How can a student combine prayers whose times are missed due to his studies and the distance of his institute from his home?

A Muslim must perform prayer at its appointed time, for Allah Almighty says: "Indeed, prayer has been decreed upon the believers at specified times." (Quran 4:103). Intentionally delaying prayer until its time has expired without a legitimate excuse is considered a major sin. You must observe your prayers at their appointed times. If you can pray Dhuhr after its time begins in your locality, then do so; otherwise, pray it after you arrive at your place of study. As for 'Asr and Maghrib prayers, you must perform them at their appointed times during your studies, and it is not permissible to delay them for this reason. You can perform Maghrib prayer after your studies conclude if its time is still remaining.