A German scientist and pioneer in the field of engineering thermodynamics, especially in heat and mass transfer, Schmidt was born on Feb. 11, 1892 at Vögelsen, near Lüneburg. He studied civil and electrical engineering at Dresden and München, and joined the laboratory for applied physics at the Technical University, München, in 1919, which was then under the direction of Oscar Knoblauch. One of his early research efforts there was a careful measurement of the radiation properties of solids, which caused him to propose and develop the use of aluminum foil as an effective radiation shield.
In 1925 he received a call to come as professor and director of the engineering laboratory to the Technical University, Danzig. Here he published papers on the now well known graphical difference method for unsteady heat conduction, and on the Schlieren and shadow method to make thermal boundaries visible and to obtain local heat-transfer coefficients. He was the first to measure the velocity and temperature field in a free convection boundary layer and the large heat-transfer coefficients occurring in droplet condensation. A paper pointing out the analogy between heat and mass transfer caused the dimensionless quantity involved to be called Schmidt Number.
In 1937 he became director of the Institute for Propulsion of the newly founded Aeronautical Research Establishment at Braunschweig and professor at the university there. In 1952 Schmidt occupied the chair for thermodynamics at the Technical University of München which before him had been held by Nusselt. Being strongly involved in the development of the international steam tables, Schmidt continued his scientific activity after his retirement (1961) until his death in 1975.
In recognition of his work, he had received the Ludwig Prandtl Ring, the Max Jacob award and the Grashof Commemorative Medal.