Thermal management system for data centre

Abstract

The embodiments of the present invention pertain to the broad technical domain of thermal engineering, with a specific focus on a thermal management system (1) for a data centre. The thermal management system (1) comprises at least two heat removal units (5), particularly heat exchangers, designed to be mounted on server racks (3) in data centres for efficiently removing heat from the server racks (3) to the environment of a CRAC unit, thereby maintaining optimal operating conditions within data centres.

Description

[0001] THERMAL MANAGEMENT SYSTEM FOR DATA CENTRE

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The embodiments of the present invention pertain to the broad technical domain of thermal engineering, with a specific focus a thermal management system. More precisely, it deals with the transfer and removal of thermal energy in various applications where efficient thermal management is critical, thereby maintaining optimal operating conditions within these applications.

[0004] BACKGROUND OF THE INVENTION

[0005] Heat or thermal management systems are widely used across numerous industries and applications, including but not limited to power generation, HVAC systems, chemical processing, petrochemical industry, food and beverage industry, pharmaceutical industry, automotive industry, marine applications, metallurgical industry, renewable energy systems, and electronics and data centres. Heat management systems are designed to treat heat from different phases, such as air-to-air, air-to-liquid, liquid-to-air, or liquid-to-liquid. This versatility is essential for meeting the diverse needs of various industries.

[0006] In data centre applications, heat management systems often utilize heat exchangers to dissipate heat. Typically, when a heat exchanger is implemented behind the servers as a rear door heat exchanger, RDHX, ambient or cool air enters the server rack, absorbs heat generated by the servers, and then hot air exits through the RDHX as cooled air into the environment. Despite the advantages of existing heat management systems, conventional designs generally use only a single heat exchanger. This limitation often results in suboptimal heat removal from the hot air when expelled, frequently remains at temperatures that are not within an acceptable range.

[0007] Recognizing this challenge and to overcome this significant disadvantage, the present invention introduces a thermal management system that incorporates unique mechanism that significantly enhances the efficiency of heat removal, ensuring that the expelled heat meets the desired temperature criteria. This innovative approach addresses the shortcomings of traditional single-unit systems, providing a more effective solution for managing thermal energy.

[0008] Overall, this invention represents a significant advancement in the field of thermal engineering, providing a robust solution for effective heat management across a variety of industries and applications, particularly the data centre applications. SUMMARY OF THE INVENTION

[0009] The present invention relates to an advanced thermal management system designed to improve the efficiency of thermal energy transfer and dissipation across various applications, particularly applications like data centres. Unlike conventional systems that typically utilize a single heat removal unit, this innovative system incorporates dual or multiple heat removal units within a single framework. This multi-unit design ensures more effective heat dissipation, maintaining the expelled air within acceptable temperature ranges.

[0010] This invention is particularly groundbreaking for applications like data centres, which currently do not utilize the thermal management system like present invention due to technical and logistical constraints. Data centres generate substantial amounts of heat, and efficient thermal management is critical to prevent overheating and maintain optimal performance of servers and other equipment. While there may have been attempts to integrate multiple heat removal units in such applications, no effective solutions or innovations have been realized until now. The present invention fills this gap by offering a reliable and efficient multi-unit heat removal system, setting a new standard for heat management in data centres and other high- demand applications.

[0011] According to the preferred embodiment of the present invention, there is provided a thermal management system for data centre comprising at least two first heat removal units arranged in parallel direction. This system is particularly designed to be mounted on server racks in data centres, facilitating efficient heat removal from the server racks to the environment or CRAC (Computer Room Air Conditioning) units.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other aspect of the present invention and their advantages will be discerned after studying the Detailed Description in conjunction with the accompanying drawings in which:

[0014] FIGS. 1-A, 1-B, 1-C and 1-D illustrate an exemplary perspective view, front view, side view, and top view, respectively, of a thermal management system for data centre according to the preferred embodiment of the present invention.

