A simple optical probe of transient heat conduction

Abstract

We use a laser beam and a stopwatch to investigate transient heat conduction in Plexiglas and glycerol samples chilled by ice water. The deflection of the laser beam is proportional to the thermal gradient in the sample. Measurements of the beam deflection allow us to calculate the thermal gradient as a function of time. Our empirical results fit the theoretical predictions very well and show an initial increase in the thermal gradient followed by a gradual decrease as the entire sample approaches the temperature of ice water. The procedure is simple and can be used as a lecture demonstration, an afternoon’s experiment, or an extended investigation in an advanced laboratory course.

Heat conduction in carrots studied with an IR-camera

“…imaging of temperature distributions using mostly infrared (IR) cameras. In the first category fall experiments using relaxation techniques [1,2] measured with arrays of thermometers or thermocouples [3,4], with a hot wire method [5], by the deflection of a laser beam through the temperature gradient in Plexiglas [6] and with an IR camera [7]. In the second category thermal imaging with thermal sensitive foils was proposed [8], but in most papers IR cameras are used for qualitative imaging of objects from daily life [9,10], vegetation [11], paintings [12], the Moon [13], black bodies [14] and heat conduction and convection processes [15].…”

An experiment in heat conduction using hollow cylinders

“…Díaz-Aguilera [4] studied the heat conduction in onedimensional solids, Ràfois and Ortín [5] presented an experimental realization of the problem of heat conduction along a one-dimensional metallic rod with Newtonian losses and Bee et al [6] analysed realistic problems involving thermal conductivity. Transient heat conduction has been experimentally analysed by Brody et al [7] using an optical set-up with a laser, while Laufer et al [8] presented a method to allow the temperature to be visualized in conducting solids using thermographic phosphors. Bacon et al [9] presented a range of experiments in heat conduction using liquid crystals suitable for upper level undergraduate laboratories and Brun and Pacheco [1] analysed the reduction in heat transfer through a wall due to conduction, convection and radiation.…”

“…Díaz-Aguilera [4] studied the heat conduction in one-dimensional solids, Ràfois and Ortín [5] presented an experimental realization of the problem of heat conduction along a one-dimensional metallic rod with Newtonian losses and Bee et al [6] analyzed realistic problems involving thermal conductivity. Transient heat conduction has been experimentally analyzed by Brody et al [7] using an optical set-up with M. Ortuño, A. Márquez, S. Gallego, C. Neipp and A. Beléndez, "An experiment in heat conduction using hollow cylinders", European Journal of Physics, Vol. 32, Nº 4, 1065Nº 4, -1075Nº 4, (2011.…”