Showing papers on "Plate fin heat exchanger published in 1983"

Passive integral solar heat collector system

Abstract: The present invention relates to an improved apparatus for collecting, absorbing, transferring, and storing solar heat energy, economically and passively, without pumps or electric power. The apparatus comprises a solar collector with a flat finned heat pipe absorber and an attached integral insulated storage tank with a double wall heat exchanger. The absorber, made of one or more slightly tilted gravity assisted heat pipes with flat absorber fins, absorbs and transfers solar heat by evaporation, vapor transport, and condensation to the slightly elevated heat storage tank. The one or more heat pipes turn on when the sun is shining and turn off automatically when the sun is not shining.

Combustion product condensing water heater.

Abstract: In a water heating system, vapor in the products of combustion gases is condensed in a secondary heat exchanger positioned in a housing with the primary heat exchanger and combustion chamber. The two heat exchangers are coaxial coils with the secondary coil positioned below the primary. Gases flow radially through the primary coil and then axially through the secondary coil at an increased velocity. The gases are then used to pre-heat a gas/air mixture in a third heat exchanger within the secondary heat exchanger. The pre-heated gas/air mixture is burned in a burner within the primary heat exchanger and the gas products are drawn through the exchangers by a blower. A water storage tank is designed to enhance stratification of hot water over cooler water. The cooler water is used to condense vapor in the secondary heat exchanger.

Heat transfer characteristics of in‐ground heat exchangers

Abstract: Most in-ground heat storage installations use a system of horizontal or vertical plastic pipes to carry heat exchanger fluid. In designing these systems it is generally assumed that the thermal effects of the plastic pipe can be neglected. This paper reports a laboratory study of the pattern of heat flow around fluid-carrying plastic pipe buried in clay soil. Heat flow measurements as well as estimated contact resistances are presented for a number of configurations. In addition, numerical model computations are given for steady-state, transient and cyclic behaviour of several configurations, and it is shown that substantially reduced heat flows are obtained when plastic pipe is used.

Techniques for Obtaining Detailed Heat Transfer Coefficient Measurements Within Gas Turbine Blade and Vane Cooling Passages

Abstract: This paper reviews the techniques developed jointly by Rolls-Royce Bristol and Oxford University for determining detailed heat transfer coefficient distributions inside turbine blade and vane cooling passages.These techniques make use of a low temperature phase change paint to map the heat flux distributions within models of the cooling passages. The paints change from an opaque coating to a clear liquid at a well defined melting point.Thus, the surface temperature history of a model subjected to transient convective heating is recorded. From this history the heat transfer coefficient distribution is deduced using a transient conduction analysis within the model. The general method may be applied to a range of model thicknesses and geometries. The Rolls-Royce data are usually obtained from the inner surface of thick walled models whereas the Oxford measurements are performed on the outside of thin walls.Results are presented for the detailed heat transfer coefficient distributions within a variety of cooling passages. Firstly, smooth ducts of circular cross section are considered and serve the purpose of validating the experimental techniques. Secondly, results for complex passages with varying cross-sectional area are presented, and the effect of introducing discrete roughness elements and film cooling exhausts into these ducts assessed. Finally, data obtained from a comprehensive examination of a typical engine multi-pass cooling geometry are presented.Copyright © 1983 by ASME

Geothermal energy conversion system

Abstract: Apparatus and a method for using terrestrial heat to increase the temperature of a liquid, such as water. A circulation pipe buried in the earth in a region of high subterranean heat allows the liquid to move in heat exchange relationship to the subterranean heat. The liquid is pumped from a tank adjacent to the surface of the earth and through the pipe back to the tank. The heated water in the tank can be removed from the tank and caused to flow through a heat exchanger also adjacent to the surface of the earth. Then, the water is returned to the tank for re-use and reheating.

Thermal storage heat exchanger systems of heat pumps

Abstract: In a heat pump having a heat source, a heat sink and a thermal storage heat exchanger in which heat energy is cyclically accumulated and discharged by circulation of a secondary refrigerant therethrough, the improvement wherein: the secondary refrigerant is a aqueous solution having a concentration which is below its Eutetic concentration, the heat sink is adapted to super cool the aqueous solution to partially freeze it to generate a partially frozen solution in which fine ice particles are retained in suspension, the thermal storage heat exchanger has a storage chamber adapted to receive said partially frozen solution from the heat sink and to separate the ice particles from the liquid phase refrigerant to form a porous ice bed and a substantially ice free liquid bath, and wherein the thermal storage heat exchanger is adapted to receive heated refrigerant and to discharge the heated refrigerant into said chamber such that it is placed in intimate contact with the ice bed in a manner such that it may pass through the pores of the porous ice bed prior to its return to the bath.

