Heat exchanger exhibiting improved mechanical and thermal stability

Claim 1

An integral metal panel for use in a solar energy collector system, said panel being formed of at least two sheets of metal, said panel having a generally rectangular shape comprising first and second opposing short edges and third and fourth opposing long edges, said sheets being partially spaced apart to define a spaced apart portion and opposing headers adjacent said first and second edges respectively of said panel connected by a plurality of tubular passageways extending between said headers and entry and exit passageways extending generally centrally between said third and fourth edges of said panel from said headers to said first and second edges respectively of said panel, said tubular passageways being defined by a plurality of individual bonded portions arranged in said spaced apart portion of said panel intermediate said headers, said individual bonded portions having a circular shape and being arranged in rows transversely to said third and fourth edges of said panel, with the individual circular bonded portions in one row being staggered and of a size just sufficient to be barely overlapped with respect to the individual bonded portions in a next adjacent row so that there is no linear path extending from said entry to said exit passageways which can be followed by a heat exchange medium flowing through said panel and so that said heat exchange medium follows a plurality of divided and subdivided random flow paths.