The Department of Thermal and Refrigeration Engineering was established in the academic year 1945–1946 within the Department of Mechanical Engineering at the then State Polytechnic, becoming one of the oldest and most sought-after departments in the structure of TU-Sofia. Its founder was Assoc. Prof. Karl Slavomir Hibaum. From the beginning, the department trained engineers in "Thermal Engineering," and its original name was "Thermal Engineering and Technical Thermodynamics." In 1956, the department was renamed "Industrial Thermal Engineering" and began training students in two specialties: "Industrial Thermal Engineering" and "Machines and Apparatus for the Chemical and Food Industries." In 1963, the Faculty of Energy Machinery Engineering was established, and the department became part of its structure, where it continues to exist and develop to this day.  

In 1975, the specialty "Machines and Apparatus for the Chemical and Food Industries" was discontinued. Training continued under a single specialty, which was renamed over the years from "Industrial Thermal Engineering" to "Thermal and Mass Transfer Engineering," "Energy Engineering and Technologies," "Thermal and Hydraulic Engineering," to finally reach its current name, "Thermal Engineering."

Throughout its development, the Department of Thermal and Refrigeration Engineering has established itself as the leading academic institution in the country in its field, with well-established traditions in both the education and training of engineering personnel in the specialty of "Thermal Engineering" and in research, design, and implementation activities in this area. Problems related to energy efficiency and heat sources are addressed here.

The specialty of "Thermal Engineering" provides students with high-quality knowledge and skills to develop their potential for professional realization in the public sector, industry, and business.
The educational process is supported by a highly qualified teaching staff, whose knowledge and experience contribute to the department's successful participation in international educational, research, and implementation projects. 

The department collaborates with world-renowned universities such as: Karlsruhe Institute of Technology, University of Strathclyde (UK), Eindhoven University of Technology, Universitat Politecnica de Catalunya (Barcelona), University of Southampton, and the Hanoi University of Science and Technology, Vietnam. This collaboration provides opportunities for continuous improvement of accumulated experience and the reflection of contemporary trends in higher education in thermal engineering in curricula and programs.