SIMULATION OF FLOW AND HEAT TRANSFER IN A CHANNEL WITH RECTANGULAR VORTEX GENERATORS AT DIFFERENT REYONALD NUMBERS AND BLADE ANGLES

Abstract

The compact heat exchanger is widely used in fields such as automobile industry, heating and air conditioning, power system, chemical engineering, electronic chip cooling and aerospace, etc. The subject of heat transfer enhancement is of significant interest in developing compact heat exchanger to meet the desire of high efficiency and low cost with the volume as small as possible and the weight as light as possible. The use of ribs/baffles placing in the cooling channels or channel heat exchangers is one of the commonly used passive heat transfer enhancement technique in single-phase internal flows. Periodically positioned ribs/baffles in the channels interrupt hydrodynamic and thermal boundary layers. Downstream of each rib/baffle the flow separates, recalculates, and impinges on the channel wall and these effects are the main reasons for heat transfer enhancement in such channels. The use of ribs/baffles increases not only the heat transfer rate but also substantial the pressure loss. The rib/baffle geometry and arrangement in the channel also alter the flow field resulting in different convective heat transfer distribution. In particular, the angled ribs, the rib cross-section, the rib-to-channel height ratio and the rib pitch-to-height ratio are all parameters that influence both the convective heat transfer coefficient and the overall thermal performance. It is, thus, difficult to realize the advantage of rib/baffle arrangements or geometry and the use of staggered ribs/ baffles with rib height and pitch spacing of 0.1 (0.5 for baffles) and 1 time of the channel height respectively is often recommended in most of the previous work.