Experimental study on the performance of a pulsating heat pipe with aqueous solution of butanol at different orientations

Heat dissipation, recovery and accumulation is more and more becoming the limiting factor in the advancement of many energy systems. The conventional heat pipes such as copper grooved heat pipes and sintered particle heat pipes have played an important role in the heat dissipation in electronic equipment. Pulsating heat pipe (PHP) is a new type of efficient heat transfer device, which was introduced in the mid-1990s by Akachi. PHP can be used for cooling of electronics because of its potential for removing high heat flux. The capillary effect is indeed provided by the small dimension of the channel, and not by the presence of a wick structure. An experimental study was conducted to investigate heat transfer performance of a closed loop pulsating heat pipe with pure water and aqueous solution of butanol (self-rewetting fluid) under various filing ratios, inclination angles and heat inputs. Self-rewetting fluids have a property that the surface tension increase with increase in temperature. Butanol is added to pure water at 0.1 wt% and 0.5 wt% concentrations to make self-rewetting fluid. The PHP is made of copper tube with inner and outer diameters of 2.0 mm and 3.0 mm, respectively. It is observed that lower thermal resistance is obtained by using aqueous solution of butanol compared with pure water. Also aqueous solution of butanol shows improved performance up to horizontal orientation, when compared with pure water.