| United States Patent Application |
20150025833
|
| Kind Code
|
A1
|
|
VanGilder; James William
|
January 22, 2015
|
SYSTEM AND METHOD FOR PREDICTION OF TEMPERATURE VALUES IN AN ELECTRONICS
SYSTEM
Abstract
In accordance with at least one embodiment, a computer-implemented method
for evaluating cooling performance of an electronics system is provided.
The method includes acts of dividing the electronics system into a
computational grid including a plurality of fluid cells and a plurality
of solid cells, determining air flow values for the plurality of fluid
cells using a potential flow model analysis, determining a temperature of
a fluid cell by calculating heat transfer into the fluid cell from any
adjacent fluid cells and from any adjacent solid cells, determining a
temperature of a solid cell by calculating heat transfer into the solid
cell from any adjacent solid cells and heat transfer out of the solid
cell into any adjacent fluid cells, and storing, on a storage device, the
air flow values and the temperature of the fluid cell and the temperature
of the solid cell.
| Inventors: |
VanGilder; James William; (Pepperell, MA)
|
| Applicant: | | Name | City | State | Country | Type | VanGilder; James William | Pepperell | MA |
US | | |
| Family ID:
|
1000000753750
|
| Appl. No.:
|
14/366500
|
| Filed:
|
December 22, 2011 |
| PCT Filed:
|
December 22, 2011 |
| PCT NO:
|
PCT/US11/66776 |
| 371 Date:
|
June 18, 2014 |
| Current U.S. Class: |
702/136 |
| Current CPC Class: |
G06F 17/5009 20130101; G06F 1/20 20130101; G01F 1/708 20130101; G01K 7/427 20130101 |
| Class at Publication: |
702/136 |
| International Class: |
G06F 17/50 20060101 G06F017/50; G01F 1/708 20060101 G01F001/708; G06F 1/20 20060101 G06F001/20; G01K 7/42 20060101 G01K007/42 |
Claims
1. A computer-implemented method for evaluating cooling performance of an
electronics system, the system including a plurality of physical
components and at least one cooling provider, the method comprising:
receiving information related to physical structures of the electronics
system; dividing the electronics system into a computational grid
including a plurality of fluid cells and a plurality of solid cells,
positions of the plurality of solid cells corresponding to positions of
the physical components within the electronics system; determining air
flow values for the plurality of fluid cells using a potential flow model
analysis; for each fluid cell of the plurality of fluid cells,
determining a temperature of the fluid cell by calculating heat transfer
into the fluid cell from any adjacent fluid cells and from any adjacent
solid cells; for each solid cell of the plurality of solid cells,
determining a temperature of the solid cell by calculating heat transfer
into the solid cell from any adjacent solid cells and heat transfer out
of the solid cell into any adjacent fluid cells; and storing, on a
storage device, the air flow values and the temperature of the fluid cell
and the temperature of the solid cell.
2. The computer implemented method of claim 1, wherein determining one of
the temperature of the fluid cell and the temperature of the solid cell
includes using a heat transfer coefficient characterizing heat transfer
from the solid cell to the liquid cell, wherein the heat transfer
coefficient is derived from one of experimental results and previously
conducted CFD analyses.
3. The computer implemented method of claim 2, wherein each of the
plurality of fluid cells is a three-dimensional cell.
4. The computer implemented method of claim 3, wherein each of the
plurality of solid cells is either a one dimensional cell or a two
dimensional cell.
5. The computer implemented method of claim 2, wherein the determination
of the temperature of each of the plurality of fluid cells and the
determination of the temperature of each of the plurality of solid cells
is performed for a plurality of contiguous time periods.
6. The computer implemented method of claim 5, further comprising
modeling an effect of a thermal disruption in the electronics system
during a time period subsequent to the thermal disruption on the
temperature of at least a portion of the plurality of solid cells.
7. The computer implemented method of claim 6, further comprising
determining modified air flow values which are maintained in the
plurality of fluid cells throughout the time period subsequent to the
thermal disruption.
8. The computer implemented method of claim 2, further comprising
modifying a configuration of the physical structures of the electronics
system based on one of the air flow values, the temperature of the fluid
cell and the temperature of the solid cell.
9. A system for evaluating equipment in an electronics system, the
equipment including a plurality of cooling consumers, and at least one
cooling provider, the system comprising: an interface; and a controller
coupled to the interface and configured to: receive information related
to physical structures of the electronics system; divide the electronics
system into a computational grid including a plurality of fluid cells and
a plurality of solid cells, positions of the plurality of solid cells
corresponding to positions of the physical components within the
electronics system; determine air flow values for the plurality of fluid
cells using a potential flow model analysis; for each fluid cell of the
plurality of fluid cells, determine a temperature of the fluid cell by
calculating heat transfer into the fluid cell from any adjacent fluid
cells and from any adjacent solid cells; for each solid cell of the
plurality of solid cells, determine a temperature of the solid cell by
calculating heat transfer into the solid cell from any adjacent solid
cells and heat transfer out of the solid cell into any adjacent fluid
cells; and store, on a storage device, the air flow values and the
temperature of the fluid cell and the temperature of the solid cell.
10. The system of claim 9, wherein the controller is configured to
determine one of the temperature of the fluid cell and the temperature of
the solid cell using a heat transfer coefficient characterizing heat
transfer from the solid cell to the liquid cell, wherein the heat
transfer coefficient is derived from one of experimental results and
previously conducted CFD analyses.
11. The system of claim 10, wherein the controller is configured to
determine the temperature of each of the plurality of fluid cells and to
determine the temperature of each of the plurality of solid cells for a
plurality of contiguous time periods.
12. The system of claim 11, wherein the controller is further configured
to model an effect of a thermal disruption in the electronics system
during a time period subsequent to the thermal disruption on the
temperature of at least a portion of the plurality of solid cells.
13. The system of claim 12, wherein the controller is further configured
to model the effect of the thermal disruption on the temperature of at
least a portion of the plurality of fluid cells.
14. The system of claim 10, wherein the interface is configured to
provide for a user to modify a configuration of the physical structures
of the electronics system.
15. A computer readable medium having stored thereon sequences of
instruction including instructions that will cause a processor to:
receive information related to physical structures of the electronics
system; divide the electronics system into a computational grid including
a plurality of fluid cells and a plurality of solid cells, positions of
the plurality of solid cells corresponding to positions of the physical
components within the electronics system; determine air flow values for
the plurality of fluid cells using a potential flow model analysis; for
each fluid cell of the plurality of fluid cells, determine a temperature
of the fluid cell by calculating heat transfer into the fluid cell from
any adjacent fluid cells and from any adjacent solid cells; for each
solid cell of the plurality of solid cells, determine a temperature of
the solid cell by calculating heat transfer into the solid cell from any
adjacent solid cells and heat transfer out of the solid cell into any
adjacent fluid cells; and store, on a storage device, the air flow values
and the temperature of the fluid cell and the temperature of the solid
cell.
