Reduced Power Precision Temperature Control Using Variable Conductance Heat Pipes

This paper assesses the use of variable conductance heat pipes (VCHPs) for reduced-power precision temperature control of photonics components. When subambient cooling is not required we consider only a VCHP and where it is required we consider a VCHP-thermoelectric module (TEM) assembly. In the former case, the setpoint of the component mounted to the VCHP is 70°C and a range of heat loads (0 to 12 W) and ambient temperatures (-5°C to 65°C), representative of a photonics component in a telecommunications environment, are imposed on the system. In passive operation, the VCHP provided good temperature control for varying heat load, but not for varying ambient temperature. In active operation, i.e., when the reservoir of noncondensable gas on the VCHP is heated, good temperature control is achieved for ambient temperatures from 10°C to 65°C. The experimental measurements are compared with the theoretical predictions of the flat front model. For the TEM-VCHP assembly experiments, the component is maintained at a representative setpoint temperature, 63±1°C, for heat loads from 2 to 7 W and ambient temperatures from 0°C to 60°C, such that a TEM is essential. The TEM-VCHP assembly power consumption is quantified and compared with a TEM-constant conductance heat pipe assembly. The maximum TEM power consumption for the TEM-VCHP assembly is over 40% lower.