Patent ID: 8154728

Claim:
An apparatus comprising an enclosure comprising an outer shell that is resistant to and compatible with an operating environment and an inner shell disposed within the outer shell such that a gap volume exists between the outer shell and the inner shell; one or more gas analyzer components disposed within the inner shell; and a mass of a phase changing material disposed within the gap volume between the outer shell and the inner shell, the phase changing material having a phase transition temperature at which the phase changing material transitions from a first phase to a second phase while absorbing or releasing a latent heat energy ΔH L , the phase transition temperature being within a desired operating temperature range of the one or more gas analyzer components, the mass M of the phase changing material being given by M ≥ F T Δ ⁢ ⁢ H L where F T is an expected net heat energy flux from the operating environment into the enclosure during a period of an operating day during which an ambient temperature outside of the enclosure exceeds the phase transition temperature.