Abstract:
A compact refrigeration apparatus for cooling sealed electronics enclosures having a sealed electronics enclosure, a single closed liquid/vapor refrigerant circuit, a compact single speed refrigerant pumping device, fluid connection lines, a compact first heat exchanger comprised of one or more, a compact refrigerant flow control device, a compact second heat exchanger of a design that prohibits entrapment of liquids and particulates comprised of one or more fans, and a compact refrigerant apparatus electronic control circuit. An AC power supply and power supply converter operably coupled to and providing AC power either directly to the refrigeration apparatus AC motor component or operably coupled first to a DC rectifier component that then provides DC power to the refrigeration apparatus DC motor component, first heat exchanger fan motors, second heat exchanger fan motors and apparatus control circuit. A preferred embodiment includes one or more sensing devices measuring temperature at specific locations within the sealed enclosure and an electronic control circuit in communication with the sensing devices that controls the initiation, termination and duration of operation of the refrigerant pumping device.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    Manole, Dan M.; U.S. application Ser. No. 10/986,704; filed Nov. 12, 2004. 
     
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       DESCRIPTION OF ATTACHED APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    This invention relates generally to the field of thermal management of high power electronics and more specifically to a refrigeration apparatus for cooling sealed electronics enclosures. 
         [0005]    The electronic and electromagnetic components of a computer system require a stable environment to ensure proper operation. The components within a computer system generate a great deal of heat during use. Absent proper environmental control, including active heat dissipation, components can and will overheat, causing erratic behavior, malfunctions, or total component failure. The computer system market demands that state of the art systems have extremely high reliability and availability. Thus, systems are typically designed with one or more cooling components. The cooling components can consist of passive heat sinks and/or fans or blowers designed to move air over the components. Simple, active cooling can be accomplished by placing a single fan at an opening to an apparatus enclosure and blowing air in or out of the enclosure on a continuous basis. Naturally, the failure of such a fan will result in overheating leading to component failure. 
         [0006]    As electronic equipment increase in speed and density, the problem of removing the heat that is generated becomes a major problem. Add to this, the placement of electronic equipment into more and more harsh environments, such as outdoor exposure, where it becomes necessary to seal the electronics from external conditions. The present invention provides a system for removing heat from sealed electronics enclosures without exposing the electronics to potential damage from solar radiation, heat, cold, dirt, biologic material such as bacteria and fungus and moisture. When electronics are placed outdoors, the air quality and temperature can vary significantly. Solar heat load is also a factor that will be additive to the heat generated by the electronic components. Increased moisture and contamination can be harmful to the electronics and result in eventual and premature failure due to corrosion and contamination. A preferred solution is to seal out these harmful conditions, however this creates problems of detrimental heat accumulation within electronics enclosures. Not only can ambient air temperature vary throughout the day, but direct solar radiation can contribute to heat accumulation and must be removed at a rate equivalent to heat generation to allow the electronic devices to operate properly. 
         [0007]    Early solutions to heat removal have included components for improving the collection of generated heat and removing it via forced convection air flow. Simple devices to accomplish this have been integrated into sealed electronics enclosures including fans, heat sinks, thermosyphons and heat pipes as well as detached air conditioning/refrigeration systems that force chilled air or liquid through the enclosure to cool individual electronic components or enclosure air. For example, U.S. application Ser. No. 10/986,704 describes a self contained refrigeration unit, wholly detachable from the elctronics to be cooled, from which chilled air and presumably chill water can be transferred to heat generating electronics components or to cool air within an electronics enclosure. Locating electronics in indoor areas has permitted these methods to be effective because computers are often located in the same building as human beings. The steps necessary to make a comfortable work environment are compatible with those needed for adequate cooling of most electronic equipment. These methods still allow ambient air into electronics enclosures, but typical thermal management of indoor environments coupled with use of air filters result in conditions suitable for proper temperature and particulate control of electronic devices. Maintenance required for air filtering in such systems is not difficult because it can be performed by people who often occupying the same indoor work space. 
