Design of a Variable Conductance Heat Pipe for a Photonic Component

Thermoelectric modules (TEMs) are widely used to provide precision temperature control in photonic applications. A problem with TEMs, however, is that when they are subjected to a large range of ambient temperatures the power of consumption of TEMs can be excessive. This study proposes the replacement of the TEM based approach with a variable conductance heat pipe (VCHP). VCHPs offer reduced power consumption compared to TEMs whilst still offering precision temperature control of the device. Using existing theory this paper investigates the use of wicked and non-wicked reservoirs and the effect of reservoir volume on the sensitivity of the evaporator temperature to changes in both ambient temperature and heat load for both heated and unheated reservoirs. The paper also investigates the effectiveness of the use of a steel collar between the reservoir and the condenser in reducing the heat loss to ambient. The paper concludes that passive control of evaporator temperature can be achieved for the case of a variable heat load, but not for the case of a variable ambient temperature, that evaporator temperature is more sensitive to reservoir temperature for a wicked than a non-wicked reservoir, and that with the use of a steel collar between the reservoir and the condenser a VCHP provides a significant power consumption reduction when compared to a TEM.

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Characterisation of a Variable Conductance Heat Pipe Prototype for a Photonic Application

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 3 ◽

10.1115/ht2007-32623 ◽

2007 ◽

Cited By ~ 3

Author(s):

Martin Cleary ◽

Ronan Grimes ◽

Marc Hodes ◽

Mark T. North

Keyword(s):

Ambient Temperature ◽

Active Control ◽

Temperature Control ◽

Passive Control ◽

Working Fluid ◽

Saturation Curve ◽

Evaporator Temperature ◽

Large Reservoir ◽

Ambient Temperatures ◽

Wide Range

Thermoelectric modules (TEMs) consume a large amount of power when used for precision temperature control of high-power photonic devices, particularly when subjected to a wide range of ambient temperatures. The use of variable conductance heat pipes (VCHPs) as a lower power alternative to TEMs is investigated here. The performance of a methanol-argon VCHP with a non-wicked reservoir for both passive and active control is characterized. The concept of an “deal” working fluid for a gas-loaded VCHP is introduced. It has a liquid-vapor saturation curve resulting in perfect passive evaporator temperature control in the limit of an infinitely-large reservoir when the VCHP is subjected to changes in heat load and/or ambient temperature. The saturation curve of this ideal fluid is compared to that of the fluid used here, i.e., methanol, showing why perfect passive control is unrealistic for varying ambient temperature. An experimental prototype was constructed and measurements obtained from it were compared to the predictions of the flat front model. It was found that, even with active control, the evaporator temperature could not be maintained sufficiently at low ambient temperatures due to axial conduction through the adiabatic section of the prototype VCHP. However, excluding these low ambient temperatures, the VCHP provides a significant reduction in power consumption compared to a TEM.

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Optimized Thermoelectric Module-Heat Sink Assemblies for Precision Temperature Control

ASME 2011 Pacific Rim Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Systems, MEMS and NEMS: Volume 2 ◽

10.1115/ipack2011-52019 ◽

2011 ◽

Cited By ~ 3

Author(s):

Rui Zhang ◽

David A. Brooks ◽

Marc Hodes ◽

Matthew van Lieshout ◽

Vincent P. Manno

Keyword(s):

Power Consumption ◽

Thermal Resistance ◽

Ambient Temperature ◽

Thermoelectric Material ◽

Temperature Control ◽

Heat Sink ◽

Heat Sinks ◽

Temperature Range ◽

Precision Temperature ◽

Precision Temperature Control

Robust precision temperature control of photonics components is achieved by mounting them on thermoelectric modules (TEMs) which are in turn mounted on heat sinks. However, the power consumption of TEMs is high because high currents are driven through Bi2Te3-based semiconducting materials with high electrical resistivity and finite thermal conductivity. This problem is exacerbated when the ambient temperature surrounding a TEM varies in the usual configuration where the air-cooled heat sink a TEM is mounted to is of specified thermal resistance. Indeed, heat sinks of negligible and relatively high thermal resistances minimize TEM power consumption for sufficiently high and low ambient temperatures, respectively. Optimized TEM-heat sink assemblies reduce the severity of this problem. In the problem considered, total footprint of thermoelectric material in a TEM, thermoelectric material properties, heat load, component operating temperature, relevant component-side thermal resistances and ambient temperature range are prescribed. Provided is an algorithm to compute the unique combination of the height of the pellets in a TEM and the thermal resistance of the heat sink attached to it which minimizes the maximum power consumption of the TEM over the specified ambient temperature range. This optimization maximizes the fraction of the power budget in an optoelectronics circuit pack available for other uses. Implementation of the algorithm is demonstrated through an example for a typical set of conditions.

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Optimized Thermoelectric Module-Heat Sink Assemblies for Precision Temperature Control

Journal of Electronic Packaging ◽

10.1115/1.4005905 ◽

2012 ◽

Vol 134 (2) ◽

Cited By ~ 2

Author(s):

Rui Zhang ◽

Marc Hodes ◽

David A. Brooks ◽

Vincent P. Manno

Keyword(s):

Thermal Resistance ◽

Ambient Temperature ◽

Thermoelectric Material ◽

Temperature Control ◽

Heat Sink ◽

Heat Sinks ◽

Ambient Temperatures ◽

Precision Temperature ◽

Precision Temperature Control ◽

Heat Loads

Robust precision temperature control of heat-dissipating photonics components is achieved by mounting them on thermoelectric modules (TEMs), which are in turn mounted on heat sinks. However, the power consumption of such TEMs is high. Indeed, it may exceed that of the component. This problem is exacerbated when the ambient temperature and/or component heat load vary as is normally the case. In the usual packaging configuration, a TEM is mounted on an air-cooled heat sink of specified thermal resistance. However, heat sinks of negligible thermal resistance minimize TEM power for sufficiently high ambient temperatures and/or heat loads. Conversely, a relatively high thermal resistance heat sink minimizes TEM power for sufficiently low ambient temperatures and heat loads. In the problem considered, total footprint of thermoelectric material in a TEM, thermoelectric material properties, component operating temperature, relevant component-side thermal resistances, and ambient temperature range are prescribed. Moreover, the minimum and maximum rates of heat dissipation by the component are zero and a prescribed value, respectively. Provided is an algorithm to compute the combination of the height of the pellets in a TEM and the thermal resistance of the heat sink attached to it, which minimizes the maximum sum of the component and TEM powers for permissible operating conditions. It is further shown that the maximum value of this sum asymptotically decreases as the total footprint of thermoelectric material in a TEM increases. Implementation of the algorithm maximizes the fraction of the power budget in an optoelectronics circuit pack available for other uses. Use of the algorithm is demonstrated through an example for a typical set of conditions.

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