System and method for thermal protection of an electronics module of an energy harvester

A thermoelectric energy harvesting system may include a thermoelectric generator and an electronics module. The thermoelectric generator may produce a voltage in response to a temperature difference across the thermoelectric generator and generate power when coupled to a load. The system may include a housing mounted on top of the thermoelectric generator. The housing may include a cavity containing the electronics module. The electronics module may condition the power generated by the thermoelectric generator. The cavity may be enclosed by an inner surface of the housing. A radiation shield may cover at least a portion of the inner surface and may block radiative heating of the cavity from the housing.

FIELD

The present disclosure relates generally to energy harvesting systems and, more particularly, to thermal management of electronic components contained in a thermoelectric energy harvesting system.

BACKGROUND

The trend towards miniaturization of microelectronic devices such as micro-sensors is necessitating the development of miniaturized power supplies. Batteries and solar cells are traditional power sources for such microelectronic devices. However, the power supplied by batteries dissipates over time requiring replacement of the batteries on a periodic basis. Solar cells, although having an effectively unlimited useful life, may only provide a transient source of power as the sun or other light sources may not always be available.

Thermoelectric generators are energy sources that convert thermal energy into electrical energy over an essentially unlimited lifetime. A thermoelectric generator produces a voltage in response to a thermal gradient across the thermoelectric generator. The thermal gradient may be provided by a heat source on one side of the thermoelectric generator and a lower-temperature heat sink on an opposite side of the thermoelectric generator. Heat from the heat source may flow through the thermoelectric generator prior to entering the heat sink where the heat may be rejected to the environment.

Certain thermoelectric energy harvesting systems may include electronic components to condition the voltage produced by the thermoelectric generator prior to delivery to a load. Electronic components may also be provided to perform application-specific functions. Electronic components typically have a maximum rated temperature up to which the electronic components may operate on a nominal basis. Approaching the maximum rated temperature of the electronic components may result in a reduction in the performance of the electronic components. Exceeding the maximum rated temperature of the electronic components may result in damage or failure of the electronic components. A failure of the electronic components may compromise the electricity-producing capability of the thermoelectric generator.

As can be seen, there exists a need in the art for a system and method of minimizing the heating of electronic components that may be included in a thermoelectric energy harvesting system.

SUMMARY

The above-noted needs associated with electronic components in energy harvesting systems are specifically addressed and alleviated by the present disclosure which provides a thermoelectric energy harvesting system having a thermoelectric generator and an electronics module. The thermoelectric generator may produce a voltage in response to a temperature difference across the thermoelectric generator which generates useful power across an electrically-connected external load. The system may include a housing mounted on top of the thermoelectric generator. The housing may include a cavity containing the electronics module. The electronics module may condition the power output of the thermoelectric generator and/or perform application-specific functions. The cavity may be enclosed by one or more inner surfaces of the housing. The system may include a radiation shield covering at least a portion of one or more of the inner surfaces. The radiation shield may prevent or reduce radiative heating of the cavity from the heat in the housing.

In a further embodiment, disclosed is a thermoelectric energy harvesting system having a thermoelectric generator producing a voltage in response to a temperature difference across the thermoelectric generator. The system may further include a housing having a cavity defined by a housing bottom upper surface and a housing side wall inner surface. The system may include a heat sink mounted on top of the housing and enclosing the cavity and having a heat sink lower surface. A radiation shield may be mounted to the housing bottom upper surface and the housing side wall inner surface for blocking or minimizing radiative heating of the cavity.

The system may include a compliant thermally-insulative layer mounted to the radiation shield. An electronics module may be mounted within the cavity on top of the compliant thermally-insulative layer. The electronics module may be configured to regulate the voltage produced by the thermoelectric generator. The electronics module may have an upper surface and a lower surface. The system may include a compliant thermal transfer pad interposed between the heat sink lower surface and the electronics module upper surface for thermal coupling therebetween. The system may additionally include a compliant thermally-conductive layer extending between the electronics module lower surface and the heat sink and forming a heat conduction path therebetween.

