Can I use the 24 hour Direct Transit visa and then the 72 Hour free transit two weeks later?

I will fly from Chicago direct to Shanghai and stay less than 24 hours. I have a US passport. Then I will travel to Ho Chi Minh for two weeks. I then return to Shanghai and my layover is about 27 hours before I leave to return to Chicago directly. Do I qualify for the72 hour free transit for this part of my trip?