Heat transfer in a reciprocating thermosyphon fitted with staggered transverse Ribs

This paper describes an experimental investigation of heat transfer in a reciprocating antigravity open thermosyphon. The thermosyphon tube is square in cross section, and two opposite walls are roughened with staggered transverse ribs. This flow/heat-transfer system has relevance, as a fundamental study, to the shaker-cooling system for the pistons of reciprocating engines. A series of experiments are undertaken to demonstrate the complex interaction that exists between inertial, reciprocating, and buoyancy forces on the performance of this form of cooling system. It is shown that reciprocation of the system significantly improves heat transfer in comparison with the stationary antigravity thermosyphon performance. The buoyancy effects from gravity and reciprocation improve heat transfer. Reductions in the effectiveness of buoyancy forces are produced when the relative strengths of inertial or/and pulsating forces increase. In the extrapolated case of zero buoyancy, it was found that the local heat transfer along the thermosyphon tube was reduced in comparison to the static case at relatively low levels of reciprocation frequency. As the reciprocation frequency was increased, this effect was reversed and heat transfer improved in comparison with the stationary case.