DESCRIPTION

Cross-Reference to Related Applications

This application claims the benefit of U.S. Provisional Application No. 62/437,731, filed on December 22, 2016. The entire disclosure of the above application is incorporated herein by referenced.

Technical Field and Background of Invention

The present invention relates generally to the field of heat exchangers and, more particularly, the invention relates to the field of heat exchangers integrated into housings for electrical, data, and telecommunication equipment.

Generally, a heat exchanger is a device used to transfer heat between one or more fluids. Heat exchangers maybe employed for many different reasons including to transfer heat away from moving parts, electrical components and other systems, which generate an undesirable amount of heat. In one such application, it is desirable to transfer heat from industrial equipment such as a housing or a cabinet, which may contain electrical, data, telecommunication equipment, and the like. The electrical equipment (herein referred to as "equipment") may be electrical controls, telecommunication systems, power switching and circuits, data systems or other sensitive electronics requiring that temperatures be maintained.

When equipment is deployed outdoors, it is potentially exposed to adverse environmental conditions including precipitation and humidity. Such conditions are problematic for electrical data, telecommunication equipment, and the like because moisture can damage such components. With respect to prior art equipment cabinets, it is common in the prior art to mount an air-to-air heat exchanger onto the cabinet, even where the cabinet will be placed in service outdoors and exposed to the weather. Air-to-air heat exchangers are utilized in the telecommunications, industrial and other electronics industries (herein referred to as "industry") to provide heat removal from equipment and/or removal of heat from cabinet/structure containing equipment generating heat.

In general, heat exchangers are used for heat removal applications where the temperature inside the equipment or inside a cabinet or structure containing electrical equipment is permitted to be higher than the outdoor temperature but some heat removal is required to maintain acceptable temperatures. For instance, a common application may allow indoor (within the equipment and/or within a cabinet/structure containing the equipment) temperatures to be up to 131 F. The design outdoor temperature is generally 90 to 115 F, which results in a cooler temperature exterior to the equipment or cabinet/structure containing the equipment relative to the permitted indoor temperature. This temperature differential between the indoor and outdoor allows heat transfer from the indoor to outdoor as heat moves from areas of high temperature to low temperature through convection. With air-to-air heat exchangers, this heat transfer occurs via indoor and outdoor airflow passing through a common heat exchanger core within separate chambers of the core.

Such a typical prior art heat exchanger may have an inlet and an outlet which allows the air to circulate. The prior art heat exchanger may have a cover and/or a security/safety grille covering the inlet and the outlet. However, there is a problem in the art wherein moisture and other contaminates make their way into the cabinet via the heat exchanger. Complete separation of the indoor and outdoor airflow path with no mixing of outdoor air and indoor air is necessary to comply with various electronics operating environmental standards to ensure equipment is not damaged. Therefore, great care must be utilized in the design, manufacturing and maintenance of heat exchangers to ensure that contaminants, including water and dust, are not transferred from the heat exchangers outdoor airflow path to the heat exchangers indoor airflow path. Thus, the method of construction of the heat exchanger core, as well as, construction methods of integrating and sealing the core into the heat exchanger unit, is of paramount concern. Typically, manufacturers rely completely upon sealants in order to ensure that all sheet metal -to-core joints and fasteners are well sealed to prevent air and water intrusion from the outdoor airflow path to indoor airflow path. If these sealant barriers are not effective, air and water may enter the sensitive equipment or cabinet/structure containing the equipment thus potentially damaging the electronics. Many times the physical design constraints of the heat exchanger and/or cost considerations require that the openings be on the heat exchangers such that they not only allow air to freely enter the outdoor airflow path, but also water. When these openings are located above the heat exchanger core, the water may enter the opening on the heat exchanger cover and through an improperly sealed or maintained joint. As a result, water may infiltrate via gravity into the indoor airflow path and into the equipment or cabinet.

As a result of many design constraints and cost considerations, the heat exchanger industry has struggled mightily for many years with the introduction of water into the indoor airflow path via leaks from the outdoor airflow path. This has been a challenge due to a lack of physical barrier at the inlet and/or outlets of the outdoor airflow path, as well as poor manufacturing techniques or quality control with proper sealant systems. The intrusion of water entering the heat exchanger indoor airflow path may potentially damage the equipment. Additionally, even those heat exchangers that may have been sealed properly after years of service and without proper maintenance heater exchangers may experience water intrusion as sealants harden from exposure to environmental conditions.

