抄録
Performances of pulse-tube refrigerators are discussed using thermoacoustic theory of inviscid fluid. Discussions are based on numerical calculations of distributions of temperature, displacement amplitudes and energy flows in a pulse tube using a method of the second step of thermoacoustic theory by A. Tominaga. Pulse-tube refrigerators are classified to three generations by boundary conditions at the hot end of pulse-tube: the first generation has no displacement at the end, as is the case of basic-type refrigerators. The second generation has finite displacement and phase difference below 90° between displacement and pressure oscillations, as is the case of orifice type refrigerators. The third generation has finite displacement and the phase difference over 90°. The followings are main results of discussions. (1) For the first generation there is heat pumping through the pulse tube due to standing-wave component when the temperature of the cold end is not so low. Large -Fsχ″ is, therefore, favourable to large heat-pumping. The phase loss of the regenerator is expected to be large, since the phase difference at the cold end is small. (2) For the second generation the phase loss of the regenerator is decreased due to progressive-wave component superposed at the hot end. The refrigeration power of the regenerator, however, decreases due to the displacement loss, if the displacement is too large. (3) For the third generation both of the regenerator losses are decreased by reduction of the standing wave component. The pulse tube of the third generation has, therefore, larger refrigeration power and lower limiting temperature than that of the second generation. (4) Small -Fsχ is favourable to reduction of heat input through the pulse tube at the pulse-tube part of the second and the third generation.
