Thermal diffusivity in low conducting solids: a capacitive method

Abstract

The thermal diffusivity of a low conducting solid is measured by means of a capacitive method, providing the thermal expansion of the specimen as a function of time. The simultaneous knowledge of the temperature profile vs. time at the thermal source, in contact with the sample base, allows a rapid, accurate and reliable determination (within ~ 2%) of thermal diffusivity. No sensor is inserted into the specimen, thus avoiding any perturbation of the temperature field.

Measuring the Thermal Diffusivity in a Student Laboratory

“…The solution of the thermal transport is obtained as in Refs. [2][3][4][5][6][7][8][9][10][11][12]. Let us consider a time interval τ small enough.…”

“…This technique reduces the thermal leaks, but, as in the case of dilatometric methods, requires a sophisticate set-up.Aiming to improve a laboratory for students with a measure of the thermal diffusivity, without increasing the overalls cost of the structure, we describe here an experimental procedure based on the use of thermocouples, adapting the numerical methods of determining the thermal field developed in Ref. [2][3][4][5][6][7][8][9][10][11][12]. The method of solution is simplified for undergraduate students.…”

“…Here then, we propose a method that allows the students to have an experimental approach to the problem of thermal transport. Years ago, the author has published some papers [2][3][4][5][6][7][8][9][10][11][12] on new methods to measure the thermal diffusivity. Some measures reported in the references were based on modelling the thermal field inside a specimen after the measure of its thermal expansion.…”

The Political Economy of Resistance and Self‐Destruction in the Crack Economy

“…This is most pronounced for the majority cohort living in New York City where Puerto Ricans have the highest welfare dependency and poverty rates and the lowest labor force participation rates of any group (Rosenberg 1990; Center on Budget and Policy Priorities; Lehman 1991). More poignantly, the Puerto Rican statistics cover some of the most humanly painful experiences ranging from the fastest growing HIV infection rates, the highest rates of bedridden disability, the most deaths due to cirrhosis of the liver, the greatest per capita proportion of heroin and crack addicts, to the highest rates of suicide attempts (Giachello 1990;Lambert 1990;Rosenwaike 1983).…”