Thermodynamic Methods of High-temperature Measurement

Thermodynamic temperature measurement techniques fall into three separate classes: pneumatic devices, heattransfer gages, and calorimetric methods. All three are characterized by the ability to measure temperatures (or related fluid properties such as enthalpy) at levels beyond the capability of thermoelectric materials or pyrometer calibration devices. The pneumatic probe consists of a tube havinc two choked (sonic) orifices in series. It may be cooled, and need not be thermally insulated. It can be used onlv lor gases, and assumption of the perfect gas law, amonR othrr stipulations, is necessary. It has been in wide uso sim-i» early 1950, and, despite its many drawbacks, is quitr .ia«».:viAt *» for certain applications. The simplest form of calorimeter in use tod^v i* as a cooling jacket; e.g., energy balances across aroint