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- Henriksson, Lisa, 1984, et al.
(author)
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CFD Method and Simulations on a Section of a Detailed Multi-Louvered Fin where the Incoming Air is Directed at 90° and 30° Relative to the Compact Heat-Exchanger
- 2013
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In: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 9
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Journal article (peer-reviewed)abstract
- This paper presents results and a Computational Fluid Dynamics (CFD) method for simulation of a detailed louvered fin for a multi-louvered compact heat-exchanger. The airflow was angled at 90°, +30° and -30° relative to the heat-exchanger to evaluate changes in static pressure drop and airflow characteristics. The investigation was based on three heat-exchangers with thicknesses of 52mm and two of 19mm. One period of a detailed louvered fin was simulated for two airflows for each heat-exchanger. The pressure drop data was thereafter compared to experimental data from a full-size heat-exchanger.From the pressure drop and the airflow characteristic results recommendations were made that those kinds of simulations could be defined as steady state, and with the kω-SST turbulence model. For the same heat-exchanger angle the airflow within the core was similar, with a turbulent characteristic behind it. The static pressure drop was reduced significantly for the ±30° cases compared to the 90° angled heat-exchanger to approximately one third, when comparing for the same mass airflow rates. Since the test section area was defined as constant the velocity through the heat-exchanger core varied for the 90° and the 30° cases. When comparing the core velocity it was observed that there were minor losses due to the redirection of the airflow for the 30° angle compared to the 90° case. The results showed that the 30° case, where the inlet airflow was parallel to the louvers, had a higher pressure drop than the other 30° case. It was also observed that even when the inlet airflow angle varied, the outlet airflow angle from the heat-exchanger only varied 4.3-6.4°.
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- Henriksson, Lisa, 1984, et al.
(author)
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CFD Simulations of one Period of a Louvered Fin where the Airflow is Inclined Relative to the Heat Exchanger
- 2015
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In: SAE International Journal of Engines. - : SAE International. - 1946-3944 .- 1946-3936. ; 8:4, s. 1733-1742
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Journal article (peer-reviewed)abstract
- This article presents Computational Fluid Dynamics (CFD) simulations of one period of a louvered fin, for a crossflow compact finned heat exchanger, where the incoming airflow was inclined relative to its core. Four inclinations were investigated: 90°, which was when the air flowed perpendicular to the heat exchanger, 60°, 30° and 10° angles relative to the vertical plane. The study included three heat exchanger designs, where two of them had symmetrical louvered fins and a thickness of 19mm and 52mm. The third had a thickness of 19mm and had the louvers angled in one direction. All heat exchangers have been simulated when the airflow entered both from above and below relative to the horizontal plane. Simulations have also been carried out when the airflow entered from the side, illustrating the heat exchanger to be angled relative to the vertical axis. Two air speeds have been investigated for each configuration, where the results were compared to experimental data.The results showed that the airflow characteristics were strongly dependent on the inclination angle. A more inclined heat exchanger generated larger separated areas at the entrance of the heat exchanger core. After approximately six louvers the airflow was fairly similar for all inclinations. The pressure drop over the core was not affected by the direction of the entered airflow. It was also seen that the heat exchanger with the louvers in only one direction resulted in approximately the same pressure drop as the one with symmetrical louvered fins. For a constant velocity in the longitudinal direction within the core, the pressure drop did not varied between the inclinations. Depending on the definition of the heat exchanger arrangement the heat transfer rate was affected. Simulated pressure drop followed the same trend as experimental data, even though the values were over-predicted.
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- Henriksson, Lisa, 1984, et al.
(author)
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Experimental Investigation of Heat Transfer Rate and Pressure Drop through Angled Compact Heat Exchangers Relative to the Incoming Airflow
- 2014
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In: SAE International Journal of Commercial Vehicles. - : SAE International. - 1946-3928 .- 1946-391X. ; 7:2, s. 448-457
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Journal article (peer-reviewed)abstract
- The investigation showed that a more inclined heat exchanger resulted in lower static pressure drop and at the same time achieved a higher heat transfer rate, for a specific mass airflow rate. This result was obtained for all three heat exchangers. When analysing the parameters at the same core speed it was seen that the static pressure drop was increased for the 10° and the 30° angled heat exchangers, compared to the 90° configuration. For the 60° cases the pressure drop was both increased and decreased compared to the 90° cases, depending on the heat exchanger design. It was also seen that the pressure drop and the heat transfer rate variation were negligible between the downflow and crossflow orientation of the heat exchanger. When defining the static pressure drop to 200Pa either a 19mm thick heat exchanger at 60° or a 52mm heat exchanger at 90° can be used to obtain the same heat transfer rate.This paper presents pressure drops and heat transfer rates for compact heat exchangers, where the heat exchangers are angled 90°, 60°, 30° and 10° relative to the incoming airflow. The investigation is based on three heat exchangers with thicknesses of 19mm and 52mm. Each heat exchanger was mounted in a duct, where it was tested for thermal and isothermal conditions. The inlet temperature of the coolant was defined to two temperatures; ambient temperature and 90°C. For the ambient cases the coolant had the same temperature as the surrounding air, these tests were performed for five airflow rates. When the coolant had a temperature of 90°C a combination of five coolant flow rates and five airflow rates were tested. The test set-up was defined as having a constant cross-section area for 90°, 60° and 30° angles, resulting in a larger core area and a lower airspeed through the core, for a more inclined heat exchanger.
