Showing papers on "Concentric tube heat exchanger published in 1984"

The plate heat exchanger: construction and design

Abstract: The gasketed plate heat exchanger is now commonly used in a wide range of applications. This paper details the construction of a plate heat exchanger (PHE) and its principles of operation. The capabilities are summarised in terms of operating pressures, temperatures and throughputs, followed by a discussion of its thermal and hydrodynamic characteristics. The paper highlights dimensionless characteristics for single phase heat exchange and discusses how these may be used in the analysis of a plate heat exchanger design. Finally qualitative and quantitative comparisons with shell and tube are given. The paper shows that within its capability range, the PHE is an excellent heat exchanger.

A numerical analysis of laminar flow and heat transfer of air in an in-line tube bank

Abstract: A numerical analysis of laminar flow and heat transfer in a tube bank is described. The two-dimensional Navier-Stokes and energy equations are solved numerically for successive subregions from the inlet to the exit of the bank by a procedure catted the “one step forward and half step backward iteration method” and by using a hybrid grid system. Calculations are carried out for an in-line square tube bank up to five rows deep, with pitch-to-diameter ratios 1.5 × 1.5, under the conditions of uniform tube wall temperature, Re = 60, 120, and 300, and Pr = 0.7. Stream, isovorticity, and isothermal lines through the whole tube bank, local and average Nusselt numbers, pressure distributions along the tube walls and in the flow directions, and friction factor are presented. The friction factor and average Nusselt number agree well with published experimental results. An analogous relation between an in-line tube bank and parallel plates with respect to developing heat transfer characteristics is presented.

Shell and tube heat transfer apparatus and process therefor

Abstract: Shell and tube heat transfer apparatus and a corresponding process of heat transfer employ a fluid flow consisting of non-turbulent boundary-layers (30) adjacent the inner (34) and outer (22) heat exchanger surfaces of the tubes and a non-turbulent core-layer (32) between the boundary-layers and interfacing therewith Interrupter-structures (28) disposed within the tube and shell flow passes and interrupt the full development of the boundary-layers at a multitude of spaced spots, leaving the heat transfer surfaces unaltered, unmodified and uninterrupted, so that the boundary-layers cannot increase in thickness but will partially separate from the surfaces and mix non-turbulently with the core-layer to effect the required heat transfer between the surfaces and the fluid The interrupter-structure preferably consists of a plurality of rows of spheres (28), with which the space remote from the heat exchange surface is filled with a space-filling material (58) to prevent the useless flow of fluid in a space not effective for heat transfer The interrupter structure may also comprise a unitary body (60) of equivalent shape

Condensate draining system for temperature regulated steam operated heat exchangers

Abstract: A system for draining condensate from a temperature regulated, steam operated heat exchanger A buffer tank having a volume at least equal to that of the steam compartment is connected to the steam side of the heat exchanger, and a drain line extends from the bottom of the buffer tank to a condensate collection pipe located above the buffer tank The drain pipe from the heat exchanger includes an air venting device and a control pipe having a non-return valve linking the top of the tank to the steam side of the heat exchanger During low load operation of the heat exchanger, air from the top of the buffer tank can flow back to the steam compartment of the heat exchanger to equalize the pressures and permit drainage of the condensate even during low load conditions

Three fluid heat exchanger with pressure responsive control

Abstract: A three fluid heat exchanger in which first and second fluids are in a normally flowing heat transfer relation, with flow of a third fluid being dependent on a changing condition of one of the first or second fluids. Tubular heat exchanger cores are comprised in a unitary body with one being perpendicular to the other for space conservation and to simplify fluid flow patterns. The described one core is in the path of flow of one of the first or second fluids and provides a flow path for the third fluid. A valve influenced by a changing condition of one of the first and second fluids controls flow of the third fluid.

Method for varying shell fluid flow in shell and tube heat exchanger

Abstract: In a conventional shell-tube heat exchanger with at least one annular distributor, apparatus and method are provided for minimizing pressure drop in the fluid passing through the shell side, by adjusting rotationally and longitudinally the position of at least one shell-side insert.

Multi-shell heat exchanger

Abstract: A multi-shell heat exchanger is disclosed in the preferred embodiment comprising at least two interconnected spherical shells wherein one shell encloses the other Tubular connectors connect the shells in spaced relation defining an annular space between the shells for a circulating cooling fluid A second fluid passage through the shells provides a continuous separate flow path for a circulating fluid to be cooled

Double wall heat exchanger

Abstract: A double wall heat exchanger for use in solar heaters and the like. An outer drawn copper tube of predetermined thickness and inside diameter is slid over a second drawn copper tube also of a predetermined thickness and outside diameter. A small axial groove, which is parallel to the longitudinal axis of the second or inner tube, is located in the surface of the inner tube and extends the entire length of the inner tube. The tubes are then placed in a furnace and annealed for a specified time and temperature. The double wall tubes are placed in a finning machine. Under a specified pressure and at a specified feed rate, integral fins are formed on the outside tube. While the fins are being formed on the outside tube, internal pressure is being applied forcing the inner tube to expand and conform to the inside diameter of the outer tube. The mating surfaces form a helical passageway which serves as part of the path of leakage. The axial groove communicates with each winding of the helical passageway and substantially shortens the total leakage path, thereby reducing the pressure differential needed to produce evidence of leakage in a given time period. The double wall heat exchanger has good surface between the tubes, has a path of leakage between the tubes at a pressure differential of as low as 3 psig, and has good heat transfer. The axial groove is small enough so as to have little effect on the overall heat transfer rate, but is of sufficient size so as to provide a leak rate that meets the requirements of the installation.

