M. Zamora

Design and construction of precision heat fluxmeters

In this paper we discuss the design and construction of thermopiles for use as heat flux measurers. Compact structure, mechanical consistency, and a wide range of dimensions and sensitivities are possible. We can thus reach thermocouple densities up to 100 cm−2 and sensitivities of approximately 1 V W−1.

New experimental apparatus for the study of the Bénard–Rayleigh problem

A new experimental system to measure the equivalent thermal conductivity of a liquid with regard to the Benard–Rayleigh problem was constructed. The liquid is enclosed within walls of polymethylmethacrylate between two copper plates in which there are thermocouples to measure the difference in temperature between the lower and upper surfaces of the layer of liquid. Heat flux is measured by means of a linear heat fluxmeter consisting of 204 thermocouples in series. The fluxmeter was calibrated and the linear relationship that exists between the heat flux and the emf generated was verified. The thermal conductivity of the polymethylmethacrylate employed was measured and measurements of the equivalent conductivity in cylindrical boundaries of two silicone oils were made. The critical value of the temperature difference and the contribution of the convective process to the transmission of heat were determined.

Canonical formalism in equilibrium thermodynamics

Gibbs’ principle is extended to systems subject to generalized constraints. It is shown that equilibrium thermodynamics can be presented under a canonical structure. Also, it is shown that the canonical phase space provides a natural representation for equilibrium states.

Experimental method of measuring energy in the Bénard–Rayleigh problem

The energy content, introduced by the thermodynamics of steady states, is measured in the Benard–Rayleigh problem using a heat fluxmeter connection. We describe the experimental apparatus, which can turn around a horizontal axis, thus inducing or destroying convective structures. After calibration, we were able to measure the heat flux through the fluid layer as well as the structural energy of the convective cells. These structural energy values confirm that the energy content is a steady‐state function.

Canonical formalism in equilibrium thermodynamics. II. Homogeneity, stability, and generalized Maxwell relations

The classical theory of equilibrium thermodynamics is formulated in a canonical context which has been recently proposed by us. It is shown that the equations of state correspond to what in analytical mechanics is called an involution system. The classical conditions of thermodynamic stability are deduced from a variational principle for the entropy function.

Device for simultaneous measurement of the Peltier and Seebeck coefficients: Verification of the Kelvin relation

We have designed and built an experimental device, which we called a ‘‘thermoelectric bridge.’’ Its primary purpose is simultaneous measurement of the relative Peltier and Seebeck coefficients. The systematic errors for both coefficients are equal with this device and manipulation is not necessary between the measurement of one coefficient and the other. Thus, this device is especially suitable for verifying their linear relation postulated by Lord Kelvin. Also, simultaneous measurement of thermal conductivity is described in the text. A sample is made up of the couple nickel‐platinum, taking measurements in the range of −20–60 °C and establishing the dependence of each coefficient with temperature, with nearly equal random errors ±0.2%, and systematic errors estimated at −0.5%. The aforementioned Kelvin relation is verified in this range from these results, proving that the behavioral deviations are ≤0.3% contained in the uncertainty ±0.5% caused by the propagation of errors.