An experimental and numerical investigation of pressure drop in a closed loop two phase thermosyphon system

The increase of heat fluxes from electronic components requires new methods of cooling of electronics. One efficient method of cooling is to use a closed loop two-phase thermosyphon system. The advantage of these systems is that extremely high heat fluxes can be dissipated at a low temperature difference due to the high heat transfer coefficients in boiling and condensation. In this paper experimental results of the pressure drop in the evaporator, riser and condenser of an advanced closed loop thermosyphon and numerical calculations of the pressure drop in the thermosyphon system, based on correlations from the literature, are presented. The thermosyphon system consists of a downcomer, an evaporator, a riser and a condenser. Heat was supplied by a power resistor and tests were performed with the heat loads 30, 60 and 90 W dissipated through the system. Two different refrigerants were tested, R134a and R600a. Pressure drop was measured across each of the four basic components by a differential pressure transducer. Comparisons between the experimental and numerical results are presented.