Performance Enhancement of Enhanced Herringbone Wavy-Fin Round Tube Inclined Heat Exchangers With and Without Hydrophilic Coating Using Evaporative Spray and Deluge Cooling

2013 ◽  
Author(s):  
Sahil Popli ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Cooling Water ◽  
Ambient Air ◽  
Spray Cooling ◽  
Round Tube ◽  
Capacity Enhancement ◽  
Side Pressure ◽  
Over The Top

An experimental study has been conducted to evaluate the performance of two herringbone wavy-fin round tube compact heat exchangers working as coolers, with frontal areas of approximately 0.24 m2 each in both dry and wet conditions. Heat exchanger capacity and air-side pressure drop were measured with the heat exchanger angle set at 20° from vertical. Deluge water cooling was achieved by incorporating a water distributor on top of the heat exchanger from which wetting water overflows as thin film over the top leading edge of the heat exchanger fins. A hollow cone nozzle was used for spray cooling. Water was used as a refrigerant, and enters the heat exchanger tubes at 43°C temperature. Ambient air, deluge and spray cooling water were maintained at 28°C temperature, and frontal air velocity was varied from 1.5 m/s to 3.0 m/s. Capacity was significantly enhanced for all heat exchangers using both deluge and spray cooling. However, the air-side pressure drop penalty ratio was much higher for deluge cooling. Furthermore, heat exchanger with hydrophilic coated fins achieved higher capacity enhancement ratios. This study contributes 8 dry cases and 48 wet cases experimental data points of wavy-fin heat exchanger performance. Future studies would aim at obtaining higher capacity enhancement ratios for spray cooling while maintaining air-side pressure drop penalty ratio of 1.0.

Impact of an Anisotropic Fin Surface Design on the Thermal-Hydraulic Performance of a Plain-Fin-and-Tube Heat Exchanger

2011 ◽  
Author(s):  
Rong Yu ◽  
Andrew D. Sommers ◽  
Nicole C. Okamoto ◽  
Koushik Upadhyayula
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Hydraulic Performance ◽  
Normal Operation ◽  
Surface Design ◽  
Tube Heat Exchanger ◽  
Silane Coating ◽  
Side Pressure

In this study, we have explored the effectiveness of heat exchangers constructed using anisotropic, micro-patterned aluminum fins to more completely drain the condensate that forms on the heat transfer surface during normal operation with the aim of improving the thermal-hydraulic performance of the heat exchanger. This study presents and critically evaluates the efficacy of full-scale heat exchangers constructed from these micro-grooved surfaces by measuring dry/wet air-side pressure drop and dry/wet air-side heat transfer data. The new fin surface design was shown to decrease the core pressure drop of the heat exchanger during wet operation from 9.3% to 52.7%. Furthermore, these prototype fin surfaces were shown to have a negligible effect on the heat transfer coefficient under both dry and wet conditions while at the same time reducing the wet airside pressure drop thereby decreasing fan power consumption. That is to say, this novel fin surface design has shown the ability, through improved condensate management, to enhance the thermal-hydraulic performance of plain-fin-and-tube heat exchangers used in air-conditioning applications. This paper also presents data pertaining to the durability of the alkyl silane coating.

Air-Side Heat Transfer Performance of Louver Fin and Multitube Heat Exchanger for Direct Methanol Fuel Cell Cooling Application

2014 ◽  
Vol 11 (4) ◽  
Author(s):  
Hie Chan Kang ◽  
Hyejung Cho ◽  
Jin Ho Kim ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Direct Methanol Fuel Cell ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Side Pressure ◽  
Direct Methanol ◽  
Methanol Fuel Cell

The present work is performed to evaluate the heat transfer performance of a heat exchanger used in a direct methanol fuel cell. Because of material constraints and performance requirements, a louver fin heat exchanger is modified for use with conventional microchannel tubes and also with multiple small-diameter tubes (called multitubes). Prototype heat exchangers are tested, and the air-side heat transfer, pressure drop, and fan power are measured in a wind tunnel and simulated using a commercial code. The air-side pressure drop and heat transfer coefficient of the multitubes show similar trends to those of the flat-tube heat exchanger if the contact resistance is negligible. The tube spacing of the prototype multitube heat exchangers has a small effect on the pressure drop and heat transfer, but it has a profound effect on the air-side heat transfer performance because of the contact resistance between the tubes and louver fins. The air-side pressure drop agrees well with an empirical correlation for flat tubes.

