NL2022808B1

NL2022808B1 - Equipment cabinet with rack and close-coupled cooling system

Info

Publication number: NL2022808B1
Application number: NL2022808A
Authority: NL
Inventors: Adrianus Henricus Van Der Kant Tom; Henricus Marinus Martinus Van Uden Eric
Original assignee: Prodrive Tech Bv
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-10-02
Also published as: WO2020193380A1; TW202045889A

Abstract

Equipment cabinet with rack and close-coupled cooling system Equipment cabinet (10), comprising an equipment rack (12) and a cooling system (13) for cooling equipment (121) mounted in the equipment rack, wherein the cooling system (13) comprises a variable speed fan (133) mounted to direct an air flow to a first side (122) of the equipment rack (12), a heat exchanger (131) for cooling air in the equipment cabinet, a pressure sensor (161, 162) for sensing a differential pressure in a flow path of the air flow, and a controller (15) operably coupled to the pressure sensor (161, 162) and to the fan (133). The controller (15) comprises a predetermined fixed value for the differential pressure and is configured to control a speed of the fan (133) so as to maintain the differential pressure sensed by the pressure sensor at the predetermined fixed value.

Description

Equipment cabinet with rack and close-coupled cooling system Technical field

[0001] The present invention is related to equipment cabinets comprising an equipment rack, such as for accommodating electric or electronic equipment modules in the rack, wherein the equipment cabinet is provided with a close-coupled cooling system for cooling the equipment in the rack. Background art

[0002] Equipment cabinets are used for accommodating electronic hardware, such as computing hardware, and comprise cooling systems to maintain the temperature of the electronic hardware between certain thresholds. Typically, these cabinets are located in server rooms or datacenters that provide a climatized and stable environment for these cabinets. A disadvantage of such server rooms is that energy is also consumed for controlling the climate of space not being occupied by the cabinets.

[0003] On the other hand, equipment cabinets with so-called close-coupled cooling systems are known which feature an internal cooling system comprising fans for maintaining an air flow in the cabinet and a heat exchanger which cools the air. Such cabinets offer the benefit that the cooling capacity is only targeted to cooling the computing hardware that resides in the cabinets.

[0004] An equipment cabinet of the above kind is known from US 2013/0081778, 4 April 2013, comprising an equipment rack and a cooling system, which comprises a heat exchanger with variable speed fans. The fans create a differential pressure. Pressure sensors are installed within the equipment rack to monitor a volume of air that is available to flow into the electrical components in the equipment rack. The pressure sensors are used in a feedback arrangement to adjust a speed at which the variable speed fans operate. A controller implements a programmable air flow volume to be maintained within each electrical component of the equipment rack. Accordingly, a variable pressure is dynamically adjusted to achieve the desired air flow volume.

[0005] Typically, cabinets are shipped to the end-user without computing hardware installed. Different hardware modules may be installed in different cabinets which affects the air flow. Moreover, the air flow may vary in time in a single cabinet, because of varying hardware being installed in the cabinet and the flow induced by the fans internal to the installed hardware. One disadvantage of the equipment cabinet of US 2013/0081778 is that the dynamic adjustment of variable pressure causes a varying force exerted on the (internal) fans installed in the computing hardware, which leads to reduced lifetime.

Summary of the invention

[0006] It is an aim of the present invention to overcome the above disadvantages.

[0007] According to a first aspect of the invention, there is therefore provided an equipment cabinet as set out in the appended claims.

[0008] An equipment cabinet according to the invention comprises an equipment rack, such as a rack used for accommodating electronic hardware or computing equipment modules, and a close-coupled cooling system for cooling equipment mounted in the equipment rack. The cooling system comprises at least one, and advantageously an array of variable speed fans mounted in the cabinet to direct an air flow towards, and advantageously through, the equipment rack. The cooling system further comprises a heat exchanger for cooling air flowing in the equipment cabinet, a pressure sensor for sensing a differential pressure in a flow path of the air flow, in particular in a flow path across the equipment rack, e.g. between a first side and a second side opposite the first side of the equipment rack. A controller is provided which is operably coupled to the pressure sensor and to the variable speed fan.

