1. Technical Field
The present invention relates generally to the field of heat transfer. More particularly, the present invention relates to a method for producing a heat transfer medium that is disposed within a conduit to rapidly and efficiently transfer heat.
2. Background Art
Efficiently transporting heat from one location to another always has been a problem. Some applications, such as keeping a semiconductor chip cool, require rapid transfer and removal of heat, while other applications, such as disbursing heat from a furnace, require rapid transfer and retention of heat. Whether removing or retaining heat, the heat transfer conductivity of the material utilized limits the efficiency of the heat transfer. Further, when heat retention is desired, heat losses to the environment further reduce the efficiency of the heat transfer.
For example, it is well known to utilize a heat pipe for heat transfer. The heat pipe operates on the principle of transferring heat through mass transfer of a fluid carrier contained therein and phase change of the carrier from the liquid state to the vapor state within a closed circuit pipe. Heat is absorbed at one end of the pipe by vaporization of the carrier and released at the other end by condensation of the carrier vapor. Although the heat pipe improves thermal transfer efficiency as compared to solid metal rods, the heat pipe requires the circulatory flow of the liquid/vapor carrier and is limited by the association temperatures of vaporization and condensation of the carrier. As a result, the heat pipe's axial heat conductive speed is further limited by the amount of latent heat of liquid vaporization and on the speed of circular transformation between liquid and vapor states. Further, the heat pipe is conventional in nature and suffers from thermal losses, thereby reducing the thermal efficiency.
An improvement over the heat pipe, which is particularly useful with nuclear reactors, is described by Kurzweg in U.S. Pat. No. 4,590,993 for a Heat Transfer Device For The Transport Of Large Conduction Flux Without Net Mass Transfer. This device has a pair of fluid reservoirs for positioning at respective locations of differing temperatures between which it is desired to transfer heat. A plurality of ducts having walls of a material that conducts heat connects the fluid reservoirs. Heat transfer fluid, preferably a liquid metal such as mercury, liquid lithium or liquid sodium, fills the reservoirs and ducts. A piston or a diaphragm within one of the reservoirs creates oscillatory axial movement of the liquid metal so that the extent of fluid movement is less than the duct length. This movement functions to alternately displace fluid within the one reservoir such that the liquid metal is caused to move axially in one direction through the ducts, and then to in effect draw heat transfer fluid back into the one reservoir such that heat transfer fluid moves in the opposite direction within the ducts. Thus, within the ducts, fluid oscillates in alternate axial directions at a predetermined frequency and with a predetermined tidal displacement or amplitude. With this arrangement, large quantities of heat are transported axially along the ducts from the hotter reservoir and transferred into the walls of the ducts, provided the fluid is oscillated at sufficiently high frequency and with a sufficiently large tidal displacement. As the fluid oscillates in the return cycle to the hotter reservoir, cooler fluid from the opposite reservoir is pulled into the ducts and the heat is then transferred from the walls into the cooler fluid. Upon the subsequent oscillations, heat is transferred to the opposite reservoir from the hotter reservoir. However, as with the heat pipe, this device is limited in efficiency by the heat transfer conductivity of the materials comprising the reservoirs and ducts and by heat losses to the atmosphere.
It is known to utilize radiators and heat sinks to remove excess heat generated in mechanical or electrical operations. Typically, a heat transferring fluid being circulated through a heat-generating source absorbs some of the heat produced by the source. The fluid then is passed through tubes having heat exchange fins to absorb and radiate some of the heat carried by the fluid. Once cooled, the fluid is returned back to the heat-generating source. Commonly, a fan is positioned to blow air over the fins so that energy from the heat sink radiates into the large volume of air passing over the fins. With this type of device, the efficiency of the heat transfer is again limited by the heat transfer conductivity of the materials comprising the radiator or the heat sink.
Dickinson in U.S. Pat. No. 5,542,471 describes a Heat Transfer Element Having The Thermally Conductive Fibers that eliminates the need for heat transferring fluids. This device has longitudinally thermally conductive fibers extended between two substances that heat is to be transferred between in order to maximize heat transfer. The fibers are comprised of graphite fibers in an epoxy resin matrix, graphite fibers cured from an organic matrix composite having graphite fibers in an organic resin matrix, graphite fibers in an aluminum matrix, graphite fibers in a copper matrix, or a ceramic matrix composite.
In my People's Republic of China Patent Number 89108521.1, I disclosed an Inorganic Medium Thermal Conductive Device. This heat-conducting device greatly improved the heat conductive abilities of materials over their conventional state. Experimentation has shown this device capable of transferring heat along a sealed metal shell having a partial vacuum therein at a rate of 5 meters per second. On the internal wall of the shell is a coating applied in three steps having a total optimum thickness of 0.012 to 0.013 millimeters. Of the total weight of the coating, strontium comprises 1.25%, beryllium comprises 1.38% and sodium comprises 1.95%. This heat conducting device does not contain a heat generating powder and does not transfer heat nor prevent heat losses to the atmosphere in a superconductive manner as the present invention.