# Patent

## Title
Hybrid heat exchanger

## Abstract

A thermoelectric cooler assembly comprises a cold plate, a first thermoelectric cooler, and a second thermoelectric cooler. The cold plate has a first side and a second side. The first thermoelectric cooler is in thermal communication with the first side of the cold plate, and the second thermoelectric cooler is in thermal communication with the second side of the cold plate. A heat exchanger assembly is also disclosed.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 11/580,671, entitled “Hybrid Heat Exchanger,” filed on Oct. 13, 2006, the disclosure of which is hereby expressly incorporated by reference in its entirety.


FIELD OF THE DISCLOSURE
This disclosure relates generally to information handling systems, and relates more particularly to a two stage thermoelectric cooler-enhanced heat exchanger having liquid cooling.
BACKGROUND
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Information handling systems include processors, which produce heat. In information handling systems such as desktop computers, the heat produced by the processors is typically managed with air cooling. However, air cooling has inherent limitations that may be exceeded by microprocessors that are increasingly dense and powerful. Thermoelectric coolers (TEC) to improve thermal performance have therefore been proposed. U.S. Patent Application Publication No. 2006/0082971, the disclosure of which is hereby incorporated by reference, shows a system and method for heat dissipation including a TEC.



BRIEF DESCRIPTION OF THE DRAWINGS
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the Figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements. Embodiments incorporating teachings of the present disclosure are shown and described with respect to the drawings presented herein, in which:
FIG. 1 is a partially exploded perspective view of a hybrid heat exchanger; and
FIG. 2 is an exploded perspective view of a thermoelectric cooler of the hybrid heat exchanger.



The use of the same reference symbols in different drawings indicates similar or identical items.
DETAILED DESCRIPTION
The following description in combination with the Figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings.
FIG. 1 shows a hybrid heat exchanger 10 for an information handling system. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a PDA, a consumer electronic device, a network server or storage device, a switch router or other network communication device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components of the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.
The hybrid heat exchanger 10 includes a passive heat exchanger or radiator 12, a fan 14 and a thermoelectric cooler (TEC) assembly 16. The radiator 12 is preferably disposed in a shroud 18, while the fan 14 and the TEC assembly 16 are disposed in a subassembly 20. The shroud 18 and the subassembly 20 together form a module 22. A micro-channel cold plate 24 is also disposed within the subassembly 20, and is adapted for physical and/or thermal communication with the CPU 26 (shown schematically). The micro-channel cold plate 24 is also adapted for fluid communication with a pair of conduits 28 and 30. A pump 31 circulates liquid coolant, such as water, to and/or from the radiator 12 and through the conduits 28 and 30 in well-known fashion.
FIG. 2 shows the TEC assembly 16 including a two-sided fluid heat exchanger or cold plate 32, an upper TEC 34, a lower TEC 36, an upper heat sink 38, and a lower heat sink 40. The cold plate 32 includes opposite surfaces 42 and 44, as well as conduits 46 and 48 through which coolant is circulated by the pump 31. The upper TEC 34 is disposed between the upper surface 42 of the cold plate 32 and the lower side of the upper heat sink 38. Similarly, the lower TEC 36 is disposed between the lower surface 44 of the cold plate 32 and the upper side of the lower heat sink 40.
Referring again to FIG. 1, the fan 14 draws air inwardly in the direction of arrow A through the radiator 12. The temperature of the coolant circulated by the pump 31 is thereby lowered, and the ambient temperature of the incoming airflow is correspondingly raised as it is drawn into the subassembly 20. The airflow is thereafter directed by the fan 14 through the TEC assembly 16 where it picks up heat from the fins of the heat sinks 38 and 40.
The hybrid heat exchanger 10 can be operated without power to the TECs 34 and 36. To obtain additional performance, various levels of power can be supplied to one or both of the TECs 34 and 36. Under power, the flow of current through the TECs creates a decrease in temperature at the region near the cold plate surfaces 42 and/or 44, which in turn draws heat from the fluid circulating through the cold plate 32. This heat is then transported through the TECs 34 and 36 to the bases of the upper and lower heat sinks 38 and 40, respectively, and finally is radiated out through the fins of the heat sink. With power applied to the TECs 34 and 36, the fluid temperature can be maintained in a range centered about three degrees Centigrade above the ambient air temperature with very high CPU power and reasonably low fan speed. Also, because the temperature of the TEC fins is in a range centered about fifteen to twenty degrees Centigrade above the fluid temperature, the TEC fins are efficient at transferring heat to the pre-heated airstream.
Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the embodiments of the present disclosure. Accordingly, all such modifications are intended to be included within the scope of the embodiments of the present disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.

