Heat Transportation by an Oscillatory Flow Through a Parallel-Plate Channel With an Inserted Slanting Plate

Heat transportation devices with small size and high transportation rate are highly required for achieving effective cooling of electronic devices and equipments. Heat transportation devices exploiting reciprocal flow are considered as one of important candidate technologies. Since a heat transportation pipe exploiting reciprocal flow was invented by Kurzweg and Zhao[1], many researchers have attempted to improve its performance. In the present paper we proposed a new concept of heat transportation channel which was a parallel-plate channel with a slanting plate inserted. The slanting plate separated the parallel-plate channel into two tapered channels. We analyzed numerically the heat transportation performance of the channel when a reciprocal flow was given at one end of the channel. Womersley number Wo was varied in a range of 7≤ Wo ≤40 and Re_max in a range of 100≤ Re_max ≤1300, by changing the tidal amplitude Am of the reciprocal flow from 0.005 to 0.102 m and reciprocal frequency from 0.07 to 2.56Hz. The present study was summarized in the followings: (1) In the present channel, oscillatory flow comprised of a reciprocal flow component superimposed on a one-directional flow component was induced. (2) u-velocity profiles in pushing phase and in pulling phase were not symmetrical when Wo was relatively small or Re_max was large. They approached symmetrical profile in large Wo range and in small Re_max range. (3) The time-averaged flow rate V remained almost constant in the Wo range from 7 to 20. They decreased with increasing Wo beyond 20. It also decreased with decreasing Re_max. (4) Heat transportation rate Q and heat transportation efficiency η decreased with increasing Wo and decreasing Re_max. (5) Work rate W increased with increasing Wo and Re_max. (6) The present heat transportation channel was able to transport about 5 to 13 times the heat with 1.4 to 4 times the efficiency by only inserting a slanting plate in a hollow parallel-plate channel.