Applications of Heat Pipe

Heat pipe has many practical applications. Some of the possible applications are listed as 

The removal of heat from laser diodes or other small localized heat generating devices. 

Removal or dissipation of heat from the leading edge of a hypersonic aircraft. 

Heat pipes are embedded in silicon radiator panel of the spacecraft to dissipate large amount of generated heat. 

Heat pipes are used for nonsurgical treatment of cancerous tissue. There is no bleeding and little pain during the operation. The probe is inserted into the tumor, and the surgery takes place by freezing. 

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Heat/Solvent Recovery. The primary application of heat pipes in the chemical industry is for combustion air preheat on various types of process furnaces which simultaneously increases furnace efficiency and throughput and conserves fuel. Advantages include modular design, isothermal tube temperature eliminating cold comer corrosion, high thermal effectiveness, high reliability and options for removable tubes, alternative materials and arrangements, and replacement or add-on sections for increased performance (see Furnaces, fuel-fired). 

E. D. Waters and co-workers, "The Application of Heat Pipes for the Trans-Alaska Pipeline," Proceedings of the 10th Intersociety Energy Conversion Engineering Conference, Newark, Del, 1975. 

The application of heat pipes in gas accumulator enables one to control the... 

Fig. 12-20 Application of heat-pipe principle to cooling of power transistor, according to Ref. 15,...

Basiulis, A., and T. A. Hummel The Application of Heat Pipe Techniques to Electronic Component Cooling, ASME Pap. 72-WA/HT-42. 

Figure 9 Application of heat pipe technology for automotive electronics [11]...

Zhang, H. and Zhuang, J. (2003). Research, development and industrial application of heat pipe technology in China. Applied Thermal Engineering, Vol. 23, Issue 9, pp. 1067-1083. 

H. Cheung, Critical Keview of Heat Pipe Theory and Applications, DCKT-50453, Lawrence Radiation Laboratory, University of California, Livermore, Calif., 1968. 

In many of the applications of heat transfer in process plants, one or more of the mechanisms of heat transfer may be involved. In the majority of heat exchangers heat passes through a series of different intervening layers before reaching the second fluid (Figure 9.1). These layers may be of different thicknesses and of different thermal conductivities. The problem of transferring heat to crude oil in the primary furnace before it enters the first distillation column may be considered as an example. The heat from the flames passes by radiation and convection to the pipes in the furnace, by conduction through the... 

Grigull (G8), 1942 Treatment of heat transfer in condensate film on vertical surface, assuming applicability of Prandtl pipe-flow relationships. Comparison with experimental data,... 

For some applications flat heat pipe panels (HPP) have advantages over conventional cylindrical heat pipes, such as geometry adaptation, ability for localized heat dissipation and the maintenance of an entirely flat isothermal surface (Fig. 14). The liquid-vapour interface formed in capillary channels inside the heat pipe panel is capable to generate self-sustained thermally driven oscillations. Thin layer (several mm) of the sorbent between mini-fins on the outer side of the heat pipe panel ensures an advanced heat and mass transfer during the cycle adsorption/de sorption. 

A variety of fluid and pipe materials have been used for heat-pipe construction, and some typical operating characteristics are summarized in Table 12-2. Very high heat fluxes are obtained for this reason research efforts are being devoted to optimum wick designs, novel configurations for specilized applications, etc. Two early theoretical analyses of heat pipes are presented by Cotter, et al. [16,17], The device is in such a state of development that the current research literature should be consulted for latest information. For our purposes we are concerned primarily with applications for the device. 

The concept of heat pipe was originally conceived by R. S.-Gaugler of the General Motors Corporation, who filed a patent application for it in... 

Wigley, T.M.L. Brown, M.C. (1971) Geophysical applications of heat and mass transfer in trubulent pipe flow. Boundary Layer Meteorology 1, 300-320. 

