Search results
Results From The WOW.Com Content Network
A number of materials contract on heating within certain temperature ranges; this is usually called negative thermal expansion, rather than "thermal contraction".For example, the coefficient of thermal expansion of water drops to zero as it is cooled to 3.983 °C (39.169 °F) and then becomes negative below this temperature; this means that water has a maximum density at this temperature, and ...
For a single component system, the "standard" three parameters are the isothermal compressibility , the specific heat at constant pressure , and the coefficient of thermal expansion . For example, the following equations are true:
The laws of thermodynamics imply the following relations between these two heat capacities (Gaskell 2003:23): = = Here is the thermal expansion coefficient: = is the isothermal compressibility (the inverse of the bulk modulus):
Negative and positive thermal expansion hereby compensate each other to a certain amount if the temperature is changed. Tailoring the overall thermal expansion coefficient (CTE) to a certain value can be achieved by varying the volume fractions of the different materials contributing to the thermal expansion of the composite. [8] [20]
A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property R that changes when the temperature changes by dT , the temperature coefficient α is defined by the following equation:
is pressure, temperature, volume, entropy, coefficient of thermal expansion, compressibility, heat capacity at constant volume, heat capacity at constant pressure. Maxwell's relations are a set of equations in thermodynamics which are derivable from the symmetry of second derivatives and from the definitions of the thermodynamic potentials .
To explain this definition, consider a reversible Carnot cycle engine, where is the amount of heat energy transferred into the system, is the heat leaving the system, is the work done by the system (), is the temperature of the hot reservoir in Celsius, and is the temperature of the cold reservoir in Celsius.
Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy ; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout.