The present disclosure relates to thermoelectric assemblies.
This section provides background information related to the present disclosure which is not necessarily prior art.
The Peltier effect is an effect in which a heat flux is created between the junction of two different types of materials. Thermoelectric modules (TEMs) are semiconductor devices which use the Peltier effect to transfer heat from one side of the TEM (the “cold side”) to the other side of the TEM (the “hot side”). The TEM, a solid-state Peltier device, effectively acts as a heat pump upon the application of a DC power source to the TEM. Heat is moved through the TEM, from one side to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument may also be called a Peltier cooler or heater, a thermoelectric heat pump, a Peltier heat pump, a solid state refrigerator, a thermoelectric cooler (TEC), or a thermoelectric module (TEM). TEMs can be used either for heating or for cooling (refrigeration), although in practice the main application is cooling.
Thermoelectric assemblies (TEAs) often include a pair of fan sinks that face outwardly in opposite directions and meet at one or more TEMs at their bases. As can be seen in
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
In one aspect, a thermoelectric assembly has a cold side and a hot side. The boundary between the hot side and the cold side may be generally defined by a plane. One or more thermoelectric modules may be in the plane and arranged in one circuit or multiple parallel circuits, and in direct thermal contact with both the hot side and the cold side.
The hot side comprises a single fan sink, whereas the cold side comprises a pair of fan sinks. A fan sink is a heat sink and a fan, each fan comprising a blade, and each heat sink comprising a fin set, where a fin set is a series of parallel protrusions on a heat sink base, the parallel protrusions aligned in a single exhaust direction.
In an embodiment, each fan sink possesses an air intake direction defined by an axis about which the blade is rotatably attached to the fan, and the air intake direction is at an angle of ninety degrees from the air exhaust direction. The air intake directions of the pair of fan sinks on the cold side are parallel. Further, the angle defined by the air exhaust directions of the pair of fan sinks on the cold side may be selected from the group consisting of zero degrees, ninety degrees, and one hundred eighty degrees.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Exemplary embodiments will now be described more fully with reference to the accompanying drawings.
TEAs operate generally as follows: On the cold side, the fan pulls the surrounding air into the heat sink channels that are defined by the space between the heat sink fins, thereby drawing substantial ambient air over the cold side fins to facilitate an eventual air-to-metal thermal transfer on the cold side. The TEMs are in physical thermal contact with the bases of the heat sinks. The TEMs pump thermal energy from the cold side heat sink base onto the base of the hot side heat sink. As the hot side heat sink warms due to the heat pumped into them by the TEMs, the hot side fan cools the fins of the hot side heat sink by drawing ambient air across them and expelling warm air from the hot side air channels. In essence, the TEMs pump heat from one side of the unit to the other while the fan sinks provide substantial surface area and air flow therethrough to enable an efficient heat transfer.
A frequent problem in the art arises from the condensation that accumulates on the cold side heat sink during operation of the thermoelectric assembly. As the temperature of the cold side heat sink dips below the dew point of the ambient air around the cold side during the operation of the assembly, moisture accumulates on the exposed surface of the cold side heat sink. This condensation can create performance issues, reduce effective surface area of the heat sink fins, and give rise to water-borne organic growth that can cause foul odors, among other problems.
Frequently, a TEA is to be installed on the vertical walls of a pre-existing structure, as opposed to installation as a part of a new construction. Due to the existing conditions of the structure, such as the placement of doors, windows, studs, wiring, vents, etc., the TEA may need to be installed with the heat sink fins running horizontally as opposed to vertically. Where the heat sink fins are horizontal, condensation moisture control is difficult to achieve with a fan alone, whereas a vertical heat sink fin arrangement may be more efficiently drained of condensate with the assistance of gravity.
Additionally, condensation moisture may permeate the interior of the TEA through holes in the heat sink used for wiring or bolts/screws. This moisture can cause performance issues on the assembly, including potentially shorting out one or more of the parallel TEM circuits or other electrical components of the unit.
Fan sinks are known mechanisms for forced air convection, which provides a more efficient air-to-metal or metal-to-air thermal transfer. Additionally, the forced convection mechanism aids in preventing oxidation of the heat sink material through the continuous movement of ambient air.
Thermoelectric modules are essentially solid state heat pumps comprising positively and negatively doped modules. They may be arranged in a single series circuit or in several parallel circuits, or any combination thereof. In non-limiting embodiments, for example where eight TEMs are present in the TEA, the TEMs may be arranged in four parallel circuits of two series connected TEMs, two parallel circuits of four series connected TEMs, or eight separate TEMs each on a single circuit.
In one aspect, a TEA comprising a hot side and a cold side is disclosed, where the cold side comprises two or more fan sinks, while the hot side comprises a single fan sink. A TEA may be mounted on a vertical surface of an enclosure, such as a wall, to provide cooling of the ambient air on one side of the enclosure wall through the transfer of heat to the other side of the enclosure wall.
As referred to herein, the terms hot side and cold side do not necessarily indicate one side as literally “hot” or “cold.” Rather, an aim of the TEA disclosed herein is to transfer heat from the cold side to the hot side, thereby providing a relative cooling to the cold side. For example, a rooftop electrical service room with a TEA device installed would transfer heat from the warm inside to the potentially cooler ambient outside. Conversely, a TEA device installed on an indoor wine cooler or wine chiller that is colder than the surrounding ambient room temperature would be cooled by transferring heat from the cooler cold side to the warmer hot side. As such, the terms hot side and cold side are not intended to be limiting in the sense that the sides are literally hot or cold, but merely intended to show an embodiment of potential thermal flow of a TEA.
