in a single vertical cavity and two four-sided frame cavities as well as more complex H- and U-shaped sections. The conjugate CFD simulations modeled the enclosed air cavities, the frame section walls, and the foam board surround panel. Boundary conditions at the indoor and outdoor air/solid interface were modeled using constant surface heat-transfer coefficients with fixed ambient-air temperatures. In general, there was good agreement between the simulations and experiments, although the accuracy of the simulations is not explicitly quantified. We conclude that such simulations are useful for future evaluations of natural convection heat transfer in frame cavities.

1 aGustavsen, Arlid1 aGriffith, Brent, T.1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/three-dimensional-conjugate01203nas a2200181 4500008004100000050001500041245008900056210006900145260002600214520056200240100002200802700002500824700002900849700002000878700002400898700002400922856007500946 1999 eng d aLBNL-4399100aTHERM 2.0: A Building Component Model for Steady-State Two-Dimensional Heat Transfer0 aTHERM 20 A Building Component Model for SteadyState TwoDimension aKyoto, Japanc09/19993 aTHERM 2.0 is a state-of-the-art software program, available without cost, that uses the finite-element method to model steady-state, two-dimensional heat-transfer problems. It includes a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed primarily to model thermal properties of windows, it is appropriate for other building components such as walls, doors, roofs, and foundations, and is useful for modeling thermal bridges in many other contexts, such as the design of equipment.

1 aHuizenga, Charlie1 aArasteh, Dariush, K.1 aFinlayson, Elizabeth, U.1 aMitchell, Robin1 aGriffith, Brent, T.1 aCurcija, Dragan, C. uhttps://facades.lbl.gov/publications/therm-20-building-component-model01900nas a2200181 4500008004100000050001500041245014300056210006900199260002500268490001600293520122000309100002201529700002501551700002901576700002001605700002401625856006901649 1998 eng d aLBNL-4210200aTeaching Students about Two-Dimensional Heat Transfer Effects in Buildings, Building Components, Equipment, and Appliances Using THERM 2.00 aTeaching Students about TwoDimensional Heat Transfer Effects in aChicago, ILc01/19990 v105, Part 13 aTHERM 2.0 is a state-of-the-art software program, available for free, that uses the finite-element method to model steady-state, two-dimensional heat-transfer effects. It is being used internationally in graduate and undergraduate laboratories and classes as an interactive educational tool to help students gain a better understanding of heat transfer. THERM offers students a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed to model thermal properties of building components such as windows, walls, doors, roofs, and foundations, it is useful for modeling thermal bridges in many other contexts, such as the design of equipment. These capabilities make THERM a useful teaching tool in classes on: heating, ventilation, and air-conditioning (HVAC); energy conservation; building design; and other subjects where heat-transfer theory and applications are important. THERMs state-of-the-art interface and graphic presentation allow students to see heat-transfer paths and to learn how changes in materials affect heat transfer. THERM is an excellent tool for helping students understand the practical application of heat-transfer theory.

1 aHuizenga, Charlie1 aArasteh, Dariush, K.1 aFinlayson, Elizabeth, U.1 aMitchell, Robin1 aGriffith, Brent, T. uhttps://facades.lbl.gov/publications/teaching-students-about-two