• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.654-659
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• 2013

This paper presents a numerical optimization of louvered fins to enhance the JF factor in terms of the design parameters, including the fin pitch, the number of louvers, the louver angle, the fin thickness, and the re-direction louver length. We carried out a parametric study to select the three most important parameters affecting the JF factor, which were the fin pitch, number of louvers, and the louver angle. We optimally designed the louvered fin by using 3rd-order full factorial design, the kriging method, and a micro genetic algorithm. Consequently, the JF factor of the optimum model increased by 16% compared to that of the base model. Moreover, the optimum model reduced the pressure drop by 17% with a comparable heat transfer rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.4
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• pp.398-403
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• 2000

Numerical analysis was conducted to investigate flow and heat transfer characteristics in louver fin exchanger, which were influenced by louver pitch, fin pitch, louver angle and inlet velocity. Standard $k-\varepsilon$ turbulent modelling was used in this study, and compared with laminar modelling. As a result of this study, Nusselt number became smaller as louver pitch or fin pitch was greater. Drag coefficient became smaller as louver pitch or fin pitch was greater, but it was little affected by inlet velocity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.201-208
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• 2005

This study presents the experimental study on improvement of frost/defrost performance in an heat pump system with newly developed fin and multiple compressors. As multiple compressors system, the variable and single speed compressor combinations has been introduced and compared with single speed 1-compressor system in a view point of improvement of frost/defrost performance. Also, newly developed corrugate shaped fin has been compared with conventional louver shaped fin. The frost/defrost performance is defined and some parameters are compared to discuss the effect of each combination. From this experimental study, it is known that if the variable and single speed compressor combination system equipped with corrugate shaped fin, the system performance has greatly improved not only for heating capacity, but also for frost performance.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.222-228
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• 2007

The effect of inclination angle on the heat transfer and pressure drop characteristics of brazed aluminum heat exchangers is experimentally investigated. Three samples having different fin pitches (1.25, 1.5 and 2.0 mm) were tested. Results show that heat transfer coefficient is not affected by the inclination angle. However, the friction factor increases as the inclination angle increases with negligible difference between the forward and backward inclination. Both the heat transfer coefficient and the friction factor are the smallest at $P_f$=1.5mm, followed by $P_f$=2.0mm and 1.25mm. Possible explanation is provided considering the louver layout. Comparison with existing correlations is also mad.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1681-1691
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• 2002

The heat transfer and pressure drop characteristics of heat exchangers with louver fins were experimentally investigated. The samples had small fin pitches (1.0 mm to 1.4 mm), and experiments were conducted up to a very low frontal air velocity (as low as 0.3 m/s). At a certain Reynolds number (critical Reynolds number), the flattening of the heat transfer coefficient curve was observed. The critical Reynolds number was insensitive to the louver angle, and decreased as the louver pitch to fin pitch ratio (L$_{p}$F$_{p}$) decreased. Existing correlations on the critical Reynolds number did not adequately predict the data. It is suggested that, for proper assessment of the heat transfer behavior, the louver pattern in addition to the flow characterization need to be considered. The heat transfer coefficient increased as the fin pitch decreased. At low Reynolds numbers, however, the trend was reversed. Possible explanation is provided considering the louver pattern between neighboring fins. Different from the heat transfer coefficient, the friction factor did not show the flattening characteristic. The reason may be attributed to the form drag by louvers, which offsets the decreased skin friction at a low Reynolds number. The friction factor increased as the fin pitch decreased and the louver angle increased. A new correlation predicted 92% of the heat transfer coefficient and 90% of the friction factor within $\pm$10%.10%.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.440-445
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• 2008

The present study was investigated the effect of the driving condition on the performance of a louver fin and tube type heat exchanger under frosting condition. Heat transfer rate and pressure drop by frost were experimentally investigated. Effects of the wet blub temperature and the shape of a fin on heat transfer performances has been also investigated. The key parameters were fin type(louver and corrugate fin) and the wet blub temperature of air (0.5, 1.0, $1.5^{\circ}C$). The heat transfer performance of the louver fin and tube type heat exchanger was higher by 0.89% than the corrugate fin type. As the wet blub temperature of air were increased, the heat transfer rate, pressure drop and mass of frost of three test models(Type A, B, C) were increased. Especially, the maximum heat transfer rate and maximum pressure drop were shown for the louver fin and tube type heat exchanger. As a experimental result, the enhancement factor(EF) of louver fin and tube type heat exchanger was $0.2{\sim}0.4$ due to the high pressure drop.