Narayanan, Vinod; Kanury, A. Murty
Description:
Design and preliminarily characterization of two thermally-actuated pumps is presented
in this thesis. The unique feature of both pumps is the presence of periodic asymmetrical
structures on the channel walls. Two heat transfer effects are used with surface
asymmetry to generate forces that drive the fluid in a preferential direction in these
pumps. Specifically, a closed-channel pump utilizing the Leidenfrost effect on a ratchetlike
asymmetrical topology and an open-channel pump utilizing the Marangoni effect on
a ratchet-like asymmetric topology are investigated. The Leidenfrost pump design
consists of a closed-channel with ratcheted sidewalls to propel the liquid. A key feature
of the closed channel pump is a proposed concept for vapor removal. The vapor is
extracted from the liquid channel to the surrounding atmosphere through separate
variable-depth channels. The Marangoni pump design consists of an open-channel with a
ratcheted bottom channel wall. Designs of the pump are debugged using proof-ofconcept
testing to yield final pump designs. These final designs are then characterized
based on mass flow rate for varying temperature inputs at a fixed pressure differential
across the pump. The Leidenfrost pump shows a large variation in mass flow rate for
lower Leidenfrost surface temperatures and more consistent flow rates at the high
Leidenfrost temperature transition. The Marangoni pump yields conflicting data that may
be improved upon with a more sensitive setup.