[0009] According to the present invention, the controller is implemented with a predetermined fixed value for the differential pressure, e.g. stored in a memory block. The controller is configured to control a speed of the variable speed fan so as to maintain the differential pressure sensed by the pressure sensor at the predetermined fixed value. The predetermined fixed value is advantageously between 2 Pa and 50 Pa, advantageously between 5 Pa and 25 Pa, for example 10 Pa.

[0010] Unlike the prior art, where a volume of air flowing through the equipment rack is maintained at a predetermined level, in the present invention, the air differential pressure along a flow path of the air, particularly across the rack, is maintained constant. By so doing, a constant pressure condition is experienced by the internal fans of the equipment modules mounted in the rack, regardless of power dissipation, number and type of installed modules, and regardless of the operation of the modules’ internal fans. This allows the modules’ internal fans to operate continuously under optimal conditions, which increases lifetime and/or reduces power consumption. When these internal fans are subjected to an overpressure, they can suffer from fatigue and spin at a slower rate, which leads to a temperature increase of the electronic components. This can lead to an increase in power consumption. Conversely, when the differential pressure across the internal fans of the equipment module in the rack is too small, insufficient heat can be removed from the electronic components.

[0011] Advantageously, the equipment cabinet comprises an airtight housing in which the equipment rack and the cooling system are arranged. As a result, the cooling system can maintain a closed loop air flow passing through the variable speed fan, the equipment rack and the heat exchanger. The equipment rack and the cooling system are advantageously arranged juxtaposed to each other in the housing, with the variable speed fan and the heat exchanger advantageously arranged one behind the other. An axis of rotation (spinning axis) of the variable speed fan is advantageously arranged oblique to a plane parallel to the front side of the equipment rack, advantageously at an angle between 30° and 60°, advantageously between 40° and 50° e.g. 45° to this plane. This reduces the footprint of the equipment cabinet, or allows for using larger fans for a given cabinet width.

[0012] Advantageously, the pressure sensor comprises an array of pressure gauges (e.g. two, three, or more pressure gauges), distributed along the rack. With such an array, pressure differences can be sensed for different areas of the rack, allowing each rack area to be controlled separately, e.g. by different variable speed fans, which can be arranged in an array as well. Furthermore, it may be advantageous to have an array having multiple sets of pressure gauges, e.g. two or three pressure gauges within each area of the rack.

[0013] The equipment cabinet can further comprise a temperature control system, comprising one or more temperature sensors for sensing a temperature of the air in the cabinet, and a flow control valve configured to adjust a flow rate of coolant fluid through the heat exchanger. Advantageously, the temperature control system is operated through a temperature control module of the controller which operates independently of a pressure control module of the controller configured to control the differential pressure. By so doing, the control of differential pressure is maintained largely independent of the temperature control in the cabinet. Brief description of the figures

[0014] Aspects of the invention will now be described in more detail with reference to the appended drawings, wherein same reference numerals illustrate same features and wherein:

[0015] Figure 1 represents a front view of an equipment cabinet according to the present invention;

[0016] Figure 2 represents a plan view of the equipment cabinet of Fig. 1;

[0017] Figure 3 represents a diagram of the controller of the equipment cabinet of Fig. 1;

[0018] Figure 4 represents a diagram of a power on sequence of a cabinet according to the present invention. Description of embodiments

[0019] Referring to Figs. 1 and 2, an equipment cabinet 10 according to the present invention comprises a housing 11 in which a rack 12 and a close-coupled cooling system 13 are arranged. The cabinet 10 has a bottom 101, a top 102, a front 103 and a rear 104. A door 111 can be provided at the front 103 in order to access the rack 12, e.g for installing or removing equipment modules into or from the rack. Door 111 hence advantageously faces a front side 122 of the rack 12. The housing 11 is advantageously airtight.

[0020] The rack 12 can be any suitable equipment rack for accommodating electric or electronic equipment or hardware modules 121, such as though not limited to computing hardware. Advantageously, rack 12 is a vertical rack, allowing for stacking different equipment modules 121 on top of one another in the rack 12. By way of example, rack 12 is a 19 inch rack.