Thus, there is a need in the art for an improved heat exchanger for equipment cabinets that reliably prevents moisture and other contaminations from entering the cabinets.

Summary of the Invention

The electrical and telecommunication industries, among others, require the application of heat exchangers on electrical equipment or cabinet/structure in particular environments, particularly outdoor and high moisture environments, and the industry has long struggled with water intrusion into the equipment or cabinet. The present invention, specifically the water deflector and associated gap (discussed further below), results in a significant reduction of water entering into the heat exchanger's outdoor airflow path. The present design provides a great benefit for applications where the openings are located above the heat exchanger core and where other design or cost constraints prevent a design that would otherwise prevent a direct path of water into the heat exchanger.

It is therefore an object of the present invention to provide a heat exchanger for an equipment cabinet that prevents moisture, including rain and other contaminate from entering the cabinet.

It is a further object of the invention to provide a heat exchanger for an equipment cabinet that may be used for applications the heat exchanger openings are located above the heat exchanger core and where other design or cost constraints prevent a design that would otherwise prevent a direct path of water into the heat exchanger. These and other aspects of the invention are achieved by providing a heat exchanger for an equipment cabinet having an air-to-air heat exchanger which includes an outdoor air inlet and an outdoor air outlet for transferring heat from the equipment cabinet. The heat exchanger also includes a water deflector, attached to the air-to-air heat exchanger, for protecting the cabinet from water and other contaminates, and a gap defined by the distance between the water deflector and the air-to-air heat exchanger. The heat exchanger also includes a cover for covering the water deflector and the air-to-air heat exchanger.

According to one embodiment of the invention, the heat exchanger prevents water from entering the cabinet when water is discharged, over a period of one hour, from a set of three nozzles at five psi located approximately fifty-six inches from the cover of the heat exchanger.

According to another embodiment of the invention, the water deflector further comprises a frame having a plurality of expanded mesh layers.

According to another embodiment of the invention, the plurality of expanded mesh layers equals four mesh layers and wherein two of the four mesh layers are corrugated in opposing direction.

According to another embodiment of the invention, the mesh layers are made of aluminum.

According to another embodiment of the invention, the water deflector includes a drain hole.

According to another embodiment of the invention, the cover includes a drain hole.

According to another embodiment of the invention, the water deflector is located on an upper opening of an upper portion of the heat exchanger. According to another embodiment of the invention, a lower opening of the heat exchanger is characterized by a lack of any water deflector.

Brief Description of the Drawing Figures

Features, aspects and advantages of a preferred embodiment of the invention are better understood when the detailed description is read with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a prior art heat exchanger attached to an equipment cabinet;

Fig. 2 is an isometric view of a prior art heat exchanger;

Fig. 2A is a partial view of the prior art outdoor air outlet of Fig. 2;

Fig. 3 is an exploded view of the prior art heat exchanger;

Fig. 4 is a side view of the prior art heat exchanger;

Fig. 5 is an isometric view of the heat exchanger according to the present invention;

Fig. 6 is an exploded view of the heat exchanger according to the present invention;

Fig. 7 is a side view of the heat exchanger according to the present invention;

Fig. 8 is an exploded view of the water deflector of the heat exchanger according to the present invention;

Fig. 9 is a side view of the water deflector of the heat exchanger according to the present invention;

Fig. 10 is a front view of the water deflector of the heat exchanger according to the present invention;

Fig. 11 is a bottom view of the water deflector of the heat exchanger according to the present invention; and Fig. 12 is drawing of water deflector test procedure.

Detailed Description

The present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present invention. The following example is provided to further illustrate the invention and is not to be construed to unduly limit the scope of the invention.

