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Applications of self-heated PTC-thermistors to flow and quantity of heat measurements

1982; Elsevier BV; Volume: 3; Linguagem: Inglês

10.1016/0250-6874(82)80017-6

1873-3050

Klaus Dostert,

Sensor Technology and Measurement Systems

Abstract PTC-thermistors on a polycrystalline doped titanate ceramic base can be operated very simply as thermostats when they are supplied with an appropriate voltage [ 7 – 9]. This thermostatic effect is very useful for constructing electrocaloric flowmeters as cheaply as possible [4]. By combining two identical electrically self-heated PTC-thermistors in a bridge circuit, with one of them in the fluid flow and the other out of it, the dependence of the measured value ( i.e. , the volume flow) on the fluid temperature can be eliminated. This new idea leads to very simple and easily calibrated evaluation circuits for flowmeters based on the electrocaloric principle. Cost-effective flowmeters can be built for various applications, such as the measurement of fuel consumption in motor vehicles or of the quantities of heat consumed in central heating systems supplied with hot liquid such as water. In the latter application, it will be necessary to introduce an appropriate bypass in order to achieve laminar flow through the flowmeter.