And on -20c because vaccume dryer first dropa temps if i am correct
It's 5 Pa for limonene and 10 Pa for water. This means water evaporates more readily. So there might be a possibility to design a process. One detail: the difference in vapour pressure is small so both will evaporate under the same conditions. The same reason that limonene gasses off at ambient temperature although it's boiling point is 173 °C at ambient pressure.
When water evaporates it requires large amounts of energy, thus cooling the surrounding space. Limonene (and other terpenes) have a lower enthalpy of vapourization which translates to less cooling and quicker evaporation. During the drying process both water and limonene evaporate. When water evaporates it reduces the local temperature, lowering the vapour pressure of nearby water, effectivly slowing the drying process. When limonene evaporates this effect is less pronounced. In a perfectly (thermally) isolated system this would cool the flower so much that the drying halts because it is too cold to evaporate.
Freeze dryers have heated shelfs for this reason. They add the heat that is taken out during evaporation. But thermal conduction is slow and depends on loading of the machine. Thick layers means large distance between heated surface and the flower that needs heating. There is also a temperature gradient with some pieces of flower being warmer than others where the difference in vapour pressure is reversed.