[0021] As shown in the figures, the close-coupled cooling system 13 and the rack 12 are advantageously arranged side-by-side. Cooling system 13 comprises a heat exchanger 131 for cooling air inside housing 11. Heat exchanger 131 can comprise a network of ducts 132 through which a coolant fluid, advantageously a liquid, is configured to flow. Air flowing through the heat exchanger 131 exchanges heat with the coolant fluid flowing through the ducts 132, thereby cooling the air.

[0022] Heat exchanger 131 is connected to a cooling device 14 allowing to cool the heated coolant fluid. Cooling device 14 can be arranged outside housing 11, e.g. ontop of it. Alternatively, when a plurality of equipment cabinets are arranged in one room, an external cooling device (not part of the cabinet 10) can be connected to each of the cabinets 10. In the latter case, the cabinet 10 can comprise an inlet 136 and an outlet 137 for the coolant fluid. The inlet 136 and outlet 137 are in fluid communication with the network of ducts 132.

[0023] Cooling system 13 further comprises at least one, and advantageously a plurality of, variable speed fans 133. The variable speed fans 133 are advantageously arranged in an array extending parallel to the rack 12. Adjusting the fan speed of the variable speed fans allows for adjusting the flow rate of air displaced by the fans 133. Fans 133 are advantageously arranged such that air blown by the fans 133 is directed to the rack 12, in particular to a front side 122 of rack 12. In this case, the fans

133 are advantageously arranged in front of the heat exchanger 131. To this end, the spinning or rotation axis of variable speed fans 133 can be arranged in any suitable orientation. As shown in Fig. 2, the orientation can be at an acute nonzero angle to the front plane of rack 12 in order to reduce the footprint of cabinet 10.

5 [0024] Fans 133 allow for maintaining a flow of air through the rack 12, from one side, e.g. front side 122, to an opposite side, e.g. rear side 123, of the rack 12. This flow of air passes through the heat exchanger 131 dividing this air stream in a cold air stream 134 and a hot air stream 135. Cold air stream 134 exits the heat exchanger 131 and enters the rack 12, whereas the hot air stream 135 exits the rack 12, after having removed heat from the modules 121, and enters the heat exchanger 131.

[0025] The equipment module 121 mounted in rack 12 typically comprises its own fan for circulating air inside the module 121, e.g. from an air inlet to an air outlet of the module (not shown). Such internal fan may generate an air flow inside the module 121 which can be, but need not be, aligned or parallel to the air stream 124 through the rack 12 generated by the variable speed fan 133. By way of example, the internal fan may generate an air flow inside module 121 which is transverse to the air stream 124. Air streams 134, 135 and module internal air stream 124 hence form a closed loop.

[0026] The cabinet 10 is provided with a pressure sensor for sensing a differential pressure in the air stream 134, 135. The pressure sensor can comprise a set of a first pressure gauge 161 and a second pressure gauge 162, between which a differential pressure can be measured. The first and second pressure gauges are advantageously mounted to allow for monitoring a pressure drop of air through the rack

12. Advantageously, the first pressure gauge 161 is mounted at an air inlet side of rack 12, e.g. at the front side 122. The second pressure gauge 162 is advantageously mounted at an air outlet side of rack 12, e.g. at the rear side 123. The pressure gauges 161, 162 are advantageously arranged in a central area portion of the front side and rear side respectively, e.g. in the middle of a front side and a rear side of the rack 12.

[0027] The cabinet 12 further comprises a controller 15, arranged within housing 11. Controller 15 is connected to the pressure gauges 161 and 162 to read measured pressure values. Controller 15 is further connected to the variable speed fans 133 in order to control and adjust the rotational speed of the fans.

[0028] According to the present invention, the controller 15 is configured to maintain the differential pressure across the rack 12 constant. This is obtained by measuring the differential pressure between pressure gauges 161 and 162 and controlling the rotational speed of fans 133 so that the measured differential pressure is substantially maintained at a fixed value.

