Heat Rejection Options for Sunpower CryoTel® Stirling Cryocoolers
The cryocooler operates by moving heat from the cold finger region to the heat rejecter region. This heat must then be removed from the cryocooler to prevent the cryocooler from overheating and getting damaged. The most common cause of cryocooler returns is overheating. The customer must always cool the cryocooler to prevent damage. The two standard ways to accomplish this are via air fins or via a water jacket.
For some applications, the customer has utilized conductive cooling to reject heat. The amount of heat rejection needs to equal the input power delivered to the controller, so at maximum power the MT needs 80 Watts, the CT 160 Watts, and the GT needs 240 Watts. The customer must be careful in the design of the system to guarantee the conductive heat rejection will meet the requirements otherwise the cryocooler will be damaged.
The drawing shows the heat rejection region where this heat is removed from the cryocooler.
Option One
Air Fins
The air fins are mounted to the heat rejecter. Heat is transferred from the heat rejecter to the fins, where forced air absorbs it and removes it from the system. In order to use the air fin option, your design must not allow for a gap > 1 mm between the air fins and the shroud. This will ensure that the air will go through the fins instead of the air gap. The minimum airflow required to maintain proper cooling is 100 cfm. Sunpower offers permanent and removable air fins.
Option Two
Water Jacket
The water jacket is placed over the heat rejection area and water is forced through the water jacket system. The standard connector is a ¼” Swagelok compression fitting. Both the air fin and the water jacket are available as removable or permanent options.