16. The computer readable medium of claim 15, wherein the instructions
will cause the processor to determine one of the temperature of the fluid
cell and the temperature of the solid cell using a heat transfer
coefficient characterizing heat transfer from the solid cell to the
liquid cell, wherein the heat transfer coefficient is derived from one of
experimental results and previously conducted CFD analyses.
17. The computer readable medium of claim 16, wherein the instructions
will cause the processor to determine the temperature of each of the
plurality of fluid cells and to determine the temperature of each of the
plurality of solid cells for a plurality of contiguous time periods.
18. The computer readable medium of claim 17, wherein the instructions
will further cause the processor to model an effect of a thermal
disruption in the electronics system during a time period subsequent to
the thermal disruption on the temperature of at least a portion of the
plurality of solid cells.
19. The computer readable medium of claim 18, wherein the instructions
will further cause the processor to model the effect of the thermal
disruption on the temperature of at least a portion of the plurality of
fluid cells.
20. The computer readable medium of claim 15, wherein the instructions
will cause the processor to modify a model of a configuration of the
physical structures of the electronics system based on one of the air
flow values, the temperature of the fluid cell and the temperature of the
solid cell.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] At least one embodiment in accordance with the present invention
relates generally to systems and methods for management and design for
electronics cooling systems, and more specifically, to systems and
methods for predicting cooling performance within an electronics system,
for example, a computer or telecommunications device or even a full-scale
data center.
[0003] 2. Discussion of Related Art
[0004] Modern electronics systems, for example, those associated with
computer installations and other types of electronics which may dissipate
heat, may exhibit improved performance when provided with a cooling
system which may maintain the electronics system within a desired
operating temperature range. A cooling system for an electronics system
may include, for example, one or more fans or other cooling devices which
may help remove heat generated from, for example, processors, power
supplies, or other components of the electronics system. It may be
desirable to model the efficacy of a cooling system for an electronic
device or system during the design stage.
[0005] A particular form of electronics system which may utilize a cooling
system to maintain a desired temperature within the system is a network
data center. A network data center typically consists of various
information technology equipment, collocated in a structure that provides
network connectivity, electrical power and cooling capacity. Often the
equipment is housed in specialized enclosures termed "racks" which
integrate these connectivity, power and cooling elements. In some data
center configurations, these rows are organized into hot and cold aisles
to decrease the cost associated with cooling the information technology
equipment. A raised floor having an air plenum beneath the floor is
typically used for providing cooling air to the racks. Cool air is
distributed from the air plenum to the racks through perforated tiles
having open areas.
[0006] Various processes and software applications, such as the data
center management systems available from American Power Conversion (APC)
Corporation of West Kingston, R.I., have been developed to aid data
center personnel in designing and maintaining efficient and effective
data center configurations. These tools often guide data center personnel
through activities such as designing the data center structure,
positioning equipment within the data center prior to installation and
repositioning equipment after construction and installation are complete.
Thus, conventional tool sets provide data center personnel with a
standardized and predictable design methodology.
SUMMARY OF THE INVENTION
[0007] A first aspect of the invention is directed to a
computer-implemented method for evaluating cooling performance of an
electronics system, the system including a plurality of physical
components and at least one cooling provider. The method includes
receiving information related to physical structures of the electronics
system, dividing the electronics system into a computational grid
including a plurality of fluid cells and a plurality of solid cells,
positions of the plurality of solid cells corresponding to positions of
the physical components within the electronics system, determining air
flow values for the plurality of fluid cells using a potential flow model
analysis, for each fluid cell of the plurality of fluid cells,
determining a temperature of the fluid cell by calculating heat transfer
into the fluid cell from any adjacent fluid cells and from any adjacent
solid cells, for each solid cell of the plurality of solid cells,
determining a temperature of the solid cell by calculating heat transfer
into the solid cell from any adjacent solid cells and heat transfer out
of the solid cell into any adjacent fluid cells, and storing, on a
storage device, the air flow values and the temperature of the fluid cell
and the temperature of the solid cell.
[0008] In accordance with some embodiments, determining one of the
temperature of the fluid cell and the temperature of the solid cell
includes using a heat transfer coefficient characterizing heat transfer
from the solid cell to the liquid cell, wherein the heat transfer
coefficient is derived from one of experimental results and previously
conducted CFD analyses.
[0009] In accordance with some embodiments, each of the plurality of fluid
cells is a three-dimensional cell.
[0010] In accordance with some embodiments, each of the plurality of solid
cells is either a one dimensional cell or a two dimensional cell.
[0011] In accordance with some embodiments, the determination of the
temperature of each of the plurality of fluid cells and the determination
of the temperature of each of the plurality of solid cells is performed
for a plurality of contiguous time periods.
[0012] In accordance with some embodiments, the method further comprises
modeling an effect of a thermal disruption in the electronics system
during a time period subsequent to the thermal disruption on the
temperature of at least a portion of the plurality of solid cells.
[0013] In accordance with some embodiments, the method further comprises
determining modified air flow values which are maintained in the
plurality of fluid cells throughout the time period subsequent to the
thermal disruption
[0014] In accordance with some embodiments, the method further comprises
modifying a configuration of the physical structures of the electronics
system based on one of the air flow values, the temperature of the fluid
cell and the temperature of the solid cell.
[0015] Another aspect of the invention is directed to a system for
evaluating equipment in an electronics system, the equipment including a
plurality of cooling consumers, and at least one cooling provider. The
system includes an interface and a controller coupled to the interface.
The controller is configured to receive information related to physical
structures of the electronics system, divide the electronics system into
a computational grid including a plurality of fluid cells and a plurality
of solid cells, positions of the plurality of solid cells corresponding
to positions of the physical components within the electronics system,
determine air flow values for the plurality of fluid cells using a
potential flow model analysis, for each fluid cell of the plurality of
fluid cells, determine a temperature of the fluid cell by calculating
heat transfer into the fluid cell from any adjacent fluid cells and from
any adjacent solid cells, for each solid cell of the plurality of solid
cells, determine a temperature of the solid cell by calculating heat
transfer into the solid cell from any adjacent solid cells and heat
transfer out of the solid cell into any adjacent fluid cells, and store,
on a storage device, the air flow values and the temperature of the fluid
cell and the temperature of the solid cell.
[0016] In accordance with some embodiments, the controller is configured
to determine one of the temperature of the fluid cell and the temperature
of the solid cell using a heat transfer coefficient characterizing heat
transfer from the solid cell to the liquid cell, wherein the heat
transfer coefficient is derived from one of experimental results and
previously conducted CFD analyses.
[0017] In accordance with some embodiments, the controller is configured
to determine the temperature of each of the plurality of fluid cells and
to determine the temperature of each of the plurality of solid cells for
a plurality of contiguous time periods.
[0018] In accordance with some embodiments, the controller is further
configured to model an effect of a thermal disruption in the electronics
system during a time period subsequent to the thermal disruption on the
temperature of at least a portion of the plurality of solid cells.