In a further embodiment, disclosed is a method of minimizing the heating of an electronics module in a thermoelectric energy harvesting system. The method may include the step of providing a temperature difference across a thermoelectric generator such that the thermoelectric generator produces a voltage. The method may include providing a housing mounted on top of the thermoelectric generator. The housing may have a cavity containing an electronics module. The housing may have heat flowing along a system heat path in response to the temperature difference across the thermoelectric generator. The method may further include the step of blocking radiative heat flow into the cavity using a radiation shield.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes of illustrating various embodiments of the present disclosure, shown inFIG. 1is a perspective view of an embodiment of a thermoelectric energy harvesting system10. The system10may contain an energy harvester22such as a thermoelectric generator24. The system10may additionally include an electronics module100and a battery118. In an embodiment, the system10may be configured as a field-deployable unit having the electronics module100and the thermoelectric generator24integrated into the system10.

In an embodiment, the electronics module100and the battery118may be contained within a housing50of the system10. For example, the electronics module100and the battery118may be contained within a cavity52(not shown) formed in the housing50for protecting the electronics module100from exposure to moisture, mechanical impact, and excessive heat. In this regard, the housing50may be configured to minimize thermal stress on the electronics module100and the battery118. Such thermal stress may compromise the functionality or operability of heat-sensitive components such as capacitors (not shown) and/or batteries. For example, excessive heating of capacitors may reduce the capability of the capacitors to hold a charge.

The system10may have a system side20, a system upper end16, and a system lower end18. The system10may include a base member36at the system lower end18. The base member36may be mounted to a heat source84. The thermoelectric generator24may be mounted on top of the base member36. The thermoelectric generator24may be environmentally sealed between the housing bottom58, the base member36, and an insulating ring44. The insulating ring44may be adhesively bonded to the base member36and to the housing50to mechanically stabilize the energy harvesting system10and to seal the thermoelectric generator24from exposure to moisture and protection from mechanical impact and other environmental effects. The thermoelectric generator24may produce a voltage in response to a temperature difference across the thermoelectric generator24. The system10may include a heat sink86at the system upper end16. The heat sink86may be mounted on top of the housing50. Heat may flow along a system heat path94from the heat source84through the thermoelectric generator24and into the housing50whereupon the heat may enter the heat sink86for discharge into the environment by radiative heat transfer, natural convective heat transfer, or conductive heat flow from forced airflow between the cooling elements92and the ambient air as described in greater detail below. Although shown as having a generally cylindrical configuration, the system10may be provided in any size, shape, and configuration, without limitation.

Referring toFIG. 2, shown is a cross-sectional view of an embodiment of the thermoelectric energy harvesting system10. The system10may include the base member36which may be configured for mounting to a heat source84. The base member36may be formed of any suitable material for thermal conduction of heat from the heat source84into the thermoelectric generator24. For example, the base member36may be formed of metallic material including, but not limited to, aluminum. The base member36may include a base member upper surface38and a base member lower surface40. The base member lower surface40may be configured for mounting to a surface of a heat source84.

In an embodiment, the base member36may include one or more magnets42which may be mounted or contained within the base member36to facilitate attachment of the system10to a heat source84formed at least partially of ferromagnetic material. In this regard, the magnet42may provide magnetic-mounting capability for industrial applications. For example, the magnet42may facilitate mounting of the system10to a motor, a bearing housing, a heated pipe, or any other system, subsystem, assembly, or structure that may provide a heat source84for the thermoelectric generator24. However, the system10may include alternative means for attaching the base member36to a heat source84and is not limited to magnetic mounting. For example, the system10may include one or more mechanical features (not shown) for mechanically coupling the system10to a heat source84.

The system10may include a thermoelectric generator24that may be coupled to the base member36. For example, the thermoelectric generator24may be mounted on top of the base member36. The thermoelectric generator24may include a thermoelectric generator upper surface26and a thermoelectric generator lower surface28which may comprise upper and lower heat couple plates (not shown) for the thermoelectric generator24. The thermoelectric generator24may be positioned between the base member36and the housing50. In an embodiment, the thermoelectric generator lower surface28may be mounted in contacting relation to the base member upper surface38. The thermoelectric generator upper surface26may be mounted in contacting relation to a housing bottom lower surface62. Thermal interface material (not shown) comprising highly-thermally conductive adhesive, grease, paste, epoxy, or other highly-thermally conductive material may be included between the thermoelectric generator lower surface28and the base member upper surface38and between the thermoelectric generator upper surface26and the housing bottom lower surface62to prevent or minimize air gaps or voids between the thermoelectric generator upper and lower surface26,28and the base member upper surface38and the housing bottom lower surface62to reduce thermal resistance therebetween. The thermoelectric generator24may be configured to produce a voltage in response to a temperature difference across a hot side14and a cold side12of the thermoelectric generator24.

The thermoelectric generator24may be configured in an in-plane configuration or in a cross-plane configuration. In an embodiment of an in-plane configuration, the thermoelectric generator24may be formed of a thin semiconductor film or substrate arranged in a coiled or spiral configuration and having a plurality of thermocouples similar to the arrangement disclosed in U.S. Pat. No. 7,629,531 entitled IMPROVED LOW POWER THERMOELECTRIC GENERATOR and issued on Dec. 8, 2009 to Stark, the entire contents of which is incorporated by reference herein. In another embodiment of an in-plane configuration, the thermoelectric generator24may be formed of a plurality of semiconductor films or substrates arranged in a stacked formation similar to the arrangement disclosed in U.S. Pat. No. 6,958,443 entitled LOW POWER THERMOELECTRIC GENERATOR and issued on Oct. 25, 2005 to Stark et al., the entire contents of which is incorporated by reference herein. In a further embodiment, the thermoelectric generator24may be configured as a planar thermoelectric generator (not shown) similar to the arrangement disclosed in U.S. Patent Publication No. 2011/0094556 entitled PLANAR THERMOELECTRIC GENERATOR and published on Apr. 28, 2011 to Stark, the entire contents of which is incorporated by reference herein. However, the thermoelectric generator24may be provided in any one of a variety of sizes, shapes, and configurations, without limitation, and is not limited to an in-plane configuration.

InFIG. 2, shown is an embodiment of the system10implementing one type of cross-plane thermoelectric generator24. The system10may include the housing50that may be thermally coupled to the thermoelectric generator upper surface26as indicated above. As indicated above, the housing50may be mechanically coupled to the base member36by means of an insulating ring44that may extend around a circumference of the housing50and the base member36. The insulating ring44may be formed of material having a relatively low thermal conductivity such that a substantial majority of heat from the heat source84flows into the base member36and through the thermoelectric generator24from the thermoelectric generator lower surface28to the thermoelectric generator upper surface26and into the housing50. In the embodiment shown, the thermoelectric generator24may be sized and configured such that an annular gap46is defined between the thermoelectric generator sides30and the insulating ring44. The annular gap46may minimize the heat transfer from the base member36to the housing50.

The housing50may include the housing side wall54and the housing bottom58. The housing bottom58may include a housing bottom upper surface60and a housing bottom lower surface62. The housing bottom lower surface62may be in contact with the thermoelectric generator upper surface26as indicated above. The housing side wall54may include a housing side wall inner surface56. The housing bottom upper surface60and the housing side wall inner surface56may define the cavity52of the housing50. The housing50may be formed of a relatively highly thermally conductive material such as a metallic material. For example, the housing50may be formed of aluminum or other thermally conductive material.

