EP2322890A1

EP2322890A1 - A marine heat exchanger

Info

Publication number: EP2322890A1
Application number: EP09176089A
Authority: EP
Inventors: David Evans; Julian Gareth Crossley
Original assignee: Thermex Ltd
Current assignee: Thermex Ltd
Priority date: 2009-11-16
Filing date: 2009-11-16
Publication date: 2011-05-18
Also published as: US20110117800A1

Abstract

A marine heat exchanger 10 comprising a housing assembly 12 and a heat exchange core assembly 14. The housing assembly 12 comprises a process fluid (P) inlet 16, a process fluid outlet 18, a coolant (C) inlet 20 and a coolant outlet 22. The housing assembly 12 defines a process fluid passageway between the process fluid inlet 16 and the process fluid outlet 18. The heat exchange core assembly 14 comprises a plurality of coolant tubes and a plurality of heat exchange fins. The coolant tubes comprise corporate alloy and the heat exchange fins comprise copper. The coolant tubes are joined to the heat exchange fins by cuprobraze joints. The coolant tubes are provides between the coolant inlet 20 and the coolant outlet 22 and define a coolant passageway. At least part of the coolant tubes and at least part of the heat exchange fins extend through the process fluid passageway.

Description

The invention relates to a marine heat exchanger.
Heat exchangers for marine vessel engines, such as charge-air coolers or intercoolers, typically comprise a number of tubes through which the process fluid, typically air, is passed for cooling through the action of a coolant flowing externally across the tubes. These heat exchangers typically also comprise a number of fins, generally in the form of metal plates, having apertures formed therein through which the coolant tubes are located. The coolant tubes are, traditionally, bullet expanded or roller expanded in order to form a close mechanical fit within the respective apertures of the cooling plate fins through which the tubes pass.
In order to minimise fuel consumption there is a need to reduce the weight of marine vessel engine heat exchangers, whilst preserving the cooling power provided by the heat exchanger. It is also desirable to make marine vessel engine heat exchangers as compact as possible in order to minimise the overall footprint of the engine.
According to an aspect of the invention there is provided a marine heat exchanger comprising:

a housing assembly comprising a process fluid inlet, a process fluid outlet, a coolant inlet and a coolant outlet, the housing assembly defining a process fluid passageway between the process fluid inlet and the process fluid outlet; and
a heat exchange core assembly comprising a plurality of coolant tubes and a plurality of heat exchange fins,
the coolant tubes comprising copper alloy and the heat exchange fins comprising copper, and the coolant tubes being joined to the heat exchange fins by cuprobraze joints, and
the coolant tubes being provided between the coolant inlet and the coolant outlet and the coolant tubes defining a coolant passageway, at least part of the coolant tubes and at least part of the heat exchange fins extending through the process fluid passageway.