         [0008]    The traditional method for cooling electronics is through convection. Heat generated by high energy density electronics is removed by forcing air flow to pass over the surfaces of the device components. Improvements in cooling efficiency have been made by use of fans to focus cooling air flow and to creat turbulent air flow over heat generating surfaces. This method is acceptable as long as the condition of the cooling air flow does not vary with respect to air temperature and quality. As the temperature of the air approaches the upper temperature limits of the electronics, individual components can fail causing rapid systemwide shutdown. Contaminates in cooling air can collect on the heat transfer surfaces and reduce convection cooling efficiency. Although filters can be added, their maintenance can become cumbersome and expensive depending on their location and local conditions. If the enclosure is sealed preventing contact between ambient and enclosure air, heat sinks connecting electronic components to ambient will remove some heat, however the effectiveness of such systems are limited by both the available heat exchange surface area external to the enclosure and more importantly, the temperature of the ambient air into which the heat is rejected. As more heat is generated and accumulates within sealed enclsosures, the required surface area of heat sinks can increase to impractical dimensions. The amount of heat removed by the heat sink is also limited by the temperature difference between the inside and outside of the enclosure. The ambient air temperature can easily be high enough to exceed the safe operating temperature of the electronics. 
         [0009]    Another method to cool electronic devices has been through liquid spray cooling. The heat generating electronics are sprayed with a special liquid which is then collected and circulated through a heat exchanger to remove the heat. The cooled liquid is then collected and is sprayed over the electronics again to complete the cycle. This method works as long as the external temperatures do not approach the upper operating temperature limits of the electronics. As the ambient temperature approaches the limit of the electronic device, the spray system is unable to produce enough heat transfer to prevent failure. 
         [0010]    An addtional method of electronics cooling is through the use of a solid state system known as the Peltier device or thermoelectric cooler to remove heat. These systems can create as much heat as they remove and are typically energy inefficient adding the need for large supplies of electricity just for electronics cooling applications. Peltier devices therefore add complexity and exceesive cost to the thermal management of high power sealed electronics enclosures. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The primary object of the invention is to provide an efficient practical refrigeration apparatus of simple construction which will effectively remove heat generated by electronic components within sealed electronics enclosures. 
         [0012]    Another object of the invention is to provide an efficient practical refrigeration apparatus of simple construction which is compact and a portion of which can be integrated into sealed electronics enclosures. 
         [0013]    Another object of the invention is to provide an efficient practical refrigeration apparatus of simple construction which makes possible the removal of transient heat loads through the utilization of apparatus electronic control circuitry 
         [0014]    A further object of the invention is to provide an efficient practical refrigeration apparatus of simple construction which is energy efficient and will operate reliably for prolonged periods of time in inclement conditions. 
         [0015]    Yet another object of the invention is to provide an efficient practical refrigeration apparatus of simple construction which will operate in environments of high ambient temperature, vibration, shock, high humidity, dust, and water spray. 
         [0016]    Still yet another object of the invention is to provide an efficient practical refrigeration apparatus of simple construction that is more energy efficient that other cooling means, requires less maintenance than other cooling means and has large mean time berfore failure. 
         [0017]    In accordance with a preferred embodiment of the invention, there is disclosed a refrigeration apparatus for cooling sealed electronics enclosures comprising: A sealed electronics enclosure, a compact refrigeration apparatus having a single closed liquid/vapor refrigerant circuit, a compact single or variable speed refrigerant pumping device, a compact first heat exchanger comprised of one or more fans and fan motors, a compact refrigerant flow control device, a compact second heat exchanger comprised of one or more fans and fan motors, and a compact refrigerant apparatus electronic control circuit. A compact AC or DC power supply and power supply converter operably coupled to the refrigeration apparatus whereby electrical power is supplied to the refrigeration apparatus motor component, first heat exchanger fan motors, second heat exchanger fan motors and apparatus control circuit that is operably coupled to said closed loop refrigerant liquid/vapor circuit. 
