Regenerative heat exchanger

A regenerative heat exchanger comprising a pair of ducts defining flow-paths for the separate passage therethrough of fluid between which heat exchange is to be effected, an aperture provided in opposite sides of each duct, a pair of transfer ducts each arranged substantially transversely of said pair of ducts to provide communication between one said aperture in one of said pair of ducts and a corresponding aperture in the other of said pair of ducts, a stationary heat-storing matrix in the form of a substantially flat panel contained in each aperture in one of said pair of ducts, a pair of valve members each in the form of a pivotally mounted plate arranged in one of said pair of ducts and defining a common wall between the flow-paths in the respective duct, and means to effect movement of the valve members between two extreme operable positions, in each of which each said valve member extends obliquely across the respective duct of said pair of ducts, in one of which extreme positions one of the fluids passes through one of said transfer ducts and said matrix associated therewith and the other of the fluids passes through said other transfer duct and said matrix associated therewith and in the other extreme position the fluid flow through the respective transfer ducts and the associated matrices is interchanged, whereby each of said matrices will be heated in succession by the hotter fluid while the other said matrix is imparting heat to the cooler fluid, each said valve member engaging in each extreme operable position an edge of each aperture in the respective duct.