Analytical　solutions　have　been　obtained　for　single　phase　flow　in　parallel　tube　platen　systems　where　the　platen　configuration　(geometric　shape　and　dimensions)　of　each　connecting　tube　within　a　platen　can　vary.　Continuous　and　discrete　mathematical　models　have　been　derived　to　study　the　distributing　and　combining　flow　characteristics　in　platens　along　header　axes　and　in　connecting　tubes　within　each　individual　platen,　respectively.　The　specific　volume　of　working　fluid　is　assumed　to　vary　linearly　along　the　connecting　tube　length,　in　order　to　close　the　mathematical　equations.　Analytical　solutions　of　static　pressure　and　velocity　in　the　headers　and　connecting　tubes　have　been　obtained　firstly　under　the　assumption　that　the　friction　along　the　headers　can　be　neglected.　Then,　these　solutions　are　corrected　to　account　for　the　effects　of　friction　along　the　headers.　Both　sets　of　solutions　are　the　general　solutions　for　all　flow　configurations　of　parallel　tube　platen　systems　where　the　flow　parameters　in　the　headers　are　one-dimensional　and　those　in　connecting　tubes　are　three-dimensional.　These　general　solutions　can　be　applied　directly　to　the　design　and　analyses　of　superheaters　and　reheaters　in　power　boilers,　and　other　heat　exchangers　of　same　configurations.　(c)　2005　Elsevier　Ltd.　All　rights　reserved.