Abstract: An improved refrigeration system is provided for use in a rail car or the like to refrigerate perishable items such as produce. The refrigeration system includes a plurality of modular ceiling panels mounted near the roof of a rail car or the like to define an upper ceiling compartment disposed over a main storage compartment. The ceiling compartment includes a central bunker for receiving a cryogenic material, such as carbon dioxide snow, wherein the bunker is separated by short partition walls from a pair of elongated plenum chambers extending along both sides of the bunker. Cryogenic gas formed by sublimation spills over the partition walls for passage from the bunker into the plenum chambers, and for further passage from the plenum chambers through downflow ports in the panels into the underlying main storage compartment to refrigerate perishable items therein.