[0029] Unlike the prior art, where a volume of air flowing through the equipment rack is maintained at a predetermined level, in the present invention, the air differential pressure across the rack is maintained constant. By so doing, a constant pressure condition is experienced by the internal fans of the equipment mounted in the rack, regardless of power dissipation, number and type of installed modules, and regardless of the operation of the modules’ internal fans. This allows the modules’ internal fans to operate continuously under optimal conditions, which increases lifetime and/or reduces power consumption. When these internal fans are subjected to an overpressure, they can suffer from fatigue and spin at a slower rate, which leads to a temperature increase of the electronic components in module 121. This can lead to an increase in power consumption. Conversely, when the differential pressure across the internal fans of the module 121 is too small, insufficient heat can be removed from the electronic components.

[0030] It has been observed that an optimal value for the differential pressure across the rack 12 is between 2 Pa and 50 Pa, advantageously between 5 Pa and 25 Pa, and advantageously between 5 Pa and 15 Pa, e.g. about 10 Pa.

[0031] An array 16 of multiple pressure gauges 161 and/or 162 can be provided, instead of a single one, at one or both sides 122, 123 of the rack 12. Such an array can be beneficial to control differential pressure in different areas of the rack, e.g. top, bottom and middle. Yet alternatively, a pressure sensor can be provided for each variable speed fan 133 arranged in an array of variable speed fans 133 to advantageously control the speed of each variable speed fan separately.

[0032] The pressure gauges 161, 162 can be fixed to the rack 12. The pressure gauges 161, 162 can be formed of a single sensor which comprises a pair of tubes extending from the sensor and affixed to either side of the rack 12, advantageously in the middle of the front and rear side of rack 12. The tubes are mounted such that their longitudinal axes are perpendicular to the direction of the air streams 134, 135. The tubes can be equipped with dust rejecting caps.

[0033] Referring to Fig. 2, a flow control valve 138 can be provided in the network of ducts 132 allowing for controlling or adjusting the flow rate of coolant fluid through the ducts 132. Flow control valve 138 is connected to controller 15, which is advantageously configured to control the flow rate through valve 138.

[0034] The cabinet 10 can further comprise a temperature sensor 163, which is connected to controller 15 which is configured to read a temperature sensed by sensor 163. The temperature sensor 163 can be arranged at any suitable position within housing 11, e.g. at the rear 123 of rack 12, at the front 122 of rack 12, along cold air stream 134, or along hot air stream 135. A plurality of temperature sensors at different positions in the housing 11 can be provided. The controller 15 is advantageously programmed to adjust flow control valve 138 on the basis of the temperature sensed by temperature sensor 163. By increasing a flow rate of coolant fluid through ducts 132, a cooling capacity of heat exchanger is increased, which lowers the temperature of air stream 134. Adjusting flow control valve 138 allows controller 15 to control the temperature inside cabinet 10.

[0035] Referring to Fig. 3, controller 15 comprises a pressure control module 151 configured for controlling the pressure difference across rack 12. Advantageously, controller 15 additionally comprises a temperature control module 152 configured for controlling the temperature inside housing 11. Pressure control module 151 and temperature control module 152 advantageously operate independently of each other, i.e. they advantageously do not exchange any data between each other.

[0036] Pressure control module 151 comprises a memory block 153 in which a predetermined value of differential pressure across the rack 12, e.g. between the pressure gauges 161 and 162, is stored. The predetermined value is a fixed value advantageously set in factory and hence does not change during operation of the cabinet. The predetermined value can be as indicated hereinabove, e.g. between 2 Pa and 50 Pa. Pressure control module 151 is further advantageously configured to determine a pressure difference (i.e., differential pressure) between the outputs of pressure gauges 161 and 162. Pressure control module 151 is further configured to determine a difference between the predetermined value stored in memory block 153 and the pressure difference that is determined from the outputs of pressure gauges 161 and 162. This difference is fed to a fan control block 154 which is configured to determine a fan speed control signal. Fan control block 154 is coupled to the variable speed fan(s) 133 for supplying the fan speed control signal thereto.

