FIELD OF THE INVENTION

This invention relates to an electronic equipment cabinet. This invention has particular application to an electronic equipment cabinet for controlling the temperature environment for electronic equipment rack mounted within the cabinet, and for illustrative purposes the invention will be described with reference to this application. However we envisage that this invention may find use in other applications such as environment conditioning of cabinets and enclosures generally.

BACKGROUND OF THE INVENTION

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the referenced prior art forms part of the common general knowledge in Australia or elsewhere.

Many data processing centres are configured around microprocessor-based, standard rack-mounted equipment adapted to be mounted in metal racks within ventilated, generally metal cabinet enclosures. A typical data processing centre will have ranks of cabinets. Microprocessor based equipment and the associated hubs, hard drive and other NAS devices are generally configured to be air cooled, with integral fans and a generally front to rear air flow path through the equipment. The equipment is thereby rendered independent of the types of cooling systems required for mini- and mainframe computer hardware. This independence from connectable cooling means that control of the condition of the air within the building space environment containing a data processing centre is used to provide overall temperature control.

The dependence on control of the condition of the environmental air to control the operating temperature has several disadvantages. The systems are not readily scalable in that the plant must be engineered to deal with the worst case peak thermal load and temperature differential. There is a basic cost for idling capacity below the peak load. More importantly, environmental air control imposes planning geometry on the space to avoid hot spots. The corollary is that there is a risk of certain cabinets getting less than optimal cooling air.

A proprietary system of Sun Microsystems lnc provides more efficient rack cooling than standard datacenter cooling systems to significantly reduce energy consumption and increase effective compute density by up to 70 percent over in- row, environmental cooling options. The system comprises a cold water or refrigerant chilled rear door to the SUN BLADE 6048 modular system. It is a passive design that does not require additional fans or electrical power to function. The cooling system removes heat from the exhaust air blade unit exhaust air and requires minimal data centre footprint. Up to 35 kW of cooling capacity per door is available, a considerable increase over traditional raised floor cooling. The system is configured with humidity sensor-mediated thermostatic control to ensure that air exiting the system is not cooled below 2°C above the dew point.

This system is specifically tailored to its proprietary Sun Microsystems environment. There is a need for a more generalized solution. It is especially not suited to installations of CISCO ^® switches, where lack of control of the incoming air may cause a DPS shutdown.

SUMMARY OF THE INVENTION

In one aspect the present invention resides broadly in an electronic equipment cabinet including: a cabinet body having a ventilated rear wall and a front opening providing access to rack mounted equipment within the cabinet of the type having an integral cooling fan venting through said ventilated rear wall; a ventilated front closure assembly adapted to selectively close said front opening and including an air-to-coolant heat exchange panel and an air filtration medium adjacent the heat exchange panel on the equipment side thereof; and forming a continuous air flow path from outside of the cabinet body through the ventilated front closure, said rack mounted equipment and said ventilated rear wall; and heat pump means connected to said heat exchange panel and operable to thermally condition air passing through said air flow path.

In most cases, the heat exchange panel and heat pump means will be selected to condition air for cooling purposes, and for the purposes of description of the invention this function will be emphasized. However, it must be envisaged that under certain circumstances it may be desirable to condition the air to heat equipment to an optimum operating temperature. This heating may be part of a controlled cycle including cooling functions, wherein the transitions between heating and cooling are managed by operation of a reverse-cycle heat pump or desiccated heat pumps driving separate heat exchange evaporator and condenser units in the heat exchange panel.

The air filtration medium may be selected from woven or non-woven materials. It has been surprisingly determined that, even with control of operation of a panel by the use of a humidity sensor, highly localized conditions can promote the formation of condensation. In the usual usage a filter medium would be located on the outside of the panel to prevent dust from entering the heat exchanger panel.

However, the location of the air filter medium adjacent to the heat exchanger panel on the inside not only prevents dust circulation but prevents occasional instances of condensation from being entrained in the airflow. The air filtration medium may comprise an air filtration web mounted on a frame supported on the inner surface of the ventilated front closure. Alternatively the air filtration medium may comprise an air filtration web trapped by a mesh faced frame supported on the inner surface of the ventilated front closure

In the event of a failure of environmental air conditioning resulting in a significant increase in humidity and temperature, or in the event of an environmental increase in humidity, condensation may form on the panel. This may be dispersed by diffusion through the air filter medium or other media facing the panel. There may be provided a condensation collection tray at the foot of the panel. The tray may be associated with wicking means do dissipate any collected water as vapour under non-condensing conditions. In preferred embodiments of the present invention there is provided air curtain means adapted to pass air vertically downward across the face of the heat exchanger panel. For example there may be provided a header fan assembly comprising housing for a barrel fan impeller and having a directional slot directing an air curtain across the face of the heat exchanger panel. It has been found that the use of an air curtain in this manner disturbs the air ahead of the panel and adds some condensation control. This is a surprising result.

