Abstract:
An explosion-proof enclosure including at least one heat exchanger for active thermal management. Equipment within the enclosure produces heat within the enclosure, while the at least one heat exchanger removes heat produced from the equipment and manages the internal temperature of the enclosure to a level suitable for hazardous locations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of and claims the benefit of U.S. patent application Ser. No. 12/466,249, titled “Explosion-Proof Enclosures with Active Thermal Management By Heat Exchange” and filed on May 14, 2009, now abandoned in the name of Joseph Michael Manahan et al, the entire disclosure of which is hereby fully incorporated herein by reference. This application also is related to U.S. patent application Ser. No. 12/435,807, titled “Explosion-Proof Enclosures with Active Thermal Management Using Sintered Elements” and filed on May 5, 2009, in the name of Joseph Michael Manahan et al, the entire disclosure of which is hereby fully incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to explosion-proof enclosures, and, more particularly, to explosion-proof enclosures having active thermal management capabilities using heat exchange. 
     BACKGROUND 
     Automation equipment can be used to preserve the life of devices such as motors and pumps by improving device performance. However, the installation of automation equipment in hazardous or explosive environments typically has been avoided due to the high heat generated by components of the automation equipment, which could result in an explosion. Hazardous area requirements dictate that such equipment must be sealed from the surrounding atmosphere to fully contain any possible sources of ignition within the enclosure, thus preventing propagation of an explosion. 
     The automation equipment could potentially be housed in an explosion-proof enclosure. Currently, explosion-proof enclosures rely on conductive heat transfer for dissipating heat produced by equipment within the enclosure. However, these enclosures do not adequately dissipate the heat produced by the automation equipment within and thus could cause a decrease in the life of the equipment or lead to an explosion within the enclosure. As a result, automation equipment is typically installed outside the boundaries of the hazardous area and long electrical cables are run to the devices within the hazardous area. Several disadvantages to this configuration exist. For example, this configuration results in lack of control at the device, as well as an increase in installation, and/or maintenance costs. 
     Therefore, a need exists in the art for an explosion-proof enclosure having automation and other equipment that can provide active thermal management in a hazardous area. 
     SUMMARY 
     The present invention can satisfy the above-described need by providing enclosures for use in hazardous areas and having heat exchangers. As used herein, the term “heat exchanger” refers to any device that transfers heat from one medium to another or to the environment. The heat exchangers aid in regulating the internal temperature of an enclosure by actively cooling or heating equipment housed within the enclosure. 
     The enclosures of the present invention include a heat exchanger device coupled thereto. In some aspects, the heat exchanger is a thermoelectric cooler, a shell and tube heat exchanger, a plate heat exchanger, or a spiral heat exchanger. The enclosures include equipment housed therein. A heat exchanger is in communication with the internal equipment and external environment, and actively transfers heat from within the enclosure to outside of the enclosure, thereby removing heat produced from the equipment within the enclosure. In certain aspects of the invention, the heat exchanger actively transfers heating from outside the enclosure to within the enclosure, thereby heating the equipment within the enclosure. In certain aspects of the invention, the heat exchanger device are controlled by a control system having a sensor and a controller. 
     The enclosures also can include at least one fan positioned proximate to the heat exchanger device. The fan can be positioned within the enclosure or externally mounted to the enclosure. The fan can be controlled by a control system having a sensor and a controller. 
     These and other aspects, objects, and features of the invention will become apparent to those having ordinary skill in the art upon consideration of the following detailed description of exemplary embodiments exemplifying the best mode for carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an explosion-proof enclosure with the cover removed according to an exemplary embodiment. 
         FIG. 2  is a semi-transparent frontal view of another explosion-proof enclosure according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     This application discloses enclosures having active thermal management capabilities. The enclosures include a heat exchanger that aids in dissipating heat from within the enclosure. The enclosures can be used for both general purposes and in hazardous areas. 
     The present invention may be better understood by reading the following description of non-limiting embodiments with reference to the attached drawings wherein like parts of each of the figures are identified by the same reference characters. 
