Thermal Management is the ability to control the temperature of a system by means of Technology based on Thermodynamics and Heat Transfer.
The phrase Thermal Management is therefore describing all possible means and processes like heat transfer, conduction, convection, condensation and radiation, etc. to increase or decrease the temperature and/or the temperature distribution of a specified system.
This system is a geometry, component or area, with defined borders. Defining the system means therefore creating a physical model, which is as accurate as necessary and as simplified as possible, to enable analytical approach of the thermodynamic questions. The system can be quite complex (area consisting of many components, different materials, combining solids, liquids and gases, big or small, stable "steady state" or changing over time "transient"). Also the outside (ambient) conditions play a very important role.
The borders are describing the ability of the system for the transfer of energy, work and mass. The definition of the content will define the ability of the system to use these transfers to change the systems temperature and temperature distribution by storing and discharging energy, work and mass. In complex systems it can be necessary to define "sub-systems" to describe the interaction between important parts of the main system. After the system is defined with its borders and contents, important parameters are fixed like the geometry, mass and material parameters.
Temperature is in Thermal Management the main state variable of a system, which - simplified - shows the energy level of the system. Each system has a given ability to store or dissolve energy. This ability is called the "heat capacity" of the system, and it can be calculated by the mass and the specific heat capacity of all materials in the system. When energy is transferred into the system or energy is created by an internal source in the system, the energy level of the system can rise. Higher energy levels of the materials in the system are causing the temperature of these materials to rise. The specific heat capacity defines the connection between absorbed or dissolved energy and the change of temperature.
When the system specifications do not fulfil the system requirements under the ambient conditions, this deviation should be described in quality and quantity. Thermal Management concepts use different strategies to solve typical gaps between requirements and specifications. Basic concepts are heating (system temperatures above ambient) and cooling (system temperatures below ambient), heat removing (system temperatures above ambient), cycling (heating and cooling with defined temperature rates and platforms over time) and temperature homogenization (creating uniform temperatures over a length, an area or a volume). Principles used for these concepts enclose enhancement of heat transfer (material selection, surface enlargement, forced convection, evaporation and condensation), thermal insulation, selective heat transfer and active cooling with Thermoelectrics.