Subway tunnel heat-exchangers could heat and cool thousands of nearby apartments

In Numerical investigation of the convection heat transfer driven by airflows in underground tunnels (Sci-Hub mirror), a group of engineers from L'Ecole Polytechnique Fédérale de Lausanne and the Swiss Federal Institute of Technology propose that low-cost heat-exchangers placed in subway tunnels could be used to heat and cool homes essentially for free (the system would last 50-100 years, and the pumps would need replacing every 25 years). Read the rest

Happy birthday, air conditioning!

Yesterday was the 110th anniversary of air conditioning. The building pictured above—1040 Metropolitan Ave. in the Williamsburg neighborhood of Brooklyn, New York—was the first building in the world to enjoy the luxury of cold air blowing on a blisteringly hot day.

A junior engineer from a furnace company figured out a solution so simple that it had eluded everyone from Leonardo da Vinci to the naval engineers ordered to cool the White House when President James A. Garfield was dying: controlling humidity.

The junior engineer who tackled the problem was Willis Carrier, who went on to start Carrier Corporation. The solution he devised involved fans, ducts, heaters and perforated pipes ... Carrier’s plan was to force air across pipes filled with cool water from a well between the two buildings, but in 1903, he added a refrigerating machine to cool the pipes faster.

It's a neat technological story, and as the New York Times piece points out, Carrier's invention wasn't just about making people comfortable. In the beginning, it was about allowing a specific job to get done even when the weather was hot. In fact, air conditioning is still the tool that makes things like computers possible, by creating dust-free, low-humidity clean rooms where the parts can be manufactured.

Read the rest of James Barron's piece in the New York Times City Room blog Read the rest