The system10may further include a heat sink86that may be mounted on top of the housing50. The heat sink86may have a heat sink upper surface88and a heat sink lower surface90. The heat sink upper surface88may include a plurality of cooling elements92for facilitating heat exchange with the environment. For example, the heat sink86may include a plurality of cooling fins or cooling pins extending upwardly from the heat sink86for radiative heat transfer and/or natural convective heat transfer into the ambient air of the surrounding environment or heat conduction via forced airflow. Although the cooling elements92are illustrated inFIG. 2-3as generally parallel cooling pins protruding straight upwardly, the cooling pins may be splayed outwardly to provide increased distance between the cooling pins and to increase the heat-exchanging volume of the heat sink86which may improve the heat-rejecting capability of the heat sink86. The base member36, the housing50, and the heat sink86may define a system heat path94along which heat may flow from the heat source84into the base member36and through the thermoelectric generator24and up through the housing50and into the heat sink86. The electronics module100may be sized and configured such that the electronics module sides110are disposed in non-contacting relation to the inner surface of the housing50to minimize conductive heat transfer into the electronics module100.

The heat sink lower surface90, the housing side wall inner surface56, and the housing bottom upper surface60may collectively enclose the cavity52. The cavity52may contain one or more electronics modules100. In the embodiment shown, the electronics module100may be communicatively coupled to the thermoelectric generator24by means of electrical wiring48such as a power line passing through an aperture64or hole that may be formed in the housing bottom58. In an embodiment, the electronics module100may include power management electronics102for managing or conditioning the power provided by the thermoelectric generator24. The conditioning of the power provided by the thermoelectric generator24may include voltage rectification, voltage stabilization, providing protection against excessively high voltage or excessively low voltage, boosting the voltage produced by the thermoelectric generator24, power matching, energy storage, and other power conditioning operations.

In an embodiment, the power management electronics102may be specifically configured to regulate the voltage produced by the thermoelectric generator24. For example, power management electronics102may provide voltage within a predetermined voltage range to a load such as a wireless sensor. In an embodiment, the electronics module100may include a battery118, a capacitor, or a super capacitor for storing electricity generated by the thermoelectric generator24. The battery118may include a battery element120for storing power and/or a battery circuit board122for managing electrical energy stored by the battery element120. The battery circuit board122may also mechanically support the battery element120.

In a further embodiment, the electronics module100may additionally include an application-specific module104. For example, an application-specific module104may be provided for any one of a variety of different applications including, but not limited to, remote sensing, data logging/recording/storage, signal processing, computational resources, wireless communication circuitry, or other applications. In an embodiment, the application-specific module104may be configured similar to the arrangement disclosed in U.S. application Ser. No. 12/316,034 published on Jun. 10, 2010 and entitled FIELD-DEPLOYABLE ELECTRONICS PLATFORM HAVING THERMOELECTRIC POWER SOURCE AND ELECTRONICS MODULE to Hofmeister et al., the entire contents of which is incorporated by reference herein. In an embodiment, the system10disclosed herein may be configured in a radio frequency identification (RFID) embodiment to facilitate recordation and/or storage of sensor data using the power supplied by the internal thermoelectric generator24with data extraction performed by power supplied by an external RF source (not shown). However, the system10disclosed herein may be configured for implementation in any one of a variety of different applications and is not limited to an RFID embodiment for remote sensing.

Referring still toFIG. 2, the system10may advantageously include a radiation shield72mounted along one or more of the inner surfaces of the cavity52to minimize radiative heating71of the electronics module100. In the embodiment shown, the radiation shield72may be installed or mounted on the housing bottom upper surface60and/or on the housing side wall inner surface56. The radiation shield72may be mounted to the housing side wall inner surface56and may extend around an inner circumference of the housing side wall54. Likewise, a radiation shield72may be mounted to a substantial portion of the housing bottom upper surface60. The radiation shield72may be specifically configured to block, prevent, reduce, minimize, or otherwise eliminate radiative heating71of the cavity52that may otherwise occur in response to the heat flowing through the housing50along the system heat path94. The radiation shield72may retard or reduce radiative heat transfer into the cavity52which may otherwise cause heating of the electronics module100.

