Showing papers on "Micro heat exchanger published in 1973"

Heat pipe interfaces

Abstract: An interface for interconnecting heat pipes is disclosed. The interface is itself a special purpose heat pipe adapted to efficiently transfer heat from the condenser of a first heat pipe to the evaporator of a second heat pipe. Using the present invention, simple heat pipes can be interconnected to form a complex heat pipe structure for particular applications.

Two fluid solar boiler

Abstract: A boiler for powering fluid pressure motors. The rays from the sun are focused by a lens through a transparent oil primary heat transfer medium and onto a heat absorber. The heat directly absorbed by the oil and by contact with the heat absorber is circulated by a thermo-siphon through a heat exchanger. The heat exchanger transfers heat and raises the temperature of a hydrocarbon fluid utilized as the secondary heat exchange medium. The expanded hydrocarbon powers a fluid pressure operated motor and is returned from the low pressure side of the motor to condensers after which it is compressed and returned to the heat exchanger in a closed cycle operation.

Calculation of single phase pressure drop in heat exchangers considering the change of fluid properties along the flow path

Abstract: The cost-optimized design of heat exchangers requires a fast but reliable calculation of pressure drop which makes a major contribution to running costs. For cocurrent and counter-current flow a simple approximating calculation method is presented, taking into account the variation of the fluid properties along the flow path. For any practical case reliable results are obtained only by calculating both the pressure drop and the local overall heat transfer coefficient at least at two points of the heat exchanger. In the special case of a gas in a turbulent flow and when, as usual, the major resistance to heat transfer is caused by the gas, it is sufficient to calculate only the pressure drop and at one point only. Pressure drops calculated exactly or by the proposed approximation compare well.

Power generation from hot brines

Abstract: Hot fluid which may contain salts and other dissolved minerals is passed through a direct contact heat exchanger in heat exchange relationship with a heating fluid that has a specific gravity sufficiently below the specific gravity of the hot fluid that it may pass from the bottom to the top of the heat exchanger chamber in contact with the hot fluid. The pressure of the chamber is maintained above the vapor pressure of the hot fluid at the entering temperature of the fluid. The heat transfer fluid is selected so that the salts and other minerals in the fluid are insoluble in the heated heat transfer fluid. The heated heat transfer fluid is passed in heat exchange relationship with a working fluid that is vaporized in the heat exchangers and is subsequently passed through a power extracting gas expansion device. Alternatively, an oily substance is added to the hot fluid which may contain salts and other dissolved minerals, and the composition is passed through one or more surface contact heat exchangers for heating a a working fluid. The oily substance coats the surface of the exchangers to prevent any mineral deposition.

Hot gas machine

Abstract: A hot gas machine is presented, suitable for use either as an engine, heat pump or a refrigerator, wherein a single stream of external fluid is in heat exchange with a working fluid in two counterflow heat exchangers to heat and cool the working fluid.

Method of making a heat exchanger

Abstract: A heat exchanger is formed by compacting metallic particles, especially of materials of high thermal conductivity to form the heat exchange surfaces, preferably against a substrate such as thermally conductive tube. The compaction involves electrical sintering, with the particle-particle interfaces and the particle-substrate interfaces metallurgically homogenized to form a monolithic structure free from corrosion sites.

Cooling apparatus and method for heat exchangers

Abstract: To improve the coefficient of heat transfer between the surfaces and the heat exchange media of heat exchangers, such as automobile radiators, steam condensers, and steam boilers. Conductive probes or conductors are energized with a low power, low current high DC potential and spaced from the surfaces a distance slightly greater than the distance at which arcing occurs while the surfaces are grounded to generate an electrostatic field.

