Ductwork improves efficiency of counterflow two pass active heat sink

Abstract

The heat removal ability of a spiral finned counterflow two pass active heat sink (“Wagner” active heat sink) is increased by eliminating a slight recirculation of heated discharge air back into the cool intake air by conducting intake air to the Wagner active heat sink with a ductworks having an orifice proximate the intake end of the heat sink. The diameter of the orifice is larger than that of the Wagner active heat sink, and if the heat sink does not extend into the orifice, then a pusher fan may be located somewhere near the entrance of the duct to fill it with pressurized air that then exits from the orifice to form a curtain of cool air around the outside of the Wagner active heat sink. This curtain of cool air replaces the certain amount of heated discharge air that otherwise recirculates back into the input of the heat sink. If the ductwork can be extended toward the Wagner active heat sink, or the heat sink moved toward the orifice, such that heat sink penetrates the orifice and is partly inside the ductwork by an amount related to the geometry of the fan within the Wagner active heat sink, then the pusher fan can be eliminated in favor of the suction provided by the Wagner active heat sink itself.

I claim:  
     
         1 . In an active heat sink having fins surrounding a fan that draws intake air into an end of the fan as well as through intake portions of the fins surrounding the fan, and which discharges air through adjacent discharge portions of the fins, a method of preventing discharged air from recirculating as intake air, the method comprising the steps of: 
 ducting air to be used as intake air to a nozzle proximate the end of the fan;    pressurizing the ducted air above the pressure of the discharged air; and    directing a curtain of pressurized air from the nozzle over both the intake and the discharge portions of the fins.    
     
     
         2 . In an active heat sink having fins surrounding a fan that draws intake air into an end of the fan as well as through intake portions of the fins surrounding the fan, and which discharges air through adjacent discharge portions of the fins, a method of preventing discharged air from recirculating as intake air, the method comprising the steps of: 
 ducting air to be used as intake air to a nozzle having an interior surface that surrounds the intake portions of the fins and that has a periphery proximate a boundary separating the intake portions of the fins from the discharge portions of the fins; and    inducing, with Bernoulli's principle and the reduced pressure of the discharged air, a curtain of air from the nozzle to flow over the discharge portions of the fins.