scholarly journals Optimization of Compressed Heat Exchanger Efficiency by Using Genetic Algorithm

2019 ◽  
Vol 24 (2) ◽  
pp. 461-472
Author(s):  
M. Ghorbani ◽  
S.F. Ranjbar
Keyword(s):  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Power Plants ◽  
Gas Flow ◽  
Equation System ◽  
Exchange Capacity ◽  
Use Of Resources ◽  
Side Pressure

Abstract Due to the application of coil-shaped coils in a compressed gas flow exchanger and water pipe flow in airconditioner devices, air conditioning and refrigeration systems, both industrial and domestic, need to be optimized to improve exchange capacity of heat exchangers by reducing the pressure drop. Today, due to the reduction of fossil fuel resources and the importance of optimal use of resources, optimization of thermal, mechanical and electrical devices has gained particular importance. Compressed heat exchangers are the devices used in industries, especially oil and petrochemical ones, as well as in power plants. So, in this paper we try to optimize compressed heat exchangers. Variables of the functions or state-of-the-machine parameters are optimized in compressed heat exchangers to achieve maximum thermal efficiency. To do this, it is necessary to provide equations and functions of the compressed heat exchanger relative to the functional variables and then to formulate the parameter for the gas pressure drop of the gas flow through the blades and the heat exchange surface in relation to the heat duty. The heat transfer rate to the gas-side pressure drop is maximized by solving the binary equation system in the genetic algorithm. The results show that using optimization, the heat capacity and the efficiency of the heat exchanger improved by 15% and the pressure drop along the path significantly decreases.

Experimental Investigation of Flat Tube-Louver Fin Heat Exchanger Performance Working as a Cooler in Dry and Wet Conditions

2012 ◽  
Author(s):  
Sahil Popli ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Water Flow Rate ◽  
Ambient Air ◽  
Water Cooling ◽  
Air Velocity ◽  
Flat Tube ◽  
Side Pressure ◽  
Dry And Wet Conditions

An experimental study has been conducted to evaluate the performance of a flat-tube louver-fin heat exchanger working as a cooler, with frontal area of 0.25 m2 in both dry and wet conditions. Deluge water cooling at different flow rates was achieved by incorporating perforated tube-type distributor on top of the heat exchanger. Water at 35°C temperature was used as heat transfer fluid at cooler inlet. Ambient air and deluge cooling water were both maintained at 22°C temperature. Heat exchanger capacity and air-side pressure drop were measured with the heat exchanger angle set at 0° and 21° from vertical, with a frontal air velocity of 1.4 m/s and 3.5 m/s without deluge water cooling, and a frontal air velocity of 1.2 m/s, 1.4 m/s with deluge water cooling. Significant capacity enhancement could be obtained both with the use of deluge water cooling and with the heat exchanger angle set at 21° from vertical. Furthermore, it was found that approximately same capacity was obtained at both 0° and 21° angle when wetting water flow rate was reduced from 0.17 kg/s to 0.063 kg/s, without significant reduction in air-side pressure drop. This study highlights the importance of wetting of heat transfer surfaces of compact flat tube heat exchangers and provides motivation for further research in this area.

Modified Manifold-Microchannel Heat Exchangers Fabricated Based on Additive Manufacturing: Experimental Characterization

2019 ◽  
Author(s):  
William C. Yameen ◽  
Nathan A. Piascik ◽  
Andrew K. Miller ◽  
Riccardo C. Clemente ◽  
Jingru Z. Benner ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Flow ◽  
Heat Exchangers ◽  
Original Design ◽  
Flow Rates ◽  
Side Pressure ◽  
Manifold Microchannel

