A review of the state of the art of solid-state caloric cooling processes at room-temperature before 2019

•A state of the art of all the developed solid-state caloric prototypes was presented.•The devices were classified as magnetocaloric, electrocaloric, elastocaloric or barocaloric.•The main design features and the energy performances shown were reported for each device.•A point of view of the future perspectives is proposed in the conclusions. The solid-state processes for cooling and heat pump technologies are based on the well-known caloric effects (magneto-, electro-, elasto- and baro-caloric). With an interest arisen in 1976, year of the development of the first room-temperature magnetic refrigerator, up to a few years ago, magnetocaloric was among the most investigated caloric cooling techniques and it was considered among the main solid-state alternatives to vapor-compression cooling and heat-pumping. During such period, a remarkable number of prototypes of magnetic refrigerators or heat pumps was built. Recently, the attention toward all the four caloric effects has recently grown; therefore, an increase in projects on solid-state prototype developing (not only on magnetocaloric) was observed. The intention of this paper is to offer a state-of-the-art of all the solid-state prototypes for cooling and heat pumps processes, devoted to room temperature operations, developed before the year 2019.