Performance evaluation of ultra-thin polymer pulsating heat pipes

An ultra-thin polymer pulsating heat pipe (PPHP) was developed by forming with UV curable polymer resin on polyethylene terephthalate films and hydrofluoroether was used as a working fluid. The casing materials were selected in consideration of compatibility between case materials and the working fluid and also the heat and pressure durability. A new apparatus was constructed to evaluate the thermal resistance of the PPHP without the heat dissipation caused by natural convection, and a simple model was developed to estimate the heat dissipation and identify their influence on the thermal performance measurement. Comparing experimental results in this apparatus with the results calculated by the model, we found that the uncertainty of the thermal resistance measurement caused by the heat dissipation could be reduced to the range of measurement error. The steady state operation of the PPHP in the horizontal orientation was confirmed by the temperature response to various heat loads and the observation of the working fluid pulsations. Performance evaluation of the PPHP using this apparatus showed that the thermal resistance of the PPHP decreased as heat load increased and reached a minimum value comparable with that of a copper plate of the same thickness.