Showing papers on "Micro heat exchanger published in 1979"

Heat exchange method using natural flow of heat exchange medium

Abstract: Heat exchange is effected in a simple and economical manner by allowing natural flow, i.e., without mechanical compressors, pumps, etc., of a heat exchange fluid such as a conventional refrigerant liquid between two heat exchangers which are exposed to air at different temperatures. The two heat exchangers, which may conveniently take the form of fin-tube heat exchangers, for example, are arranged with one end at a higher elevation than the other, the upper ends of the two exchangers being connected in direct communication and the lower ends being likewise connected. As the refrigerant liquid absorbs heat and evaporates in the heat exchanger exposed to the warmer air the vapor travels through the upper connecting line to the other heat exchanger, where it rejects heat and is condensed, the liquid flows through the lower connecting line back to the first heat exchanger, and so on, with heat exchange between the two air streams or masses occurring during the natural, continuous flow of the refrigerant in gaseous and liquid form.

Temperature Distribution and Heat Exchange in Multipass Shell-and-Tube Exchangers with Baffles

Abstract: A model predicting the temperature distribution and the mean temperature difference in multipass shell-and-tube heat exchangers with baffles is presented. The exchanger is treated as a cascade of cells with mixing taking place in each fluid. From the computed results, design rules are deduced to enable the choice of the construction that leads to the highest efficiency. The effect of leakage currents on exchanger effectiveness is ignored in this analysis and is treated separately in another paper.

Heat transfer to horizontal tubes in fluidized beds : experiment and theory

Abstract: approved:_ jRedacted for privacy T'homeij. l'itdOrald Heat transfer to horizontal tubes is of particular significance for fluid-bed combustion of coal and other materials. Very little information exists for beds operating with particles larger than 0.4 mm. A detailed study was undertaken with the goal of filling this gap and producing data and correlations of value for design. An instrumented cylinder was developed making possible simultaneous measurements of instantaneous, as well as time -averaged, local hea.t transfer coefficient s, voidage, and surface pressure variations at several positions around its circumference. The instrument enabled the collection of a large body of data which give detailed information about fluid dynamic and heat transfer behavior in the vicinity of the instrumented tube and suggest answers to some crucial heat transfer problems. Experimental work was performed at room temperature and atmospheric pressure, in a bed of a 0.48 m x 0.13 m cross section, with air as he fluidizing gas. Runs were made with a single immersed tube, as well as with a closely spaced tube array. Heat transfer and voidage results, covering a wide range of particle sizes (0.3f -6.6 mm) and superficial gas velocities (0. 1 -5. 6 m/s), are reported and discussed from a design standpoint. Among several findings, two are most notable: a) voidage at the surface of the rube varies much less with gas velocity than the overall bed voidage, and b) the gas convective component of heat transfer is not affected by the superficial velocity. Data for conditions near minimum fluidization are compared with the recently developed Adams analytical model of heat transfer for large particles. The model gives accurate predictions of local instantaneous and time-averaged coefficients, with and without the presence of bubbles. All of its aspects, except the radiative heat exchange, are fully verified. A theoretical model, applicable over a wide range of fluidizing conditions in bubbling and slugging beds, is proposed. The theory assumes that heat exchange between a cold fluidized bed and a horizontal tube takes place by three parallel paths --heat is transferred by packets of particles, by gas percolating between the particles and the tube surface, and by gas bubbles or slugs. Correlations are presented for the corresponding particle convective, gas convective, and bubble heat transfer coefficients, as well as for the voidage around the tube. An analysis snows that, from a heat transfer standpoint, particles may be classified as fine (d < 0.4 mm), intermediate (0.4 mm < d < 1 mm), and large (dp > 1 mm). For each these cases, equations for the timeaveraged beat transfer coefficient to the tube as a whole are given. Predictions based on the proposed theory are compared with the experimental results of this study, as well as with literature data for intermediate and large particles. The model is shown to be vent; reliable for a variety of operating conditions. it is therefore introduced as a general model for the conductive aril convective modes of heat transfer. Heat Transfer to Horizontal Tubes in Fluidized Beds! Experiment and Theory by Niko la Milivoj Catipovic A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed March 1.979 Commencement June 1 7 9

Solar energy collector and system

Abstract: A solar collector whose absorber plate is made of a conventional building material, e.g., tile, stucco, concrete or the like, and forms the outer surface, e.g., wall or roof, of the building. The fluid to be heated, typically air, flows behind the absorber rather than between an absorbing plate and a cover of glass or other transparent material, and heat is transferred to the fluid by metal conductors which extend from adjacent the outside surface of the absorber to, and define at least part of the flow passage. The system includes a cold tank of liquid in which heat is stored at a relatively low temperature, a heat tank of liquid at a relatively higher temperature; and a heat pump for transferring heat from the cold tank to the heat tank. There is a cold exchanger in the cold tank for receiving heated fluid from the collector and transferring heat therefrom to the liquid in the cold tank, and a heat exchanger in the heat tank for the transferring heat from the liquid in the heat tank to the air used to heat the building interior.