       FIG. 1  shows a perspective view of an explosion-proof enclosure  100  with a cover (not shown) removed.  FIG. 2  shows a semi-transparent frontal view of an explosion-proof enclosure  200  with a cover ( 210 ) coupled to the housing  102 . The enclosures  100 ,  200  each include a rectangular housing  102 . Each housing  102  includes a top wall  102   a , a bottom wall  102   b , two side walls  102   c , a rear wall  102   d , and a cavity  102   e . Each housing  102  also includes a flange  102   f  extending orthogonally from the top, bottom, and two side walls  102   a ,  102   b ,  102   c . In certain embodiments, the housing  102  is constructed from aluminum and is a NEMA 7 compliant enclosure for indoor or outdoor use in locations classified as Class I, Groups A, B, C, or D. 
     Each enclosure  100 ,  200  also includes automation equipment  110  positioned within the cavity  102   e  and coupled to the rear wall  102   d . In alternative embodiments, the automation equipment  110  can be coupled to the top wall  102   a , the bottom wall  102   b , or one of the side walls  102   c . The automation equipment  110  produces heat within the enclosures  100 ,  200  which should be dissipated to maintain a desired temperature within the enclosure  100 ,  200 . In certain embodiments, the automation equipment  110  may include a controller, such as a variable frequency drive (VFD) that controls the frequency of electrical power supplied to an external device, such as a pump or a motor (not shown). In certain embodiments, the automation equipment  110  may also include a transformer, a programmable logic controller (PLC), and/or a line reactor. 
     Each enclosure  100 ,  200  also includes a heat exchanger system  111  that includes a heat exchanger  120  and a plate  130 . The heat exchanger  120  in  FIG. 2  is coupled to the exterior of the housing  102 . The heat exchanger  120  may be coupled to the housing  102  by any suitable means, such as by mating threads or by bolting a flange (not shown) on the heat exchanger  120  to the housing  102 . In certain alternative embodiments, as shown in  FIG. 1 , the heat exchanger  120  can be positioned in proximity to the housing  102  but not be attached. 
     The plate  130  of the heat exchanger system  111  is positioned within the cavity  102   e . In certain embodiments, the plate  130  is coupled to the automation equipment  110 . In certain embodiments, as shown in  FIG. 2 , the plate  130  also is coupled to the side wall  102   c . The plate  130  is fabricated from thermally conductive material. Suitable examples of thermally conductive materials include, but are not limited to, copper, aluminum, titanium, stainless steel, other metal alloys, and thermally conductive polymers. In certain embodiments, the plate  130  may be constructed from multiple thin plates. The size and shape of the plate  130  can be configured based on the amount of heating or cooling desired. In certain embodiments, the plate  130  is constructed from copper or aluminum. 
     The heat exchanger  120  is in communication with the plate  130  via inlet pipe  134  and outlet pipe  136 . The inlet and outlet pipes  134 ,  136  are coupled to the heat exchanger  120  to the plate  130  through the side wall  102   c . The inlet and outlet pipes  134 ,  136  may be sealed within the side wall  102   c  so as to maintain the hazardous rating integrity of the enclosure  100 . In certain embodiments, the automation equipment releases heat, which is absorbed by the plate  130 . A cooled fluid flows from the heat exchanger  120  through the inlet pipe  134 . The cooled fluid enters a cavity (not shown) within the plate  130  and absorbs heat from the plate  130  before exiting the enclosure  100  through outlet pipe  136  as a heated fluid. The heated fluid returns to the heat exchanger  120  where it is cooled again before returning to the plate  130  via inlet pipe  134 . 
     In certain alternative embodiments, the enclosures  100 ,  200  may include equipment (not shown) that requires heating. In these instances, a heated fluid flows from the heat exchanger  120  through the inlet pipe  134 . The heated fluid enters the cavity (not shown) within the plate  130  and gives off heat to the plate  130 , which in turn heats the equipment within the enclosure, before exiting an enclosure  100 ,  200  through outlet pipe  136  as a cooled fluid. The cooled fluid returns to the heat exchanger  120  where it is heated again before returning to the plate  130  via inlet pipe  134 . 
