Is it permissible for a traveler whose exam times overlap with prayer times, making it difficult for him to perform the prayer at its prescribed time, to combine the Dhuhr and Asr prayers with a delayed combination (jam‘ ta’kheer)?

The duration that permits shortening prayers (qasr) is less than four days, not counting the days of arrival and departure. So, if you travel on Tuesday and return on Saturday, your stay is three days, which is a duration that permits qasr and combining prayers (jama'). Therefore, you are permitted to delay Dhuhr to combine it with Asr as a delayed combination (jama' ta'khir). It is encouraged to attend congregational prayers in mosques if possible.