The radiation shield72may be formed of a core74material such as a sheet or layer of foam, paper, aramid, or other material having a relatively low thermal conductivity. The core74may include a low-emissivity coating78applied to at least one side of the core74. For example, the core74may include a low-emissivity metallic80coating such as an aluminum coating that may be applied to at least one side of the core74or to both sides of the core74. In an embodiment, the core74may be provided in a corrugated configuration76having opposing face sheets (not shown) mounted to opposing sides of the corrugated core76. A low-emissivity coating78such as a metallic80coating (e.g., aluminum) may be applied to one or both of the opposing face sheets. Advantageously, in any of the embodiments disclosed herein, the radiation shield72may be configured to function as a thermally reflective layer to reflect heat within the housing50. In this manner, the radiation shield72may significantly reduce radiative heating71of the cavity52which may otherwise add to the heating of the electronics module100.

The system10may further include a compliant thermally-insulative layer66that may be mounted within the cavity52. For example, a compliant thermally-insulative layer66may be mounted on top of the radiation shield72of the housing bottom58. The electronics module100may be mounted on top of the compliant thermally-insulative layer66. The compliant thermally-insulative layer66may be compliant in the sense that the compliant thermally-insulative layer66may mechanically comply or conform to the surface contours of the electronics module lower surface108and/or the housing bottom upper surface60. In addition, the compliant thermally-insulative layer66may be compliant in the sense that the compliant thermally-insulative layer66is resiliently compressible to absorb vibration, shock, and other mechanical movement of the electronics module100. The resilient compressibility of the compliant thermally-insulative layer66may also urge the electronics module100upwardly into thermal contact with the heat sink86and/or into thermal contact with a compliant thermal transfer pad68that may be mounted between the electronics module upper surface106and the heat sink lower surface90to improve the drawing of heat out of the electronics module100as described in greater detail below.

In an embodiment, the compliant thermally-insulative layer66may be formed of material having a relatively high thermal insulative capability. For example, the compliant thermally-insulative layer66may be formed of a thermally insulative silicone-based material. In an embodiment, the compliant thermally-insulative layer66may be formed from a sheet of silicone rubber or silicone foam having a relatively high insulative capability. The foam may comprise a resiliently compressible silicone-based foam rubber. In this regard, the compliant thermally-insulative layer66may be formed of a resiliently compressible foam material and configured such that heat conducting pins114of the electronics module100shown inFIG. 3may be maintained in substantially contacting relation with the heat sink lower surface90as described in greater detail below.

InFIG. 2, the system10may further include a mechanically-resilient or compliant thermal transfer pad68configured to substantially conform to the heat sink lower surface90. The compliant thermal transfer pad68may facilitate thermal coupling of the electronics module100to the heat sink86for conductive heat transfer therebetween. In the embodiment shown, the system10may further include a compliant thermally-conductive layer70that may be sandwiched between the electronics module upper surface106and the compliant thermal transfer pad68to provide a direct heat conduction path82between the electronics module100and the heat sink86as described in greater detail below.

The compliant thermal transfer pad68may be formed of a material having a relatively high thermal conductivity, relatively low thermal resistance, and relatively high electrical insulative capability. For example, the compliant thermal transfer pad68may be formed of a silicone-based material filled with a highly-thermally conductive material such as alumina powder in a silicone matrix as may be commercially available from Laird Technologies, Inc. of St. Louis, Mo., or commercially available from Berquist, Inc. of Chanhassen, Minn. Alternatively, the compliant thermal transfer pad68may be formed of graphite sheet sandwiched between thin plastic or electrically-insulative layers or coatings. In an embodiment, the compliant thermal transfer pad68may be formed of metal foil (e.g., copper foil) that may be coated with or sandwiched between an electrically-insulating coating such as silicone. Such compliant thermal transfer pad68may include adhesive on one or both sides to adhesively bond the compliant thermal transfer pad68to the electronics module100and/or the heat sink86. The compliant thermal transfer pad68may be coupled to the heat sink lower surface90by adhesive bonding such as with a pressure sensitive adhesive. Alternatively, the compliant thermal transfer pad68may be mechanically coupled to the heat sink86. Advantageously, the compliant thermal transfer pad68may improve thermal sinking of the electronics module100to draw heat from the electronics module100into the heat sink86.

