| 摘要 |
<p>A cryogenic heat exchange system with particular application to a freeze dryer comprising a heat exchanger having at least one pass for receiving a cryogenic heat exchange fluid; a reversing circuit connected to the at least one pass having an inlet for receiving the cryogenic heat exchange fluid, means for introducing the cryogenic heat transfer fluid into the at least one pass and for reversing flow direction of the cryogenic heat transfer fluid so that the cryogenic heat exchange fluid flows through the at least one pass in one flow direction and then in an opposite flow direction, and an outlet for receiving a portion of the cryogenic heat transfer fluid from the at least one pass after having passed therethrough as spent cryogenic heat exchange fluid; recirculation means connected to the outlet of the reversing circuit for receiving the spent cryogenic heat transfer fluid and having a mixing chamber for mixing the spent cryogenic heat transfer fluid with a cryogen, to form the cryogenic heat exchange fluid and thereby to increase the enthalpy of the cryogenic heat transfer fluid over that of the cryogen, a mixing chamber outlet in communication with the inlet to the reversing circuit for introducing the cryogenic heat transfer fluid into the reversing circuit, and means for circulating the cryogenic heat transfer fluid to the reversing circuit, through the at least one pass and back to the mixing chamber as the spent cryogenic heat exchange fluid; and vent means for venting a remaining portion of the cryogenic heat transfer fluid after having passed through the at least one pass of the at least one heat exchanger. <IMAGE></p> |