## Claims

1. A heat exchanger assembly comprising:
a radiator disposed in a shroud;
a subassembly in direct physical communication with the shroud;
a thermoelectric cooler assembly located within the subassembly, the thermoelectric cooler assembly including:
a cold plate having a first side and a second side;
a first thermoelectric cooler in thermal communication with the first side of the cold plate; and
a second thermoelectric cooler in thermal communication with the second side of the cold plate; and

a fan located within the subassembly, the fan adapted to draw air through the radiator and to blow air through the thermoelectric cooler assembly, wherein an ambient temperature of the air is raised as it enters the subassembly.

2. The heat exchanger assembly of claim 1, the thermoelectric cooler assembly further comprising a first heat sink in thermal communication with the first thermoelectric cooler.

3. The heat exchanger assembly of claim 2, the thermoelectric cooler assembly further comprising a second heat sink in thermal communication with the second thermoelectric cooler.

4. The heat exchanger assembly of claim 1, wherein coolant circulates through the cold plate.

5. The heat exchanger assembly of claim 1, the thermoelectric cooler assembly further comprising a pump for circulating coolant through the cold plate.

6. A method comprising:
drawing, by a fan located within a subassembly, air through a passive heat exchanger of a heat exchanger assembly, wherein the passive heat exchanger is disposed in a shroud that is in direct physical communication with the subassembly, wherein an ambient temperature of the air is raised as it enters the subassembly; and
blowing, by the fan, air through an active heat exchanger located within the subassembly of the heat exchanger assembly.

7. The method of claim 6, wherein the active heat exchanger comprises a cold plate having a first side and a second side.

8. The method of claim 7, further comprising:
circulating coolant through the cold plate.

9. The method of claim 8, wherein circulating of the coolant through the cold plate is performed by a pump.

10. The method of claim 7, further comprising:
placing a first thermoelectric cooler in thermal communication with the first side of the cold plate; and
placing a second thermoelectric cooler in thermal communication with the second side of the cold plate.

11. The method of claim 10, further comprising:
placing a first heat sink in thermal communication with the first thermoelectric cooler.

12. The method of claim 11, further comprising:
placing a second heat sink in thermal communication with the second thermoelectric cooler.

13. The method of claim 6, wherein the passive heat exchanger comprises a radiator.

14. A method comprising:
drawing, by a fan located within a subassembly, air through a passive heat exchanger of a heat exchanger assembly, wherein the passive heat exchanger is disposed in a shroud that is in direct physical communication with the subassembly, wherein an ambient temperature of the air is raised as it enters the subassembly;
blowing, by the fan, air through an active heat exchanger located within the subassembly of the heat exchanger assembly; and
circulating, by a pump located within the subassembly, coolant through the active heat exchanger.

15. The assembly of claim 14, wherein the active heat exchanger comprises a cold plate having a first side and a second side.

16. The method of claim 15, further comprising:
placing a first thermoelectric cooler in thermal communication with the first side of the cold plate; and
placing a second thermoelectric cooler in thermal communication with the second side of the cold plate.

17. The method of claim 16, further comprising:
placing a first heat sink in thermal communication with the first thermoelectric cooler.

18. The method of claim 17, further comprising:
placing a second heat sink in thermal communication with the second thermoelectric cooler.

19. The method of claim 14, wherein the passive heat exchanger comprises a radiator.