Calorimetry in the real world?

yes, in designing heating systems for buildings.

Yes and there are photographs of Elvis taken the day after he died coming down the steps of a Private Jet, and we have snapshots of the Loch Ness Monster looking very fishy, and sleepy pie nighty night pictures of Aliens at Roswell looking like they drank too much Booze. And we have Jack the Rippers Diary, a 8mm Movie film of Adolf Hitler doing weight lifting and showing off his muscles. And we have all those photographs of Harry Houdini wearing swimming Trunks. Yes I kid you not, dozens of photographs of Harry in swimming trunks. What is the mystery there you will no doubt ask? Because Harry was always photographed nude standing among crowds of his fans, the trunks were inked onto the photos by prudish American Editors later on.

That is how they get the numbers that they put onto food containers as part of the nutrition label. They either take the whole thing and burn it in a calorimeter or they add up all the ingredients and use the calorimeter numbers known for those ingredients.

it's used in nuclear plants too.

http://www.ashemorris.com/batch-technologies.aspx