Passive cooling systems... for the perfect climate
|
From the perspective of pure physics, there is no such thing as the cold. Rather, everything is warm to either a greater or lesser extent and ultimately everything gets converted into heat. So why go in pursuit of something that does not really exist? Of course, you can't just apply this standard definition of cold in a general way when dealing with technical issues. In this kind of context it is more usual to think in terms of heat dissipation and heat input. Depending on whether a higher or a lower temperature is required within an enclosed system, structures are used to supply or dissipate heat. This principle applies regardless of whether the elements involved are active or passive.
Active elements, e.g. fans, air conditioning systems, Peltier elements, etc. are characterised by the fact that the desired heat transfer is initiated and maintained by inputting additional energy (generally in the form of electrical energy). In the case of passive elements, such as heat sinks, heat pipes and forced ventilation equipment, etc., this additional energy is not required.
|
Caption: Heat pipe application including heat spreader for a PC board.
|
| In spite of the above, it has to be said that temperature stabilisation only represents one aspect of enclosure climate control, and although necessary it also has its inadequacies. As everyone knows, rapid drops in temperature can result in condensate and this can have devastating consequences within an enclosure. As well as having a corrosive effect, the condensation water formed due to the moisture in the air can damage electrical and electronic components beyond repair. To prevent this, measures such as membranes can be implemented to ensure equilibrium between the internal and external climates. In light of the fact that electronic components are becoming increasingly powerful and applications are becoming increasingly complex when space is at a premium, the enclosure construction industry is having to face up to fresh challenges. Straightforward and low-maintenance passive systems can also be found for your application. The following table provides a comparison of various climate control elements: |
| Element |
Design |
Advantage |
Disadvantage |
| Peltier |
Active |
High cooling capacity |
Condensate formation
Expensive |
| Fan |
Active |
Easy assembly |
Filter required |
| Air conditioning system |
Active |
Complete climate
control |
Requires a lot of effort,
expensive, bulky |
| Heat sink |
Passive |
Maintenance-free
Inexpensive |
Impaired design |
| Heat-pipe |
Passive |
Maintenance-free
Inexpensive |
Expensive to construct |
| PTC |
Active |
No temperature
control required |
Add. heat distribution required |
| Heating foil |
Active |
Min. space requirements |
Add. heat distribution required |
| Forced ventilation equipment |
Passive |
Straightforward design |
Open type of construction
Low IP class |
| Compensating membrane |
Passive |
Straightforward design |
Contamination from outside is critical |
|
