US20080223560A1

US20080223560A1 - Heat exchanger

Info

Publication number: US20080223560A1
Application number: US12/043,727
Authority: US
Inventors: Paulo Rossano Hoenisch; Gustavo Henrique Pacheco Zattar
Original assignee: Whirlpool SA
Current assignee: Whirlpool SA
Priority date: 2007-03-13
Filing date: 2008-03-06
Publication date: 2008-09-18
Also published as: BRPI0700912A

Abstract

A heat exchanger of the single circuit type, to be coupled to a fluid circulation circuit and comprising: an upper tubular head element and a lower tubular head element horizontally arranged and which are each provided with a nozzle and through slots provided in an inner longitudinal wall portion; and a plurality of vertically disposed fluid conduction tubes, each internally defining a plurality of longitudinal microchannels. The opposite ends of the fluid conduction tubes are affixed to the inner longitudinal wall portion of the upper tubular head element and lower tubular head element, respectively, so as to communicate the ends of the microchannels of each tube with a through slot of the respective tubular head element and, thus, the fluid conduction tubes with the interior of the upper tubular head element and lower tubular head element.

Description

CROSS REFERENCE TO PRIOR APPLICATIONS

This application claims priority to Brazilian Patent Application No. PI 0700912-7, filed on Mar. 13, 2007, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention refers to a heat exchanger of the single circuit type to be used as a condenser or as an evaporator, in diverse applications, particularly in air conditioner appliances, aiming to facilitate the manufacture and to improve the heat exchange efficiency.
2. Prior Art
Nowadays, the heat exchangers manufactured with fluid conduction tubes of oval flat section, containing microchannels, are horizontally arranged with corrugated fins, being coupled to the vertically arranged head elements, at the side ends of the fluid conduction tubes, which form more than one circuit or are manufactured in the coil type configuration.
This type of heat exchanger assembly, besides being of high industrial complexity, has the limitation of not being able to work as an evaporator, since the oval flat fluid conduction tubes with microchannels have a flattened form and are mounted with corrugated fins, retaining the water condensed from air moisture therebetween, impairing the operation of the heat exchanger and making unfeasible its application as an evaporator.
These heat exchangers also have high resistance to the dragging of refrigerant fluid condensed in its interior, provoking high load losses in the refrigerating circuits, and demanding a higher power from the compression equipment.

SUMMARY OF THE INVENTION

As a function of the inconveniences mentioned above and regarding the known constructive solutions for the heat exchangers of the above-considered type, the present invention has the object of providing a heat exchanger of the single circuit type, which is easy to construct and which presents more versatility in order to be used as a condenser and as an evaporator, improving the heat exchange efficiency in any of said applications, by using the same basic elements defined by tubular head elements that are coupled to and communicate with the ends of a plurality of fluid conduction tubes.
The object above is attained by the provision of a heat exchanger of the single circuit type, to be coupled to a fluid circulation circuit and comprising: an upper tubular head element and a lower tubular head element, which are horizontally arranged and have closed ends, each tubular head element being provided with a nozzle for connection to the fluid circulation circuit, and a plurality of through slots provided in an inner longitudinal wall portion of the respective tubular head element and which are transversal to the longitudinal axis of the tubular head element; and a plurality of fluid conduction tubes of substantially elongated rectangular cross-section and vertically arranged side-by-side, each fluid conduction tube internally defining a plurality of longitudinal microchannels with open ends, the opposite ends of said fluid conduction tubes being affixed against the inner longitudinal wall portion of the upper and lower tubular head elements, respectively, so as to tightly communicate the ends of the microchannels of each fluid conduction tube with a through slot of the upper and lower tubular head elements, respectively, and thus the fluid conduction tubes with the interior of the upper and lower tubular head elements.
The construction proposed herein improves the heat efficiency of the heat exchanger due to the arrangement and to the increase of the number of fluid conduction tubes in the same area and to the reduction of the load loss of the refrigerant circuit, as a consequence of the single unidirectional circuit through the fluid conduction tubes, i.e., without changing direction and also due to the fact that the condensed refrigerant flows directly downwards, when the heat exchanger operates as a condenser, efficiently separating the gaseous part from the liquid part and further permitting the refrigerant fluid, evaporated in the gaseous state, to flow directly upwardly, when the heat exchanger operates as an evaporator, also efficiently separating the phases of gas+liquid mixture from the saturated or superheated gas. This arrangement of fluid conduction tubes in the vertical position can be applied to condensers and evaporators of vapor-compression refrigerating and/or heating systems, since, in the case of the application as an evaporator, all the water condensed at the surface of the tubes will flow by gravity, thus leaving the surface free for a more effective heat exchange.
The present constructive solution further contributes to a better efficiency of the ventilation system, mainly when applied to forced ventilation systems, since it has less resistance to air passage, thus contributing to reduce the dimensions and the power required for the motor of the air impeller, which is generally defined by a fan.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below, with reference to the enclosed drawings, given by way of examples of possible embodiments of the present heat exchanger and in which:

