Experimental Study on the Forced Heating and Natural Cooling of a Colloidal Damper

Abstract

Colloidal dampers are able to dissipate large amounts of mechanical energy without significant heating, and such result is surprising since traditional hydro-pneumatic absorbers transform almost integrally the dissipated energy into heat. Trying to get deeper insight into this phenomenon, in this experimental work, using a thermographical method the temperature distributions on the external surface of a colloidal damper are recorded during its forced heating followed by its natural cooling. Employed compression-decompression cylinder is axially divided into two chambers, one of constant volume and the other of variable volume. Silica particles are introduced inside the cavity of fixed volume (silica tank), and a micro-filter is used to separate it by the chamber of variable volume, in which only water is supplied. Two main heat sources are identified at the silica tank (colloidal effect) and the packing used to seal the cylinder (frictional effect). Tests prove that heating/cooling through colloidal effect is much slower than heating/cooling through frictional effect. However, depending on the working frequency, generated heat power through colloidal effect can exceed the generated heat power through frictional effect. Based on the experimentally observed slow speed of heating/ cooling through colloidal effect, one suggests that silica tank can be regarded from a thermal standpoint as a thermostat. Mechanism of energy dissipation is justified based on the molecular and cluster vibration modes of the liquid water, variation of the radiation absorption coefficient of liquid water versus the electromagnetic wavelength, and changes in the arrangement of water octamers.