A marine heat exchanger is thus provided which has a smaller amount of metal required for joining the coolant tubes and the heat exchange fins by using cuprobraze joints. The marine heat exchanger is thus able to have the same cooling capacity for a smaller weight or a larger cooling capacity for the same weight, as compared to prior art heat exchangers in which coolant tubes are joined to heat exchange plates by means of bullet expanded joints. The use of cuprobraze joints between the ends of the coolant tubes and the tube plates additionally reduces the weight of the tube plates as compared to prior art heat exchangers where such joints are made using bullet expanded joints.
The use of cuprobraze joints enables a more thermally efficient and reliable joint to be formed between the coolant tubes and the tube plates than is achievable using bullet expanded or roller expanded joints. The marine heat exchanger provides improved performance against pressure losses as compared to a heat exchanger constructed using bullet expanded or roller expanded joints for the same cooling capacity.
Preferably, the coolant comprises water, which may be one of sea water, engine water and jacket water. The process fluid may comprise one of air, oil and water. The use of cupronickel within the heat exchanger protects the heat exchanger against erosion and corrosion when sea water is used as the coolant.
In an embodiment, the coolant tubes comprise cupronickel copper alloy. The cupronickel cooper alloy preferably comprises at least 70% copper, and most preferably comprises at least 90% copper. In an embodiment, the coolant tubes have a substantially round or obround cross-sectional shape.
In an embodiment, the heat exchange fins each have a corrugated form, and most preferably have a square-wave corrugated form. In an alternative embodiment, the heat exchange fins each have a substantially flat sheet form. In an embodiment, the fins are provided with secondary surfaces.
The use of corrugated heat exchange fins is enabled by the use of cuprobraze joints. The use of corrugated heat exchange fins enables the marine heat exchanger to provide an improved thermal performance. The use of corrugated heat exchange fins enables the marine heat exchanger to be constructed with a smaller footprint and/or lower weight than a heat exchanger constructed using bullet expanded or roller expanded joints for the same cooling capacity.
In an embodiment, the coolant passageway comprises a single pass through the process fluid passageway. In an alternative embodiment, the coolant passageway comprises two or more passes through the process fluid passageway.
In an embodiment, the heat exchange core assembly further comprises first and second tube plates respectively provided towards each end of the coolant tubes. In an embodiment, the tube plates comprise a copper alloy and the coolant tubes are joined to the respective tube plates by cuprobraze joints. In an embodiment, at least one tube plate comprises a flexible tube plate. In an embodiment, the flexible tube plate comprises an expansion section having a substantially S-shaped sectional profile.
The flexible tube plates enables the marine heat exchanger to be rigidly and securely constructed whilst accommodating expansion and contraction of the coolant tubes caused by changes in the temperature of the coolant and the process fluid. Providing the flexible tube plate with an expansion section having a substantially S-shaped sectional profile enables the flexible tube plate to undergo controlled, diaphragm like flexing within its central region, whilst retaining secure and rigid coupling to the heat exchange core assembly.
In an embodiment, the heat exchange core assembly further comprises first and second side plates comprising copper alloy and the side plates are joined to adjacent heat exchange fins by cuprobraze joints.
In an embodiment, the heat exchanger further comprises an inlet manifold tank, provided in fluid communication between the coolant fluid inlet and an inlet end of the coolant passageway, and an outlet manifold tank, provided in fluid communication between an outlet end of the coolant fluid passageway and the coolant outlet. In an embodiment, where the coolant passageway comprises two or more passes through the process fluid passageway, the heat exchanger further comprises a return manifold tank provided in fluid communication with the coolant tubes and forming a part of the coolant passageway.
In an embodiment, the heat exchange core assembly is arranged within the housing assembly such that the heat exchange core assembly is free to expand within the housing assembly.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a diagrammatic representation of a marine heat exchanger according to a first embodiment of the invention;
Figure 2 shows the heat exchange core assembly, manifold tanks and coolant inlet and outlets of the heat exchanger of figure 1;
Figure 3 shows the heat exchange core assembly of the heat exchanger figure 1, from its return end;
Figure 4 shows a diagrammatic cross-sectional view along line A-A of figure 2;
Figure 5 is a diagrammatic sectional view along line B-B of figure 2; and
Figure 6 is a diagrammatic sectional view through the heat exchange core assembly, manifold tanks and coolant fluid inlet and outlet of a marine heat exchanger according to a second embodiment of the invention.

