Hello Rui,
There are 4 things you need to consider:
-Are they considered projects? Projects are defined as a temporary endeavor undertaken to create a unique product, service or result. From my understanding of what PhD research is, I think you are good on this one.
-Depending on how much time you spent on the project, you may have already gain enough hours to meet the 4500-hour requirement
-What was your involvement in the projects? Did you lead the projects in all process groups (Initiation, Planning, Executing, Monitoring & Control, Closing). Best way to find out is to take a PMP course, it will help you tremendously on writing your application too, also goes towards the 35-contact-hour requirement, win-win.
-Do you have someone (for example: Project sponsor, manager) to prove that you have led those projects and sign off the audit document? (In case you have been select for audit)
More info from PMI:
Application Tips
PMP Handbook
