Understanding enclosures

The software calculates infrared (IR) radiation in enclosures. Within an enclosure, the solver computes the view or partial view between each element and all other elements. This influences the amount of radiative energy that particular element will be able to exchange with the other elements of the enclosure.

The view or partial view an element has of another element is called a black body view factor. When the solver factors in the emissivity of the element and the effect of reflections, the view is called a gray body view factor. For more information on view factors, see Understanding view factors.

Enclosure definition

An enclosure is a set of surfaces that can exchange radiative energy with each other, either directly or indirectly (by reflection). Typically, it divides three dimensional space into two or more compartments between which radiation cannot pass, either by direct incidence or by reflection.

Enclosure example

Imagine a large hollow ball floating in space. The inside surface of the ball is one enclosure. The outside surface of the ball is another. No radiative energy can pass between the inside enclosure and the outside enclosure.

The outside surface of the ball exchanges heat with the radiative environment. Therefore, the outside enclosure must include the radiative environment. (Note that surfaces are affected by heat exchange with the radiative environment, but the radiative environment is not affected.)

To expand this example, imagine the following operations performed on the system:

• Place a small object inside the ball. This object blocks (or "shadows") the view that some elements have of some other elements. It also exchanges radiative energy with the inside surface. In order to fully model the radiative exchange inside the ball, the object must be part of the inside enclosure.

• Cut a small opening in the surface of the ball, so that some of the radiative heat inside the ball can be exchanged with the radiative environment. With the geometry thus changed, the inside enclosure now includes the radiative environment as well. The outside enclosure is unaffected, apart from being a bit smaller.

• Place another object outside the opening and a short distance from it. The object exchanges radiative heat with both the outside and inside surfaces of the ball. Also, through reflection, the inside and outside surfaces also exchange radiative heat (though the amount might be small). This makes the entire system interdependent, with all surfaces and the environment included in a single enclosure.

• If the opening is small enough, you might want to ignore its effect to save calculation time. You could accomplish this by using the Enclosure Radiation type when modeling this system.

Before the software can simulate radiative exchange within an enclosure, it needs to mathematically define the geometrical relationship of the surfaces with regard to radiation. To accomplish this, it calculates black body view factors for each element.

How do I

Define Radiation

Learn more

Radiation types

Understanding view factors

Understanding the Hemicube Rendering calculation method

Example 1 - Using the All Radiation type

Example 2 - Using multiple Enclosure Radiation type objects

Understanding the Monte Carlo calculation method

Monte Carlo Settings

Inputs to expressions

Look up more details

Auto-generated expressions

Quick links

Simcenter 3D Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal boundary conditions

Thermal/Flow, Electronic Systems Cooling, and Space Systems Thermal

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Understanding enclosures, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });