This experimental study examines the detailed Nusselt number (Nu) distributions for a tilted reciprocating square-sectioned thermosyphon duct with a jet entry flow. Detailed heat transfer measurements over the thermosyphon wall at the jet Reynolds numbers of 15,000, 20,000, 25,000, 30,000, 35,000 with the reciprocating frequencies of 0, 0.33, 0.5. 0.67 and 0.83 Hz are performed using the steady-state infrared thermo-graphic method. The coupling effects of jet-inertial, reciprocating and buoyancy forces in the tilted reciprocating thermosyphon exhibit synergistic influences on heat transfer performances. A selection of experimental data illustrates the full-field Nu variations responding to the changes of jet Reynolds (Re-j), pulsating (Pu) and reciprocating Grashof (Gr(p)) numbers. Parametric analysis is subsequently followed to identify the individual and interdependent Re. Pu and Gr(p) effects on the area-averaged Nusselt number ((Nu) over bar) in the attempt to generates the physically consistent (Nu) over bar correlation to assist the design of the shaker-jet piston cooling system. Within the parametric ranges tested, (Nu) over bar over the tilted reciprocating thermosyphon is raised to 1.25-2.85 times of the heat transfer levels in the static thermosyphon, which confirm the improved heat transfer performance by reciprocation for such cooling configuration. (C) 2009 Elsevier Ltd. All rights reserved.