Direct application of heat via in situ combustion or via superheated steam generation at the surface and injection are other effective methods to boost production, either in mature oil fields or in heavy oil fields where the petroleum is naturally quite viscous. While both formation heating methods achieve production rate improvements by viscosity reduction, the apparent simplicity of the in situ combustion concept is offset by the difficult separation of recovered oil from an aqueous solution containing nitrogen oxides, sulfur oxides, and other polar combustion products. The acids present in the aqueous phase contribute to the stability of the emulsions obtained from the producing wells and are highly corrosive to steel pipes and tanks. 

Although worldwide production of heat pipes designed for applications involving the thermal control of electronic components or devices was in excess of 1,000,000 per year in 1992, it is difficult to calculate a mean time to failure (MTTF) for heat pipes, thermosyphons, and other similar devices due to the relatively small amount of data that exists on actual products in operation. Experience with a wide variety of applications ranging from consumer electronics to industrial equipment has demonstrated that mechanical cleaning of the case and wick-... 

Other high-temperature applications of alkali metals are in the field of heat or energy transfer. Heat pipe make use of the latent heat of evaporation and condensation of the alkali metals. The advantage of these devices to transfer energy is the low temperature gradient between the heat source and the sink. The application of different alkali metals allows the use of heat pipe in the temperature range of 400 to nearly 1500 °C... 

Cyhndrical articles such as pipe and drums can by made by centrifugal casting. In this process the cylindrical metal mold is charged with granular polymer and rotated. The granules cover the walls of the mold and are fused in place by the application of heat from the outside. 

The notebook computer is the most popular heat pipe application for CPU cooling. Many millions of heat pipes are made per month for this use, and they are now also used in memory chips. Some desktops have five or more heat pipes in their cabinet. The units in Figure 11.20 are of triangular cross-section and are used in a Korean sub-notebook . 

LANL have an extensive history in developing heat pipes and their many applications within and out with chemical engineering applications. Current work is further developing the use of heat pipes in outer space although current applications are extremely vast from cooling CPUs to nuclear power cells. 

Nuclear heat from the reactor core is removed passively by a lead-bismuth eutectic alloy coolant [XXIX-4], which flows due to natural circulation between the bottom and top plenums, upward through the fuel tubes and returning through the downcomer tubes. On top of the upper plenum, the reactor has multi-layer heat utilization vessels to provide an interface to systems for high temperature heat applications. A set of sodium heat pipes is in the upper plenum of the reactor to passively transfer heat from the upper plenum to the heat utilization vessels with a minimum drop of temperature. Another set of heat pipes transfers heat from the upper plenum to the atmospheric air in the case of a postulated accident. To shut down the reactor, a set of seven shut-off rods has been provided, which fall by gravity in the central seven coolant channels. Appropriate instmmentation like neutron detectors, fission/ ion chambers, various sensors and auxiliary systems such as a cover gas system, purification systems, active interventions etc. are being incorporated in the design as necessary. 

Plastics are divided into two basic groups, thermosetting and thermoplastic, both of which are used in the manufacture of plastic pipe. Thermoplastics, as the name implies, soften upon the application of heat and reharden upon cooling they can be formed and reformed repeatedly. This characteristic permits them to be easily extruded or molded into a wide variety of useful shapes, including pipe and fittings. Because thermoplastics are shaped, by a die or mold, while in a molten state their properties are essentially isotropic (i.e., independent of direction). In some processes and under some conditions, some anisotropy (i.e., direction dependence) may result. 

The ambient temperature conditions dictate the rate of cure for the resins used in the system. The air is to be dehumidified to avoid moisture present on the substrate during installation. The ambient air temperature during the time of application cannot be below 40 °F or above 100 °F. The CFRP system is to have a minimum of 85% cure before the pipe is returned to service. Durability of CFRP is affected by the degree of cure of the CFRP. CFRP curing time varies between products, and is shortened significantly by application of heated air. 

R. A. Ereggens, Experimental Determination of Wick Propertiesfor Heat Pipe Applications, ST-4086, RCA Electronics Components, Lancaster, Pa., 1969. 

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