         [0018]    In accordance with a preferred embodiment of the invention, there is disclosed a method of cooling sealed electronics enclosures using said refrigeration apparatus comprising the steps of: temperature measurement at one or more locations in said sealed enclosure, using measured temperature thresholds to initiate and terminate operation of said refrigeration apparatus, and using said refrigeration apparatus to remove heat from said sealed electronics enclosure by means of thermal energy transfer between the sealed enclosure air and the ambient environment external to the sealed enclsoure using compact heat exchangers. 
         [0019]    In accordance with a preferred embodiment of the invention, heat removal from sealed electronics enclosures is achieved by employing a partitioned two phase vapor compression system in which the compact first heat exchanger, functioning as a refrigerant evaporator, is disposed external to the electronics enclsoure and the compact second heat exchanger, functioning as a refrigerant condenser, is disposed internal to the sealed electronics enclosure both of which are in fluid communication with a refrigerant pumping device disposed external to the sealed electronics enclosure. The invention uses a standard refrigeration cycle to transfer heat from inside a sealed electronics enclosure to ambient air. The evaporator is mounted inside the sealed enclosure so as to completely seal enclosed electronics from outside conditions and improve evaporator function efficiency. As electronic components such as computer CPU&#39;s and capacitors generate heat during operation, the evaporator absorbs this heat and passes it to refrigerant fluid contained within evaporator tubing circuitry. The refrigerant absorbes thermal energy sufficient to reach its latent heat of vaporization and changes phase from a liquid to vapor. The refrigerant vapor passes out of the evaporator through refrigerant fluid connecting lines that pass through hermetically sealed enclosure penetrations and flows to the compressor where energy is added to increase its pressure. The pressurized refrigerant vapor is then pumped by the compressor to the condenser which transfers thermal energy from the pressurized refrigerant vapor to the atmosphere thereby causing it to condense to low pressure liquid. The refrigerant passes through an expansion valve installed between the condenser and evaporator where it again absorbs thermal energy from heat generating electronic components and evaporates to complete the cycle. 
         [0020]    Other objects and advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. 
           [0022]      FIG. 1  is a perspective, partially sectional view of one embodiment of a refrigeration system of the present invention configured to cool a sealed electronics enclosure. 
           [0023]      FIG. 2  is a cross sectional view of the refrigeration system of  FIG. 1  along line  1 - 1 . 
           [0024]      FIG. 3  is an elevational view of the refrigeration system of  FIG. 1  viewed from the right side of  FIG. 2 . 
           [0025]      FIG. 4  is a fluid flow diagram the refrigeration system invention. 
           [0026]      FIG. 5  is a cross sectional view of the refrigeration system of  FIG. 1  along line  2 - 2 . 
           [0027]      FIG. 6  is an electrical flow diagram of the operations that comprise the refrigeration system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    Detailed descriptions of the preferred embodiment are provided herein. It is to be understood, however, that the present invention may be embodied in various forms, therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner. 
         [0029]    Turning first to  FIG. 1  there is shown one embodiment of the self contained refrigeration system for sealed electronics enclosures, a computer or other electronics hereafter referred to as the sealed electronics enclosure refrigeration system (SEERS) S. SEERS  5  includes a sealed enclosure  6  fabricated of rigid material such as metal, plastic or other appropriate material, having operably disposed therein, a compact first heat exchanger in the form of an evaporator  9 , an air flow generating device in the form of a bank of one or more evaporator fans and fan motors  10 , an electronics system or electronics backplane in the form of circuit board connections  8 , electronics circuit board(s)  12 , an air flow separator plenum panel  13 , and a SEERS  5  electronics controls circuit  18 . In the preferred embodiment of the illustrated SEERS  5 , the sealed enclosure  6  is constructed such that a thickness of insulation  7  may be applied for prevention of heat transfer through the sealed enclosure  6 .  FIG. 1  illustrates the SEERS  5  with the front cover panel  30  removed; disposed exterior to the SEERS  5  and attached adjacent to the rear outerwall of the sealed enclosure  6 , a compact second heat exchanger in the form of a condenser  16  and an air flow generating device in the form of a bank of one or more condeser fans and fan motors  17 . 