FIG. 1 represents a front top perspective view of the heat exchanger;

FIG. 2 represents a front view of the heat exchanger of FIG. 1;

FIG. 2A represents an enlarged detail view of the lower end of the heat exchanger of FIGS. 1 and 2, taken according to the limits defined by the circle “A” illustrated in FIG. 2;

FIG. 3 represents an elevation view of the right side of the heat exchanger of FIGS. 1-2A;

FIG. 4 represents, simultaneously, a top plan view and a lower plan view of the inner longitudinal walls of the lower and upper tubular head elements, respectively, of the heat exchanger of FIGS. 1-3, deprived of the fluid conduction tubes;

FIG. 4A represents an enlarged detailed view of an end of the lower and upper tubular head elements of the heat exchanger of FIGS. 1-4, taken according to the limits defined by the circle “B” illustrated in FIG. 4;

FIG. 5 represents an enlarged cross sectional view of the fluid conduction tube of the heat exchanger of FIGS. 1-4A; and

FIG. 6 represents an enlarged cross sectional view of a constructive variant for the fluid conduction tube of the heat exchanger of the previous figures.

DETAILED DESCRIPTION OF THE INVENTION

As already previously mentioned and illustrated in the enclosed drawings, the invention refers to the construction of a heat exchanger to be used as a condenser or as an evaporator in several applications, particularly in air conditioner appliances, said heat exchanger being of the single circuit type.
According to the present invention, the heat exchanger comprises an upper tubular head element 10 and a lower tubular head element 20, constructed in any adequate material, such as for example, carbon steel, stainless steel, thermoplastic material, etc., and which are horizontally arranged and have their ends closed, so that each tubular head element defines a tube extension whose cross section can vary according to the heat exchanger project. In the embodiment illustrated in the drawings, the upper tubular head element 10 and the lower tubular head element 20 present a rectangular cross section, having an inner longitudinal wall 10 a, 20 a turned to the heat exchanger structure and which, in the case of the embodiment of rectangular section, defines a flat surface, also of rectangular contour. The upper tubular head element 10 and the lower tubular head element 20 each further presents, in said construction of rectangular cross section, an outer longitudinal wall 10 b, 20 b, turned outwardly from the heat exchanger body or structure.
Each upper tubular head element 10 and lower tubular head element 20 is provided, generally in one of its closed ends, with a nozzle 11, 21, for connecting said upper tubular head element 10 and lower tubular head element 20 to a fluid circulation circuit with which the heat exchanger is operatively associated. These nozzles 11, 21 can present different constructions that are well known in the prior art, its particular construction not being a relevant aspect to the object of the present invention.
As illustrated in the enclosed drawings, each upper tubular head element 10 and lower tubular head element 20 presents, in an inner longitudinal wall portion 10 a, 20 a, a plurality of through slots 12, 22 arranged transversal to the longitudinal axis of the respective tubular head element, said through slots 12, 22 generally presenting an elongated rectangular contour that is similar to and slightly smaller than that of the fluid conduction tubes 30. The through slots 12, 22 are arranged side-by-side, each extended substantially over the whole width of the inner longitudinal wall 10 a, 20 a of the respective upper tubular head element 10 and lower tubular head element 20. In case of constructing the tubular head elements with a rectangular cross section, the through slots 12, 22 present an extension which substantially corresponds to the width of the inner longitudinal wall of the tubular head element.
The present heat exchanger further comprises a plurality of fluid conduction tubes 30 presenting a substantially elongated rectangular cross-section and being vertically arranged side-by-side. Each fluid conduction tube 30 is constructed so as to internally define a plurality of longitudinal microchannels 31 with open ends coinciding with the ends of the respective fluid conduction tube 30, the opposite ends of said fluid conduction tubes 30 being affixed, by any adequate process, such as brazing, against the inner longitudinal wall portion 10 a, 20 a of the upper tubular head element 10 and lower tubular head element 20, respectively, so as to allow the occurrence of a tight fluid communication between the ends of the microchannels 31, of each fluid conduction tube 30, with a through slot 12, 22 of the upper tubular head element 10 and lower tubular head element 20, respectively and, consequently, between the fluid conduction tubes 30 and the interior of the upper tubular head element 10 and lower tubular head element 20 through the through slots 12, 22.
As illustrated, the present construction allows the fluid conduction tubes 30 to be arranged side-by-side, with its longitudinal extension parallel to the direction of the airflow passing through the spacings defined between said fluid conduction tubes 30 and along their side walls, thereby facilitating the airflow through the heat exchanger, without the existence of elements which cause undesired load loss to the through airflow. In order to facilitate airflow, the fluid conduction tubes 30 can be constructed with their opposite end longitudinal edges 32 tapered or simply configured in a convex arc, as illustrated in FIGS. 5 and 6 of the enclosed drawings. The fluid conduction tubes 30 can be constructed with externally smooth side walls or also incorporating small projecting side fins 33, extending along at least a substantial part of the height of the fluid conduction tubes 30. These small projecting side fins 33 are formed in the material that constitutes the respective fluid conduction tubes 30, considerably facilitating the construction of said elements and allowing an effective increase in its heat exchange outer surface area.
It should be understood that, in the case of providing fluid conduction tubes 30, such as in the construction illustrated in FIG. 6, the spacing between each pair of adjacent fluid conduction tubes 30 is designed to define an adequate distance between the free ends of the confronting small projecting side fins 33, so as not to impair the heat exchange airflow passing between said fluid conduction tubes 30 of the heat exchanger.
While only two possible constructive forms of the present heat exchanger have been illustrated herein, it should be understood that alterations can be made in the form and physical arrangement of the elements, without departing from the constructive concept defined in the claims that accompany the present specification.

