The subject of heat transfer enhancement has significant interest to develop the compact heat exchangers in order to obtain a high efficiency, low cost, light weight, and size as small as possible. Therefore, energy cost and environmental considerations are going on to encourage attempts to invent better performance over the existence designs. Streamwise vortices can be generated using small flow manipulators or protrusions such as wings and winglets configurations. Single-pair, single row, or two dimensional array of vortex generators (VGs) can be punched, mounted, attached or embedded in the boundary layer of flow channel. VGs generate longitudinal and transverse vortices, while longitudinal vortices are more efficient for heat transfer enhancement than transverse vortices. A dramatic augmentation in thermal performance of the thermal system can be achieved but pressure drop penalty is existed. Several parameters have been overviewed in this paper, which have pronounced effect on the convective heat transfer coefficient and pressure drop penalty. These parameters are: attack angle of VG, geometry of VG, standard and novel types of VG, spacing between the VG tips, number of pairs of VGs in the flow direction, rectangular or circular array arrangement of VGs, common-flow upper (CFU) or common-flow down (CFD) configuration of VG, pointing up (PU) or pointing down (PD) arrangement of VG with flow direction, Re number, channel aspect ratio, number of tubes of fin-tube heat exchanges (HE), circular or oval tubes of fin-tube HE, and location of VG respect to the tube of HE or from leading edge of the channel. This paper gives an overview about the early studies done in order to improve the performance of thermal systems with minimal pressure losses to derive systems with less negative impact on the environment and high level of energy economic. This study also provides an outlook for future work using nanofluids with vortex generators. This article is also summarizes the recent experimental and numerical developments on the thermal conductivity measurements of nanofluids, thermal conductivity enhancement, convection and conduction heat transfer, some applications, main problems and suggestions for future works.

An overview on heat transfer augmentation using vortex generators and nanofluids: Approaches and applications

Optimization of heat exchangers with vortex-generator fin by Taguchi method

Thermal behavior in solar air heater channel fitted with combined rib and delta-winglet

Enhancement of heat transfer in a fin-tube heat exchanger using rectangular winglet type vortex generators

This paper summarizes the current state of the art related to improvement of the heat exchanger surfaces using streamwise longitudinal vortices Primarily, the improvements related to fin-tube cross-flow heat exchangers and the plate-fin heat exchangers have been addressed Protrusions in certain forms, such as delta wings or winglet pairs, act as vortex generators, which can enhance the rate of heat transfer from the heat-exchanger surfaces that may be flat or louvered The strategically placed vortex generators create longitudinal vortices, which disrupt the growth of the thermal boundary layer, promote mixing between fluid layers, and hence lead to augmentation in heat transfer The flow fields are dominated by swirling motion associated with modest pressure penalty Heat transfer is augmented substantially for all the proposed configurations of the longitudinal vortex generators, such as delta wings, rectangular winglet pairs, and delta winglet pairs, with varying degree of pressure penalty Both comp

Augmentation of Heat Transfer by Creation of Streamwise Longitudinal Vortices Using Vortex Generators

Numerical study of the relationship between heat transfer enhancement and absolute vorticity flux along main flow direction in a channel formed by a flat tube bank fin with vortex generators

Vortex generators (VGs) can generate developing boundary layers, swirl, and flow destabilization, and can be used to enhance heat transfer. In compact heat exchangers with VG enhancement, there are tubes and VGs, all of them will generate vortices, and these vortices interact. In this article, a numerical study of interactions of vortices generated by VGs and the effects of such interactions on heat transfer enhancement of flat tube bank fins are carried out. The results show that for some cases, interactions of vortices generated by VGs located upstream and downstream will take place, and the heat transfer enhancement on the fin surface is weakened.

Numerical study of interactions of vortices generated by vortex generators and their effects on heat transfer enhancement

The common way to obtain the fin pattern of a tube bank fin heat exchanger with good heat transfer performance is through experiments. Such experiments are complex, expensive, and very difficult to carry out. Recently, numerical analysis has become a powerful method for selecting the fin pattern of tube bank fin heat exchangers. In this article, we focus on testing the reliability of the numerical method by comparing local numerical results with local experimental results obtained through naphthalene sublimation. The target of numerical analyses carried out here is a flat tube bank fin heat exchanger mounted with vortex generators. The results show that using body-fitted coordinates, with proper treatment of vortex generators penetrating the fluid flow, leads to reliable local and average results.

Comparisons of Local Experimental Results with Numerical Results of Heat Transfer Enhancement of a Flat Tube Bank Fin with Vortex Generators

Convective Heat Transfer and Absolute Vorticity Flux along Main Flow in a Channel Formed by Flat Tube Bank Fins with Vortex Generators Mounted on Both Fin Surfaces

Dong-Liang Sun

Papers

Numerical study of the relationship between heat transfer enhancement and absolute vorticity flux along main flow direction in a channel formed by a flat tube bank fin with vortex generators

Numerical study of interactions of vortices generated by vortex generators and their effects on heat transfer enhancement

Comparisons of Local Experimental Results with Numerical Results of Heat Transfer Enhancement of a Flat Tube Bank Fin with Vortex Generators

Convective Heat Transfer and Absolute Vorticity Flux along Main Flow in a Channel Formed by Flat Tube Bank Fins with Vortex Generators Mounted on Both Fin Surfaces