Abstract In this study, the additive manufacturing technique has been utilized to fabricate air-water heat exchangers for the application of thermoelectric power plants. Additive manufacturing is a powerful fabrication method that has enabled fabrication of complex geometries that are either challenging or impossible to fabricate based on conventional techniques. Three manifold-microchannel heat exchangers with different interior designs were fabricated by additive manufacturing and from stainless steel. The heat exchangers were tested at different air flow rates and different inlet water temperatures. One heat exchanger was designed and fabricated based on an original design of the manifold-microchannel heat exchanger. Two other heat exchangers were designed with some modifications compared to the original design. In one modified heat exchanger, cylindrical pin arrays were considered on air manifold walls in order to enhance air disturbance, and thus, increase heat transfer between water and air. The second modified heat exchanger contained same pins and also had microchannels in the perpendicular orientation compared to the original design in the outlet manifolds. This design modification was done in order to reduce air-side pressure drop in the heat exchanger. The heat transfer characteristics along with air-side pressure drop were measured and compared with the original design of the manifold-microchannel heat exchanger. Results indicated that the heat flow rate, convection heat transfer coefficient, and pressure drop did not significantly change in modified heat exchangers. For air Reynolds number between around 800 and 4,000, the heat flow rates obtained in the original heat exchanger (type A) and for 50° C water inlet temperature were between 63.9 and 228 W for the lowest and the highest air flow rates, respectively. For the same inlet water temperature, these heat flow rates were between 64.2 and 211 W for the lowest and the highest air flow rates and in one of the modified heat exchangers (type B), respectively. Similarly, while the highest air-side pressure drop in the original heat exchanger was 3458 Pa, this property was measured at 3525 (type B) and 3884 (type C) for the two modified heat exchangers.

An Experimental Investigation of the Shell-Side Pressure Drop of Enlarged-Hole Whole-Rounded Baffle Heat Exchanger

2010 ◽  
Vol 160-162 ◽  
pp. 1622-1627 ◽  
Author(s):  
Hai Yang Sun ◽  
Cai Fu Qian
Keyword(s):  
Experimental Investigation ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Flow Characteristics ◽  
Shell Side ◽  
Pressure Drops ◽  
Side Pressure

In this paper, the flow characteristics of the whole-rounded enlarged-hole baffle heat exchangers are experimentally studied with the stress on the shell-side pressure drops. It is found that the shell-side pressure drops for the whole-rounded baffles with the enlarged holes are greatly decreased. Compared with the square layout, the enlarged-hole whole-rounded baffles in the case of triangle layout is even more effective in decreasing the pressure drop. The shell-side pressure drops for the heat exchangers with the enlarged-hole whole-rounded baffles are proportional to the square of the flow rate.

scholarly journals Shell-Side Pressure Drop in the Multi-Baffled Shell-and-Tube Heat Exchangers

1965 ◽  
Vol 8 (32) ◽  
pp. 644-651 ◽  
Author(s):  
Seikan ISHIGAI ◽  
Eiichi NISHIKAWA ◽  
Yoshiaki NAKAYAMA ◽  
Shigeo TANAKA ◽  
Ikuo SAIDA ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Heat Exchangers ◽  
Shell Side ◽  
Side Pressure ◽  
Shell And Tube

A Method to Design Shell-Side Pressure Drop Constrained Tubular Heat Exchangers

1977 ◽  
Vol 99 (3) ◽  
pp. 441-448 ◽  
Author(s):  
K. P. Singh ◽  
M. Holtz
Keyword(s):  
Pressure Drop ◽  
Heat Exchangers ◽  
Solution Procedure ◽  
Design Guidelines ◽  
Solution Technique ◽  
Nuclear Heat ◽  
Side Pressure ◽  
Flow Induced Vibrations ◽  
The Subject ◽  
Shell And Tube

In shell and tube heat exchangers, the triple segmental baffle arrangement has been infrequently used, even though the potential of this baffle system for high thermal effectiveness with low pressure drop is generally known. This neglect seems to stem from the lack of published design guidelines on the subject. Lately, however, with the rapid growth in the size of nuclear heat exchangers, the need to develop unconventional baffling pattern has become increasingly important. A method to effectively utilize the triple segmental concept to develop economical designs is presented herein. The solution technique given in this paper is based on a flow model named “Piecewise Continuous Cosine Model.” The solution procedure easily lends itself to detailed analysis to determine safety against flow-induced vibrations.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

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