Experimental resuts on dynamic behaviour of thermistor flowmeters

The influence of non linear effects on dynamic behaviour of self-heated thermistor flowmeters is studied. The non linear equation which describes the device thermal balance is solved by numerical methods and the theorical prevision are compared with the results of experimental measurements. The results emphasizes that a description of dynamic behavior of thermistor flowmeters by means one time constant is very unsotisfacoty. Either response time ore sensitivity can be change appreciably by changing the bias conditions of the self-heated thermistor and a criterion is suggested for the choice of bias conditions which provide the best response speed and sensitivity of the system.