EP-4739018-A1 - COOLING DISTRIBUTION UNIT WITH CONSTANT PRESSURE AND VARIABLE FLOW

EP4739018A1EP 4739018 A1EP4739018 A1EP 4739018A1EP-4739018-A1

Abstract

A cooling distribution unit associated with at least one rack system of a data center includes a first cooling system having a primary cooling circuit through which a heat transfer fluid is configured to circulate and including a heat exchanger. A second cooling system has a secondary cooling circuit through which a coolant is configured to circulate and includes a pump. The second cooling system is thermally coupled to the first cooling system at the heat exchanger. A pressure at the pump remains constant as a load at the first heat exchanger varies.

Inventors

GRABON, MICHEL
FERVEL, Pierre Alain

Assignees

Carrier Corporation

Dates

Publication Date: 20260506
Application Date: 20251030

Claims (15)

A cooling distribution unit associated with at least one rack system of a data center, the cooling distribution unit comprising: a first cooling system having a primary cooling circuit through which a heat transfer fluid is configured to circulate, the first cooling system including a heat exchanger; a second cooling system having a secondary cooling circuit through which a coolant is configured to circulate, the secondary cooling circuit including a pump, wherein the second cooling system is thermally coupled to the first cooling system at the heat exchanger; and wherein a pressure at the pump remains constant as a load at the first heat exchanger varies.
The cooling system of claim 1, wherein the load at the cooling distribution unit is controlled via operation of the pump.
The cooling system of claim 1 or claim 2, wherein the pump fluidly connected to the secondary cooling circuit is a variable speed pump.
The cooling system of any of claims 1-3, wherein a portion of the coolant output from the pump is selectively recirculated to the pump to increase a pressure at the pump.
The cooling system of claim 4, further comprising a recirculation conduit having an inlet fluidly connected to the secondary cooling circuit downstream from the pump and an outlet fluidly connected the secondary cooling circuit upstream from the pump; optionally wherein at least one of the inlet is fluidly connected to the secondary cooling circuit directly downstream from the pump and the outlet is fluidly connected the secondary cooling circuit directly upstream from the pump.
The cooling system of claim 5, further comprising a valve arranged along the recirculation conduit, the valve being operable to control a flow of the coolant returned to an inlet of the pump.
The cooling system of any of claims 1-6, wherein the pump is operated within a zone of stable operation as the load at the cooling distribution unit varies.
The cooling system of claim 7, further comprising a controller, wherein the controller is configured to determine a differential pressure across the heat exchanger.
The cooling system of claim 8, further comprising a first sensor arranged within the secondary cooling circuit upstream from the heat exchanger and a second sensor arranged within the secondary cooling circuit downstream from the heat exchanger, wherein the first sensor and the second sensor are operably coupled to the controller and are operable to sense a pressure, a difference between the pressure at the first sensor and the pressure at the second sensor being the differential pressure across the heat exchanger.
The cooling system of claim 9, wherein the controller is configured to: compare the differential pressure with a differential pressure set point to determine a difference between the differential pressure measured by the first sensor and the second sensor and the differential pressure set point; and adjust at least one operational parameter of the pump in response to the difference between the differential pressure measured by the first sensor and the second sensor and the differential pressure set point; optionally wherein the at least one operational parameter of the pump is speed.
The cooling system of claim 10, wherein the controller is configured to evaluate if operation of the pump with the at least one operational parameter is within the zone of stable operation; optionally wherein the controller is configured to: adjust operation of the pump to a minimum flow and pressure required to operate within the zone of stable operation; and recirculate a portion of the coolant output from the pump to an inlet of the pump to increase a pressure at the pump.
A method of operating a cooling distribution unit, the method comprising: circulating a heat transfer fluid through a primary cooling circuit; circulating a coolant through a secondary cooling circuit, the secondary cooling circuit including a pump, wherein the cooling distribution circuit and the secondary cooling circuit and thermally coupled via a heat exchanger; detecting a differential pressure within the secondary cooling circuit, and selectively recirculating a flow of coolant within the secondary cooling circuit to the pump to maintain a constant pressure within the secondary cooling circuit.
The method of claim 12, wherein selectively recirculating a flow of the coolant within the secondary cooling circuit to the pump further comprises diverting a portion of the coolant provided at an outlet of the pump directly to an inlet of the pump.
The method of claim 12 or claim 13, further comprising: comparing the differential pressure to a differential pressure setpoint; and determining at least one operational parameter of the pump in response to a difference between the differential pressure and a differential pressure set point; optionally further comprising: determining that operation of the pump with the at least one operational parameter to determine is within a zone of stable operation associated with the pump; and implementing the at least one operational parameter; and optionally further comprising: determining that operation of the pump with the at least one operational parameter to determine is within a zone of instable operation associated with the pump; adjusting operation of the pump to a minimum flow and pressure associated with the zone of stable operation; and opening a valve to recirculate a portion of a flow of the coolant output from the pump to the inlet of the pump.
The method of claim 14, wherein the at least one operational parameter of the pump is speed.