Claims

1. A heat exchanger of the single circuit type, to be coupled to a fluid circulation circuit, comprises: an upper tubular head element and a lower tubular head element which are horizontally arranged and have closed ends, each tubular head element being provided with a nozzle for connection to the fluid circulation circuit, and with a plurality of through slots provided in an inner longitudinal wall portion of the respective tubular head element and which are transversal to the longitudinal axis of the tubular head element; and a plurality of fluid conduction tubes, of substantially elongated rectangular cross-section, vertically arranged side-by-side, each fluid conduction tube internally defining a plurality of longitudinal microchannels with open ends, the opposite ends of said fluid conduction tubes being affixed against the inner longitudinal wall portion of the upper tubular head element and lower tubular head element, respectively, so as to tightly communicate the ends of the microchannels of each fluid conduction tube with a through slot of the upper tubular head element and lower tubular head element, respectively, and thus the fluid conduction tubes with the interior of the upper tubular head element and lower tubular head element.

2. The heat exchanger, as set forth in claim 1, wherein the upper tubular head element and lower tubular head element present a rectangular cross section.

3. The heat exchanger, as set forth in claim 2, wherein the through slots present an elongated rectangular contour, similar to and slightly smaller than that of the fluid conduction tubes.

4. The heat exchanger, as set forth in claim 3, wherein the through slots are arranged side-by-side, each extending substantially over the whole width of the inner longitudinal wall of the respective upper tubular head element and lower tubular head element.

5. The heat exchanger, as set forth in claim 2, wherein the through slots present an elongated rectangular contour, similar to and slightly smaller than that of the fluid conduction tubes.

6. The heat exchanger, as set forth in claim 1, wherein the nozzle is arranged in one of the closed ends of the upper tubular head element and lower tubular head element.

7. The heat exchanger, as set forth in claim 1, wherein the fluid conduction tubes have opposite end longitudinal edges in convex arc.

8. The heat exchanger, as set forth in claim 1, wherein the fluid conduction tubes incorporate small projecting side fins extended along at least a substantial part of the height of the fluid conduction tubes.