Heat pipe cooling

Matty engineering applications such as heat pipes, cooling ponds, and the familiar perspiration involve condensation, evaporation, and transpiration in the presence of a noncondensable gas, and thus the dijfnsioi of a vapor through a stationary (or stagnant) gas. To understand and analyze such processes, consider a liquid layer of species A in a tank surrounded by a gas of species B, such as a layer of liquid water in a tank open to the atmospheric air (Fig. 14-34), at constant pressure P and temperature T. Equilibrium exists between the liquid and vapor phases at the interface (.v - 0), and thus the vapor pressure at the interface must equal the saturation pressure of species A at the specified temperature. We assume the gas to be insoluble in the liquid, and both the gas and the vapor to behave as ideal gases. 

The considered experimented set - up can be applied in two different ways. The first one is to use is as a semiconductor sensor cooler with low heat dissipation to cool the sensor down to the ambient temperature. It is interesting to be applied in cryogenic range of temperatures. The second option is related with the cooler for high energy dissipation devices (for example laser diode cooler). The first set of experiments was performed with sorption heat pipe and ammonia as a working fluid to demonstrate the basic possibility to decrease the temperature of the heat loaded wall to compare with the temperature of this wall in the phase of loop heat pipe cooling mode. 

The effective thermal conductivity provided by a heat pipe is the key factor for designing a highly efficient heat pipe cooling device. For the conventional heat pipe, the thermal resistance in the heat pipe is mainly from the wick stmcture. Because conventional wicks do not exist in a micro heat pipe, the prediction of thermal resistance occurring in the micro heat pipe is different from the conventional heat pipe. 

Heat pipe cooled reactor - Brayton energy conversion system... 

ROTATING HEAT PIPE COOLING TECHNIQUE WITH SELF-EVAPORATING CIRCULATING LIQUID FOR ROTOR IN CONTINUOUS MIXER... 

While the NRPCT evaluated reactor plant concepts for gas cooled reactors, liquid metal cooled reactors, and heat pipe cooled reactors for the reactor concept selection in eariy 2005 (Reference 3-1), Jet Propulsion Laboratory (JPL) and Northrop Grumman Space Technology (NGST) developed a preliminary spaceship arrangement, called the Prometheus Baseline 1 (PB1). The PB1 reactor plant concept was a liquid metal reactor with four parallel Brayton energy conversion loops. Redundant Brayton loops were assumed for several reasons ... 

Heat pipes are used to perform several important heat-transfer roles ia the chemical and closely aUied iadustries. Examples iaclude heat recovery, the isothermaliziag of processes, and spot cooling ia the mol ding of plastics. In its simplest form the heat pipe possesses the property of extremely high thermal conductance, often several hundred times that of metals. As a result, the heat pipe can produce nearly isothermal conditions making an almost ideal heat-transfer element. In another form the heat pipe can provide positive, rapid, and precise control of temperature under conditions that vary with respect to time. 

Mold Coolers for Plastic Injection Molding. Heat pipes are used for local temperature control in the injection molding of plastics (see Polymerprocessing). A heat pipe is often used to force local cooling within a mold to speed operation, control viscosity, retention of material in a difficult mold area, or to reduce thermal stresses on cooling. 

The need to ensure that the stresses ia piping systems meet the appropriate code requirements and the concern that cycHc stresses resulting from events such as periodic heating and cooling of the piping may lead to fatigue failures, make accurate evaluation of the stresses and strains ia piping systems a necessity. 

Fig. 8. (a) Heat pipe showing the use of finned tubing for both heating and cooling and (b), heat pipe exchanger ain heater system. ID = induced draft and... 

Bayonet Heaters A bayonet-tube element consists of an outer and an inner tube. These elements are inserted into tanks and process vessels for heating and cooling purposes. Often the outer tube is of expensive alloy or nonmetalhc (e.g., glass, impeivdous graphite), while the inner tube is of carbon steel. In glass construction, elements with 50.8- or 76.2-mm (2- or 3-in) glass pipe [with lengths to 2.7 m (9 ft)] are in contact with the external fluid, with an inner tube of metal. 

External Coils and Tracers Tanks, vessels, and pipe hnes can be equipped for heating or cooling purposes with external coils. These are generally 9.8 to 19 mm (% to V4 in) so as to provide good distribution over the surface and are often of soft copper or aluminum, which can be bent by hand to the contour of the tank or hne. When necessary to avoid hot spots, the tracer is so mounted that it does not touch the tank. 

Wastage is pronounced in equipment contacting high-pH fluids. Chemical process equipment, heat exchangers, water-cooled process reactors, valving, transfer pipes, and heating and cooling systems are often affected. 

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