[0037] In case an array 16 of pressure gauges is provided, pressure control module 151 may determine an average pressure for each side of the rack, in which case, the pressure control module 151 can operate as stated herein above based on the average differential pressure measured. Alternatively, it may be advantageous to divide the rack 12 up in different zones or areas, e.g. top, bottom and middle, and perform pressure control for each of these rack areas separately. In this case, a plurality of pressure control modules 151 can be provided in controller 15, one for each area of the rack that is to be controlled. Each of the pressure control modules can control one or more variable speed fans 133 mounted at a location corresponding to the rack area. In addition, each of the pressure control modules can read one or more pressure gauges

161, 162 which are mounted at positions corresponding to the rack area that is to be controlled.

[0038] Temperature control module 152 comprises a memory block 155 in which one or more predetermined threshold values for the temperature in the housing 11 are stored. By way of example, memory block 155 can store a temperature setpoint value, around which value the temperature control module 152 is configured to control the temperature in cabinet 10. Temperature control module 152 can be configured to control the temperature within a temperature range of 10°C or less about the temperature setpoint, advantageously 5°C or less about the temperature setpoint. In addition, or alternatively, memory block 155 can store a lower temperature threshold and an upper temperature threshold, which may be used for generating an alarm state when the temperature exceeds the lower or upper temperature threshold, e.g.in case of malfunction. The lower temperature threshold can be selected as a temperature level below which there is a risk of condensation within the cabinet, referred to as dewpoint. The upper temperature threshold can be selected as a temperature level above which there is a risk of overheating of the electronic components in the modules 121 of rack

12. Temperature control module 152 is configured to read an output from temperature sensor 163 and to compare the output with the one or more predetermined threshold values in a valve control block 156. Valve control block 156 is configured to determine a flow control signal, e.g. based on the difference or comparison between temperature threshold value(s) and the sensed temperature level, which is fed to flow control valve 138 in order to control the flow rate of coolant fluid through heat exchanger 131 and therefore the cooling capacity of heat exchanger 131.

[0039] Controller 15 can further comprise a diagnostics module 157 for monitoring an operational condition of the cabinet 10. Diagnostics module 157 can be connected to temperature sensor 163 for reading an output of the sensor. In addition, the cabinet 10 can comprise a temperature sensor 164 for sensing a temperature level of the coolant fluid flowing through ducts 132 and/or a flow rate sensor 139 for sensing a flow rate of the coolant fluid through ducts 132. Either one, or both sensors 164 and 139 can be coupled to diagnostics module 157, and diagnostics module 157 can be configured to read an output of either one or both sensors 164 and 139 and possibly compare the output with predetermined thresholds, which may be stored in a memory in diagnostics module 157. Based on the outputs of one or more of sensors 163, 164 and 139, the diagnostics module may determine whether an abnormal condition exists and output one or more alarm signals that may trigger a corrective action to safeguard components residing in the cabinet 10. By way of example, when the temperature of the coolant fluid is too low, there is a risk of condensation within housing 11. When this temperature is too high, there is a risk of overheating, and/or the heat exchanger 131 cannot operate appropriately.

[0040] The cabinet 10 can comprise a shut off valve 140 for closing the inlet 136 and/or the outlet 137 of ducts 132 to prevent inflow and/or outflow of coolant fluid. The shut off valve 140 can be a normal closed valve which needs to be powered to open the valve. Alternatively, the flow control valve 138 can additionally act as a shut off valve. The cabinet can comprise a power relay 158 to disconnect the rack 12 from the mains supply 171. Diagnostics module 157 can be connected to the shut off valve 140 and/or the power relay 158 and be configured to operate them in case an abnormal condition is determined.

[0041] The cabinet 10 can comprise an Ethernet network connection 172, and diagnostics module 157 may be connected to Ethernet connection 172, e.g. in order to send out an alarm signal.

[0042] Referring to Fig. 4, when the cabinet is started up in step 201, controller 15 is powered on while power relay 158 remains open and the rack 12 remains disconnected from the mains supply 171. In step 202, diagnostics module 157 may run to perform a status check in order to check whether an abnormal condition exists. In step 203, pressure control module 151 and/or temperature control module 152 may run to operate the variable speed fans 133 and the flow control valve 138, respectively. Steps 202 and 203 may be carried out simultaneously, or sequentially. In step 204, diagnostics module 157 has determined that the status is clear and no abnormal condition exists. In that case, diagnostics module 157 can operate power relay 158 to power the rack 12 bringing the cabinet 10 to a fully operational status.

