Experimental investigations of a closed-loop oscillating heat pipe

Results are given of experimental investigations of an oscillating heat pipe (OHP) made in the form of a closed-loop coil of a copper capillary tube with an inside diameter of $2$ mm, $4.5$ m long, and filled with water in an amount of $50\%$ of internal volume. The starting characteristics of OHP are studied in the range of heat loads from $30$ to $100$ W under conditions of cooling by way of natural and forced air convection. The pattern of temperature pulsations in the zones of heating, heat transport, and cooling is investigated. It is found that temperature pulsations exhibit a chaotic pattern. In cooling of an OHP by way of natural convection, the increase in heat load is accompanied by an increase in the maximal temperature of the heating zone with a simultaneous decrease in the nonuniformity of the temperature field. When an OHP is cooled by way of forced convection, a decrease in the maximal temperature of the heating zone is observed; however, this is accompanied by an increase in the amplitude of temperature pulsations and in the nonuniformity of the temperature field.