Heat transfer analyses are generally performed to determine heat flows or overall heat transfer characteristics, and identify whether a design meets a particular insulation or conductivity requirement, or whether temperatures are acceptable.
Examples of heat transfer analyses performed by Eatec Engineering Analysis are given below.
Insulation characteristics of roofing systems
Some roofing systems lead to thermal bridges occurring. These are detrimental to the thermal performance, and need to be taken into account when determining whether a proposed building complies with Part L of the Building Regulations.
Projects have been undertaken to assess proposed roofing designs to determine the thermal transmittance (U value), taking into account thermal bridges and the minimum internal surface temperature. Details of a typical project are given below.
In order to assess the effects of thermal bridges on the heat transfer characteristics of a particular roof design, it was necessary to perform a three dimensional FE analysis. The FE model represented an appropriate section of the roof, and included the thermal bridges. It was important that the conductivity of the thermal bridges was represented accurately, and hence the insulation pads, air gaps and different interfaces needed to be modelled.
Using results the from FE analysis, it was possible to determine the overall thermal transmittance (U value) of the roof, and assess whether it had the required performance. It was found this was not the case, and the design was improved, and the FE model modified and rerun to represent longer halters and an increased thickness of insulation.
Heat transfer from a sealed electronics unit
A client was designing a sealed enclosure, which was to contain a number of electronics components which produced significant quantities of heat. A study was required to assess the heat transfer from the heat sources to the external air, and the temperatures the devices would reach under a range of ambient conditions.
It was agreed that hand calculations would provide the required level of accuracy, and would enable different enclosure designs to be assessed in a cost-effective way.
The calculations took into account heat transfer through conduction, convection and radiation. By means of the hand calculations, it was possible to assess a number of design concepts in an efficient manner, and identify the optimum one.