TEC in many cases provides cooling below below ambient. The target temperature often is below dew point of regular ambient.

Moving down below dew point leads to water condensation from moist ambient. The water condensation is a reason of short circuit in TEC and  degradation of thermoelectric material.

If TECs must work in regular ambient, to prevent the problem it is necessary to protect TECs against moisture. TECs with special protections are supplied by customer demands. RMT has patented method of such protection.

In a case of miniature single and multistage TECs which are usually placed into evacuated volume it is necessary that filling gas should have dew point below target cold temperature.

Well-known approximation used to calculate the dew point T_d gives the relative humidity RH and the actual temperature T of air as:

where the temperatures are given in degrees Celsius and "ln" refers to the natural logarithm. The constants are: a = 17.27, b = 237.7 °C.

To prevent water condensation filling gas must be dry and have dew point lower than cooling temperature.

Examples

In the table there are advised some typical cooling temperatures provided by different types (stages) TECs. For such typical applications filling gas must have dew point exactly below the temperatures.

* - at room temperature