Apparatus and method for utilization of waste heat of an internal combustion engine

A method for a device for utilization of waste heat of an internal combustion engine (2) having a line circuit (4) in which a feed pump (6), at least one heat exchanger (8), an expansion machine (10) and a capacitor (12) are arranged, in the line circuit (4) circulating a working medium, wherein a means for storing thermal energy (30) in the line circuit (4) is arranged, being arranged the means for storing thermal energy (30) between the heat exchanger (8) and the expander (10) is characterized in that a control device (37) monitors the charge state of the device for storing thermal energy (30), that the working medium is passed through the device for storing thermal energy (30) when the normal operating range for operating the line circuit is exceeded or undershot, and in that a means for activating (38) a supply of thermal energy from the egg nrichtung to store thermal energy (30) to the working medium triggers when the normal operating range is exceeded.