Referring to the drawings, Figures 1, 2, 2 A, 3 and 4 illustrate a typical prior art heat exchanger that allows moisture, including rain, as well as other contaminates to enter the equipment cabinet. Figure 1 reflects a typical prior art application of an air-to-air heat exchanger mounted on an electronics or telecommunication cabinet. Air-to-air heat exchangers are primarily the least costly heat exchanger in the industry and are thus used most frequently. Heat removal is accomplished by opposing airflow in two separate airflow paths at a particular temperature differential with these airflow paths crossing in separate chambers perpendicularly (or at various other angles) within a heat exchanger core. Cores may be designed out of various materials; however, they are most commonly aluminum. Figures 2, 2A, 3, and 4 illustrate the design of typical prior art heat exchangers. Although arrangement and size may vary from manufacturer to manufacturer and/or from capacity to capacity, all require an outdoor air intake opening and an outdoor air exhaust opening location. Without these outdoor openings, the heat exchanger would not function as no air movement would be provided through the outdoor chamber(s) of the heat exchanger core. Although these openings typically include standard grilles that comply with industry standards for safety and/or to prevent vandalism/theft, these grilles have openings that allow both air and water to freely pass with very little restriction. Of course, it is the intent to have air pass through the grille with as little restriction as possible, however, this also provides significant water introduction to the heat exchanger's outdoor airflow path and thus provides an opportunity for water leakage if the unit is not manufactured or maintained properly.

Referring now to Figures 5, 6, 7, 8, 9, 10 and 1 1 , the heat exchanger 10 of the present invention is designed to be employed in situations such that water may freely pass and, as such, the construction of the present invention significantly reduces the amount of water permitted to pass into the outdoor airflow path of the heat exchanger. As a result, any leaks that are present due to manufacturing defects and/or inadequate maintenance will be reduced significantly.

As shown in Figures 6, 7 and 8, a water deflector is used to create an indirect air path. This path minimally restricts airflow while greatly reducing water intake.

As shown in Figures 8, 9, 10 and 11, the water deflector 20 is constructed of a frame with four expanded mesh aluminum layers 23, 24, 25, and 26. Two of these sheets, 24 and 25, the middle sheets, are corrugated in opposing direction. As shown, sheet 24 has horizontal waves and sheet 25 has vertical waves. Sheets 24 and 25 may be rotated, but they must be installed with waves perpendicular to one another. Sheets 23 and 26 are aluminum mesh layers. The result is an indirect flow path where water is trapped and knocked down to drain prior to entering the heat exchangers airflow path 30.

As shown in Figures 5, 6 and 7, the heat exchanger 10 according to the present invention incorporates a physical separation 40 (herein referred to as a "gap") between the heat exchanger cover 50 and the front panel 60 of the heat exchanger 10. This gap 40, shown best in Figure 7, allows water deflected by a water deflector 20 to drain down to drain holes 52 rather than be channeled into the heat exchanger. As shown in Figures 7, 8 and 11, the water deflector 20 includes drains 52 and is installed within an airflow/water channel 30. The water deflected by the water deflector 20 will drain down and through the side of the cover 52 allowing the water to be diverted to the outdoor environment rather than entering the heat exchanger's outdoor airflow path, which flows from outdoor, air inlet 54 to outdoor air outlet 56.

Further, as shown in Figures 6 and 7, the water deflector 20 is only located on the opening 56 on the top, as this opening is above the heat exchanger core and all critical sheet metal and core joints. With the opening higher, any leaks would result in gravity drainage from the outdoor airflow path to the indoor airflow path. However, the lower opening 54 on the cover 50, as shown in Figures 6 and 7, is below the core and critical joints therefore any leaks at or below this opening are not critical, as water would drain out the bottom of the heat exchanger through other drain holes 57. Therefore, the lower air path is not required to include a separate water deflector.

Figure 12 is directed to test conditions to which the present invention meets and/or surpasses. The heat exchanger according to the present invention maybe tested using Underwriters Laboratory ("UL") Type 3R test, UL 50/50E. For a test pass, the unit must not receive any water within the enclosure that will affect the electronics, with a typical pass resulting in less than a dime size amount of water. The Type 3R test consists of water being discharged from three nozzles 70 at 5 psi located approximately 56 inches from the test specimen 10, with the test period being one hour.

Using the test apparatus 80 shown in Figure 12, which fully complies with the Type 3R test standard, the heat exchanger according to the present invention was tested as was a prior art heat exchanger such as shown in Figures 1, 2, 3 and 4. During the testing, water was captured within bags at the opening of the respective heat exchanger's front panel. The amount of water was weighed and the results were overwhelmingly successful with an approximate 95% reduction in water entering the heat exchanger outdoor airflow path 56 when the present invention is compared to the prior art heat exchanger of Figures 1, 2, 3, and 4.

The foregoing has described a heat exchanger for an equipment cabinet. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.