You need DSC (differential scanning calorimetry) not DTA to evaluate enthalpy.

See you my papers in reseachgate

I agree my colleagues that DSC is the most indicate thermal technique to obtain enthalpy changes in particular for phase transitions of first order. Normally temperature increase of 10° per minute in N2 atmosphere are used.

For an heterogeneous mixture, I think TG/DTA is more useful than the DSC. Because the mass loss can be determined from TGA, which can be used to normalise the energy associated with each peak while conducting a number of repetitions of the test.