[0019] In accordance with some embodiments, the controller is further
configured to model the effect of the thermal disruption on the
temperature of at least a portion of the plurality of fluid cells.
[0020] In accordance with some embodiments, wherein the interface is
configured to provide for a user to modify a configuration of the
physical structures of the electronics system.
[0021] Another aspect of the invention is directed to a computer readable
medium having stored thereon sequences of instruction including
instructions that will cause a processor to receive information related
to physical structures of the electronics system, divide the electronics
system into a computational grid including a plurality of fluid cells and
a plurality of solid cells, positions of the plurality of solid cells
corresponding to positions of the physical components within the
electronics system, determine air flow values for the plurality of fluid
cells using a potential flow model analysis, for each fluid cell of the
plurality of fluid cells, determine a temperature of the fluid cell by
calculating heat transfer into the fluid cell from any adjacent fluid
cells and from any adjacent solid cells, for each solid cell of the
plurality of solid cells, determine a temperature of the solid cell by
calculating heat transfer into the solid cell from any adjacent solid
cells and heat transfer out of the solid cell into any adjacent fluid
cells, and store, on a storage device, the air flow values and the
temperature of the fluid cell and the temperature of the solid cell.
[0022] In accordance with some embodiments, the instructions will cause
the processor to determine one of the temperature of the fluid cell and
the temperature of the solid cell using a heat transfer coefficient
characterizing heat transfer from the solid cell to the liquid cell,
wherein the heat transfer coefficient is derived from one of experimental
results and previously conducted CFD analyses.
[0023] In accordance with some embodiments, the instructions will cause
the processor to determine the temperature of each of the plurality of
fluid cells and to determine the temperature of each of the plurality of
solid cells for a plurality of contiguous time periods.
[0024] In accordance with some embodiments, the instructions will further
cause the processor to model an effect of a thermal disruption in the
electronics system during a time period subsequent to the thermal
disruption on the temperature of at least a portion of the plurality of
solid cells.
[0025] In accordance with some embodiments, the instructions will further
cause the processor to model the effect of the thermal disruption on the
temperature of at least a portion of the plurality of fluid cells.
[0026] In accordance with some embodiments, the instructions will cause
the processor to modify a model of a configuration of the physical
structures of the electronics system based on one of the air flow values,
the temperature of the fluid cell and the temperature of the solid cell.
BRIEF DESCRIPTION OF DRAWINGS
[0027] The accompanying drawings are not intended to be drawn to scale. In
the drawings, each identical or nearly identical component that is
illustrated in various figures is represented by a like numeral. For
purposes of clarity, not every component may be labeled in every drawing.
In the drawings:
[0028] FIG. 1 is a block diagram of one example of a computer system with
which various aspects in accord with the present invention may be
implemented;
[0029] FIG. 2 a schematic of one example of a distributed system including
an electronics system management system;
[0030] FIG. 3 demonstrates the use of grid cells in accordance with at
least one example;
[0031] FIG. 4 is a flowchart of a process in accordance with one example;
[0032] FIG. 5 is a flowchart of a process in accordance with one example;
[0033] FIG. 6 is a diagram of a heated solid block cooled by a flow of
air; and
[0034] FIG. 7 is a comparison between the predicted airflow and
temperature of the heated block of FIG. 6 as computed by a computational
flow dynamics method and an embodiment of a method in accord with the
present invention.
DETAILED DESCRIPTION
[0035] At least some embodiments in accordance with the present invention
relate to systems and processes through which a user may design and
analyze electronics system configurations. These systems and processes
may facilitate this design and analysis activity by allowing the user to
create models of electronics system configurations from which performance
metrics may be determined. Both the systems and the user may employ these
performance metrics to determine alternative system configurations that
meet various design objectives.
[0036] A networked data center is described herein as one form of
electronics system to which various aspects and embodiments of the
invention may apply. However, it should be understood that networked data
centers are only described as an illustrative example, and aspects and
embodiments of the present invention may apply to other systems as well,
for example, computers, audio and/or video systems, telecommunications
systems, or other electronics systems which may produce heat.
[0037] As described in U.S. Pat. No. 7,991,592, titled "System and Method
for Evaluating Equipment Rack Cooling," issued Aug. 2, 2011 (referred to
herein as "the '592 patent"), in U.S. patent application Ser. No.
11/342,300, titled "Methods and Systems for Managing Facility Power and
Cooling" filed Jan. 27, 2006 (referred to herein as "the '300
application"), and in U.S. patent application Ser. No. 12/884,832, titled
"System and Method for Predicting Perforated Tile Airflow in a Data
Center" filed Sep. 17, 2010 (referred to herein as "the '832
application"), each of which are assigned to the assignee of the present
application, and each of which are hereby incorporated herein by
reference in their entirety for all purposes, typical equipment racks in
modern data centers draw cooling air into the front of the rack and
exhaust air out of the rear of the rack. The equipment racks and in-row
coolers are typically arranged in rows in an alternating front/back
arrangement creating alternating hot and cool aisles in a data center
with the front of each row of racks facing the cool aisle and the rear of
each row of racks facing the hot aisle. Adjacent rows of equipment racks
separated by a cool aisle may be referred to as a cool aisle cluster, and
adjacent rows of equipment racks separated by a hot aisle may be referred
to as a hot aisle cluster. Further, single rows of equipment may also be
considered to form both a cold and a hot aisle cluster by themselves. A
row of equipment racks may be part of multiple hot aisle clusters and
multiple cool aisle clusters. In the referenced applications, tools are
provided for analyzing the cooling performance of a cluster of racks in a
data center. In these tools, multiple analyses may be performed on
different layouts to attempt to optimize the cooling performance of the
data center.
[0038] In descriptions and claims herein, electrical or electronic
components which may generate heat, for example equipment in racks, or
the racks themselves in network data centers, may be referred to as
cooling consumers. Cooling consumers are not limited to these examples,
and may include other electronic systems, for example, computers or
audio/video equipment, or other electrical or electronic systems known in
the art. Devices such as fans, liquid cooling systems, and in the example
of network data centers, in-row cooling units and/or computer room air
conditioners (CRACs), may be referred to herein as cooling providers.
Cooling providers are not limited to these examples, and may include
other systems, for example, evaporative coolers, peltier effect coolers,
or other cooling systems known in the art.
[0039] In at least one embodiment, a method is provided for performing, in
real-time, an analysis on a layout of equipment in a data center for
providing predictions of air temperatures within and at inlets and
exhausts of equipments racks and cooling providers and the ambient
temperature of a data center.
[0040] The aspects and embodiments of the present invention disclosed
herein are not limited in their application to the details of
construction and the arrangement of components set forth in the following
description or illustrated in the drawings. These aspects are capable of
assuming other embodiments and of being practiced or of being carried out
in various ways. Examples of specific implementations are provided herein
for illustrative purposes only and are not intended to be limiting. In
particular, acts, elements and features discussed in connection with any
one or more embodiments are not intended to be excluded from a similar
role in any other embodiments.