Vertical concentric-tube ground-coupled heat exchangers

Abstract: An experimental and analytical project to study the design of vertical, concentric-tube ground-coupled heat exchangers for use in heat pump applications is described. The experimental apparatus consists of a concentric configuration of two 155-ft (47.2-m) polyvinylchloride (PVC) pipes (sealed at both ends with connections so that hot or cold water could be pumped through the system) with instrumentation to measure heat transfer. This heat exchanger was placed in a well with an 8-in (0.20-m) inside diameter (ID), which was backfilled with sand to establish good thermal contact. Heat transfer was measured for heat exchanger operation under several sets of operating conditions. A mathematical model was developed and converted into a computer program to simulate the operation of the ground-coupled heat exchanger. Data collected using the experimental apparatus was used to validate the computer program, and the computer model was then used to study the effects of variations in heat exchanger length, diameter, flow rate, and thermal conductivity and the thermal conductivity of the ground on the heat exchanger performance. Results are presented.

Tube‐wall catalytic reactor cooled by an annular heat pipe

Abstract: Cooling a tube-wall reactor using an annular heat pipe (AHP) is more temperature-stable, more flexible and more productive than cooling by conventional means. Tube-wall reactors cooled by an annular heat pipe arrangement exhibit flatter temperature profiles and uniform redistribution of the imposed heat load. The combination of tube-wall reactor and annular heat pipe is subject to the usual capacity limitations of the heat pipe: sonic flow, boiling heat transfer, liquid entrainment, and capillary flow of the working fluid.

Method and apparatus for efficient recovery of heat from hot gases that tend to foul heat exchanger tubes

Abstract: A method, together with suitable apparatus therefor, is provided useful in recovering heat from a high temperature cracked hydrocarbon gas, in which a liquid wash is injected into the tubes of a vertically oriented multitube transfer line heat exchanger to minimize deposition of coke The wash liquid is introduced into a plenum chamber located above the top tube sheet and it then flows through a perforated plate This distributes the liquid uniformly over the plate where it flows into the tubes to dissolve and/or flux condensates and coke

Heat exchanger, in particular for heat pumps

Abstract: Heat exchanger for absorbing heat from the groundwater, in particular for heat pumps, with pipes flowed through by liquid, the pipes being bent to form a coil with spaced turns and a return line guided internally, and the coil being built freely into a groundwater-bearing layer.

Time-Dependent Heat Exchanger Modeling

Abstract: A quasi-finite-element model of a multipass shell-and-tube heat exchanger is developed after the method of Gaddis and SchlUnder. The present model includes time-dependent inlet conditions and heat exchange. It is therefore applicable as a tool in system modeling for dynamic processes involving this type of heat exchanger. Under steady-state conditions, the present model reduces to that of Gaddis and SchlUnder.

Process for the cleaning of heat exchangers for exhaust gases from engines

Abstract: The efficiency of heat exchangers for cooling exhaust gases from internal combustion engines of stationary plants for the operation of heat pumps or for the combined generation of current and heat, and for the cleaning of the heat exchangers is increased. The heat exchanger, after a liquid secondary heat transfer medium is emptied therefrom, or with the circulation of a gaseous secondary heat transfer medium cut off, is periodically heated by the hot exhaust gases to a temperature which is sufficient for the automatic cleaning of the heat exchanger surfaces.

Convective boiling of ammonia and Freon 22 in plate heat exchangers

Abstract: An Alfa-Laval plate heat exchanger, previously used as the Mini-OTEC evaporator, was refurbished and tested in the Argonne National Laboratory (ANL) heat-exchanger test facility. Several series of tests were carried out with ammonia as the working fluid, followed by one with Freon 22. Configurations utilizatng all high angle plates and all low angle plates, and alternate high and low angle plates, were tested to determine the optimum combination for OTEC applications. The effects of ammonia contaminated by water on the thermal performance of the heat exchanger were evaluated. The use of the Linde High-Flux Surface on the working-fluid side of a Transfer plate heat exchanger was investigated to determine its effect on performance.

Improved formulations for the analysis of convecting and radiating finned surfaces

Abstract: The study of the heat flow within finned surfaces involving combined convective and radiative heat dissipation is conventionally based upon unidirectional analyses with attention restricted solely to the fin side. In this study the heat conduction within the interface to which the fins are attached, and the heat transfer from the unfinned side of this interface are also considered. The general situation in which the fins and the base surface have different thermal conductivities and different surface emissivities is examined. Fin-to-base-surface, fin-toenvironment, fin-to-fin, and base-surface-to-environment radiant interactions are all accounted for, but the convective fluids are assumed to be radiatively transparent. Oneand two-dimensional formulations are developed for analyzing the heat flow. These represent a major extension of the previously employed formulations. The results obtained indicate, in particular, that the previously employed formulations are inadequate for the effective design of finned heat exchangers.

