Patent ID: 8015841

Claim:
A cryogenic refrigeration system for lyophilization comprising: a cryogenic heat exchanger system wherein a liquid cryogen is vaporized and the resulting gaseous cryogen is used to cool a heat transfer fluid; a primary recirculation loop in fluid communication with the cryogenic heat exchanger system wherein some or all of the cooled heat transfer fluid is directed to a lyophilization chamber and wherein the heat transfer fluid exiting the lyophilization chamber is recycled back to the lyophilization chamber or returned to the cryogenic heat exchanger system; a secondary recirculation loop in fluid communication with the cryogenic heat exchanger system wherein some or all of the cooled heat transfer fluid is directed to a condenser and wherein the heat transfer fluid exiting the condenser is returned to the cryogenic heat exchanger system; a first three way control valve disposed downstream of the heat exchanger system, the three way control valve directing the cooled heat transfer fluid to the condenser via the secondary recirculation loop or directing the cooled heat transfer fluid to the lyophilization chamber via the primary recirculation loop or directing the cooled heat transfer fluid to both the condenser via the secondary recirculation loop and to the lyophilization chamber via the primary recirculation loop; and a first diversion valve and diversion loop disposed downstream of the first three way control valve between the secondary recirculation loop and the primary recirculation loop, wherein a portion of the heat transfer fluid in the secondary recirculation loop upstream of the condenser is diverted to the primary recirculation loop upstream of the lyophilization chamber to mix with the heat transfer fluid in the primary recirculation loop and lower the temperature of the heat transfer fluid in the primary recirculation loop directed to the lyophilization chamber.