US-12621965-B2 - High-efficiency cooling systems and methods for a computer data center using refrigerant recirculation

US12621965B2US 12621965 B2US12621965 B2US 12621965B2US-12621965-B2

Abstract

To facilitate the use of high-efficiency heat exchangers in a computer data center, a refrigerant recirculation line is provided to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger through an in-line refrigerant pump to mix with the refrigerant from the refrigerant supply and then flow to the first refrigerant inlet of the first heat exchanger. At least partial recirculation of refrigerant facilitates the use of warmer inlet refrigerant while still providing sufficient heat extraction.

Inventors

Bradley John Klein
Nicholas Ben Barrowclough

Assignees

Bradley John Klein
Nicholas Ben Barrowclough

Dates

Publication Date: 20260505
Application Date: 20240701

Claims (13)

1 . A cooling system for a facility employing equipment requiring active cooling, the cooling system comprising: a refrigerant supply line providing a refrigerant at a first pressure from a refrigerant source, a refrigerant return line directing the refrigerant at a second pressure toward the refrigerant source for cooling and recirculating of the refrigerant at the refrigerant source, wherein the second pressure is lower than the first pressure, a first heat exchanger configured to use the refrigerant circulating through the first heat exchanger to cool air or liquid which passes through the first heat exchanger and is used for active cooling of the equipment in the facility, the first heat exchanger having a first refrigerant inlet configured to receive at least some refrigerant from the refrigerant supply line, the first heat exchanger having a first refrigerant outlet operably connected to direct at least some refrigerant to the refrigerant return line, and a first recirculation line configured to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger through an in-line refrigerant pump to mix with the refrigerant from the refrigerant supply line and then flow to the first refrigerant inlet of the first heat exchanger, wherein the in-line refrigerant pump is configured to increase refrigerant pressure from the second pressure to the first pressure, and wherein the in-line refrigerant pump is configured to provide flow only to refrigerant in the first recirculation line and not to any other refrigerant in the cooling system, wherein the in-line refrigerant pump is configured not to provide refrigerant flow to the refrigerant source, thereby increasing the heat exchanging efficiency of the first heat exchanger by recirculating at least some refrigerant flowing through the first heat exchanger.
2 . The cooling system of claim 1 , further comprising at least one temperature sensor configured to measure refrigerant temperature at the first refrigerant inlet of the first heat exchanger and/or at the first refrigerant outlet of the first heat exchanger.
3 . The cooling system of claim 1 , further comprising at least one additional heat exchanger, wherein the first recirculation line is configured to direct at least some refrigerant from the first refrigerant outlet of the first heat exchanger or from a refrigerant outlet of the at least one additional heat exchanger through the in-line refrigerant pump to flow to the first refrigerant inlet of the first heat exchanger.
4 . The cooling system of claim 1 , further comprising a return line temperature sensor positioned in the refrigerant return line downstream of the first heat exchanger, wherein the return line temperature sensor is configured to measure refrigerant temperature in the refrigerant return line prior to reaching the refrigerant source.
5 . The cooling system of claim 1 , wherein the refrigerant and/or the liquid passing through the first heat exchanger is selected from a group consisting of a one-phase refrigerant, a two-phase refrigerant, water, and a mix of water and glycol.
6 . The cooling system of claim 1 , wherein the facility is a computer data center and the air or liquid passing through the first heat exchanger is used for active cooling of computer equipment of the data center.
7 . The cooling system of claim 1 , wherein the cooling system further comprises a refrigerant circulation loop comprising the first heat exchanger and a supplemental heat exchanger positioned downstream of the first heat exchanger, the supplemental heat exchanger is placed outside the facility.
8 . The cooling system of claim 7 , further comprising a circulation bypass line with an in-line circulation bypass valve, the circulation bypass line configured to direct the refrigerant directly downstream and not through the supplemental heat exchanger when an ambient temperature is at or above a refrigerant temperature at the first refrigerant outlet of the first heat exchanger.
9 . A method for cooling a facility employing equipment requiring active cooling, the method comprising the following steps: a. directing a refrigerant from a refrigerant supply line pressurized at a first pressure through a first heat exchanger, wherein the first heat exchanger is configured to use the refrigerant circulating through the first heat exchanger to cool air or liquid which passes through the first heat exchanger and is used for active cooling of the equipment in the facility, b. directing the refrigerant to flow from the first heat exchanger to a refrigerant return line at a second pressure, wherein the second pressure is lower than the first pressure, and c. using an in-line refrigerant pump that provides flow only to refrigerant in a first recirculation line and not to the refrigerant source or any other refrigerant in the cooling system, and that is configured not to provide refrigerant flow to the refrigerant source, directing at least some refrigerant after passing through the first heat exchanger to mix with the refrigerant from the refrigerant supply line and then flow again through the first heat exchanger, wherein the in-line refrigerant pump increases refrigerant pressure from the second pressure to the first pressure, thereby recirculating at least some refrigerant to flow through the first heat exchanger to increase heat extraction therefrom.
10 . The method of claim 9 , wherein the facility is a computer data center and the air or liquid passing through the first heat exchanger is used for active cooling of computer equipment of the data center.
11 . The method of claim 9 , further comprising a step of providing a supplemental heat exchanger positioned outside the facility, and directing refrigerant from the first heat exchanger to the supplemental heat exchanger only when an ambient temperature is below a refrigerant temperature at the first refrigerant outlet of the first heat exchanger to at least partially extract heat from the refrigerant prior to directing the refrigerant to the refrigerant return line.
12 . The method of claim 11 , further comprising a step of bypassing the supplemental heat exchanger and directing the refrigerant directly to the refrigerant return line when the ambient temperature is at or above the refrigerant temperature at the first refrigerant outlet of the first heat exchanger.
13 . The method of claim 9 , further comprising a step of directing at least some refrigerant after passing through the first heat exchanger to flow through at least one additional heat exchanger prior to directing the refrigerant to the refrigerant return line.