[0041] For example, according to one embodiment of the present invention,
a computer system is configured to perform any of the functions described
herein, including but not limited to, configuring, modeling and
presenting information regarding specific electronics system
configurations. Further, computer systems in embodiments may be used to
automatically measure environmental parameters in an electronics system,
and control equipment, such as chillers or coolers to optimize
performance. Moreover, the systems described herein may be configured to
include or exclude any of the functions discussed herein. Thus the
embodiments are not limited to a specific function or set of functions.
Also, the phraseology and terminology used herein is for the purpose of
description and should not be regarded as limiting. The use herein of
"including," "comprising," "having," "containing," "involving," and
variations thereof is meant to encompass the items listed thereafter and
equivalents thereof as well as additional items.
Computer System
[0042] Various aspects and functions described herein in accordance with
the present embodiments may be implemented as hardware or software on one
or more computer systems. There are many examples of computer systems
currently in use. These examples include, among others, network
appliances, personal computers, workstations, mainframes, networked
clients, servers, media servers, application servers, database servers
and web servers. Other examples of computer systems may include mobile
computing devices, such as cellular phones and personal digital
assistants, and network equipment, such as load balancers, routers and
switches. Further, aspects in accordance with the present embodiments may
be located on a single computer system or may be distributed among a
plurality of computer systems connected to one or more communications
networks.
[0043] For example, various aspects and functions may be distributed among
one or more computer systems configured to provide a service to one or
more client computers, or to perform an overall task as part of a
distributed system. Additionally, aspects may be performed on a
client-server or multi-tier system that includes components distributed
among one or more server systems that perform various functions. Thus,
the embodiments are not limited to executing on any particular system or
group of systems. Further, aspects may be implemented in software,
hardware or firmware, or any combination thereof. Thus, aspects in
accordance with the present embodiments may be implemented within
methods, acts, systems, system elements and components using a variety of
hardware and software configurations, and the embodiments are not limited
to any particular distributed architecture, network, or communication
protocol.
[0044] FIG. 1 shows a block diagram of a distributed computer system 100,
in which various aspects and functions in accord with the present
embodiments may be practiced. Distributed computer system 100 may include
one more computer systems. For example, as illustrated, distributed
computer system 100 includes computer systems 102, 104, and 106. As
shown, computer systems 102, 104, and 106 are interconnected by, and may
exchange data through, communication network 108. Network 108 may include
any communication network through which computer systems may exchange
data. To exchange data using network 108, computer systems 102, 104, and
106 and network 108 may use various methods, protocols and standards,
including, among others, token ring, Ethernet, wireless Ethernet,
Bluetooth, TCP/IP, UDP, Http, FTP, SNMP, SMS, MMS, SS7, Json, Soap, and
Corba. To ensure data transfer is secure, computer systems 102, 104, and
106 may transmit data via network 108 using a variety of security
measures including TLS, SSL or VPN among other security techniques. While
distributed computer system 100 illustrates three networked computer
systems, distributed computer system 100 may include any number of
computer systems and computing devices, networked using any medium and
communication protocol.
[0045] Various aspects and functions in accordance with the present
embodiments may be implemented as specialized hardware or software
executing in one or more computer systems including computer system 102
shown in FIG. 1. As depicted, computer system 102 includes processor 110,
memory 112, bus 114, interface 116, and storage 118. Processor 110 may
perform a series of instructions that result in manipulated data.
Processor 110 may be a commercially available processor such as an Intel
Pentium, Motorola PowerPC, SGI MIPS, Sun UltraSPARC, or Hewlett-Packard
PA-RISC processor, but may be any type of processor, multi-processor,
microprocessor or controller as many other processors and controllers are
available. Processor 110 is connected to other system elements, including
one or more memory devices 112, by bus 114.
[0046] Memory 112 may be used for storing programs and data during
operation of computer system 102. Thus, memory 112 may be a relatively
high performance, volatile, random access memory such as a dynamic random
access memory (DRAM) or static memory (SRAM). However, memory 112 may
include any device for storing data, such as a disk drive or other
non-volatile, non-transitory, storage device. Various embodiments in
accordance with the present invention may organize memory 112 into
particularized and, in some cases, unique structures to perform the
aspects and functions disclosed herein.
[0047] Components of computer system 102 may be coupled by an
interconnection element such as bus 114. Bus 114 may include one or more
physical busses, for example, busses between components that are
integrated within a same machine, but may include any communication
coupling between system elements including specialized or standard
computing bus technologies such as IDE, SCSI, PCI and InfiniBand. Thus,
bus 114 enables communications, for example, data and instructions, to be
exchanged between system components of computer system 102.
[0048] Computer system 102 also includes one or more interface devices 116
such as input devices, output devices and combination input/output
devices. Interface devices may receive input or provide output. More
particularly, output devices may render information for external
presentation. Input devices may accept information from external sources.
Examples of interface devices include keyboards, mouse devices,
trackballs, microphones, touch screens, printing devices, display
screens, speakers, network interface cards, etc. Interface devices allow
computer system 102 to exchange information and communicate with external
entities, such as users and other systems.
[0049] Storage system 118 may include a computer readable and writeable,
nonvolatile, non-transitory, storage medium in which instructions are
stored that define a program to be executed by the processor. Storage
system 118 also may include information that is recorded, on or in, the
medium, and this information may be processed by the program. More
specifically, the information may be stored in one or more data
structures specifically configured to conserve storage space or increase
data exchange performance. The instructions may be persistently stored as
encoded signals, and the instructions may cause a processor to perform
any of the functions described herein. The medium may, for example, be
optical disk, magnetic disk, or flash memory, among others. In operation,
the processor or some other controller may cause data to be read from the
nonvolatile recording medium into another memory, such as memory 112,
that allows for faster access to the information by the processor than
does the storage medium included in storage system 118. The memory may be
located in storage system 118 or in memory 112, however, processor 110
may manipulate the data within the memory 112, and then may copy the data
to the medium associated with storage system 118 after processing is
completed. A variety of components may manage data movement between the
medium and integrated circuit memory element and the presently described
embodiments are not limited thereto. Further, the embodiments are not
limited to a particular memory system or data storage system.
[0050] Although computer system 102 is shown by way of example as one type
of computer system upon which various aspects and functions in accordance
with the present embodiments may be practiced, any aspects of the
presently disclosed embodiments are not limited to being implemented on
the computer system as shown in FIG. 1. Various aspects and functions in
accord with the presently disclosed embodiments may be practiced on one
or more computers having a different architectures or components than
that shown in FIG. 1. For instance, computer system 102 may include
specially-programmed, special-purpose hardware, such as for example, an
application-specific integrated circuit (ASIC) tailored to perform a
particular operation disclosed herein. While another embodiment may
perform the same function using several general-purpose computing devices
running MAC OS System X with Motorola PowerPC processors and several
specialized computing devices running proprietary hardware and operating
systems.
