Investigation of dry ice blockage in an ultra-low temperature cascade refrigeration system using CO₂ as a working fluid

Dry-ice blockage in a CO₂-solid-gas-flow-based ultra-low temperature cascade refrigeration system is investigated experimentally by a visualization test and a system study of the liquid CO₂ blew into an expansion tube through a Throttle needle valve. The visualization test shows that dry ice sedimentation occurs in low flow velocity and the dry ice formation makes the heat transfer behavior of CO₂ complicated. The sedimentation also occurs at low condensation temperature and low heating power input. Based on the present investigation, it is found that the present ultra-low temperature cascade refrigeration system is better to work at heating power input above 900W and condensation temperature above -20oC. At suitable operating condition, the present ultra-low temperature cascade refrigeration system has been shown the capability of achieving ultra-low temperature -62oC continuously and stably. Copyright © 2010 Elsevier Ltd and IIR All rights reserved.