Referring to figures 1 to 5, a first embodiment of the invention provides a marine heat exchanger 10 comprising a housing assembly 12 and a heat exchange core assembly 14. The housing assembly 12 comprises a process fluid inlet 16, a process fluid outlet 18, a coolant inlet 20 and a coolant outlet 22. The housing assembly 12 defines a process fluid passageway between the process fluid inlet 16 and the process fluid outlet 18.
The heat exchange core assembly 14 comprises a plurality of, in this example 40, coolant tubes 24 and a plurality of, in this example 9, heat exchange fins 26. The coolant tubes comprise cupronickel copper alloy tubes having an obround cross-sectional shape, as shown in figure 5. In this example, the cupronickel is 90/10 cupronickel but it may alternatively be 70/30 cupronickel.
The heat exchange fins 26 have a square wave corrugated form, as shown best in figure 6, and are formed from copper metal sheeting. The coolant tubes 24 are arranged in a spaced array of 8 layers of 5 tubes 24. A heat exchange fin 26 is provided between each layer of tubes 24. Heat exchange fins 26 are additionally provided on top of the uppermost layer of tubes and below the lower most layer of tubes, as shown in figure 5. The coolant tubes 24 are joined to the respective adjacent fins 26 by cuprobraze joints.
It will be appreciated that the heat exchange fins 26 may have any physical configuration which presents a suitable surface for connection to the coolant tubes 24 by means of a cuprobraze joint, include a flat sheet form and other corrugated forms. Similarly, it will be appreciated that the coolant tubes may have any cross-sectional shape which provides a suitable surface for connection to the heat exchange fins, including a round section.
The heat exchange core assembly 14 is arranged within the housing assembly 12 such that at least part of the coolant tubes 24 and at least part of the heat exchange fins 26 extend through the process fluid passageway between the process fluid inlet 16 and the process fluid outlet 18. In this example, the housing assembly 12 defines an internal cavity in which the heat exchange core assembly 14 is located and through which the process fluid flows. The coolant tubes 24 and the heat exchange fins 26 thereby extend through the process fluid passageway and the process fluid flows around and across the heat exchange fins and the coolant tubes 24 as it flows from the process fluid inlet 16 to the process fluid outlet 18. The flow of the process fluid is indicated by the arrows P in the figures. The flow of coolant is indicated by the arrows C in the figures.
The coolant tubes 24 define a coolant passageway between the coolant fluid inlet 20 and the coolant fluid outlet 22. In this example the coolant tubes 24 are arranged such that the coolant passageway comprises 2 passes through the process fluid passageway. A first set of the coolant tubes 24, being the lower 4 layers of tubes shown in figure 4, form a first part of the coolant fluid passageway which comprises a first pass through the process fluid passageway. A second set of the coolant tubes 24, being the upper 4 layers of the coolant tubes shown in figure 4, form a second part of the coolant fluid passageway through the process fluid passageway.
The heat exchange core assembly 14 further comprises first and second side plates 28. The side plates 28 comprise cupronickel and are joined to the respective adjacent heat exchange fins 26 by cuprobraze joints.
The heat exchange core assembly 14 further comprises a first tube plate 30 and a second tube plate 32. The tube plates 30, 32 comprise copper alloy, which in this example takes the form of the same cupronickel alloy as the coolant tubes 24. Each tube plate 30, 32 is provided with a matrix of apertures adapted to receive an end of a respective coolant tube 24. The coolant tubes 24 are joined at each end to the respective tube plate 30, 32 by cuprobraze joints.
In this example, one of the tube plates 32 is a flexible tube plate and is provided with an expansion section 32a which enables the flexible tube plate 32 to flex, in the manner of a diaphragm, under the action of elongate expansion of the coolant tubes 24. As shown most clearly in figure 4, the expansion section has a substantially S-shaped sectional profile and, as best shown in figure 3, the expansion section extends around the matrix of apertures coupled to the coolant tubes 24.
It will be appreciated that both tube plates 30, 32 may alternatively comprise flexible tube plates or both may comprise fixed tube plates.
The expansion of the coolant tubes 24 may alternatively be accommodated within the heat exchanger 10 by mounting the heat exchange core assembly 14 for free movement within the housing assembly 12, thus enabling the entire heat exchange core assembly 14 to expand with the coolant tubes 24.
Referring in particular to figures 2 and 4, the heat exchanger 10 further comprises an inlet manifold tank 34, an outlet manifold tank 36 and a return manifold tank 38. The inlet manifold tank 34 is provided in fluid communication between the coolant fluid inlet 20 and the inlet end of the first set of coolant tubes 24, being the inlet of the coolant fluid passageway. The outlet manifold tank 36 is provided in fluid communication between the outlet end of the second set of coolant tubes 24, being the outlet end of the coolant fluid passageway, and the coolant outlet 22. The return manifold tank is provided in fluid communication between the outlet ends of the first set of coolant tubes 24 and the inlet ends of the second set of coolant tubes 24.
In operation, coolant fluid (C), which in this example comprises sea water, flows in through the coolant inlet 20 and through the inlet manifold tank 34 to the inlet ends of the coolant tubes 24 in the first set of the coolant tubes. The coolant flows through the first set of coolant tubes 24, undertaking a first pass through the process fluid passageway, to the outlet end of the first set of coolant tubes 24 and into the return manifold tank 38. The coolant flows around the return manifold tank 38 and enters the inlet ends of the second set of coolant tubes 24. The coolant then flows through the second set of coolant tubes 24 and out through the outlet manifold tank 36 and the coolant outlet 22.
The coolant water may alternatively comprise engine water or jacket water, which may be pre-cooled before delivery to the marine heat exchanger 10.
A second embodiment of the invention provides a marine heat exchanger comprising a heat exchange core assembly 40, a coolant inlet 42, an inlet manifold tank 44, an outlet manifold tank 46 and a coolant outlet 48, as shown in figure 6. The marine heat exchanger of this embodiment is substantially the same as the marine heat exchanger 10 of the first embodiment, with the following modifications. The same reference numbers are retained for corresponding features.
In this embodiment, the coolant passageway comprises a single pass through the process fluid passageway, and the coolant (C) therefore flows from the inlet manifold tank 44 through all of the coolant tubes 24 to the outlet manifold tank 46. The coolant inlet 42 and the coolant outlet 48 are provided on opposing sides of the housing assembly in this embodiment.
The use of cuprobraze joints between the coolant tubes 24 and the heat exchange fins 26 in the described marine heat exchangers provides the advantage of a parent metal joint between the parts and therefore a more thermally efficient joint. The use of cuprobraze joints between the coolant tubes 24 and the heat exchange fins 26 enables the use of corrugated fins within the marine heat exchangers, which provides enhanced thermal performance. As a result, a marine heat exchanger having a smaller size and footprint can be constructed. Further, a marine heat exchanger can be produced having either the same cooling capacity for a lower weight or a greater cooling capacity for the same weight. The use of cuprobraze joints can also reduce the amount of metal required for each of the fins 26, since the metal flange provided around each aperture in a heat exchange fin when coolant tubes are joined to the fins using the method of bullet expanding or roller expanding is not produced. Similarly, the use of cuprobraze joints between the ends of the coolant tubes 24 and the tube plates 30, 32 provides a more thermally efficient joint between these parts. It also reduces the weight of the tube plates as compared to those joined using the bullet expansion or roller expansion methods.
The provision of a flexible tube plate enables the heat exchanger to be rigidly and securely constructed whilst accommodating expansion and contraction of the coolant tubes 24 caused by changes in the temperature of the coolant. The expansion section 32a in the flexible tube plate 32 provides a tube plate 32 which may be securely and rigidly coupled to the side plates 28 and to the housing assembly 12, whilst allowing diaphragm like flexing of the tube plate 32 within its central region coupled to the coolant tubes 24.
The use of cupronickel within the heat exchanger protects the heat exchanger against erosion and corrosion when using sea water as the coolant and the general salt water environment on board a marine vessel.

