As a university student, is it permissible for me to combine the Dhuhr and Asr prayers by performing them early (Jam' Taqdeem), knowing that my university is 30 km away from my home, I return home near Maghrib prayer, and I cannot perform ablution at the university?

The mentioned distance is not considered a travel distance that necessitates the presence of a mahram, nor is it a distance that permits travel concessions such as shortening or combining prayers. The distance for qasr (shortening prayers) is 83 km. It is not permissible to combine prayers without necessity. Dhuhr prayer can be performed at home, and Asr prayer at the university. Not being able to perform taharah (purification) properly except at home might be a waswasah (whispering from Satan/obsessive thought). Combining prayers is permissible according to some scholars, such as the Hanbalis, if there is a legitimate need recognized by Islamic law due to hardship or difficulty.