Showing papers on "Concentric tube heat exchanger published in 1974"

Spiral concentric-tube heat exchanger

Abstract: A composite tube composed of an inner tube extending through and spaced from an outer tube by radial partition walls is coiled helically. The helical composite tube coil is housed in a tank having an interior silvered reflective surface and evacuated to minimize heat loss through the tank wall. A carburetor supplies a combustible gas mixture to one end of the inner tube, the gas mixture burns in such tube, and a centrifugal blower draws the combustion gas through the tube. A vaporizable liquid is supplied under pressure to the end of the outer tube adjacent to the centrifugal blower for passage of the vaporizable liquid through the outer tube in the direction opposite the flow of combustion gas through the inner tube for vaporization of the combustible liquid under pressure, such as for producing superheated steam from water.

Control of temperature profile across a heat exchanger

Abstract: The temperature profile established across a heat exchanger, such as employed on an extrusion die, for example, is controlled by introducing fluid into the heat exchanger at a predetermined temperature. The temperature of the fluid withdrawn from the heat exchanger is measured, and the rate of flow of fluid through the heat exchanger is controlled in response to the measured temperature to maintain the measured temperature at a predetermined value.

Rotary heat exchangers in the form of turbines

Abstract: One of two axially spaced annular heat exchangers, interconnected in a closed circuit traversed by a fluidic heat carrier, serves to preheat a flow of ambient air downstream of a compressor which impels that flow toward a combustion chamber where an air-fuel mixture is ignited to drive a turbine coupled with the compressor. The other heat exchanger, which extends radially beyond the first-mentioned heat exchanger to create a thermosiphon effect for the circulation of the carrier, abstracts residual heat from the expanding gas flow downstream of the turbine. In one embodiment, the compressor and the turbine are interconnected by a central shaft surrounded by a coaxial tubular member which carries the two heat exchangers; in another embodiment this relationship is reversed.

Heat generator of the combustion product condensation type and process for heating a heat-carrying fluid

Abstract: A heat generator of the type condensing the combustion products of a liquid or gaseous hydrogen fuel suitable for the heating of a heat-bearing fluid, including a tank containing at the top a zone of direct contact between the heat-bearing fluid and the combustion products, a collector for the heat-bearing fluid coming from the zone of direct contact, a convection heat exchanger arranged in the path of the combustion products, a combustion zone at a pressure close to atmospheric pressure, and a conduit which connects the collector of the heat-bearing fluid to the convection heat exchanger and is provided with a pump for replacing under pressure the portion of the heat-bearing fluid coming from the collector and intended to pass through the convection heat exchanger.

Optimization of annular fins on a horizontal tube

Abstract: A combination of uniform-thickness annular fins evenly spaced on a tube is a common extended-surface heat exchanger configuration. An analytical model is developed and is verified by comparing total heat transfer predicted by the model to available experimental data. A direct-pattern search technique is applied to the model to optimize the fin/ tube geometry. Optimum dimensions and spacing of fins are established to provide the maximum free convection heat transfer from a fin/tube combination. The optimum arrangement is dependent on fin thermal conductivity, tube diameter, volume of fin material per unit length of tube, and temperature difference between the tube and the surrounding air. Calculated results indicate that a fin in the optimum fin/tube system is shorter and thicker than an isolated fin optimized for minimum material (with no consideration of the effects of fin spacing).

Heat exchanger system and ducting arrangement therefor

Abstract: A heat exchanger system and ducting arrangement therefor includes a pair of heat exchanger units defining an elongated space between them, and individually having a first fluid flow path and a second fluid flow path therethrough for transferring heat from a relatively hot fluid to a relatively cool fluid, a bifurcated inlet channel for delivering the hot fluid to the heat exchanger units, a pair of exhaust conduits for conducting the hot fluid away from the heat exchanger units after heat is extracted therefrom during its travel through the first fluid flow paths, an elongated duct for delivering the cool fluid to the elongated space and from there oppositely outwardly to the heat exchanger units, and a pair of outlet manifolds for conducting the relatively cool fluid away from the heat exchanger units after it is beneficially heated during its travel through the second fluid flow paths.

Turbulent Heat Transfer by Downward Flow of Liquid Bismuth in a Concentric Annulus

Abstract: This note describes turbulent heat transfer to liquid bismuth flowing downward in a concentric annulus from an electrically heated mock fuel rod with uniform heat flux. Experiments were carried out using the bismuth loop of the Nuclear Power Experiment Facility in the Department of Nuclear Engineering, Kyoto University. The experimental arrangement is shown schematically in Fig. 1. Each element of the bismuth loop was heated by sheathed heaters. Liquid bismuth was forced up from the reservoir (4) to the loop by the pressure of Ar gas, and thereafter it was circulated by the difference in density existing between the liquid bismuth and the two-phase mixture of liquid bismuth and Ar gas which was injected from the argon gas nozzle (8). The Ar gas was subsequently separated in the separator (1), beyond which single phase liquid bismuth flowed downward along the test section (3). The flow rate of the liquid bismuth was measured by the rectangular weir (7). This weir was calibrated with water. The test section for measuring the heat transfer is shown in Fig. 2. The outer diameter D2 of the annulus was 52.7 mm and the inner diameter D1 20.0 mm. The outer tube was thermally insulated. The mock fuel rod is shown in Fig. 3. In the center of the mock fuel rod there was a nichrome heater insulated with MgO. This fuel rod was sheathed with 304 stainless steel 2.6 mm Fig. 1 Experimental arrangement