Development of the compact heat exchanger for the HTGR, (II) heat transferand fluid characteristics test

High performance plate fin type recuperator core model (= core width X heig ht X length, 100mm X 100mm X 100 mm) was fabricated with ultra fine off-set fin (= fin height X thickness X off-set length X pitch, 1.2mm X 0.2mm X 5. 0mm X 1.6mm), and heat transfer and fluid characterization tests of the cor e model were performed. With these results, the following conclusions were derived, (1) Heat transfer coefficient and pressure drop of the core model obtained by present experiments were estimated by 10 similar to 13%, 0 similar to 27 % lower values than that calculated by Wieting formula. (2) On the basis of present experiment, high accuracy new formulas for heat transfer and fluid characterization of the core model were proposed as the following, (Heat transfer model) Nu = 9.76 X 10(-2) (x/de)(-0.162) (w/H)(-0.184) Re-0.693 Pr-1 /3 (Pressure drop model) f = 0.924 (x/de)(-0.384) (w/H)(-0.092) Re-0.402 where Nu is the Nusselt number, Pr is the Plandle number, Re is the Reynols number, f is the friction coefficient, de is the equivalent diameter, w is the distance between fins, H is the fin height and x is the fin length in the flow direction. Heat transfer coefficient and flow friction characteristics of the recupera tor core model obtained in present study can be predicted by these formulas with accuracy of 90% by +/- 5 % deviation and 85% by +/- 5 % deviation, re spectively.