Visualization of oscillating flow in a double-inlet pulse tube refrigerator with a diaphragm inserted in a bypass-tube

The double-inlet pulse tube refrigerator that has a diaphragm inserted in a bypass-tube, which enabled it to transmit a pressure oscillation whereas to obstruct a DC gas flow, was manufactured and tested. The oscillating flow behavior inside of the refrigerator was studied by using a smoke-wire flow visualization technique. It was found that if the diaphragm was optimized, the performance would be improved more than that of the refrigerator with a bypass valve due to the increase in the P–V work of the gas and the decrease in the convective heat loss caused by a secondary flow.

► A pulse tube refrigerator with a diaphragm DC gas flow suppressor was studied. ► Flow visualization was used to observe flow phenomena in the refrigerator. ► Effectiveness of the suppressor on performance of the refrigerator was evaluated. ► The performance is improved by using the appropriate suppressor. ► A P–V work increased and a convective heat loss decreased by the suppressor.