         [0030]      FIG. 2  schematically illustrates the SEERS  5  of  FIG. 1  along section view  1 - 1  and shows one embodiment of the SEERS  5  in which the condenser  16 , condenser fans  17 , condenser to evaporator refrigerant flow line  22 , flow control valve  19 , and compressor  20  are are all disposed exterior to the SEERS  5  and attached adjacent to the rear outerwall of the sealed enclosure  6 . Turning now to  FIG. 3  there is shown a side view of the exterior of the SEERS  5  that further illustrates one embodiment of the invention having a front cover  30  that may be attached to the four fixed side surfaces of the sealed enclosure  6  with screws, bolts, cam locks or other appropriate methods including the use of hinged connections on any front cover  30  edges. In alternative embodiments of the current invention, the front cover  30  may be relocated to replace any other exterior surface of the sealed enclosure  6 , or multiple covers may be used to permit multi-axis entrance to the SEERS  5  sealed enclosure  6 . 
         [0031]      FIG. 3  clearly illustrates the condenser to evaporator refrigerant flow line  22 , that in the preferred embodiment of the current invention passes through a sealed penetration in the rear outerwall of the sealed enclosure  6  and is in fluid communication with the condenser  15  by means of a flow control valve  19 .  FIG. 3  also shows the operable connection between the compressor and condenser as compressor to condenser refrigerant flow line  21 , and compressor  20  mounted by means of bolts, welds, straps or other appropriate methods, on compressor stabilizer base  31  that is mounted on the external surface of the sealed enclosure  6  by means of welds, screws, bolts or other appropriate methods. 
         [0032]    The Illustrated SEERS  5  embodiment requires no additional external or internal operably coupled devices or refrigerant connection lines to transfer heat from the SEERS  5  sealed enclosure  6  to ambient nor redirection of refrigerant or other chilled liquid to locations requiring heat transfer. A benefit of this embodiment of the current invention is the miniaturized volumetric footprint occupied by the SEERS  5  relative to the sealed enclosure  6  as compared to that of other two phase refrigerant cooling methods. Devices such as heat sinks, heat pipes thermosyphons or other appropriate heat dissipation devices may be fluidically or thermally coupled to local electronic components and the evaporator  9  to assist in the transfer of heat to the SEERS  5  evaporator  9 , however, the current embodiment of the invention relates to the use of directed airflow generated by one or more evaporator fans and fan motors  10  as the carrier medium of heat from the sealed enclosure  6  electronic components and electronics board(s)  12  to the SEERS  5  evaporator  9 . 
         [0033]    In the preferred embodiment the SEERS  5  evaporator  9  is equipped with thermal exchange features, such as metal fins or other conductive materials in high surface area arrangements to provide enhanced collection of heat from airflow directed by one or more evaporator fans and fan motors  10  across electronic components and electronics board(s)  12 . The term “thermal exchange features” used hereafter refers to any such mating surfaces attached to SEERS  5  evaporator  9  or condenser  16  through or over which heat can be passed to enhance heat transfer. In the preferred embodiment the SEERS  5  condenser  16  is equipped with thermal exchange features that inhibit entrapment of ambient particulates and moisture, and provide enhanced rejection of heat contained in compressed refrigerant vapor using airflow directed through or over the thermal exchange features by one or more condenser fans and fan motors  17 . Two particular benefits of the SEERS  5 , as compared to other cooling methods, arise as the result of the orientation of the evaporator  9  and evaporator fans and fan motors  10  located inside sealed enclsoure  6 , namely 1) the capacity to produce highly turbulent air flow leading to enhanced heat transfer rates from heat generating electronics and 2) the capability to integrate focused turbulent air flow over particularly troublesome electronics hot spots through the use of air knives, air nozzels, cold plates attached to hot spots or other appropriate devices. The SEERS  5  compressor  20  can be of any type appropriate to a achieve efficient compression of refrigerant vapor. In the preferred embodiment of the invention, the SEERS  5  compressor  20  may be a positive displacement compressor, rolling piston compressor, scroll compressor or of any other approriate and sufficiently compact type or design that is disposed external to the sealed enclosure  6  so as to prevent additional internal heat generation due to vapor compression kinetics. 
