A current return network element for aircraft particularly with high conductivity. The device comprises a cylindrical body including crosspieces of appropriate shape and in appropriate arrangement inside it. The second fluid is electro-conductive or polar. Other features may include internal amplification that may be stand-alone or integrated into an audio signal source such as a radio or compact disc player or combinational device such as an automobile head unit. The controlling component sets a vehicle interior discharge air temperature at a position downstream of the heater to a target temperature. The closed position is useful for storing the food, heating the food, transporting the food between the point of service and the point of consumption, andor disposing of the remnants of the food once the meal is completed.