Passive conditioning systems for temperature control in telecommunications equipment enclosures

The application of phase-change materials to the control of internal temperature in telecommunications equipment enclosures has resulted in the development of passive conditioning systems (PCS) which will maintain temperatures within equipment operating limits without the use of conventional air conditioning. PCS-equipped enclosures can readily protect electronic systems of up to 30 kW dissipation, and because the system is passive, the reliability of the electronic installation is that of the prime equipment rather than that of the far less reliable air-conditioning equipment. A further advantage is that, with temperatures closely controlled without air exchange from the outside environment, there is a resultant stabilization of internal humidity at acceptable levels, again without active control equipment. The basic principles of such systems are presented, and attention is given to the design philosophy, construction, the heat-exchanger option, manufacturing, and life-cycle costs