HOT END LOSS AT PULSE TUBE REFRIGERATORS

Most pulse tube refrigerators need an additional heat exchanger at the hot end of the working space in contrast to other refrigerators with regenerators. There is a periodic, alternate gas flow which passes thr ough this hot heat exchanger. Due to this fact the hot heat exchanger has to be considered not only with a desired recuperative effect but a lso with a regenerative effect. This regenerative effect of the hot en d heat exchanger acts as a loss. In this contribution the so-called ho t end loss is described by means of an orifice pulse tube refrigerator and is compared with that of a four valve pulse tube refrigerator. Ex perimental investigations on a four valve pulse tube refrigerator veri fy this loss. An orifice pulse tube refrigerator without hot end loss is presented. (C) 1998 Elsevier Science Ltd. All rights reserved.