Claims

A marine heat exchanger comprising:
a housing assembly comprising a process fluid inlet, a process fluid outlet, a coolant inlet and a coolant outlet, the housing assembly defining a process fluid passageway between the process fluid inlet and the process fluid outlet; and

a heat exchange core assembly comprising a plurality of coolant tubes and a plurality of heat exchange fins,

the coolant tubes comprising copper alloy and the heat exchange fins comprising copper, and the coolant tubes being joined to the heat exchange fins by cuprobraze joints, and

the coolant tubes being provided between the coolant inlet and the coolant outlet and the coolant tubes defining a coolant passageway, at least part of the coolant tubes and at least part of the heat exchange fins extending through the process fluid passageway.
A marine heat exchanger as claimed in claim 1, wherein the coolant comprises one of sea water, engine water and jacket water and the process fluid comprises one of air, oil and water.
A marine heat exchanger as claimed in claim 1 or 2, wherein the coolant tubes comprise cupronickel copper alloy.
A marine heat exchanger as claimed in any preceding claim, wherein the coolant tubes have a substantially round or obround cross-sectional shape.
A marine heat exchanger as claimed in claim 4, wherein the heat exchange fins each have a corrugated form.
A marine heat exchanger as claimed in any preceding claim, wherein the heat exchange core assembly further comprises first and second tube plates respectively provided towards each end of the coolant tubes, the tube plates comprising a copper alloy and the coolant tubes being joined to the respective tube plates by cuprobraze joints.
A marine heat exchanger as claimed in claim 6, wherein at least one tube plate comprises a flexible tube plate.
A marine heat exchanger as claimed in claim 7, wherein the flexible tube plate comprises an expansion section having a substantially S-shaped sectional profile.
A marine heat exchanger as claimed in any of claims 1 to 6, wherein the heat exchange core assembly is arranged within the housing assembly such that the heat exchange core assembly is free to expand within the housing assembly.
A marine heat exchanger as claimed in any preceding claim, wherein the heat
exchange core assembly further comprises first and second side plates comprising copper alloy and the side plates are joined to adjacent heat exchange fins by cuprobraze joints.