A spiral freezer for continuous duty in continuous food process lines has a freezer compartment enclosing a double-helix arrangement, of which there is a helical run of a food-carrying conveyor in combination with a helical ramp or slideway for the food-carrying conveyor's helical run to ascend or descend on. The helical ramp is an assembly of numerous heat exchanger tubes, each wound helically and positioned in set lanes in the overall assembly of the ramp. An external refrigerant-circulating system is connected to circulate refrigerant through the heat exchanger tubes in order that hot components like compressors and condensers be kept outside of the freezer compartment for better energy efficiency. The foregoing conveyor and heat exchanger arrangement provides close proximity between the source(s) of heat in the food product on the conveyor and the sink of that heat to the refrigerant flowing inside the heat exchanger tubes.