Description

The invention pertains to the art of thermal management, and more particularly, relates to thermal management of a server within a data center. A "data center" refers to the physical location of one or more servers. A data center and the servers housed within a data center typically consume a significant amount of electrical power. Existing servers are designed to be cooled at least partially by a flow of air. Such servers usually include one or more printed circuit boards having a plurality of operable heat-generating devices mounted thereto. The printed circuit boards are commonly housed in an enclosure having vents configured to direct external air from the data center into, through and out of the enclosure. The air absorbs heat dissipated by the components and after being exhausting from the enclosure, mixes with the ambient air. An air conditioner is then used to cool the heated air of the data center and to recirculate it, repeating the cooling process. Higher performance server components typically dissipate more power. However, the amount of heat that a conventional air-cooled cooling system can remove from a server is in part limited by the extent of the air flow available and air proprieties relative to heat transfer capacity of the air. To increase the power density of a cooling system, liquid cooling is required. Liquid cooling allows significant increase of dissipated heat from servers. According to a first aspect of the present invention, a cooling distribution unit associated with at least one rack system of a data center includes a first cooling system having a primary cooling circuit through which a heat transfer fluid is configured to circulate and including a heat exchanger. A second cooling system has a secondary cooling circuit through which a coolant is configured to circulate and includes a pump. The second cooling system is thermally coupled to the first cooling system at the heat exchanger. A pressure at the pump remains constant as a load at the first heat exchanger varies. Optionally, the load at the cooling distribution unit is controlled via operation of the pump. Optionally, the pump fluidly connected to the secondary cooling circuit is a variable speed pump. Optionally, a portion of the coolant output from the pump is selectively recirculated to the pump to increase a pressure at the pump. Optionally, a recirculation conduit has an inlet fluidly connected to the secondary cooling circuit downstream from the pump and an outlet fluidly connected the secondary cooling circuit upstream from the pump. Optionally, at least one of the inlet is fluidly connected to the secondary cooling circuit directly downstream from the pump and the outlet is fluidly connected the secondary cooling circuit directly upstream from the pump. Optionally, a valve arranged along the recirculation conduit is operable to control a flow of the coolant returned to an inlet of the pump. Optionally, the pump is operated within a zone of stable operation as the load at the cooling distribution unit varies. Optionally, a controller is configured to determine a differential pressure across the heat exchanger. Optionally, a first sensor is arranged within the secondary cooling circuit upstream from the heat exchanger and a second sensor is arranged within the secondary cooling circuit downstream from the heat exchanger. The first sensor and the second sensor are operably coupled to the controller and are operable to sense a pressure. A difference between the pressure at the first sensor and the pressure at the second sensor being the differential pressure across the heat exchanger. Optionally, the controller is configured to compare the differential pressure with a differential pressure set point to determine a difference between the differential pressure measured by the first sensor and the second sensor and the differential pressure set point, and adjust at least one operational parameter of the pump in response to the difference between the differential pressure measured by the first sensor and the second sensor and the differential pressure set point. Optionally, the at least one operational parameter of the pump is speed. Optionally, the controller is configured to evaluate if operation of the pump with the at least one operational parameter is within the zone of stable operation. Optionally, the controller is configured to adjust operation of the pump to a minimum flow and pressure required to operate within the zone of stable operation and recirculate a portion of the coolant output from the pump to an inlet of the pump to increase a pressure at the pump. According to a second aspect of the present invention, a method of operating a cooling distribution unit includes circulating a heat transfer fluid through a primary cooling circuit and circulating a coolant through a secondary cooling circuit. The secondary cooling circuit includes a pump and the cooling distribution circuit and the secondary cooling circ