[0015] FIGS. 2- A and 2-B showcase a practical application of the thermal management system of the present invention on a server rack, depicted in perspective and side views, respectively, complete with an optional array of fans mounted behind the dual -heat exchanger unit. FIGS. 3-A, 3-B, 3-C, and 3-D illustrate various embodiments of the thermal management system of the present invention.

[0016] FIGS. 4-A, 4-B, 4-C, and 4-D illustrate, respectively, the exploded view, perspective view, side view, and top view of the thermal management system according to one embodiment of the present invention where the optional fan array in implemented in between the two heat exchangers, comprising one dual heat exchanger unit.

[0017] FIGS. 5-A, 5-B and 5-C illustrate the internal components of the thermal management system according to one embodiment of the present invention.

[0018] FIG. 6 illustrates an exemplary example of a single microchannel of the thermal management system according to one embodiment of the present invention.

[0019] FIG. 7 presents a chart depicting the temperature variations within a single microchannel of the thermal management system during operation, as per one embodiment of the present invention.

[0020] FIG. 8 displays a chart showcasing the temperature fluctuations of the on -coil air, off- coil air, and the microchannel wall across various zones within a single microchannel of the thermal management system, as outlined in one embodiment of the present invention.

[0021] FIG. 9 illustrates multiple microchannels within a tube of a complete heat removal unit, showcasing the airflow around and through a series of microchannels.

[0022] FIG. 10 showcases two complete heat removal units arranged in parallel to each other, each with multiple microchannels within a tube, while also demonstrating the airflow around two sets of microchannels.

[0023] FIGS. 11-A, 11-B, 11-C, and 11-D showcase the embodiment in FIGS 2-A and 2-B the present invention in various views, respectively, with an optional array of fans mounted behind the thermal management system. DETAILED DESCRIPTION OF THE DRAWINGS

[0024] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by the person having ordinary skill in the art that the invention may be practised without these specific details. In other instances, well known methods, procedures and / or components have not been described in detail so as not to obscure the invention.

[0025] The invention will be more clearly understood from the following description of the embodiments thereof, given by way of example only with reference to the accompanying drawings, which are not drawn to scale.

[0026] As used in this disclosure and the appended claims herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates or denotes otherwise.

[0027] Throughout the disclosure and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal embodiment, “such as” is not used in a restrictive sense, but for explanatory purposes.

[0028] The embodiments of the present invention are centered around a thermal management system (1) designed for data centres. This thermal management system (1) aims to provide efficient and effective cooling for server racks (3), which are critical for maintaining optimal operating conditions and preventing overheating.

[0029] In the depicted preferred embodiment, illustrated in FIGS. 1-A, 1-B, 1-C, and 1-D, the perspective view, front view, side view, and top view, respectively, of the thermal management system (1) of the present invention are shown. This system (1) comprises at least two first heat removal units (5), arranged substantially parallel to each other, forming a layered configuration. This parallel configuration essentially means that the thermal management system (1) of the present invention comprises at least two layers of heat removal units (5a, 5b). This design allows for double action heat removal, significantly enhancing the efficiency and capacity of thermal management within data centres. Preferably, each heat removal unit (5) is a heat exchanger. More specifically, each heat removal unit (5) is preferably a rear door heat exchanger, specifically designed to be mounted on the rear parts or the rear doors of server racks (3), facilitating direct heat capture from the servers and efficient heat dissipation, as depicted in FIGS. 2-A and 2-B. By doing so, the system (1) can directly capture and dissipate heat generated by the servers, either to the surrounding environment or to a CRAC (Computer Room Air Conditioning) unit.

[0030] Although FIG. 1 illustrates the thermal management system (1) comprising a doublelayered heat removal units (5a, 5b) or heat exchangers, it is contemplated that the thermal management system (1) of the present invention may comprise more than two heat removal units (5a, 5b) or heat exchangers. The system (1) is designed to accommodate additional units if needed. This flexibility allows the system (1) to be scaled up to meet higher thermal loads or specific cooling requirements of larger data centres.