[0051] Computer system 102 may be a computer system including an operating
system that manages at least a portion of the hardware elements included
in computer system 102. Usually, a processor or controller, such as
processor 110, executes an operating system which may be, for example, a
Windows-based operating system such as Windows NT, Windows 2000 (Windows
ME), Windows XP, or Windows Vista operating systems, available from the
Microsoft Corporation, a MAC OS System X operating system available from
Apple Computer, one of many Linux-based operating system distributions,
for example, the Enterprise Linux operating system available from Red Hat
Inc., a Solaris operating system available from Sun Microsystems, or a
UNIX operating system available from various sources. Many other
operating systems may be used, and embodiments are not limited to any
particular implementation.
[0052] The processor and operating system together define a computer
platform for which application programs in high-level programming
languages may be written. These component applications may be executable,
intermediate, for example, C-, bytecode or interpreted code which
communicates over a communication network, for example, the Internet,
using a communication protocol, for example, TCP/IP. Similarly, aspects
in accord with the presently disclosed embodiments may be implemented
using an object-oriented programming language, such as .Net, SmallTalk,
Java, C++, Ada, or C# (C-Sharp). Other object-oriented programming
languages may also be used. Alternatively, functional, scripting, or
logical programming languages may be used.
[0053] Additionally, various aspects and functions in accordance with the
presently disclosed embodiments may be implemented in a non-programmed
environment, for example, documents created in HTML, XML or other format
that, when viewed in a window of a browser program, render aspects of a
graphical-user interface or perform other functions. Further, various
embodiments in accord with the present invention may be implemented as
programmed or non-programmed elements, or any combination thereof. For
example, a web page may be implemented using HTML while a data object
called from within the web page may be written in C++. Thus, the
presently disclosed embodiments are not limited to a specific programming
language and any suitable programming language could also be used.
[0054] A computer system included within an embodiment may perform
additional functions outside the scope of the presently disclosed
embodiments. For instance, aspects of the system may be implemented using
an existing commercial product, such as, for example, Database Management
Systems such as SQL Server available from Microsoft of Seattle Wash.,
Oracle Database from Oracle of Redwood Shores, Calif., and MySQL from
MySQL AB, a subsidiary of Oracle or integration software such as Web
Sphere middleware from IBM of Armonk, N.Y. However, a computer system
running, for example, SQL Server may be able to support both aspects in
accord with the presently disclosed embodiments and databases for sundry
applications.
Example System Architecture
[0055] FIG. 2 presents a context diagram including physical and logical
elements of distributed system 200. As shown, distributed system 200 is
specially configured in accordance with the presently disclosed
embodiments. The system structure and content recited with regard to FIG.
2 is for exemplary purposes only and is not intended to limit the
embodiments to the specific structure shown in FIG. 2. FIG. 2 uses a data
center as an example of an electronics system to which aspects and
embodiments of the preset invention may apply, however, the present
invention contemplates application to other systems, for example,
computers, audio/video systems, consumer electronics, or any other
electric or electronic systems known in the art. As will be apparent to
one of ordinary skill in the art, many variant system structures can be
architected without deviating from the scope of the presently disclosed
embodiments. The particular arrangement presented in FIG. 2 was chosen to
promote clarity.
[0056] Information may flow between the elements, components and
subsystems depicted in FIG. 2 using any technique. Such techniques
include, for example, passing the information over the network via
TCP/IP, passing the information between modules in memory and passing the
information by writing to a file, database, or some other non-volatile
storage device. Other techniques and protocols may be used without
departing from the scope of the presently disclosed embodiments.
[0057] Referring to FIG. 2, system 200 includes user 202, interface 204,
data center design and management system 206, communications network 208,
and data center database 210. System 200 may allow user 202, such as a
data center architect or other data center personnel, to interact with
interface 204 to create or modify a model of one or more data center
configurations. According to one embodiment, interface 204 may include
aspects of the floor editor and the rack editor as disclosed in Patent
Cooperation Treaty Application No. PCT/US08/63675, titled "Methods and
Systems for Managing Facility Power and Cooling," filed on May 15, 2008,
which is incorporated herein by reference in its entirety and is
hereinafter referred to as PCT/US08/63675. In other embodiments,
interface 204 may be implemented with specialized facilities that enable
user 202 to design, in a drag and drop fashion, a model that includes a
representation of the physical layout of a data center or any subset
thereof. This layout may include representations of data center
structural components as well as data center equipment. The features of
interface 204, as may be found in various embodiments in accordance with
the present invention, are discussed further below. In at least one
embodiment, information regarding a data center is entered into system
200 through the interface, and assessments and recommendations for the
data center are provided to the user. Further, in at least one
embodiment, optimization processes may be performed to optimize cooling
performance and energy usage of the data center.
[0058] As shown in FIG. 2, data center design and management system 206
presents data design interface 204 to user 202. According to one
embodiment, data center design and management system 206 may include the
data center design and management system as disclosed in PCT/US08/63675.
In this embodiment, design interface 204 may incorporate functionality of
the input module, the display module and the builder module included in
PCT/US08/63675 and may use the database module to store and retrieve
data.
[0059] As illustrated, data center design and management system 206 may
exchange information with data center database 210 via network 208. This
information may include any information needed to support the features
and functions of data center design and management system 206. For
example, in one embodiment, data center database 210 may include at least
some portion of the data stored in the data center equipment database
described in PCT/US08/63675. In another embodiment, this information may
include any information needed to support interface 204, such as, among
other data, the physical layout of one or more data center model
configurations, the production and distribution characteristics of the
cooling providers included in the model configurations, the consumption
characteristics of the cooling consumers in the model configurations, and
a listing of equipment racks and cooling providers to be included in a
cluster.
[0060] In one embodiment, data center database 210 may store types of
cooling providers, the amount of cool air provided by each type of
cooling provider, and a temperature of cool air provided by the cooling
provider. Thus, for example, data center database 210 includes records of
a particular type of CRAC unit in a data center that is rated to deliver
airflow at the rate of 5,600 cubic feet per minute (cfm) at a temperature
of 68 degrees Fahrenheit. In addition, the data center database 210 may
store one or more cooling metrics, such as inlet and outlet temperatures
of the CRACs and inlet and exhaust temperatures of one or more equipment
racks. The temperatures may be periodically measured and input into the
system, or in other embodiments, the temperatures may be continuously
monitored using devices coupled to the system 200.
[0061] Data center database 210 may take the form of any logical
construction capable of storing information on a computer readable medium
including, among other structures, flat files, indexed files,
hierarchical databases, relational databases or object oriented
databases. The data may be modeled using unique and foreign key
relationships and indexes. The unique and foreign key relationships and
indexes may be established between the various fields and tables to
ensure both data integrity and data interchange performance.
[0062] The computer systems shown in FIG. 2, which include data center
design and management system 206, network 208 and data center equipment
database 210, each may include one or more computer systems. As discussed
above with regard to FIG. 1, computer systems may have one or more
processors or controllers, memory and interface devices. The particular
configuration of system 200 depicted in FIG. 2 is used for illustration
purposes only and embodiments of the invention may be practiced in other
contexts. Thus, embodiments of the invention are not limited to a
specific number of users or systems.
