Speed of temperature change in the material during time varying heat transfer

Heat transfer in connection with variation of working parameters during extremely short time periods is connected with appropriate change of temperature in the construction material of the energy equipment. In the cases with time varying working regimes we may find in the literature directives for limitation of these changes, which may reduce the arise of time varying strain conditions. Usually in these cases no additional data are available which may describe the change of temperature in the material. In this paper we shall try to present the speed of temperature changes in the material during the extremely fast changes of working fluid temperature, which override the permitted limits for changes of working parameters during the time varying processes. (Author)