Heat transfer enhancement in solar air channel with broken multiple V-type baffle
TL;DR: In this article, an experimental analysis of the heat transfer behavior and optimum relative width parameter of the solar air channel of aspect ratio of 10.0 with 60° angled broken multiple V-type baffles was conducted.
About: This article is published in Case Studies in Thermal Engineering.The article was published on 2016-09-01 and is currently open access. It has received 49 citations till now. The article focuses on the topics: Baffle & Heat transfer enhancement.
Citations
More filters
TL;DR: In this article, a comprehensive literature review of the various heat transfer strategies used to improve the performance of smooth air channels (SACs) is presented, including attached, semi-attached, or detached; parallel, orthogonal or inclined; solid, perforated, or porous; and simple, corrugated or shaped.
Abstract: The topic is of paramount importance. Heating, cooling, or solar air ducts are used in several sectors and in very diverse fields. The improvement in their performance has been and is still of major concern to theorists and practitioners. The issue of exchanging heat between fluid and the heated surfaces within a smooth air channel relies mainly on the value of the heat transfer coefficient. This coefficient is a mine of factors that affect the heat exchange between working fluid and heated walls. Therefore, it is an ambitious attempt to work on such a topic. Obstacles, such as staggered or in-line, transverse, or longitudinal baffles, fins, or ribs have long been utilized in several thermal systems like shell-and-tube heat exchangers with segmental baffles, compact heat exchangers, flat-plate solar air collectors, microelectronics, and various other industrial applications, because of their high thermal loads and reduced structural parameters. The channels, through which the cooling or heating fluid is supplied, are generally mounted with several obstacles in order to increase the cooling or heating level. This configuration is mostly used in designing heat exchangers and solar air collectors. Through this contribution, we present a comprehensive literature review of the various heat transfer strategies used to improve the performance of smooth air channels (SACs). Various research works were made on (SACs) either numerical or experimental in order to improve their performance. Different models and configurations of obstacles are reviewed and discussed, including attached, semiattached, or detached; parallel, orthogonal or inclined; solid, perforated, or porous; and simple, corrugated, or shaped, of various sizes, positions, attack angles, perforations, porosities, arrangements, and orientations. In these studies, the obstacles are principally used to change the direction of the flow field, to modify the distribution of the local heat transfer coefficient, and also to increase the turbulence levels, thus resulting in larger heat transfer between the fluid and the heated walls.
74 citations
TL;DR: In this paper, the authors carried out a review on the recent investigations on the potential applications of different inserts including baffles, wire coils, vortex generators, and twisted tapes, in different solar thermal energy processes.
63 citations
TL;DR: In this paper, the authors studied the performance of the curved-corrugated channel with ZnO-water nanofluid and the presence of L-shaped baffles and found that the formation of vortex flow and increased turbulence due to effects of corrugations and baffles can improve the heat transfer enhancement.
Abstract: High heat generation is seen as a major issue in most mechanical and manufacturing industries, carrying with huge sub-problems. One of the possible cooling techniques is the combination of two or more passive methods, in particular for those parts with complex geometry. In this study, flow structure and heat transfer characteristics of the novel channel namely: curved-corrugated channel are numerically studied with using ZnO-water nanofluid and presence of L-shaped baffles. The influences of corrugations, baffles manner arrangement, and geometric parameters; corner angle (γ= 30°,45°,60°, and 90°) and blockage ratio (BR=0.25,0.3. 0.35, and 0.4), at different Reynolds number (8000–32000) and volume fraction of ZnO particles (0–4%) are evaluated using thermal-hydraulic performance method. The multi-phase mixture and the κ-e model are used to simulate turbulent nanofluid flows inside the curved-corrugated channels at constant temperature condition (T = 355 K). The results reveal that the formation of vortex flow and increased turbulence due to effects of corrugations and baffles can improve the heat transfer enhancement. Inline arrangement of baffle is superior to the staggered arrangement in thermal-hydraulic performance (PEC), and at lowest angle 30° provide the best PEC. Regarding the friction ratio and compared to those of a plain channel, the effect of blockage ratio is considerable as it yields a multiplier impact of the corner angle. Reducing the blockage ratio and the corner angle, i.e. 0.25 and 30°, yields to the best PEC at 1.99. New correlations for Nusselt number and friction factor for baffled curved-corrugated channel with using nanofluid are also reported.
46 citations
TL;DR: In this article, an experimental study on Nusselt number ( Nu rs ) and friction factor ( f rs ) of heat exchanger circular tube fitted with multiple square perforated with square wing twisted tape inserts is presented.
44 citations
TL;DR: In this article, an experimental study of Nusselt number and friction factors in a solar air passage with multiple type V-pattern dimpled obstacles on the heated wall was performed. And the results showed that the thermal hydraulic performance of multiple type DV-pattern obstacles pattern is around 7.0% higher as compared to other obstacles shapes solar- air passage.
41 citations
References
More filters
Journal Article•
7,568 citations
TL;DR: In this paper, the influence of the oblique delta-winglet twisted tape (O-DWT) arrangement on thermal performance was investigated in a uniform wall heat flux tube.
260 citations
"Heat transfer enhancement in solar ..." refers background in this paper
...[17] investigated the heat transfer augmentation in a SAC with winglet delta twisted tape baffles with different βO and H H / B D....
[...]
TL;DR: In this paper, performance analysis of a flat-plate solar air heater (SAH) with several obstacles (Type I, Type II, Type III and without obstacles) was performed for two air mass flow rates of 0.0074 and 0.52 kg/s.
223 citations
"Heat transfer enhancement in solar ..." refers background in this paper
...[20] experimentally investigate the performance analysis of four types of SAH with different obstacles and without obstacle....
[...]
TL;DR: In this paper, the performance of a pair of new vortex generators, curved trapezoidal winglet (CTW) has been experimentally investigated and compared with traditional vortex generators using dimensionless factors, which indicated the advantages of using this kind of vortex generators for heat transfer enhancement.
179 citations
TL;DR: In this article, an experimental investigation has been carried out to study the heat transfer coefficient and friction factor by using artificial roughness in the form of specially prepared inverted U-shaped turbulators on the absorber surface of an air heater duct.
141 citations