The equipment may be supported in the cabinet on support means which may comprise a standard or proprietary racking arrangement for one or more units of equipment. In certain embodiments of the present invention, the support means is a racking arrangement mounted within a metal equipment cabinet. Such cabinets are usually configured for airflow, having a net flow path from the front and/or floor and venting to the back and/or top.

The heat exchange panel may comprise a front closure for a cabinet housing the support means and the equipment supported thereby. The front closure may include a frame member defining a front aperture into which is mounted the heat exchange panel. The front closure may be removably secured to the cabinet. Alternatively the front panel may be hinged to the cabinet in the form of a door. Equipment may be stacked vertically in 19" (480mm) standard equipment racks in standard metal cabinets, wherein the front closure may replace the standard cabinet front door.

Cabinet closure-forming heat exchange panels have a particular advantage in that the cooling air inlet vents of the rack-mounted equipment can be maintained in relatively close proximity to the heat exchanger. Accordingly the cooling air passing into the equipment has for the most part passed through only that portion of the heat exchanger adjacent the equipment. The heat exchanger may include separately cooled zones corresponding to the position of the respective equipment items. However, where the heat exchanger is monolithic, the localization of air flow means that heat transfer occurs most in the region of the equipment. The heat is then distributed by the coolant and/or by conduction throughout the heat exchanger body depending on the cooling method employed. The effect is one of self regulation where the cooling effort supplied by the heat exchanger is automatically proportional to the population of equipment items in the cabinet.

The heat exchange panel may be associated with other air conditioning devices such as upstream particulate filters including HEPA filters, adsorbents, and the like. For example, in cabinet closure types of heat exchanger panels, the frame may include a mount for a filter assembly, such as a slide-in mount for a filter assembly having a bordering frame.

The heat exchange panel may be selected from any suitable heat exchange means including but not limited to solid state cooling devices, Carnot cycle heat pump or phase change regenerative cooling or Siemens cycle heat pump. For example the heat exchange panel may comprise the evaporator unit or reverse cycle evaporator/condenser unit of a conventional refrigeration plant. The heat exchanged by the heat exchanger panel may be disposed of the local environment. However, it is preferred that the heat be conveyed for remote disposal or recovery. For example the radiator of the heat pump may be co- located with the heat exchanger and coupled to a heat disposal exchanger cooled by air or liquid coolant. Where conventional refrigeration plant is used, the heat exchanger may be connected in circuit with a remote compressor/condenser assembly.

Where remote refrigeration plant is used, this may be of the single head or multi- head design. For example, there may be used a remote compressor/condenser unit that is capable of operating two or more heat exchange panels such as the abovementioned cabinet door units.

The heat exchange panel may be associated directly or indirectly with control means for monitoring and controlling the heat pump activity of the panel. For example, the heat exchange panel may include thermally conductive parts including a reference part having a transducer or other sensor mounted thereon. The sensor may be used to control a TX valve or other suitable scaling device selected according to the type of heat pump and the direction of the cycle at the time. Cabinet enclosures or other housings may include sensors to detect any one of both of temperature and air flow. In addition or in the alternative, the operating temperature may be sensed and appropriate control signals generated by monitoring means associated with the equipment perse.

In a further aspect the present invention resides broadly in a method of temperature-controlling electronic equipment of the type having a native thermal regulating air flow, including supporting the equipment relative to a heat exchange panel having a heat exchanging air flow path therethrough, and operating heat pump means connected to said heat exchange panel to thermally condition air passing through said heat exchanging air flow path, whereby temperature regulating air is drawn by said native thermal regulating air flow from said heat exchanging air flow path.