The system10may further include a compliant thermally-conductive layer70that may extend between the electronics module lower surface108and up along the electronics module side110to the heat sink86to form a heat conduction path82therebetween. For example, inFIG. 2, a horizontal section of the compliant thermally-conductive layer70may be sandwiched between the battery118and the electronics module lower surface108at an electronics board-battery interface116. A vertical section of the compliant thermally-conductive layer70may extend upwardly along a side (e.g., a left-hand side—FIG. 2) of the electronics module100within the gap between the electronics module side110and the radiation shield72. A horizontal section of the compliant thermally-conductive layer70may be sandwiched between the compliant thermal transfer pad68and the electronics module upper surface106. The compliant thermally-conductive layer70may be formed of a material that is highly thermally conductive such that a direct and substantially continuous or uninterrupted heat conduction path82is formed from the electronics module lower surface108and/or battery118up to the heat sink86.

In a further embodiment, the system10may include a compliant thermally-conductive layer70having a horizontal section that may be sandwiched between the battery element120and the battery board122(e.g., circuit board) at a battery element-battery board interface124. A vertical section of the compliant thermally-conductive layer70may extend upwardly along a side (e.g., a right-hand side—FIG. 2) of the electronics module100. A horizontal section of the compliant thermally-conductive layer70may be sandwiched between the compliant thermal transfer pad68and the electronics module upper surface106to form a direct and substantially continuous heat conduction path82from the battery element-battery board interface124up to the heat sink86. The compliant thermally-conductive layer70may be adhesively bonded to the compliant thermal transfer pad68. Alternatively, the compliant thermal transfer pad68may be omitted and the compliant thermally-conductive layer70may be mounted directly to the heat sink lower surface90such as by adhesive bonding or by mechanical attachment or any combination thereof.

Referring toFIG. 3, shown is an alternative embodiment of the system10having a plurality of heat conducting pins114that may extend generally upwardly from the electronics module upper surface106. For example, the electronics module100may include an electronics circuit board112which may contain heat conducting pins114extending upwardly from high heat locations on the electronic circuit board or in locations containing heat-sensitive components. The heat conducting pins114may extend at least partially into a thickness of the compliant thermal transfer pad68.

Alternatively, the heat conducting pins114may extend substantially completely through the thickness of the compliant thermally-conductive layer70and/or through the thickness of the compliant thermal transfer pad68. In an embodiment, the heat conducting pins114may be spring-loaded (not shown) such that the heat conducting pins114are maintained in substantially continuous and direct contact with the heat sink lower surface90to improve thermal transfer. Advantageously, the resiliently compressible compliant thermally-insulative layer66upon which the electronics module100may be mounted may provide upward urging of electronics module100which may facilitate mechanical contact of the heat conducting pins114with the heat sink lower surface90.

In an alternative embodiment not shown, the system10may include a plurality of heat sink extensions (not shown) or protrusions that may extend generally downwardly from the heat sink lower surface90. Such heat sink extensions may extend through the compliant thermal transfer pad68and through the compliant thermally-conductive layer70into contact with the electronics module upper surface106. The heat sink extensions may improve heat conduction from the electronics module100into the heat sink86.

Referring toFIG. 4, shown is a method200that may be implemented for minimizing the heating of the electronics module100contained within the thermoelectric energy harvesting system10. Step202of the method may include coupling the base member36to the heat source84such as by magnetic coupling using a magnet42that may be mounted within the base member36. The base member36may be structurally coupled to the housing50using a thermal insulating ring44as described above.