[0031] This parallel or layered configuration is a novel approach that has not been previously implemented or observed in the industry. While prior art may involve the use of two or more heat exchangers for server racks (3), conventional designs typically arrange these heat exchangers perpendicularly, with one heat exchanger placed on top of the other. In contrast, the present invention’s parallel arrangement optimizes space utilization and enhances the system’s overall heat dissipation efficiency and capacity.

[0032] In one embodiment of the present invention, one of the distinguishing features of the thermal management system (1) of present invention is the variation in length between the first heat removal units (5) while being arranged in a parallel configuration. Specifically, one of the first heat removal units (5) can be longer or shorter than the other. This variability allows the system (1) to be adapted to different spatial configurations and cooling requirements of server racks. For instance, as depicted in FIGS. 3-A, 3-B, 3-C and 3-D, the front first heat removal unit (5a) can be either shorter or longer than the rear first heat removal units (5b). In embodiments where more than two first heat removal units (5) are used, the lengths of these units can either be equal to each other or vary, depending on specific needs.

[0033] In one embodiment of the present invention as depicted in FIGS. 4-A, 4-B, 4-C and 4-D, the system (1) may comprise at least one second heat removal unit (7) positioned or sandwiched between the two first heat removal units (5a, 5b). This second heat removal unit (7) generally comprises at least an exhaust fan (7a) or a plurality of exhaust fans. These fans (7a) ensure continuous and reliable heat removal and help direct the airflow of the heated air from the front first heat removal unit (5a) to the rear first heat removal unit (5a), thereby enhancing the overall cooling efficiency.

[0034] In one embodiment of the present invention as depicted in FIGS 5-A, 5-B and 5-C, each first heat removal unit (5) comprises several key components. Each first heat removal unit (5) comprise at least one frame (9); and at least a tube (11) or a plurality of tubes arranged vertically or horizontally within the frame (9), with each tube (11) spaced apart from the others to ensure efficient fluid flow and heat transfer. Layers of heat transfer surfaces (13), including but not limited to fin-like elements, are provided within the frame (9) and situated between the spacedapart tubes or surrounding the tubes (11). These heat transfer surfaces (13) significantly enhance the heat exchange process by increasing surface area for heat dissipation. Each first heat removal unit (5) further comprises at least one fluid inlet (15) for directing fluid into the tubes (11) and at least one fluid outlet (17) for directing the fluid out from the tubes (11). This arrangement ensures a continuous flow of fluid, promoting efficient heat transfer. In essence, each first heat removal unit (5) functions as a finned-tube heat exchanger, with the incorporation of fin-like elements further amplifying the surface area available for heat transfer, making the system (1) highly effective in dissipating heat.

[0035] Each tube (11) within the heat removal units (5) comprises at least one microchannel (19) or a plurality of microchannels (19). These microchannels (19) increase the heat transfer coefficient by promoting phase changes within the fluid flow, thereby enhancing the overall heat exchange efficiency. The fluid directed into the tubes (11) from the inlet (15) is refrigerant, typically a liquid, which absorbs heat from the server components. As the fluid flows through the tubes (11), it undergoes phase change or significant heat exchange, and the fluid exiting the tubes (11) through the outlet (17) may be in a gaseous state, depending on the specific design and operating conditions.

[0036] Referring now to FIG. 6, a single microchannel (19) is illustrated, demonstrating the two- phase change of fluid from liquid to vapor. The microchannel (19) can be divided into three zones: the subcooling zone at the bottom, where the liquid enters at a temperature below its normal boiling point; the saturating zone in the middle, where boiling begins, typically at 16 degrees Celsius, as an example; and the superheated zone at the top, where the fluid is heated above its boiling point containing no more liquid remained in the microchannel to boil. When the system (1) is operational, hot air from the server racks flows perpendicularly towards the microchannel (19). Liquid enters the microchannel (19) from the bottom, filling the subcooling zone as a subcooled liquid at a temperature below the boiling temperature. In this zone, boiling does not start until the fluid heats up and enters the saturating zone, as indicated by line X. In the saturating zone, the microchannel absorbs heat, causing the liquid to start boiling, absorbing greater amount of heat through the onset of the phase change. This liquid, now referred to as saturated liquid, begins to decrease while vapor formation increases towards the upper portion of the microchannel (19), leading to a dry-out phase within saturating zone where the liquid no longer wets the inner surface of the microchannel, named as Dry-Out zone. The remaining liquid particles flowing inside the tube still evaporates, but less efficient since there is no wetted liquid on the inner surface of the microchannels to absorb the heat directly from the inner surface of the microchannel. The liquid particles flowing inside the microchannel through the Dry-out zone will eventually and completely evaporates leaving no liquid, hence the fluid is now considered saturated vapor. The vapor then continues to be heated in the superheated zone, as indicated by line Z, due to the continuous supply of heat from the hot air flowing across the microchannels.