Apparatus in accordance with the foregoing may be powered by energy efficient means such as direct solar to LV compressor technology or may be integrated into the grid by conventional solar-to-inverter technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the following non-limiting embodiment of the invention as illustrated in the drawings and wherein:

Fig. 1 is an isometric view of apparatus in accordance with the present invention;

Fig. 5 is a plot of air flow through the apparatus of Fig. 1 ; Fig. 6 is; a plot of dew point inside the equipment cabinet of the air flow through the apparatus of Fig. 1 Fig. 7 is a plot of air temperature inside the equipment cabinet of the air flow through the apparatus of Fig. 1 ;

Fig. 8 is a plot of high temperature test air temperature passing into the equipment cabinet of the apparatus of Fig. 1 ; Fig. 9 is a plot of high temperature test air temperature having passed into the equipment cabinet of the apparatus of Fig. 1 ; and

Fig. 10 is a plot of the evaporator core temperature during the high temperature test of Figs. 8 and 9.

In Fig. 1 there is provided an electronic equipment cabinet including a cabinet carcass 15 mounting rack mounted computer equipment 16 in a conventional manner. The equipment is fan cooled and exhaust air 17 exits at the rear of the cabinet 15. A front closure assembly 11 is hinged by lift-off hinges 12 and is shown in an open position for servicing the front closure 11 and/or the racked equipment 16. Figs. 2-4 illustrate the exploded components of the front closure 11.

The front closure assembly 11 is built up on a door frame 14 is supported on the cabinet 15 by the hinges 12. An outer filter and screen assembly 16 is supported on the outer face of the door frame and includes a perforated metal protective screen. The lower edge of the door frame 14 is provided with a condensation trap 20.

The door frame 14 supports on its inner face an evaporator assembly 11 connected to a remote, approximately 2kW heat pump capacity, compressor/condenser assembly (not shown). The evaporator assembly includes regulation elements including a combined dew point sensor and thermostat 13. The suction and delivery lines 18 are connected by flexible lines to enable operation of the door. A non-woven filter web 19 acts a micro-droplet catcher on the inner face of the door assembly.

In use, the equipment 16 rack mounted in the cabinet 15 operates and generates heat. Internal sensors switch internal fans drawing cooling air from front vents and exhausting air through rear vents. The fans are thermally switched to save energy. Fig. 5 illustrates a data-logged period of time from 2300hrs to 0541 hrs of an installed stack of equipment having 6 fan modes in total. Environmental and peak processing load variables results in a flux of air from front to back of the cabinet. When all units are at maximum cooling, the maximum velocity V _max measured through the plane of the door assembly is approximately 23 m.min ^"1 . The plot of Fig. 5 shows integer air flows being highest from 2200 to 0200 and lowest from 0200 to the end of the log, forming in essence two broad cooling states.

The evaporator assembly 11 is operated under the primary control of the thermostat 13 and secondary control of the dew point sensor. Figs. 6 and 10 indicate an initial state of fluctuating dew point and temperature under load from start-up at 2300 to 0000, as the oscillating feedback loop of temperature and dew point operate the panel. After 0000, an approximate steady state operating temperature of the evaporator panel per se is reached (Fig. 10).

The dew point of air on the equipment side of the evaporator assembly 11 plots an average curve from about 23.8°C at 0000 to a broad peak of about 25.25 centred about 0300 (Fig. 6). This is a measure of the absolute moisture content of the environmental air. Simultaneously, the temperature plot curve of Fig. 7, measuring the exhaust air temperature from the cabinet, slowly increases from 30 ⁰ C at 2300 to a broad peak of about 31.1 ⁰ C between 0100 and 0200, followed by a steep decline corresponding exactly to the switching off of 2/3 of the cooling fans at 0200. The minimum temperature of 28.8°C is safely above the dew point at the same time, as is the dew point at each relevant point of the air temperature plot, despite there being no direct coupling of the dew point (dependent only on the environment) and temperature (dependent on both control feedback and equipment thermal load) plots.

In Figs 8 and 9, there is illustrated the results of a thermal stress test where hot air is applied to the exterior front of the evaporator assembly. Fig. 8 is the plot of temperature against time measured by a probe supported adjacent to but thermally insulated from the evaporator assembly. The plot shows that the air temperature increased steeply from start up at just after 2300 to 60 ⁰ C and then increased more or less smoothly to a plateau of about 68.3°C. At the same time, the exit air temperature plot of Fig 9 shows two plateaus, a first between 0000 and 0200 of about 34.5°C and a second between 0200 and 0500 of about 33.5°C. These plateaux correspond exactly to the peak and off-peak processing load cooling requirements. The comparison indicates that apparatus in accordance with the present invention can cope with environmental shock such as long term environmental air conditioning failure.

It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is set forth in the claims appended hereto.