Step204of the method200ofFIG. 4may include providing a temperature difference across the thermoelectric generator24. When the heat source84is at a higher temperature than the heat sink86, heat may flow along a system heat path94from the base member36across the thermoelectric generator24and into the housing50. The heat may pass into the heat sink86whereupon the heat may be the radiated or convectively transferred to the environment by means of cooling elements92such as cooling pins or cooling fins protruding from the heat sink86.

Step206of the method200ofFIG. 4may include providing the housing50with a cavity52for mounting the electronics module100. The cavity52may be sized and configured such that the electronics module sides110are disposed in non-contacting relation with the housing side wall inner surfaces56. The housing50may be mounted above the thermoelectric generator24and in direct thermal and physical contact therewith. The housing50may have heat flowing along the system heat path94as shown inFIG. 2.

Step208of the method200ofFIG. 4may include thermally insulating the electronics module100from the housing bottom58using the compliant thermally-insulative layer66. As described above, the compliant thermally-insulative layer66may be formed of a resiliently compressible material. The resiliently compressible material of the compliant thermally-insulative layer66may bias or urge the electronics module upper surface106upwardly into thermal contact with the heat sink lower surface90. For example, the compliant thermally-insulative layer66may urge the electronics module upper surface106into compressive contact with the compliant thermally-conductive layer70and with the compliant thermal transfer pad68. In this manner, the combination of the compliant thermally-insulative layer66, compliant thermally-conductive layer70, and the compliant thermal transfer pad68may improve thermal conduction of heat from the electronics module100into the heat sink86.

Step210of the method200ofFIG. 4may include thermally coupling the electronics module100to the heat sink86using the compliant thermal transfer pad68. As described above, the compliant thermal transfer pad68may facilitate conduction of heat from the electronics module100into the heat sink lower surface90. In addition, the mechanical compliance of the compliant thermal transfer pad68may improve the thermal contact between the heat sink86and the compliant thermally-conductive layer70.

Step212of the method200ofFIG. 4may include reducing, minimizing, preventing, or eliminating radiative heating71of the cavity52from the heat within the housing50by including a radiation shield72along at least a portion of the housing side wall inner surfaces56. For example, the radiation shield72may be applied to a substantial portion of an inner circumference of the housing side wall inner surface56. In addition, a radiation shield72may be applied to the housing bottom upper surface60to reduce or retard radiative heating71of the cavity52from heat in the housing bottom58.

Step214of the method200ofFIG. 4may include conducting heat through the compliant thermally-conductive layer(s)70extending between the heat sink86and the electronics module100. As described above, the system10may include one or more compliant thermally-conductive layers70mounted to the electronics module100to form one or more direct heat conduction paths82to the heat sink86. For example, heat may be conducted through a compliant thermally-conductive layer70to define a direct heat conduction paths82between the heat sink86and the battery118.

Advantageously, the radiation shield72may limit or minimize the amount of radiative heating71of the cavity52which may prevent overheating of sensitive electronic components contained within the housing50. Furthermore, the compliant thermal transfer pad68and the compliant thermally-conductive layers70may advantageously provide direct heat conduction paths82from the electronics module100to the heat sink86to improve cooling of sensitive electronics. In this regard, the radiation shield72, the compliant thermal transfer pad68, and the compliant thermally-conductive layers70, operating alone or in combination with one another, may advantageously maintain the electronics module100below a maximum rated temperature (e.g., 65° C.) of such electronics module100. In this manner, the system10and method disclosed herein may improve the operating efficiency of the thermoelectric generator24and electronics module100. In addition, by maintaining the electronics module100below a predetermined temperature or maximum rated temperature, the operating life of the electronics module100may be extended.

Additional modifications and improvements of the present disclosure may be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present disclosure and is not intended to serve as limitations of alternative embodiments or devices within the spirit and scope of the disclosure.