         [0034]      FIGS. 4 ,  5  and  6  schematically illustrate the operation of the SEERS  5  of  FIG. 1 . From fluid flow schematic  FIG. 4 , it is seen that during operation the compressor  20  collects suction side vaporized refrigerant from the evaporator  9 , mechanically compresses vaporized refrigerant and discharges the high pressure refrigerant to condenser  16 . Condenser  16 , disposed external to sealed enclosure  6 , removes heat  34  from the compressed refrigerant vapor to ambient by means of air flow generated by one or more condenser fans and fan motors  17  that is directed through or over thermal exchange features attached to condenser  16 . Upon cooling, high pressure refrigerant vapor condenses to liquid by means of falling film condensation inside condenser  16  and is directed through evaporator fluid line  22  to fluid flow control device  19 , such as a capillary tube or electromechanical valve disposed external to sealed enclosure  6 . Reduced pressure liquid refrigerant is released by fluid flow control device  19  to evaporator  9 , where it absorbs thermal energy generated by electronic components and electronics board(s)  12  disposed inside sealed enclosure  6  and is converted from liquid to vapor phase. Heat  35  transfer from electronic components and electronics board(s)  12  to evaporator  9  is enhanced by airflow through or over evaporator thermal exchange features from one or more evaporator fans and fan motors  10 . Refrigerant vapor generated inside of evaporator  9  is directed through fluid line  21  to compressor  20  and the cycle is then repeated. A primary advantage of the SEERS  5  operation as described is that the evaporator  9  is disposed inside of the sealed enclosure  6  isolating it from ambient heat sources that can significantly decrease its heat absorption efficiency. Additionally, only clean dry air within the sealed enclosure  6  is distributed over or through evaporator  9  thermal exchange features preventing particulate or moisture fouling of the thermal exchange features. Moreover, the SEERS  5  design described eliminates the neccessity for large diameter airflow duct penetrations through sealed enclosure  6  surfaces, therefore increasing the reliability of enslosure penetration seals since only small diameter penetrations are necessary to pass refrigerant tubing and electrcial power lines between the internal and external surfaces of sealed enclosure  6 . This latter feature also results in significantly less complex and less costly hermetic seal fabrication that possess longer mean time before failure. 
         [0035]      FIG. 5  illustrates section  2 - 2  of  FIG. 1 , which demonstrates one possible embodiment of evaporator airflow  14  circulation generated by one or more evaporator fans and fan motors  10 , that is heated across electronic components and electronics board(s)  12 , transfers heat through vaporization of liquid refrigerant in evaporator  9  and returns to absorb additional heat from electronic components and electronics board(s)  12  as chilled airflow  15 . In one embodiment of the invention an air flow separator plenum  13  of metal, plastic or other appropriate rigid material isolates heated evaporator airflow  14  from chilled airflow  15 , thereby preventing mixing of the two and subsequent loss of evaporator efficiency. In other embodiments, separator plenum  13  may be placed in other locations within sealed enclosure  6  or possess alternative physical geometry or spacial orientation. Separator plenum  13  may also be in the form of a perforated airflow distribution weir of various configurations, an air flow distribution manifold supplying air flow to one or more air knives, air nozzels or a combination thereof to provide optimum airflow turbulence, velocity or mass flow rate across SEERS  5  heat generating components. 
