I would be going to Tianjin (Changri-La Hotel) from Beijing Capital Airport,

You are not advised to take a taxi from PEK to Tianjin. The fare would be expensive. Upon landing, you can take a coach from PEK to Tianjin Tianhuan Bus Station first. The bus schedules are from 06:30 to 23:00. The duration is around 2.5 hours. The ticket fare is CNY 82 per person. After arriving, take a cab to the destination. It would cost around CNY 20 in the day time.