Description

CROSS-REFERENCE DATA This patent application is a divisional application from a co-pending U.S. patent application Ser. No. 18/749,543 filed on Jun. 20, 2024, and entitled “HIGH-EFFICIENCY COOLING SYSTEMS AND METHODS FOR A COMPUTER DATA CENTER”, which is incorporated herein by reference in its entirety. BACKGROUND Without limiting the scope of the invention, its background is described in connection with data center cooling systems. More particularly, the invention describes a high-efficiency cooling system using bypass lines to maximize heat extraction of the heat exchangers used therein. The problem of heat generation in large, enclosed data centers, which arises from operating multiple computers simultaneously, is a critical issue that affects the efficiency, longevity, and operational costs of these facilities. Data centers, crucial hubs for storing, processing, and disseminating vast amounts of digital information, house numerous servers and other computing hardware that inherently produce significant amounts of heat during operation. This heat generation is primarily due to the electrical power consumed by the servers, which, when converted into energy to run computational tasks, also releases heat as a byproduct. As more servers are packed into a data center to handle increasing data demands, the cumulative heat produced can escalate rapidly. This concentrated heat generation can lead to elevated temperatures within the data center, which, if not properly managed, can surpass the optimal operating conditions recommended for electronic hardware. High temperatures can degrade the performance of servers, increase the likelihood of hardware failures, and shorten the lifespan of the equipment. Furthermore, the need to cool these environments to maintain safe operating temperatures leads to significant energy consumption through cooling systems like air conditioners and chillers, which in turn increases operational costs and can have a detrimental environmental impact due to increased carbon emissions. Managing this heat effectively is therefore not only critical for maintaining system reliability and performance but also for achieving energy efficiency and reducing the environmental footprint of data centers. The implementation of advanced cooling techniques, strategic data center layout design, and the adoption of energy-efficient technologies are among the approaches employed to tackle the heat management challenges in modern data centers. Conventional air conditioning is one of the primary methods used to cool large data centers, alongside a variety of innovative cooling approaches designed to enhance efficiency and sustainability. The conventional method typically involves the use of Computer Room Air Conditioning (CRAC) units or Computer Room Air Handlers (CRAH) units. These systems regulate the temperature and humidity in the data center by circulating chilled air. Air is drawn in, cooled by refrigerants or chilled water in heat exchangers, and then distributed throughout the data center to absorb heat emitted by servers and other equipment. This warm air is then cycled back to the CRAC or CRAH units to be re-cooled and recirculated. In addition to conventional air conditioning, alternative, and supplementary cooling strategies are also employed to manage heat in data centers more effectively. One such approach is the use of in-row cooling, where cooling units are placed directly between server racks. This setup minimizes the distance cold air must travel before reaching the servers, improving cooling efficiency and reducing the mixing of hot and cold air streams. Another innovative method is hot aisle/cold aisle configuration, which organizes computer racks in alternating rows with their backs facing each other, creating hot aisles and cold aisles. Warm air goes up to the ceiling plenum and from there is recirculated by an air pump through the built-in chiller of the air conditioning system to enter a sub-floor space, before entering cold aisles. This configuration helps to manage airflow more predictably by confining and extracting the warm air emitted from the servers more efficiently. For more sustainable options, some data centers utilize free cooling systems, which leverage external environmental conditions to aid in cooling. When the outside temperature is sufficiently low, outside air can be brought in to cool the facility, significantly reducing the reliance on mechanical cooling and thereby lowering energy consumption. Advanced versions of this technique include the use of economizers, which can switch between outside air and refrigeration-based cooling depending on the external weather conditions. Additionally, liquid cooling is a rapidly emerging technique that involves using water or other liquids in direct contact with components to absorb heat more effectively than air, which is particularly useful in high-density configurations where traditional air cooling is insufficient. These div