Method to monitor or measure heat transfer to determine flow state of flowing medium; involves comparing thermal resistance of thermistor when unheated and when heated

摘要

The method involves comparing the thermal resistance of a temperature measuring element when it is unheated with that when it is heated and subject to the cooling effect of the medium flow. The heating is periodic and pulsed. The heated temperature measuring element is part of a bridge circuit in which a control element ensures that variations in the temperature of the medium do not affect the signal produced by the heating pulse. The control arrangement is connected in series with the temperature measuring element.