Additionally, the TEA may include a series of moisture barrier measures that, when used in concert and installed on a TEA, substantially eliminate the moisture problems seen in the art. Primarily, these moisture barrier measures include a sealing layer in or near the plane that defines the hot and cold sides, an O-ring sealed screw joint, and a moisture protected wire seal. Each of these individually may be considered a suitable means for moisture protection. In an embodiment, each of the sealing layer, screw joint, and wire seal together comprise a comprehensive moisture barrier system.
Though heat sinks are not so limited in shape, heat sinks suitable for use in TEA generally comprise a rectangular base upon which a series of fins, referred to as a fin set, protrude. Fins may be substantially parallel panels of material, often the same material as the base. Two exemplary types of heat sinks can be seen in
As seen in
A fan sink generally comprises a heat sink and a fan. An exemplary fan sink can be seen as a component of the thermoelectric assembly of
Referring further to the Figures,
Referring now to
Further, the cold side heat sinks 204 of
Improving upon the insulation gasket 210, however, it was found that adding additional sealing layers 214 for each cold side heat sink 204, particularly those with protrusions 206, to pass through to the TEMs 208 further reduced moisture penetration. Traditional insulation gaskets are not flexible enough to seal around the heat sinks at their base, particularly because the bases of heat sinks can be rough from skiving or other manufacturing processes. By adding additional semi-closed or closed foam cell insulation to the TEAs, the TEA may be further sealed against moisture permeation.
In addition to the moisture seal improvements via the sealing layers 214 seen in
For example, the wire seal 216 of
Addressing the issue of moisture passing through the screw holes, it was found that creating a frustal surface at the top of a screw hole permitted the insertion of an O-ring below the screw head. This may be seen in
The TEA may further comprise electrical wiring such that the TEMs, as previously discussed, are in one or more parallel circuits, and sufficient to power the fans. Electrical components and connections may be housed in an electrical bay 202 between the cold side fan sinks 110 as shown in
Referring to
As stated herein, a TEM is considered in direct thermal contact with a heat sink base where a substrate is flush against the base of a heat sink. Frequently the entire surface areas of each substrate of the TEM are covered by a heat sink base to provide optimal thermal transfer. In this manner, the TEMs are sandwiched between two heat sinks, and surrounded by thermally insulating material. It should be understood by one of skill in the art that a TEM and heat sink may be considered in direct thermal contact even in the presence of a thermal grease or paste or other thermal interface material. Such paste (not shown in the Figures) may be, just for example, aluminum oxide particles, or zinc oxide particles, in a silicone carrier.
The assembly need not be limited to only a single hot side fan sink and a pair of cold side fan sinks. Any number of configurations of thermoelectric assemblies that include a plurality of additional fan sinks on both the hot and cold sides are embraced by this disclosure. For example, a thermoelectric assembly may include dual hot side fan sinks that have air output in opposite directions as well as three cold side fan sinks with air output directions in a variety of possible configurations. Additionally, an assembly could have two dual hot side fan sinks as well as dual cold side fan sinks.
The assembly is additionally not limited to single directional output from the cold side fan sinks. A single cold side fan sink may provide two directions of air exhaust in opposite directions, depending on the housing of the fan sink, with the cold side fan sink not exhausting air towards the electrical components that may reside between dual cold side fan sinks. The housing of the cold side fan sink may be open on both ends of the heat sink to permit such dual direction exhaust.
The assembly may be modularly configurable and customizable, potentially either by the end user or the manufacturer, to permit drainage of the cold side heat sink, even where the spatial limitations of the existing structure requires horizontally mounting the assembly.
Replacing the single, large cold side heat sink with two separate cold side heat sinks in the same general footprint that includes a space therebetween did not result in a significant loss of efficiency of the cold side of the assembly or of the assembly as a whole. In contrast to conventional TEAs of the prior art, such as that seen in
The hot side/cold side thermal flow could be reversed in a TEA by merely reversing the current in the TEM circuits, thereby altering the TEM heat flow. The assembly disclosed herein may include a switch that reverses the current of the TEMs without the need to rewire the assembly or the power source into the assembly. Such a reversal of current, however, may not result in equal thermal transfer efficiency in each direction, given variables such as the size, shape, and configuration of the respective heat sinks, as well as other factors.
In summary, among the many benefits of the disclosed device apparent to those of skill in the art from this description, it was discovered that the replacement of a single, large cold side heat sink with a pair of smaller cold side heat sinks provides numerous benefits: reduced moisture penetration by virtue of reduced mechanical stresses from expansion and contraction; reduced incidences of failure by shifting of an installed unit shifting by virtue of those same stresses; less cost in manufacture of heat sinks due to reduced material mechanical tolerance requirements; negligible loss of otherwise expected thermal transfer performance; directional flexibility and modularity of the cold side fan sinks; and the availability of space between the fan sinks for electrical components. Further, the moisture penetration resistance of TEAs has been enhanced through the inclusion of a series of moisture barrier measures, including a sealing layer in or near the plane that defines the hot and cold sides, an O-ring sealed screw joint, and a moisture protected wire seal. These and other benefits meet pressing needs in the art, needs unmet by existing thermoelectric assemblies.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the claims. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the claims, and all such modifications are intended to be included within the scope of the claims.
This patent application is a continuation of and claims the benefit of International Application No. PCT/US2012/064375 filed Nov. 9, 2012 (published as WO2014/074110 on May 15, 2014). The disclosure of the application identified in this paragraph is incorporated herein by reference in its entirety.
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Number | Date | Country | |
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20150192332 A1 | Jul 2015 | US |
Number | Date | Country | |
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Parent | PCT/US2012/064375 | Nov 2012 | US |
Child | 14661933 | US |