The Ljungstrom air preheater is a regenerative heat exchanger, invented in the 1920s and soon used throughout the world. Dr. Fredrik Ljungstrom, then technical director at Aktiebolaget Ljunstrom Angturbin, invented it for preheating combustion air in boiler plants, but the use has expanded to include energy recovery in combination with the removal of oxides of sulfur and nitrogen.
1995
YearAdded:
Image Credit:
Public Domain
Image Caption:
Ljungstrom Air Preheater
Era_date_from:
1920
1995
Queretaro's aqueduct, in Central Mexico, is one of the most eloquent symbols of colonial Mexico. As one of the early major hydraulic engineering projects in North America, it defines the city both nationally and internationally. The aqueduct, designed in 1723 by Juan Antonio de Urrutia y Arana, Marquis of Villa del Villar del Aquila, was inspired by the aqueducts of Segovia, Merida and Tarragona in Spain. It began supplying clean water to the city in this arid region of Mexico on October 17, 1738.
YearAdded:
Image Credit:
Courtesy Wikipedia/Ephobius (CC BY-SA 3.0)
Image Caption:
Acueducto de Queretaro
Era_date_from:
1726
1995
In his laboratory at Western Reserve University (Now Case Western Reserve University), Edward W. Morley carried out his research on the atomic weight of oxygen that provided a new standard to the science of chemistry. The accuracy of his analyses has never been superseded by chemical means. His great work, published in 1895, also gave important insight into the atomic theory of matter.
He observed, after carefully analysis of the volume proportions in which hydrogen and oxygen unite, that the atomic weight of oxygen was 15.879.
The plaque commemorating the event reads:
YearAdded:
Image Credit:
Courtesy ACS
Image Caption:
Morley with students and instructors, ca. 1893.
Era_date_from:
1995
