For the calculation of the heat dissipation you need the power dissipation (Pd) of the device. Unfortunately this value is usually not available in the technical data of the devices. But you can calculate an approximate value when you have the max. power consumption of the device.
Of course, the power dissipation is always lower than the max. power consumption of the device, but the calculated value is on the secure side.
As MOBATIME devices have a small power consumption, the difference is not too big.
Example of calculation with DTS 4138 device:
From technical data in manual: DC power supply: 24 VDC, 10 W
P = 10 W => simplification: Pd = 10 W
Pd (W) = Heat energy per time => (Wh / h) (heat load)
1 Wh / h = 3.6 kJ / h (heat dissipation)
Heat dissipation formula = Pd (W) * 3.6 kJ / h
Heat dissipation DTS 4138 = 10 W * 3.6 = 36 kJ / h
Heat dissipation < 36 kJ / h