Claims

CONCLUSIONS

An equipment cabinet (10), comprising an equipment rack (12) and a cooling system (13) for cooling equipment (121) mounted in the equipment rack, the cooling system (13) comprising: a variable speed fan (133) mounted to direct an air flow to a first side (122) of the equipment rack (12), a heat exchanger (131) for cooling air in the equipment cabinet, a pressure sensor (161, 162) for measuring a differential pressure in a flow path of the air flow, and a controller (15) operatively coupled to the pressure sensor (161, 162) and to the fan (133), characterized in that the controller (15) comprises a predetermined fixed value for the differential pressure and that the controller is configured to control a speed of the fan (133) to maintain the pressure differential sensed by the pressure sensor at the predetermined fixed value.

Equipment cabinet according to claim 1, wherein the predetermined fixed value is between 2 Pa and 50 Pa, preferably between 5 Pa and 25 Pa, preferably between 8 Pa and 12 Pa, preferably about 10 Pa.

An equipment cabinet according to any preceding claim, wherein the first side (122) is a front of the equipment rack (12).

An equipment cabinet according to any preceding claim, wherein the pressure sensor (161, 162) is configured to sense a pressure differential across the rack.

The equipment box of claim 4, wherein the pressure sensor (161, 162) is configured to sense a pressure difference between the first side (122) and a second side (123) of the equipment rack opposite the first side.

The equipment box of claim 5, wherein the pressure sensor includes a first pressure gauge (161) disposed on the first side (122) and a second pressure gauge (162) disposed on the second side (123).

An equipment cabinet according to any of claims 4 to 6, wherein the pressure sensor comprises an array (16) of pressure gauges, the array extending parallel to the equipment rack (12).

The equipment box of claim 7, wherein the regulator (15) is configured to determine a differential pressure for each of the different pressure gauges (161, 182) of the array (186), the different pressure gauges corresponding to individual positions in the equipment rack ( 12).

An equipment box according to any one of the preceding claims, wherein the heat exchanger (131) comprises a channel (132) for passage of a cooling fluid for cooling the air and a flow control valve (138) for controlling a flow of the cooling fluid. through the channel (132), the regulator (15) being operatively coupled to the flow control valve (138).

An equipment box according to any one of the preceding claims, comprising a temperature sensor (163) configured to sense a temperature of the air, the controller (15) being operatively coupled to the temperature sensor (163).

An equipment box according to claims 9 and 10, wherein the controller (15) is configured to control the flow control valve (138) based on a temperature sensed by the temperature sensor (163).

An equipment box according to claim 10 or 11, wherein the controller (15) comprises a pressure control module (151) configured to control the differential pressure and a temperature control module (152) configured to control the temperature.

The equipment box of claim 12, wherein the pressure control module (151) and the temperature control module (152) operate independently such that the pressure differential is controlled independently of the temperature.

Apparatus cabinet according to any of the preceding claims, which is airtight.

An equipment cabinet according to any preceding claim, comprising a housing (11) having a bottom (101), a top (102), a front (103) and a back (104), the equipment rack (12) being located between the bottom (101) and top (102), and wherein the variable speed fan (133) and heat exchanger (131) are positioned laterally of the equipment rack (12), viewed from the front (103).

An equipment box according to claim 15, wherein the variable speed fan (133) and the heat exchanger (131) are arranged between the front (103) and the rear (104) and one behind the other, the fan (133) with variable speed is arranged to maintain a closed loop air flow passing through the equipment rack (12) and through the heat exchanger (131).

The equipment cabinet of claim 15 or 16, wherein the variable speed fan (133) includes a series of fans extending between the bottom (101) and the top (102).

An equipment box according to any of the preceding claims, wherein an axis of rotation of the variable speed fan (133) is inclined to a plane parallel to the first side (122) of the rack, preferably at an angle between 30 ° and 60 ° to the plane parallel to the first side of the rack, preferably about 45 °.