One of the important innovations of refrigeration industry occured at KTH in 1920s.
Two inventors Baltazar von Platen and Carl Munters managed to develop a system without any solution pump on the Carre absorption system. They developed a classical unit without any moving parts which has the intriguing capability of performing the task of transferring heat from a low temperature to a higher - by using (high temperature) heat as operating energy.
The original work began in the year 1922 as a Master thesis work at the Royal Institute of Technology (KTH) Stockholm, at the department which today is the division of Applied Thermodynamics and Refrigeration. Later on, the development was continued and commercialized by Electrolux - and sometimes the system is called Electrolux refrigerator. This scheme has attracted many scientists. As a mater of curiousity it might be mentioned that, in 1926, the famous scientists Albert Einstein and Leo Szilard filed a patent on a competing scheme.