TITLE:
Heat Transfer Enhancement by Vortex Generators for Compact Heat Exchanger of Automobiles
AUTHORS:
Shigeru Ogawa, Soma Usui
KEYWORDS:
Exhaust Gas Recirculation (EGR), Vortex Generator, Thermal Fluid Analysis, Longitudinal Vortex
JOURNAL NAME:
Open Journal of Fluid Dynamics,
Vol.8 No.3,
September
20,
2018
ABSTRACT: The paper describes the effects of heat transfer enhancement and gas-flow
characteristics by wing-type-vortex-generators inside a rectangular gas-flow
duct of a plate-fin structure exhaust gas recirculation (EGR) cooler used in a
cooled-EGR system. The analyses are conducted using computational fluid
dynamics (CFD). The numerical modelling is designed as a gas-flow rectangular
duct of an EGR cooler using two fluids with high temperature gas and
coolant water whose flow directions are opposite. The gas-flow duct used to
separate two fluids is assembled with a stainless steel material. The inlet temperature
and velocity of gas flowed inside gas-flow duct are 400°C and 30
m/s, respectively. Coolant water is flowed into two ducts on both a top and a
bottom surface of the gas-flow duct, and the inlet temperature and velocity is
80°C and 0.6 m/s, respectively. Wing-type-vortex-generators are designed to
achieve good cooling performance and low pressure drop and positioned at
the center of the gas-flow duct with angle of inclination from 30 to 150 degrees
at every 15 degrees. The temperature distributions and velocity vectors
gained from numerical results were compared, and discussed. As a result, it is
found that the vortices guided in the proximity of heat transfer surfaces play
an important role in the heat transfer enhancement and low pressure drop.
The collapse of the vortices is caused by complicated flow induced in the
corner constituted by two surfaces inside gas-flow duct.