[0037] FIG. 7 displays a chart showing the temperature changes of the fluid in different zones of the microchannel (19). Just as an example, the temperature of the on-coil air, i.e., heated air from the server racks, typically exceeds 40 degrees Celsius. The liquid entering the microchannel (19) and the subcooling zone is typically at below 16 degrees Celsius, as an example. As the liquid enters the saturating zone and absorbs heat from the heated air, it starts to boil, resulting in a phase change from liquid to vapor. The temperature remains constant at the boiling point of approximately 16 degrees Celsius, in this example. As the vapor enters the superheated zone, its temperature rises above its boiling point.

[0038] FIG. 8 presents a chart further depicting the temperature changes of the on-coil air, off- coil air, and the microchannel wall (19a) in different zones. On-coil air refers to the heated air from the server racks, while off-coil air is the air that flows through the microchannel (19). The microchannel’s wall (19a) and off-coil air experience a sharp temperature increase in the dry-out phase of the saturated zone, as all the surface liquid has been evaporated and can no longer effectively absorb heat. As a result, the heat of the off-coil air flowing above the dry-out phase cannot be removed, because no surface liquid remains above this phase in the microchannel (19), leading to an increase in the temperature of the microchannel wall (19a). Consequently, the air flowing through the bottom part of the microchannel (19) is cooled, while the air flowing through the upper part is uncooled and remains hot.

[0039] Referring now to FIG. 9, a complete tube (11) with multiple microchannels (19) is illustrated, along with the airflow through each microchannel (19). When the on-coil air temperature is higher or the velocity is faster, more heat is removed through each microchannel (19), causing the dry-out phase to set in earlier, lowering the locus of the dry-out line in the microchannel (19). As a result, the air exiting the first heat removal unit (5a) remains hot at the upper part, mirroring the inefficiencies of prior art systems that utilize only one heat exchanger.

[0040] Referring now to FIG. 10, the thermal management system (1) for data centres of the present invention is depicted. This system (1) comprises double-layered or multiple-layered first heat removal units (5a, 5b) arranged parallelly, with optional second heat removal units (7), such as arrays of exhaust fans (7a), positioned or sandwiched between the two first heat removal units (5a, 5b). These fans (7a) assist in airflow, compensating for the reduction in flow rate caused by the added resistance from multiple first heat removal units (5a, 5b). With at least two first heat removal units (5a, 5b), more microchannels (19) are introduced, sufficiently absorbing the heat generated by the server racks. Consequently, the air temperature is significantly reduced as it passes through the first heat removal units (5a, 5b).

[0041] Referring now to FIGS. 11 -A, 11-B, 11-C, and 11-D, another embodiment of the thermal management system (1) for data centres is illustrated in isolated view, front view, side view, and top view, respectively. In this embodiment, the thermal management system comprises at least one second heat removal unit (7) mounted at the back of the thermal management system (1), specifically behind the rear first heat removal unit (5a). This second heat removal unit (7) typically comprises at least one exhaust fan (7a) or a plurality of exhaust fans. These fans (7a) ensure continuous and reliable heat removal and help direct the cooled air from the rear first heat removal unit (5a) to the environment, thereby enhancing overall cooling efficiency.

