1. A thermal management device for dissipating heat from one or more electrical components in an aircraft, the thermal management device including:a heat spreader comprising a plurality of layers of annealed pyrolytic graphite, the heat spreader having higher thermal conductivity in a plane defined by the layers than in a direction perpendicular to the layers;
a flow path for a cooling fluid defined through the heat spreader, such that at least a portion of the flow path is surrounded by the heat spreader, wherein the flow path is helical, around a central axis extending through the plurality of layers; and
a housing encasing the heat spreader, the housing arranged to have the one or more electrical components mounted there-on and to form a thermal interface between the heat spreader and the one or more electrical components,
wherein a pipe extends straight through the housing, and wherein the thermal management device further comprises:
a static helical baffle arranged on the exterior of the pipe;
a void formed in the heat spreader around the pipe and baffle; and
slots formed in a section of the pipe within the housing, to provide fluid communication between the interior of the pipe and the void,
wherein the flow path is defined on the exterior of the pipe, by the baffles.