22 research outputs found
Thermohydraulic characteristics of co/counter swirl flow through a round tube fitted with helical screw tape and twisted tape
145-155Influence of co/counter swirl flow on the
characteristics of friction, heat transfer and thermal performance factor in
heat exchanger tubes has been experimentally investigated. Each twisted tape is
inserted into a helical screw tape and then these combined tapes are subsequently
equipped in a heat exchanger tube for generating the swirl flow. The combined
tapes are arranged in two different forms, namely (i) co-swirl arrangement in
which their twist are in the same direction and (ii) counter-swirl
arrangement in which their twists directions are in the opposite directions.
The experiments using helical tapes alone are also performed for assessment.
The helical screw tapes are used at three different tape-twist ratios (PR = p/D
= 1.0, 1.5 and 2.0), each with three different tape-width ratios (WR = w/D =
0.15, 0.2 and 0.25), while twisted tapes are used at three different twist
ratios (YR = y/W = 3, 4 and 5). The results show the maximum thermal
performance factor of 1.49 for helical tape alone with PR=2.0 and WR=0.2. At
similar conditions, the heat transfer rate associated with the combined tapes
in counter-swirl arrangement is 3.4% and 10% higher than those in co-swirl
arrangement and helical tape alone