Plate fin heat exchanger for superhigh pressure service

Abstract: A plate fin heat exchanger adapted to applications using superhigh-pressure fluids was fabricated by brazing, the heat exchanger using as fin stock an alloy consisting essentially of 0.3 to 1.0 wt. % Si, 0.05 to 0.25 wt. % Cu, 0.6 to 1.5 wt. % Mn and 0.45 to 0.9 wt. % Mg, the balance being aluminum and impurities, wherein said impurities contain up to 0.8 wt. % Fe. At least one component selected from the group consisting of 0.05 to 0.25 wt. % Cr, 0.01 to 0.25 wt. % Ti, 0.03 to 0.25 wt. % Zr and 0.01 to 0.25 wt. % V may be added to the above fin alloy stock. By using the above plate fin, excessive silicon diffusion from a brazing alloy into the fin, which may cause reduction of width of the brazed joint, is suppressed, and as a result, lowering of the bonding strength of the brazed joint is eliminated.

Study of hydraulic resistance and heat transfer in perforated-plate heat exchangers

Abstract: An experimental study is made of the hydraulic resistance and heat transfer in heat exchangers made of perforated plates with different internal geometries. Generalizing theoretical relations are obtained.

Method of regulating the heat transfer coefficient of a heat exchanger and improved heat exchanger for practicing said method

Abstract: Method and apparatus for regulating the heat transfer coefficient between a granular material and an exchange surface inside a heat exchanger in which a descending flow of a charge of material is arranged in the form of a mobile bed in contact with an elongated exchange member extending between lower and upper levels of the tank of the exchanger. The latter is provided with injection means for a gas into the charge of material. The flow conditions of the gas passing through the charge from below upwards are regulated so that the ascending flow speed is initially less than, at the base of the tank, the critical fluidization speed and then increases gradually to reach such critical speed at an adjustable level comprised between the lower and upper levels of the exchange member. The invention is especially applicable to heat exchangers used for cooling a granular material and/or for the heating of a heat transfer fluid.

Heat exchanger and vaporizer for a stove flue

Abstract: A heat exchanger and vaporizer adapted for mounting on an existing flue for utilizing heat which is otherwise lost and for providing moisture for space heating and conditioning. The heat exchanger and vaporizer includes a central stack for unimpeded transport of flue gases; a casing, with air inlet and outlet, enveloping the stack; a vaporizor contained within the casing for efficient heat transfer and for room conditioning; and a motor-fan unit for producing an airflow through the casing. The vaporizer is in the form of non-corrosive heat conductive helical tubing for maximizing heat transfer in a given volume, for maintenance free use and for convenience in assembly. The vaporizer is provided with a plurality of vapor vents on its upper surface and a pour spout located externally of the casing.

Reliability Problems of Heat Transfer Equipment

Abstract: In its simplest form, a heat exchanger consists of a bundle of tubes arranged between two thick perforated tube plates and enclosed by an outer shell Covers over the tube plates allow one fluid to pass inside the tubes while a second hotter or cooler fluid is introduced via openings in the shell Since they contain no moving parts it might be expected that heat exchangers would be highly reliable pieces of equipment However, everyday experience with small domestic and automotive heaters and coolers suggests this is not always the case In the case of mass-produced items such as these, replacement of a defective component is usually relatively straightforward and inexpensive However, for the much larger heat exchangers used in the process chemical and power industries, a single failure may result in significant financial losses

Water preheater system

Abstract: A heat transfer liquid 38 collects heat in a solar collector 10 and transfers the heat to water in a preheater heat exchanger 12. Use of a negative-pressure collector 10 by means of an ejector 24 and pressure relief valve 32 allows inexpensive and readily available materials to be used in the collector 10. Preferably, the preheat heat exchanger 12 is a converted gas hot water heater in which the heat transfer liquid 38 is sprayed onto a portion of the storage tank 20 and is collected in a reservoir 18. The negative-pressure solar collector 10 can also be used to heat swimming pool water.

Systematic Procedure for Selection of Heat Exchangers

Abstract: This paper is addressed to the engineer responsible for preparing the heat transfer equipment data sheet, on which will be specified all the parameters required by the vendor for tendering for the equipment. Initially, the engineer must decide the type of equipment best suited for his application; guidelines for this selection are given in Part A of this paper. Finally he must supply all the data required by the specialist for preparing his design. In the case of proprietary equipment, this data will be limited to process details. For more general equipment, especially shell and tube heat exchangers, he also needs to supply some equipment specifications. Part B of the paper gives guidelines for preparing shell and tube heat exchanger data sheets.