Airflow and Temperature Prediction Tool
[0063] Aspects and embodiments of a Potential Flow Model (PFM) to predict
airflow patterns, pressures, air temperatures, and capture indices for
data center applications was described in U.S. patent application Ser.
No. 12/970,605, titled "System and Methods for Rack Cooling Analysis"
filed Dec. 16, 2010 (referred to herein as "the '605 application"), which
is assigned to the assignee of the present application, and which is
hereby incorporated herein by reference in its entirety for all purposes.
In some electronics systems, for example, data centers incorporating
equipment racks and coolers, solid surfaces such as the sides of racks
and coolers, walls, etc. pose an obstruction to airflow but do not
directly take part in heat transfer. Generally, no heat flows into or out
of solid surfaces except at a flow boundary (for example a rack exhaust
or cooler return). To provide accurate predictions of solid-object
temperatures, it may be desired that the "conjugate" heat transfer
problem be solved. The "conjugate" heat transfer analysis is the
simultaneous prediction of the coupled fluid and solid temperatures and
involves heat transfer across a solid-fluid interface. The prediction of
solid temperatures may also be called a "conduction analysis" because
conduction is the only mode of heat transfer at play inside a solid. This
is routinely done in full Computational Fluid Dynamics (CFD) methods for
applications such as predicting the temperatures of important components
(for example, the "junction" temperature inside a CPU). Computational
methods in accordance with embodiments of the present invention employing
PFM may provide similar predictions as a full CFD analysis but with
significantly fewer calculations.
[0064] At least some aspects and embodiments of the present invention
extend the PFM approach to handle conjugate heat transfer where the
primary application is electronics cooling. However, aspects and
embodiments of the present invention may apply to many systems in which
fluid and solid temperatures must be computed simultaneously. Other
notable applications include data centers, consumer electronics, general
commercial and public buildings, and industrial applications where the
fluid involved may be air, water, or any other liquid or gas.
Conjugate PFM (CPFM)
[0065] The combined PFM and solid conduction heat transfer will be
referred to herein as "Conjugate PFM (CPFM)." For steady-state
applications, the fluid flow may only need to be determined once;
however, for transient analysis, the fluid flow pattern may be determined
as many times as needed, for example, following a fan failure or a fan
speed change. In some embodiments a new fluid flow pattern is only
determined once following a transient event. The same new fluid flow
pattern may be used in temperature calculations for a number of time
periods following the transient event. Determining the fluid flow
patterns using a PFM analysis will not be reviewed here as this has been
well described in, for example, the '605 application. However, it is
noted that in electronics-cooling and other applications, the flow rate
through fans often depends strongly on the environment in which the fans
are placed. In this case, pressures in addition to velocities may be
computed so that the fan flow rate can be determined based on
manufacturer-supplied data. This would be similar to determining the
airflow through perforated tiles as described in the '832 application.
[0066] In PFM, the fluid flow is idealized as irrotational. This
idealization places some limitations on the ability of PFM to predict
complex recirculation zones, jets, and other flow features. Additionally,
buoyancy forces are not typically included in PFM predictions.
Consequently, CPFM will be more accurate the smaller buoyancy forces are
relative to momentum forces, for example, in air flows driven by fans. In
return for the loss of some fidelity to the real physics, PFM is vastly
simpler and more reliable than CFD (i.e., it essentially always converges
to an answer) and solution times are typically a few seconds compared to
minutes to hours for CFD. For many applications the reduction of accuracy
relative to CFD may be minimal and other cases it may be modest but
justifiable because, for example, only reasonable estimates are required
at an early design stage or precise input data is unobtainable so that
the additional theoretical solution accuracy of CFD would not be realized
in practice.
Steady-State Applications
[0067] With CPFM, the volume to be modeled is divided up into grid cells
as done with PFM, but with CPFM, a computational grid is defined within
the solids as well as within the fluid. In various aspects, the grid
cells may be either one-dimensional, two-dimensional, or three
dimensional. In further aspects, solid objects may be represented as one
dimensional thermal networks rather than with multi-dimensional cells. In
some embodiments only the interface between a solid object and a fluid,
such as air, is taken into account, and calculations are not performed
for temperatures or heat flow within the solid object. FIG. 3 shows
general fluid and solid grid cells on either side of a fluid-solid
interface. The subscripts "N," "S," "E," and "W" in the cell labels in
this figure refer to cells to the north, south, east, and west,
respectfully of a cell of interest with a subscript "i." The superscripts
"f" and "s" in the cell labels in this figure indicate whether the cell
is part of a fluid (for example, air) or a solid, respectfully. The black
arrows represent the assumed direction of heat flow across cell faces and
also the direction of fluid flow for the fluid cells. For simplicity and
clarity of the analysis which follows, grid cells are assumed to be
perfectly cuboidal with all sides of length .DELTA.x and equations are
developed only for the 2D case. In some embodiments, the method can
easily be extended to include non-uniform grid cells, unstructured grids,
and 3D scenarios. In the examples which follow, airflow velocities are
assumed to be known from a PFM analysis.
[0068] A steady-state energy balance on the fluid grid cell yields an
equation for the temperature of fluid cell:
T i f = ( 1 1 + h V W .rho. f c p f ) T W
f + ( 1 1 + V W .rho. f c p f h ) T i s
( 1 ) ##EQU00001##
[0069] Where T.sub.i.sup.f is the temperature of fluid cell i,
T.sub.w.sup.f is the temperature of the fluid cell to the west of fluid
cell i, T.sub.i.sup.s is the temperature of solid cell i, V.sub.N,
V.sub.E, and V.sub.W are the known flow velocities across cell boundaries
to the North, East, and West respectively, h is the heat transfer
coefficient, .rho..sup.f is the density of the fluid, and c.sub.p.sup.f
is the specific heat of the fluid. Equation (1) has also been simplified
to reflect the fact that, for this simple example,
V.sub.N+V.sub.E=V.sub.W. The heat transfer coefficient h is defined by
Newton's Law of Cooling:
q'''=h(T.sup.s-T.sup.f) (2)
where q''' is the heat transfer per unit area (for example, in W/m.sup.2)
and T.sub.s and T.sup.f are the solid and fluid temperatures,
respectively. The heat transfer coefficient depends on the flow pattern
near the surface as well as the physical properties of the fluid and has
been extensively correlated against experimental measurements for simple
configurations like that of uniform flow past a flat plate. Correlations
for a flat plate configuration are:
Nu=0.664Re.sup.1/2Pr.sup.1/3 is Re<5.times.10.sup.5
Nu=(0.037Re.sup.4/5-871)Pr.sup.1/2 if Re.gtoreq.5.times.10.sup.5 (3)
[0070] where,
Nu = hL k = Nusselt Number , a
dimensionless from of the heat
transfer coefficient ##EQU00002## Re = .rho.