Heat exchangers for stirling cycle engines

Abstract: A structural arrangement for a heat exchanger provides for movements without significant stresses of a heat exchanger in a Stirling Cycle Engine during changes of operating temperature. Two coaxial shell sections are arranged with a plurality of parallel heat exchange pipes axially mounted therebetween and affixed to the two sections. A flexible sealing element is sandwiched between the two shell sections to allow movement of the shell sections perpendicular to the axes of the heat exchange, pipes. A spacer separating the heat exchange pipes in the middle allow the pipes to bow as unit with evenly distributed deformation during temperature changes. Fluid conveyance pipes are connected to each shell section at the opposite ends of the heat exchange pipes.

Development of a high capacity variable conductance heat pipe.

Abstract: The high-capacity, pressure-primed, tunnel-artery wick concept was used in a gas-controlled variable conductance heat pipe. A variety of techniques were employed to control the size of gas/vapor bubbles trapped within the artery. Successful operation was attained with a nominal 6-foot long, 1-inch diameter cold reservoir VCHP using ammonia working fluid and nitrogen control gas. The pipe contained a heat exchanger to subcool the liquid in the artery. Maximum transport capacity with a 46-inch effective length was 1200 watts level (more than 50,000 watt-inches) and 800 watts at 0.5-inch adverse tilt.

Heat pipes. I. Operation and characteristics

Abstract: Heat-transport problems in nuclear reactors and in space applications have in recent years stimulated intensive research in many, countries on a heat- transport method whose principle has long been known, the method of transporting heat in its latent form, i.e., the latent heat of vaporization. Heat conductors based on this principle, called heat pipes,'' can have a thermal resistance more than 10,000 times smaller than that of a copper rod of the same dimensions. Heat pipes are of considerable interest for heat transport for Stirling engines and the development of isothermal ovens. The design and operating characteristics of heat pipes are discussed. (auth)

Investigation of the effects of organic additives on the hydraulic resistance and heat transfer in a flow

Abstract: Results are given of a study of the effects of organic additives on the hydraulic resistance and heat transfer in turbulent flow.

Fix a fin tool

Abstract: A tool for straightening bent and deformed fins of heat exchangers of a type illustrated by heat exchangers used as condensers and evaporators in air conditioners.

Study of heat exchange in closed air interlayers at reduced pressure

Abstract: The heat transfer coefficient is measured in air interlayers at reduced pressure. The results are compared with criterial relationships.

Design and test of a self-controlled heat pipe radiator.

Abstract: A 15,000-W spacecraft waste heat rejection system utilizing heat pipe radiator panels has been investigated. Of the several concepts initially identified, a series system was selected for more in-depth analysis. As a demonstration of system feasibility, a nominal 500-W radiator panel has been designed, built, and bench tested. The panel, which is a module of the 15,000-W system, consists of a variable conductance heat pipe (VCHP) header, and six isothermalizer heat pipes attached to a radiator. The thermal load to the VCHP is supplied by a Freon 21 liquid loop via an integral heat exchanger. This paper describes the results of the system studies and the radiator design. Also presented are test data on the VCHP, heat exchanger and isothermalizer heat pipes.

Flow and heat transport in slotted channels with obstacles

Abstract: We study the flow conditions in narrow channels with obstacles of various shapes at small and moderate Reynolds numbers. The observed flow conditions are compared with experimental data on heat transfer in a channel with obstacles.

Heat transfer during boiling of liquid nitrogen at coiled heat exchangers

Abstract: An experimental study was made of the heat transfer during the boiling of liquid nitrogen at various types of immersed heat exchangers. The values of the heat-transfer rate are given for various temperature differences and heat load levels.

Steady-state heat transfer between fluids separated by a thin partition

Abstract: The solution is obtained of the conjugate problem of steady-state convective heat exchange between two viscous fluids separated by a thin-walled wedge. The solution is employed in the design of heat exchangers of the “star” type.

Generalization of test data pertaining to the mean heat transfer coefficient for tube bundles in a turbulent longitudinal stream of air and superheated steam

Abstract: A method has been developed for the generalization of test data on heat transfer which takes into account the effects of the temperature factor and of the bundle geometry From a compilation and an analysis of the test data have come out new and reliable recommendations for the thermal design of heat exchangers