     The heat exchanger systems (e.g., heat exchanger system  111 ) of the present invention can be any device capable of heating and/or cooling equipment within an enclosure  100 ,  200  by heat transfer. Suitable examples of heat exchanger devices include, but are not limited to, Peltier devices or thermoelectric coolers, shell and tube heat exchangers, plate heat exchangers, and spiral heat exchangers. In certain embodiments, the heat exchanger devices are integrated into the housing  102  and a first portion of the heat exchanger device interfaces with the interior of the enclosure  100 ,  200  and a second portion of the heat exchanger device is positioned exterior to the enclosure  100 ,  200 . 
     In certain embodiments, as shown in  FIG. 2 , a fan ( 240 ) may be positioned within the housing  102  and proximate to the plate  130  to facilitate heat transfer. The fan  240  can be powered by an internal power source, such as a battery (not shown), or receive power from a source (not shown) external to the enclosure  200 . In certain alternative embodiments, as shown in  FIG. 1 , a fan ( 140 ) may be externally mounted to the housing  102  to facilitate heat transfer. One having ordinary skill in the art will recognize that any number of configurations having a fan are possible. 
     In certain embodiments, as shown in  FIG. 2 , the enclosure  200  may include a control system ( 220 ) for monitoring and controlling the heat exchanger system  111 . In certain embodiments, the control system  220  monitors and controls the fan  240 . The control system  220  generally includes a sensor  230  that is coupled to a controller  222  that controls the heat exchanger system  111  and/or the fan  240 . The sensor  230  actively or passively monitors conditions within the enclosure  200 . Based on the conditions within the enclosure  200 , the controller  222  can turn on or off the heat exchanger system  111  and/or the fan  240 . For example, the sensor  230  may be a temperature gauge that senses the temperature within the enclosure  200 . When the sensor  230  indicates that the temperature within the enclosure  200  is too high, the controller  222  turns on the heat exchanger system  111  and/or the fan  240  inside the enclosure  200  to remove heat from within the housing  102  to an exterior of the housing  102 . Similarly, when the sensor  230  indicates that the temperature within the enclosure  200  is low, the controller  222  can turn on the heat exchanger system  111  and/or the fan  240  externally mounted to the enclosure  200  to heat the air within the enclosure  200 . In some embodiments, the control system  220  cycles on and off passively. For example, the control system  220  can cycle such that the heat exchanger system  111  and/or the fan  240  is active for ten minutes every thirty minutes. In certain embodiments, the control system  220  includes a sensor  230  capable of detecting humidity changes within the enclosure  200 . If the sensor  230  detects that the relative humidity within the enclosure  200  is too high, the control system  220  can turn on the fan  240  inside the enclosure  200 . In certain other embodiments, the control system  220  includes a sensor  230  capable of determining whether an explosion has occurred by detecting a rapid temperature or pressure change. Upon detection of an internal explosion, the sensor  230  communicates the state change to the controller  222 , which communicates the state change to a local indicator (not shown) or wirelessly to a remote location. One having ordinary skill in the art will recognize that the control system  220  can be programmed any number of ways to meet specifications of a given area and include any number or type of sensors (e.g., sensor  230 ) to determine various states within the enclosure  200 . In certain embodiments, the control system  220  is controlled wirelessly by a user in a remote location. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to a person having ordinary skill in the art and the benefit of the teachings herein. Having described some exemplary embodiments of the present invention, the use of alternative configurations having heat exchangers in communication with an enclosure is within the purview of those in the art. For example, the heat exchanger system can be positioned on any wall of the enclosure or a portion may be external to the enclosure. Additionally, while the present application discusses a single heat exchanger external to the enclosure, it is understood that a number of other heat exchangers may be used based on the heat transfer properties desired and using the teachings described herein. In addition, the exemplary embodiments of the present invention may be used to actively displace cold air from within the enclosures to the atmosphere. While numerous changes may be made by one having ordinary skill in the art, such changes are encompassed within the scope and spirit of this invention as defined by the appended claims. Furthermore, the details of construction or design herein shown do not limit the invention, other than as described in the claims below. It is therefore evident that the particular exemplary embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.