Tube-in-tube heat exchanger

Abstract: The tube-in-tube heat exchangers known to date, which are built from round tubes placed centrally, or else non-centrally, in one another, and form straight or spiral tube bundles, give rise in production to a number of design as well as construction problems. It is the object of the invention to develop a compact tube-in-tube heat exchanger which is very effective in terms of heating engineering and can be used for a plurality of functions (cooler, condenser, evaporator, preheater). This is achieved when a smooth tube or a tube with an annular, spiral corrugation is mounted in the interior of the enclosing tube, this enclosing tube having an oval or elliptical cross-section. Owing to this shape of the outer tube, the inner tube is seated firmly by means of punctiform, linear, or else areal contact of the two tubes. Vibrations are reduced to a high degree. The performance of tube-in-tube heat exchangers designed in this way is also enormously increased, owing to the turbulence of the medium, which is particularly promoted by the design.

Heat exchanger core and heat exchanger employing the same

Abstract: A heat exchanger core including a heat conducting tube. A plurality of spines are mounted on the tube in opposed groups and are separated by spine free areas, one of which faces the direction of air flow and the other of which faces away from the direction of air flow.

Structure of heat transfer tube of heat exchanger

Abstract: PURPOSE:To improve the heat transfer performance due to the turbulent acceleration by providing on the heat transfer pipe spiral projections on the outer surface of the tube or spiral projections on the inner surface thereof or both projections, said projections having lead angles with respect to the tube axis in a predetermined range. CONSTITUTION:When around the outer periphery of the heat transfer pipe 1 are provided with spiral grooves 2, and spiral fins are formed by rolling or the like, spiral projections 4 are formed in correspondence with the grooves 2 on the inner surface of the tube. In this case, when lead angles alpha and alpha' of the fins 3 and the projections 4 with respect to the tube axis are set in the proximity of 45 deg., the fins 3 assume an angle of approximately 45 deg. with respect to a perpendicular flow 5 and a parallel flow 5' of the fluid outside of the tube and the projections also assume an angle of approximately 45 deg. with respect to a flow 6 of the fluid inside of the tube. Thus, an ideal heat transfer tube in which the thermal conductivity is high and further the increase in the friction loss is small, can be obtained. Moreover, there are slight differences in the effect of the heat transfer and the rate of the increase in the friction loss depending on the property of the fluid, and hence, the lead angles alpha and alpha' are set in the range of 30-50 deg..

Gas convection oven with egg-shaped heat exchanger tube

Abstract: A gas-fired convection oven for processing food, for example, having a fan for moving air along a circulatory path over, along and about the food to be processed. A package type gas burner outside the oven is directed into a heat exchanger tube of substantial length extending into the oven. High-temperature exhaust gases are discharged from the burner to be directed through the heat exchanger into the circulatory path of air flowing through the convection oven. Relatively proximate the burner the heat exchanger has a linear portion that is of egg-shaped or elliptical cross section, and that portion is oriented with respect to the outlet of the convection blower and walls of the convection blower chamber to draw air over substantially the entire surface area of such portion for maximum cooling/heat exchange function with respect thereto. The outlet from the flow outlet of the heat exchanger is aerodynamic and is positioned proximate the intake to the convection blower wheel whereby the latter tends to draw the hot gases/products of combustion through the heat exchanger tube.

Finned heat exchanger tube having optimized heat transfer characteristics

Abstract: A metal heat exchanger tube which provides for optimized heat transfer characteristics and which is particularly adapted for use in the direct expansion shell and tube type evaporators of mechanical refrigeration systems. The metal heat exchanger tube incorporates integral external and internal fins wherein the dimensional and geometrical proportions of the surface or heat transfer areas of the external and internal fins and the cross-sectional flow area of the heat exchanger tube, in conjunction with the lead angle of the internal helical fins have been correlated in conformance with predetermined mathematical criteria in order to optimize the heat transfer capacities of the tubes, particularly when the tubes are to be employed in direct expansion evaporator of mechanical refrigeration systems.

Heat exchanger having adjustable baffles

Abstract: A heat exchanger of the type having a tube assembly made up of a number of tubes through which a first medium flows and around and between which a second medium flows to accept heat from, or transfer heat to, the first medium One of the media is constrained by baffles to follow a tortuous path through the heat exchanger According to the invention, the baffles are completely separate from the tubes, so permitting them to be replaced or adjusted without the necessity of disassembling the tube assembly The baffles can be carried releasably on rods which allow their spacing to be adjusted at will, with the result that heat exchangers according to the invention are more versatile than conventional heat exchangers where the baffles are fixed to the tubes

Rod baffle heat exchange apparatus and method

Abstract: A novel supported tube bundle, useful for improving the shell fluid flow distribution in a shell and tube heat exchanger is improved by varying the number and position of rods that comprise the rod baffles in the heat exchanger. The number and position of rods are varied to provide fewer rods adjacent the inlet and outlet of the shell than at other portions of the shell so that flow of shell fluid through areas where the flow normally tends to channel is diverted to areas where flow normally tends to by-pass.

Theoretical and experimental analysis of 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. A mathematical model was developed and converted into a computer program to simulate the operation of the ground-coupled heat exchanger. The experimental apparatus consisted of a concentric configuration of two 47.2-m (155-ft) polyvinyl chloride (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 excanger was placed in a 0.20-m (8-in.) inside diameter (ID) well and backfilled with sand to establish good thermal contact with the surrounding ground. Heat transfer was measured for heat exchanger operation under several sets of operating conditions. Data collected using the experimental apparatus were used to validate the computer program, and the computer model was then used to study the effects of variations in heat exchanger length and diameter, flow rate, and tube and ground thermal conductivities on the heat exchanger performance. Results are presented.