The so-called hot-wire method of determining the thermal conductivity of refractory materials over a wide range of temperatures has come into widespread use in recent years.In the literature it is known also as the method using a linear source and a constant-power cylindrical probe.The method is based on the mechanism of the heating of an unbounded medium into which is embedded a thin filament heated by an electric current of constant power. After a brief interval of time following the connection of the current the change in the temperature of the wire is expressed by an exponential curve.The theoretical equation for the calculation of the thermal conductivity of the medium is as follows:where % is the thermal conductivity of the medium (or specimen), W/m.~ ql' quantity of heat given off per unit length of the wire, W/m; t~ and t2, temperature of the filament (i.e., wire), ~ at the instants of time r~ and T2 after the current was connected, min.The method consists of passing a current of constant power for 12-15 min through a wire not more than 0.5 mm embedded in the medium of interest and measuring the rise of the temperature of the wire.The quantity % calculated from the measured values of ql and t=It~ relates to the temperature of the medium (i.e., specimen) at which the current passes through the wire so that the method gives the true thermal conductivity, i.e., for a specific temperature of the medium (specimen).The various versions of the experimental apparatus and certain points in the theory underlying the method were examined in [i-18].The most common type of apparatus for determining. Schematic drawings of devices with a " measuring cross" for determining % of refractory materials by the hot-wire method: i) furnace; 2) specimen consisting of two bricks or two capsules containing a pulverized material; 3) hot wire; 4) thermocouple of the measuring cross; 5) thermostat; 61) current source; 7) equivalent resistance; 8) potentiometric probes; 9) voltmeter; i0) ammeter; ii) compensator; 12) lateral thermocouple; 13) recording instrument; a) measuring the rise of the wire temperature using a compensator; b) measuring the rise of the wire temperature on the basis of differential readings.All-Union Institute of Refractories.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.