How to read the performance diagrams
The performance diagrams of Europeltier air-to-air coolers are the result of intensive tests carried out in the laboratory with each type of device. The tests show the exact performance of the equipment in relation to the ambient temperature and in relation to the temperature of what is intended to be cooled.
There are two ways of using the diagram. But before you start, choose a Europeltier machine data sheet and its diagram.
1) Identify the power (W) to be cooled
1. Choose a sloping line that represents the temperature of the environment (e.g.: 40 ºC),
2. Define the temperature difference on the X-axis with respect to the ambient temperature,
3. Draw a vertical line from the X-axis to the chosen ambient temperature line,
4. Draw a horizontal line from the intersection of these two lines to the Y-axis,
5. The approximate cooling power can be found on the Y-axis.
Considering 40 ºC ambient temperature and a temperature difference of 5 ºC from the ambient, the power of the Europeltier cooler should be approximately 70 W. Therefore, a 75 W device has the necessary power to perform the cooling.
2) Identify the internal temperature to be reached
A. Choose on the Y-axis the value that represents the thermal power verified inside the box to be cooled (e.g.: 60 W),
B. Draw a horizontal line to the chosen ambient temperature (e.g.: 40 ºC),
C. From the intersection of these two lines draw a vertical line to the X-axis,
D. The internal temperature will be the approximate value found on the X-axis subtracted from the chosen ambient temperature.
Considering that the internal power of the box is 60 W, and the ambient temperature is 40 ºC, the approximate value is 7 ºC. The internal temperature of the box will be approximately 33 ºC (40 ºC - 7 ºC). Therefore, the 75 W Europeltier device has the necessary power to reach the expected internal temperature.
NOTES
If the cooling power found is not enough, it will be necessary to increase the power of the device and make a new evaluation with the curve of this new device.
The diagram does not take into account the heat transmission through the walls of the enclosure to be cooled.