when Tony Stark secretly follows captain and Bucky all the way to Siberia we see that he detects heat signatures along the way it's good to see you Tony you two I got heat signatures how many uh one he finds only one heat Trace which belongs to Zemo but we know that black panther was also there so why couldn't he detect him we know that Black Panther's vibranium suit has the ability to store kinetic energy and I believe it can also absorb the heat energy released from the human body that's why Tony couldn't detect Black Panther's heat signature