         [0036]    Referring now to  FIG. 6 , the current embodiment of SEERS  5  is illustrated as an electrical flow diagram. AC power supply/converter  25  is disposed inside sealed enclosure  6  and operably coupled to DC power supply  24 , also disposed inside sealed enclosure  6 . DC power supply  24  provides 24-volt DC power to one or more condenser fans and fan motors  17 , compressor  20 , SEERS electronic control circuit  18 , flow control valve  19 , and one or more evaporator fans and fan motors  10 , by means of wired DC power connections  33 . In the preferred embodiment of the invention, SEERS electronic control circuit  18  is operably coupled by wired digital or analog DC signal connections  32  to one or more temperature sensors  26  that may be attached to local heat generating sources or other devices or components, data acquisition electronics boards  12 , DC power supply  24 , one or more evaporator fans and fan motors  10 , one or more condenser fans and fan motors  17 , and compressor  20 .  FIG. 6  distinguishes the SEERS  5  components that are completely or partially disposed inside of sealed enclosure  6  and therefore exposed only to inside enclosure air  28  from those completely or partially disposed outside of sealed enclosure  6  and therefore exposed only to ambient air  29 . Disposal of AC power supply/converter  25 , DC power supply  24  and electronic control circuit  18  inside of sealed enclosure  6  provides two distinct advantages over prior art: 1) these are typically heat generating devices with efficiency curves inversely proportional to operating temperature, therefore cooling these components inside enclosure  6  prevents degradation of operating efficiency and 2) these components are protected from exposure to potentially damaging sunlight, particulates and moisture. 
         [0037]    As indicated in  FIG. 6 , temperature sensors  26  may either individually or in conjunction with specialized data acquisition electronics boards  12  provide digital or analog data to electronic control circuit  18  which uses stored computer algorithms to compare collected data to set point values that benchmark minimum or maximum acceptable component or SEERS  5  system operating threshold values. Benchmark values may be in the form of component temperature, air temperature, power consumption, duration of component operating interval, fault signals or other appropriate data that can be used to asses system function by the electronic control circuit  18 . Based upon comparing sensor data to benchmark values, electronic control circuit  18  may send signals by means of wired digital or analog DC signal connections  32  to DC power supply  24  causing initiation or termination of 24-volt DC power to one or all of SEERS  5  components. Electronic control circuit  18  may further be programmed to provide for initiation or termination of 24-volt DC power to one or all of SEERS  5  components based upon conditional timer algorithms, conditional power consumption algorithms, conditional temperature comparator algorithms or other appropriate methods that are meant ensure proper SEERS system operation and protection of any or all electronic components and electronics board(s)  12  from thermal damage. The benefits of the described embodiment of operation of the invention are: 1) criti SEERS  5  and electronic components and electronics board(s)  12  may be individually monitored for operational health by data acquired from temperature sensors  26  and/or other data acquisition electronics boards  12 , therefore all components can be evaluated individually and their health and operation prioritized, 2) electronic control circuit  18  can terminate or initiate operation of individual components whose function or lack thereof might otherwise cause damage to other components, and 3) electronic control circuit  18  can power down critical component(s) or all non-SEERS  5  related computer electronics while maintaining operation of the SEERS  5  cooling systems to enable proper cool down during or after shutdown and prior to reboot or startup. During normal operation, electronic control circuit  18  will evaluate acquired data from the sources described and initiate and terminate SEERS  5  cooling system operation in order to protect all system components from thermal damage. 
         [0038]    The refrigeration system of the present invention has been described herein as including a converter that is operably coupled to an AC power supply and which provides DC power to refrigeration system components. It is however also possible for the converter to be couple to a DC power supply and/or an AC power supply and therefore may use either power input type that is available to provide conditioned DC or AC power to all SEERS  5  component described. 
         [0039]    This invention has been described as A Compact Refrigeration Apparatus for Cooling Sealed Electronics Enclosures, but is intended to cover other applications involving electronic system cooling including, but not limited to, cooling liquid crystal display (LCD) glass in indoor and outdoor applications, cooling various video display lamps or light sources that generate heat within electronics enclsoures and combinations of computer electronics and video display systems integrated into a single sealed electronics enclsosure. 
         [0040]    This invention has been described as having an exemplary design leading to the noteworthy benefits also described herein. The present invention may however be further modified within the spirit and scope of this disclosure to therefore cover any variations, uses or adaptations of the invention using its general design and operational principles. 
         [0041]    While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.