Breathing gas temperature modification device

A device for modifying the temperature of breathing gas supplied through an inhalation conduit to a user's facemask, comprising:

• a heat exchanger mounted in-line with the inhalation conduit, wherein the breathing gas is caused to pass through said heat exchanger prior to being passed to the user's facemask;
• a thermoelectric device having first and second thermally conductive plates separated by at least one thermoelectric couple, said first thermally conductive plate in thermal contact with said heat exchanger;
• a voltage source connected to said at least one thermoelectric couple for applying a voltage to said at least one thermoelectric couple so that said first and second thermally conductive plates are maintained at different temperatures;
• a phase change material, in thermal contact with said second thermally conductive plate, for changing from a first phase to a second phase at a phase change temperature between said different temperatures as heat is transferred between said heat exchanger and said phase change material via said thermoelectric device;
• a thermally insulating shell encasing said heat exchanger, said thermoelectric device and said phase change material;
• a second heat exchanger thermally coupled to said phase chance material for transferring heat between the ambient environment and said phase chance material to aid in the restoration of said phase change material in said second phase to said first phase;
• and
• means for thermally isolating said second heat exchanger from the ambient environment until the temperature of the ambient environment is suitable to begin restoring said phase change material in said second phase to said first phase.