Oscillation and elevation difference of thermally driven two-phase on its thermal performances
微型热驱动回路的脉动及位差对热性能的影响

A high speed data acquisition system was used to detect the pressure and temperature oscillations of the thermally driven two-phase loop for different operation parameters using methanol as working fluid. The oscillation time period and the amplitudes are smaller at high heat flux than those at low heat flux. It was found that bubbly flow or slug flow exists in the vapor line at low heat flux, while the annular flow exists at high heat flux. In addition to these, the effect of the relative elevation difference between the evaporator and the condenser on the operation of the thermally driven two-phase loop was studied. The maximum heat flux of evaporator was obtained with the pure natural or the forced air convection of the fin heat sink condenser under the condition of the upper limit temperature of 90${^\circ}$C of the heating block. The present study is to provide guidelines for the design and operation of the miniature electric cooling.