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| 5. |
- Henriksson, Lisa, 1984, et al.
(author)
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Experimental Investigation of Heat Transfer Rates and Pressure Drops through Compact Heat Exchangers
- 2014
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In: JSAE Annual Congress on 5, 22 ,2014. Paper 220145253.
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Conference paper (peer-reviewed)abstract
- This paper presents pressure drops and heat transfer rates for compact heat exchangers, where the heat exchangers are angled 90°, 60°, 30° and 10° relative to the incoming airflow. The investigation is based on two heat exchangers with different thicknesses. The experiments were performed for five airflow rates and five coolant flow rates, where the inlet temperature of the coolant was defined to two temperatures; ambient temperature and 90°C. The investigation showed that the 30° angled heat exchanger resulted in the lowest pressure drop and at the same time achieved the highest heat transfer rate, for a specific mass airflow rate.
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| 6. |
- Henriksson, Lisa, 1984, et al.
(author)
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Experimental investigation of heat transfer rates and pressure drops through compact heat exchangers: Where the Heat Exchanger is Angled Relative to the Incoming Airflow
- 2015
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In: International Journal of Automotive Engineering. - : Society of Automotive Engineers of Japan, Inc.. - 2185-0992 .- 2185-0984. ; 6:1, s. 7-14
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Journal article (peer-reviewed)abstract
- This paper presents pressure drops and heat transfer rates for compact heat exchangers, where the heat exchangers are angled 90°, 60°, 30° and 10° relative to the incoming airflow. The investigation is based on two heat exchangers with different thicknesses, 19mm and 52mm. The experiments were performed for five airflow rates and five coolant flow rates, where the inlet temperature of the coolant was defined to two temperatures; ambient temperature and 90°C. The test set-up is defined as having a constant cross-section area for 90°, 60° and 30° angles, resulting in a larger core area and a lower airspeed through the core, for a more inclined heat exchanger. The investigation showed that the more inclined heat exchangers resulted in lower static pressure drops and at the same time achieved higher heat transfer rates, for a specific mass airflow rate.
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| 7. |
- Henriksson, Lisa, 1984
(author)
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Performance of Compact Heat Exchanger in Non-Perpendicular Cooling Airflows
- 2015
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Doctoral thesis (other academic/artistic)abstract
- During recent years the main focus in the vehicle industry has been on cutting the fuel consumption and emissions as well as improving the vehicle performance. To be able to meet these demands additional systems are being introduced into the vehicle. These implementations do not only affect the engine power and the emission levels, they also tend to increase the operating temperature in the engine bay, which in turn increases the cooling demand. Therefore, a trend toward increased cooling performance for vehicles is also seen. There are a number of solutions to solve this demand and for heavy vehicles the most suitable way is to install additional heat exchangers positioned at other locations in the vehicle, due to the limited underhood space. These extra heat exchangers may not be located in the most appropriate position and it is not unusual that the airflow is not perpendicular to the heat exchanger core. For some vehicles today these types of installations can already be seen. Therefore, it is important to evaluate the effects on cooling airflows. Since both heat transfer and pressure drop over the heat exchanger will be affected by the angled airflow these parameters as well as the flow field characteristics, have to be analysed and evaluated.This thesis presents the evaluation of the performance of standard automotive compact heat exchangers and their performance in non-perpendicular airflows. Four angles have been tested to predict variances in pressure drop, heat transfer rates and airflow characteristics. Laboratory experiments and 3D Computational Fluid Dynamics (CFD) simulations have been conducted to study the effects. Methods have been developed to simulate heat exchangers in angled conditions as well as internal parts of the core. The results have been correlated with the experiments to find similarities and deviations.The results showed that the additional loss due to the angling of the heat exchanger, is due to the forced re-direction of the airflow into the core. This loss is increased with the magnitude of the angling. Neither the static pressure drop nor the heat transfer rate was significantly affected by the inclination angle of the heat exchanger relative to the airflow. To reduce the pressure drop within the installation the surrounding geometries had to be considered to prevent areas of losses. If a specific installation is going to be evaluated the information presented in this thesis is of great importance and could be used to find an optimal design for the system.
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