A cooling system for a heat-generating device includes: coolant fluid; an evaporator for holding the coolant fluid and for heating the coolant fluid; said evaporator in close proximity to the heat-generating device for removing unwanted heat. The cooling system also includes a plurality of tubes for providing a flow path for the coolant fluid and gases produced by the evaporator; a heat exchanger through which the tubes pass for cooling the coolant fluid. The heat exchanger includes: a reservoir, a coolant, and a heating element for heating the gas so that it expands and pushes cool coolant fluid back to the evaporator. The heating element may be located inside the reservoir.