[0042] Although FIGS. 11-A, 11-B, 11-C, and 11-D depict the second heat removal unit mounted at the back of the thermal management system without showing the embodiment of the second heat removal unit sandwiched between the first heat removal units (5a, 5b) as shown in FIGS. 4-A, 4-B, 4-C, and 4-D, it is contemplated that this embodiment may also apply to the configuration in FIGS. 4-A, 4-B, 4-C, and 4-D. In other words, the thermal management system (1) may have an arrangement comprising of a front first heat removal unit (5a), a second heat removal unit (7), a rear first heat removal unit (5b), followed by another second heat removal unit (7).

[0043] In conclusion, the novel parallel configuration of the heat removal units (5a, 5b) offers several significant advantages over traditional perpendicular arrangements. By arranging the heat removal units (5a, 5b) in parallel, the thermal management system (1) can achieve more effective and complete heat removal from the hot air. Each heat removal unit (5) operates simultaneously to remove heat from the server racks, ensuring that the expelled air maintains acceptable temperature levels. The layered design optimizes the use of space within data centres. Unlike perpendicular configurations that stack heat exchangers, the parallel arrangement allows for a more compact and efficient setup, maximizing available space. The double action heat removal provided by the parallel configuration enhances the system's capacity to manage high thermal loads. This design ensures consistent cooling performance, which is critical for maintaining the optimal operation of servers in data centres with high power servers. The system's design allows for easy scalability. Additional heat removal units (5) can be integrated into the system (1) as needed, providing a tailored solution that can adapt to the evolving cooling requirements of data centres.

[0044] While the present invention has been shown and described herein in what are considered to be the preferred embodiments thereof, illustrating the results and advantages over the prior art obtained through the present invention, the invention is not limited to those specific embodiments. Thus, the forms of the invention shown and described herein are to be taken as illustrative only and other embodiments may be selected without departing from the scope of the present invention, as set forth in the claims appended hereto. The scope of the invention encompasses numerous alternatives, modifications and the equivalents. Of necessity, there are many alternative ways of configuring and implementing the invention to suit particular installations and environments while providing biological outcomes of differing design.

Claims

CLAIMS1. A thermal management system (1) for data centre, characterized in that it comprising: at least two first heat removal units (5), wherein the first heat removal units (5) are arranged substantially parallel to each other.

2. The thermal management system (1) for data centre as claimed in Claim 1, wherein one of the first heat removal units (5a) is longer or shorter in length compared to the other first heat removal unit (5b).

3. The thermal management system (1) for data centre as claimed in Claim 1 or 2, wherein the system (1) is a rear door heat exchanger.

4. The thermal management system (1) for data centre as claimed in any preceding claim, wherein each first heat removal unit (5) comprises: at least one frame (9); a plurality of tubes (11) arranged within the frame (9), each tube (11) being spaced apart from the others; layers of heat transfer surfaces (13) provided within the frame (5) and situated between the spaced-apart tubes (11); at least one fluid inlet (15) for directing at least a fluid into the plurality of tubes (11); at least a fluid outlet (17) for directing the fluid out from the plurality of tubes (11).

5. The thermal management system (1) for data centre as claimed in Claim 4, wherein each tube (11) comprises at least a microchannel (19) or a plurality of microchannels (19).

6. The thermal management system (1) for data centre as claimed in Claim 4 or 5, wherein the heat transfer surfaces (13) are fin-like elements.

7. The thermal management system (1) for data centre as claimed in Claim 4 or 5, wherein each first heat removal unit (5) is a finned-tube heat exchanger.

8. The thermal management system (1) for data centre as claimed in any one of Claims 4 to 7, the fluid directed into the tubes (11) from the inlet (15) is liquid and the fluid directed out from the tubes (11) to the outlet (17) is vapor.

9. The thermal management system (1) for data centre as claimed in any one of the preceding claims, wherein at least a second heat removal unit (7) is provided between two first heat removal units (5a, 5b).

10. The thermal management system (1) for data centre as claimed in Claim 9, wherein said second heat removal unit (7) comprises at least an exhaust fan (7a) or a plurality of exhaust fans (7a).

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