A refrigerated transport system (20) comprises a body (22) enclosing a refrigerated compartment (69). A refrigeration system (30) comprises: a vapor compression loop (31) having a first heat exchanger (38) positioned to reject heat to an external environment in a cooling mode. A heat transfer loop (32) has a second heat exchanger (58) positioned to absorb heat from the refrigerated compartment in the cooling mode. An inter-loop heat exchanger (44) has a first leg (42) along the vapor compression loop and a second leg (43) along the heat transfer loop in heat exchange relation with the first leg.