VL .mu. = Reynolds Number , a
dimensionless number which determines flow
regime ##EQU00002.2## Pr = .mu. c p k =
Prandtl Number , a dimensionless number
summarizing certain physical properties of
the fluid ##EQU00002.3##
[0071] L=characteristic length scale
[0072] k=thermal conductivity of the fluid
[0073] V=characteristic flow velocity
[0074] .mu.=viscosity of fluid
[0075] In the derivation of Equation (1) above, a standard "upwind" model
was utilized which assumes that energy is conducted into or out of the
grid cell only in the direction of the flow. This equation also neglects
conduction heat transfer in the fluid as convection (i.e., energy
transfer to the bulk movement of fluid) is usually dominant. In other
embodiments, these terms could be included in the analysis and terms for
the temperatures of all neighboring cells would appear in Equation (1).
[0076] Energy transfer through the faces of the solid grid cell of FIG. 3
is due purely to conduction except for the top face where there is
convection heat transfer with the fluid. A steady-state energy balance on
the solid cell yields an equation for the temperature of the solid cell
i:
T i s = ( 1 3 + h .DELTA. x k s ) (
T W s + T E s + T S s ) + ( 1 1 + 3 k s h
.DELTA. x ) T i f ( 4 ) ##EQU00003##
[0077] where T.sub.W.sup.s, T.sub.E.sup.s, and T.sub.S.sup.s are the solid
temperatures of cells to the West, East, and South respectively and
k.sup.s is the thermal conductivity of the solid.
[0078] For a steady-state application, equations similar to Equations (1)
and (4) may be written for all grid cells. The exact form of the
equations may vary depending on the location of the cell which defines
the conditions on each face of the cell. For example, for fluid or solid
cells completely surrounded by other cells of their same type, there is
no fluid-solid interface and the equations will not contain the heat
transfer coefficient, h. The equations may be solved using any one of a
variety of techniques, for example, Gauss-Seidel iteration, and the
solution may sweep through all solid and fluid cells at each iteration or
many iterations may be performed separately in the fluid and the solid
before returning to the other region. Some iteration back and forth
between fluid and solid may be required as the temperature of the
boundary cells affects the temperature in the other region. The coupling
of the fluid and solid temperatures is facilitated by the heat transfer
coefficient h. The heat transfer coefficient is determined from either
experimental correlations or empirical correlations determined from CFD
analyses performed "offline" and the h may be based, in part, on the
local fluid flow velocities as determined in the PFM analysis.
[0079] A flow chart of the steady-state solution process is shown in FIG.
4, indicated generally at 400. After reading all data related to the
configuration of the data center (act 410), a computational grid is
defined (act 420), and the fluid flow pattern, i.e., the velocity at each
cell face, is determined from a PFM analysis (act 430). Next the
temperature distributions in the fluid and solid cells are determined
sequentially (acts 440-460). The process continues until residual error
(imbalance of energy flows over all cells) is considered to be smaller
than a threshold (act 470), for example, 0.5% of all of the power
dissipated in the system being analyzed. Results may then be output to a
user (act 480).
Transient Applications
[0080] In the transient scenario, the fluid flow may be modeled as a
series of steady-state flow patterns, where the number of flow patterns
predicted depends upon the scenario being analyzed. The scenario may
include a thermal disruption; an event where heat produced from a source
of heat is either increased or decreased, including events when the
source of heat is enabled or disabled, or an event where a cooling
provider becomes more or less capable of removing heat from a system,
including events where the cooling provider becomes enabled or disabled.
Consider, for example, a scenario in which a desktop computer is
operating normally, then, at some reference time t=0, one of two cooling
fans fails. If it is desired to determine component temperatures at times
following t=0, at least two airflow patterns should be determined: the
initial airflow pattern with both fans running and the later airflow
pattern when only one fan is running.
[0081] An equation for the temperature of fluid cell i of FIG. 3 including
the transient heating or cooling of the fluid contained in the grid cell
is derived as follows. The transient term can be represented as:
the rate of change of stored
energy = .rho. f c p f V f T t f t
.apprxeq. .rho. f c p f V f T i f + - T i f
.DELTA. t ( 5 ) ##EQU00004##
[0082] where T.sub.i.sup.f+ is the temperature of fluid cell i after a
time step of .DELTA.t, .rho..sup.f is the density of the fluid,
c.sub.p.sup.f is the specific heat of the fluid and
V.sup.f=.DELTA.x.sup.3 is the fluid cell volume. Including this term in
the energy balance for grid cell i leads to the following expression for
the temperature of the fluid cell at a future time:
T i f + = T i f + .DELTA. t .DELTA. x
[ V w ( T W f - T i f ) + h .rho. f c p f (
T i s - T i f ) ] ( 6 ) ##EQU00005##
[0083] An energy balance including the transient heating or cooling of
solid cell i of FIG. 3 leads to:
T i s + = T i s + h .DELTA. t .DELTA.
x .rho. s c p s ( T i f - T i s ) + k
.DELTA. t .DELTA. x 2 .rho. s c p s
( T E s + T W s + T S s - 3 T i s ) ( 7 )
##EQU00006##
[0084] where T.sub.i.sup.s+ is the temperature of solid cell i after a
time step of .DELTA.t.
[0085] Equations (6) and (7) are "explicit" representations of the
temperature in the fluid and solid cells respectively at a future time.
Therefore, with this approach, the temperature over all cells can be
computed sequentially for a given time step. Then, these temperatures are
used on the right-hand side of Equations (6) and (7) to compute
temperatures at the next time step. This process continues until the
desired transient period has been covered. In some embodiments, in
Equation (5), the temperatures of all neighboring cells at the current
time are evaluated.
[0086] In some embodiments it is also possible to represent the
temperatures of all neighboring cells also at the future time. This is
referred to herein as an "implicit" approach because the temperature at
cell i cannot be isolated and in Equations (6) and (7), all
neighboring-cell temperatures would be denoted with a "+" superscript and
become unknowns. With the implicit approach, in some embodiments, all
T.sub.i.sup.f+ and T.sub.i.sup.s+ values over all cells could be
determined simultaneously using a solver, for example, Gauss-Seidel
iteration, to determine temperatures at each time step. The explicit
approach has the advantage of great simplicity; however, it only
converges to a sensible result if sufficiently small time steps are used.
The implicit method has the advantage that it will converge regardless of
time-step size and therefore, since larger time steps can be used, the
total solution time may be less.
[0087] The steps in an embodiment of the CPFM for transient applications
is shown in a flowchart, indicated generally at 500 in FIG. 5. In this
method, acts 510, 520, and 530 are similar to acts 410, 420, and 430 of
flowchart 400. Act 510 includes an additional act of determining a number
of time periods over which to perform the transient analysis. A greater
number of shorter time periods may provide more accurate results than a
lesser number of longer time periods. Acts 560, 570, 580, 590, and 600 of
flowchart 500 are similar to acts 440, 450, 460, 470, and 480,
respectively of flowchart 400. Flowchart 500 includes a decision act 540
where it is determined whether an event causes the airflow Boundary
Conditions (BCs) to change. If so, the altered fluid flows are calculated
in act 550 before proceeding to calculate the new fluid and solid
temperatures for the associated time period. Acts 540-600 are repeated
for each time period. In some embodiments, the results may be output (act
600) after the completion of the analysis for all time periods.