Cylindrical heat exchanger using heat pipes

Abstract: This invention relates to an improvement in a heat exchanger of the type using heat pipes which permits reduction in size of the heat exchanger and enhancement in heat exchange efficiency and more particularly to a cylindrical heat exchanger principally comprising a cylindrical or polygonal tubular casing provided with openings in the middle parts of its upper and lower sides and in its circumferential side, a transverse partition plate which divides the inside of the casing into upper and lower parts and a group of vertical heat pipes arranged to pierce through the peripheral portion of the partition plate in an annular plan configuration as a whole.

The RODbaffle Heat Exchanger

Abstract: The RODbaffle exchanger offers a solution to the vexing problem of tube failures in shell-and-tube exchangers resulting from tube vibration. Additional benefits are good heat transfer rates, low pressure drop, and lower fouling rates. The ratio of heat transfer rate to pressure drop can be more than double that of the conventional plate-type baffle in a comparable application.

Means and method for sealing heat exchanger walls

Abstract: A new type of sealing partition around heat exchanger tubes in heat exchanger walls is disclosed. A support structure is used to position and hold the tubes in place. Overlapping inserts are then inserted over the tubes adjacent the support structure and welded together to seal the heat exchanger chambers. When a heat exchanger is assembled using the invention the heat exchanger is easily and inexpensively assembled and the sealing partition in conjunction with the support structure provides structural support for the tubes and seals the chambers while allowing heat expansion and contraction of the chambers due to the varying temperatures in the heat exchanger.

Apparatus for the recovery of useful heat from refrigeration gases

Abstract: An improvement is provided in a heat extraction device provided in association with a heat exchanger system including a condenser, an evaporator, means for circulating a compressed liquid heat exchange fluid between the condenser and the evaporator and a heat exchanger disposed in the system to heat external water. The improvement resides in the use of conical heat exchanger coils in order to maximize heat exchange, and the provision of control means for sensing pressure, temperature and state of the heat exchange fluid and which regulates the entire operation safely and economically.

Open cycle heat pump system and process for transferring heat

Abstract: Two or more open cycle vapor compression heat pumps of interdependently different capacities are placed in parallel arrangement intermediate a heat sink and a heat source for the transfer of sensible heat therebetween.

Heat reclaimer for a heat pump

Abstract: This invention relates to a heat reclaiming device for a heat pump. The heat reclaimer is able to absorb heat from the compressor by circulating cooling fluid through a circuit which is mounted in good heat transfer relationship with the condenser, then around the shell of the motor-compressor and lastly around the hollow tube which connects the condenser to the compressor. The reclaiming circuit is connected into a fluid circulating loop which is used to supply heat to the evaporator coil of the heat pump.

Heat exchangers with tube bundles

Abstract: Heat exchanger for heat-transfer between substances of high pressure difference including a shell, a region through which a cooler substance is conveyed; an inlet for the cooler substance; a bundle of tubes arranged in a cooler substance compartment; and riser conduits operatively connectible to the shell and communicating with the compartment, with the substance to be cooled being passed through the tubes having a high temperature at the inlet of the heat exchanger and at the outlet; a tube bottom of predetermined thickness arranged at the heat exchanger inlet; and a device including a support-grating arranged in the vicinity of the tube bottom, operatively connectible to the shell and extending at least nearly perpendicular to the tube bottom in the region through which the cooler substance is conveyed. The heat exchanger also includes a top provided with apertures and the like which are easily accessible from the steam-water space of the heat exchanger with cooling channels being provided which are adapted to be in communication with the apertures and riser conduits provided outside the heat exchanger proper.

Industrial heat pipe energy recovery package unit

Abstract: OF THE DISCLOSURE This invention relates in general to an industrial heat ex-changer package unit for transferring heat energy between cool intake air flowing into an industrial process, and hot exhaust air flowing out of an industrial process. Each package units specif-ically includes, integral finned heat pipe heat exchangers, face and bypass damper assemblies, tilted base frames, bypass ducts, supply inlet filter assemblies, and supply inlet louver assemblies which are arranged in such a manner as to provide a percentage of total volume control over the amount of supply or exhaust air introduced into the heat exchange chambers.

Heat transfer in linearl flows of non-newtonian fluids

Abstract: The average rate of heat transferred to the channel wall when a hot incompressible third-order fluid, in rectilinear motion, flows (i) between two infinite parallel plates and (ii) in a circular tube is studied. A heat transfer coefficient has been evaluated for several values of a non-Newtonian parameter which is a measure of non-linear effects in the fluid. Enhancement of the heat transfer coefficient is found for those fluids which exhibit large strain rate gradients in the region of the channel wall.

Enclosure for electronic equipment generating heat losses - contains cooling ducts acting as heat exchanger and filled with evaporable medium

Abstract: The application is to electronic equipment employing power circuits which produce heat losses and therefore require cooling. The housing (1) comprises a lid with a vertical section (3) and a horizontal section (2). Embedded in these sections are continuous, closed heat pipes (4) forming a spaced out cooling system. The main heat generating elements (6), for example power transistors, are mounted on a strip (5) at the base of the vertical section (3). The heat pipes are filled with a liquid which vaporises by the heat from the circuit elements (6) and condenses again in the horizontal part of the cover. In this way the thermal losses are dissipated in a system acting as a heat exchanger. The space requirements are less than for a direct air cooled system employing convection.

Post weld heat treatment of shell and tube heat exchangers and apparatus

Abstract: An apparatus and method is provided for heat treating a tubular type heat exchanger. A heat fluid is passed through the tube bundle in order to heat the exchanger from within.