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.