[0088] With the transient process, airflow patterns, and subsequently
temperatures, may have to be recomputed several times depending on the
number of transient events. If a transient event causes the airflow BCs
to change, for example, a fan is shut off, then airflow patterns may be
recalculated; however, if the transient event is limited to a power or
temperature change, for example, a component starts dissipating
additional heat, then only temperatures need be recalculated.
Example
[0089] Consider the 2D steady-state airflow over a heated solid block as
shown in FIG. 6. For purposes of distributing the 30 W dissipated by the
block, the entire system is assumed to be 150 mm deep in the direction
into the paper. This configuration could represent, for example, an
electronics-thermal application where the primary goal is to determine
the temperature of the heated solid block, which could represent a
printed circuit board covered with heat-dissipating components. In this
simple example, the block is uniformly heated and has a fairly high
thermal conductivity so that, in equilibrium, all parts of the block will
largely attain a single uniform temperature. In addition to predicting
the block temperature, it is desired to also predict the airflow pattern
surrounding the block and the temperature of the air everywhere within
the enclosure.
[0090] The calculation of velocities and temperatures in the fluid follows
the PFM approach described in, for example, the '605 application. To
couple the solid-conduction and fluid-convection solutions, it is
desirable to accurately predict heat transfer at the fluid-solid
boundary.
[0091] With the conjugate PFM (CPFM) approach, heat transfer at the
fluid-solid boundary may be empirically computed. It is generally not
necessary to predict the shape of the velocity or temperature profile
close to the wall to a high level of detail. Instead, a heat transfer
coefficient, h (for example, in units of W/(m.sup.2.degree. C.)), may be
utilized to determine the heat transfer as a function of fluid velocities
and temperatures near the boundary.
[0092] FIG. 7 shows a comparison of the airflow and temperatures from CFD
and CPFM calculation methods for the Example of FIG. 6. In this example,
the heat transfer coefficients for CPFM were taken from the CFD model.
Although this virtually guarantees similar block temperature estimates,
in theory, a very good library of hs can be compiled from CFD runs
performed "offline."
Advantages of Conjugate PFM (CPFM)
[0093] The advantages of CPFM over CFD are similar to those of PFM over
CFD as the time and effort of the problem is dominated by the
airflow-solution portion not the conduction-solution portion. The
advantages are related to speed, reliability, and simplicity of the model
relative to CFD. The high-reliability of the method (i.e., it produces a
reasonable result most or all of the time unlike CFD which frequently
fails to converge) means that non-physical aspects of the numerical
modeling like computational grid and convergence parameters may be hidden
from the user. Consequently, such tools can be used by less sophisticated
users with less training and support than full CFD and be made available
more economically. CPFM tools can be used to analyze problems in seconds
or minutes that take hours or days to solve in CFD.
[0094] The approach to handling turbulence in CFD and CPFM are markedly
different. In CFD this may be handled in one of two ways: in laminar
flow, the user has to be responsible to define enough computational grid
cells so that the steep temperature gradient just on the fluid side of
the interface is sufficiently resolved. This often requires grid cells on
the order of 1 mm or smaller in the direction perpendicular to the solid
surface and predictions are slow and highly grid dependent. When
turbulence is selected by a CFD software user, a "wall function" may be
employed. A wall function is an empirical expression for the shapes of
the velocity and temperature profiles just on the fluid side of the
interface. Because of the empiricism, the simulation is much less grid
dependent and larger cells can be used to yield reasonable results.
Unfortunately, CFD generally does not do a good job at handling regions
in "transition," i.e., somewhere in the awkward state between fully
laminar and fully turbulent flow and the quality of results are very
CFD-code and application dependent and the user needs to decide a priori
as to whether the flow is laminar or turbulent.
[0095] Since CPFM utilizes prescribed heat transfer coefficients to model
heat transfer at fluid-solid boundaries the user never needs to decide if
the flow is laminar or turbulent; this decision is made in the CPFM
analysis automatically when the proper heat transfer coefficient is
selected based on local flow conditions. Although CPFM is not nearly as
sensitive to grid size as CFD, the issue of grid size in CPFM is largely
irrelevant to the user. In some embodiments, an algorithm may generate a
computational grid without any involvement with or even knowledge of the
user.
[0096] As a result of the tremendous increase in simplicity and solution
speed, CPFM tools can quickly analyze multiple design configurations and
include optimization features that would be otherwise prohibitively slow
in CFD based tools.
[0097] In embodiments above, processes and systems are provided that can
determine relevant temperatures and air flows in electronic system in
steady state conditions. The processes and systems may also determine
changes in airflows and temperatures in an electronics system which may
occur following a cooling system event which includes a change in heat
produced (either an increase or decrease) by one or more components of
the electronics system, or an initiation or disruption in operations of
part or all of a cooling system. The systems and methods can be used to
provide optimized design of electronics systems and other applications.
As readily understood by one of ordinary skill in the art, in at least
some embodiments, the air flow and/or temperature values determined are
predictions for actual values that will occur for systems having the
parameters modeled. In methods of at least one embodiment of the
invention, after successful modeling of a cluster in a data center, the
results of the model may be used as part of a system to order equipment,
ship equipment and install equipment in a data center as per the designed
layout.
[0098] In at least some embodiments of the invention discussed herein, the
performance of assessments and calculations in real-time refers to
processes that are completed in a matter of a few seconds or less rather
than several minutes or longer as can happen with complex calculations,
such as those involving typical CFD calculations.
[0099] In at least some embodiments described above, the design of an
electronics system and/or actual parameters in an electronics system are
altered based on predicted air flow. For example, a user of the design
and management system may change the location of components and/or
cooling apparatus that are used in the actual layout of equipment or the
proposed layout of equipment in the electronics system. These alterations
may be implemented to improve the cooling performance and/or may be
implemented to provide cost and/or power savings when the performance is
found to be within predetermined specifications. Further, based on
determined airflow values, a data management system in accordance with
one embodiment, may control one or more CRACs in a data center to adjust
the airflow, and in addition, one or more equipment racks can be
controlled to reduce power if the airflow is not adequate to provide
sufficient cooling.
[0100] In at least some embodiments described above, tools and processes
are provided for determining airflow in electronics systems. In other
embodiments, the tools and processes may be used for other types of
systems, for example, in mobile applications, including mobile data
centers.
[0101] Having thus described several aspects of at least one embodiment of
this invention, it is to be appreciated various alterations,
modifications, and improvements will readily occur to those skilled in
the art. Such alterations, modifications, and improvements are intended
to be part of this disclosure, and are intended to be within the spirit
and scope of the invention. Accordingly, the foregoing description and
drawings are by way of example only.
* * * * *