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ISSN : 1598-6721(Print)
ISSN : 2288-0771(Online)
The Korean Society of Manufacturing Process Engineers Vol.17 No.5 pp.23-29
DOI : https://doi.org/10.14775/ksmpe.2018.17.5.023

Numerical Analysis on the Thermal and Fluid in Air Conditioning Duct for Marine Offshore

Chung-Seob Yi*, Byung-Ho Lee**, Do-Hun Chin**#
*Gyeognam National University of Science and Technology
**Department of Automotive Engineering, Kyungnam College of Information & Technology
***R&D Center, Dawon Tech LTD., CO.
Corresponding Author : chindohun@hanmail.net Tel: +82-51-327-2301, Fax: +82-55-327-2310
15/06/2018 21/06/2018 11/07/2018

Abstract


This study is about the distribution of heat transfer in air conditioning ducts used for marine vessels and oil drilling platforms. As the convective heat transfer coefficient increased, heat transfer was conducted dynamically to inside as it exited to the outlet of duct. The experiment was to determine if the amount of heat transfer generated at the duct exit increased as the convective heat transfer coefficient increased. When the convective heat transfer coefficient was low, the temperature of the duct showed a relatively high temperature difference between the outside and inside of the duct due to the temperature influence of the internal fluid. In case of temperature distribution generated the volume of the duct along the change of the convective heat transfer coefficient, the temperature descended as heat transfer was promoted and the convective heat transfer coefficient increased.



해양 구조물용 공조덕트 열유동에 관한 수치해석

이 중섭*, 이 병호**, 진 도훈**#
*경남과학기술대학교
**경남정보대학교
***다원텍(주)기술연구소

초록


    © The Korean Society of Manufacturing Process Engineers. All rights reserved.

    This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

    1. Introduction

    Currently, air-conditioning ducts are normally installed for ventilation in the columns and pontoons, which act as the legs of a submersible semi-drilling rig among several marine plants.

    For air-conditioning ducts used in marine and oil drilling ships, a light gauge watertight duct is widely employed, which is installed as a module type inside the columns, and a bellows section is formed at the surface in the longitudinal direction to enable a design with reinforced strength and lightweight.

    As the strength of light gauge watertight air-conditioning duct is increased by the bellows section, the thickness of the air-conditioning duct can become relatively thin, thereby reducing the overall weight, which is suitable for efficient applications in marine and oil drilling ships. Thus, most major oil companies in Europe have attempted the light-weighting of newly built oil drilling ships[1-4].

    As shown in Fig. 1, the air-conditioning ducts installed in the columns are made of simple flat-surface steel plates, and their ends are welded and connected. Thus, this study aims to perform the numerical analysis of the thermal and flow behaviors that occurred inside the air-conditioning duct.

    2. Heat flow analysis method

    This study was performed with a 550-mm-diameter air-conditioning duct, as shown in Fig. 2, and aimed to identify the effect of the bellows installed inside the duct on the flow field and heat transfer.

    Fig. 3 shows the boundary condition for performing the heat flow analysis on the air-conditioning duct. The inlet and outlet were extruded by five and seven times the hydraulic radius to ensure the stability of the flow.

    As shown in Fig. 3, a convective heat transfer coefficient was set to a variable outside the light gauge watertight duct. Here, the ambient temperature was assumed to be 25℃. In addition, an air inflow rate of 1m/s in the inlet and air temperature of 5 0℃ flowing through the duct were assumed. For the outlet, the atmospheric pressure was assumed[5-7].

    Fig. 4 shows the controlled volume for heat flow analysis. The thickness of the duct in the solid area was 3 mm, and it consisted of five mesh-type layers.

    Fig. 5 shows the temperature distribution at five regions every 250 mm from the duct inlet from a virtual sensor to measure the inner temperature distribution in the radial direction with regard to the longitudinal direction of the light gauge watertight duct. The 250-mm region is the central position between the bellows.

    3. Heat flow analysis results

    Fig. 6 shows the inner temperature distribution in the duct according to a change in the convective heat transfer coefficient that acted on the outside surface of the light gauge watertight duct. As shown in the figure, gradual cooling was verified inside the duct as heat transfer occurred at the duct surface, thereby generating heat exchange with the outside. As the convective heat transfer coefficient increased, heat transfer occurred actively as the air was discharged to the outlet in the duct. Fig. 7 shows the temperature distribution at each region according to a change in the convective heat transfer. In this figure, 0 in the X-axis refers to the center of the duct. Overall, the figure verified that the duct inside cooled faster as it was nearer to the outlet due to the heat exchange with the outside of the duct while passing through the duct.

    The figure also verified that heat transfer progressed deep inside the duct as heat exchange was facilitated with the increase in the convective heat transfer coefficient.

    Fig. 8 shows the temperature distribution of the solid duct solid area. As shown in Fig. 8, heat transfer between the inside and outside of the duct slowed down when the convective heat transfer coefficient was lower, thereby exhibiting a relatively high temperature distribution due to the temperature effect of the inner fluid in the duct. In contrast, the figure result verified that the temperature in the duct surface became lower as heat exchange was facilitated with the increase in the convective heat transfer coefficient.

    The temperature distribution on the inside and outside surfaces of the duct displayed that the inside surface had relatively higher temperature distribution due to the high temperature of the working fluid, whereas the outside surface showed a relatively lower temperature distribution due to the convective heat exchange with the outside.

    The heat exchange inside the duct in the travel direction of the working fluid revealed that heat exchange was facilitated as air passed through the outlet, resulting in lower temperature distribution.

    Fig. 9 shows the heat transfer that occurred in the duct. It verified that the increase in heat transfer occurred in the duct as the convective heat exchange coefficient increased. This was because heat exchange with the working fluid that flowed inside the duct was facilitated as the convective heat transfer coefficient acting on the outside surface of the duct increased.

    Fig. 10 shows the temperature distribution that occurred in the duct volume according to a change in the convective heat transfer coefficient. The figure verified that the temperature dropped as the heat transfer was facilitated with the increase in the convective heat transfer coefficient.

    4. Conclusions

    This study conducted a heat transfer analysis of the air-conditioning ducts used in marine structures and derived the following conclusions.

    1. As the convective heat transfer coefficient increased, heat transfer occurred actively as the air was discharged to the outlet in the duct. Thus, this verified that the increase in heat transfer occurred in the duct as the convective heat exchange coefficient increased.

    2. Heat transfer between the inside and outside of the duct slowed down when the convective heat transfer coefficient was lower, thereby exhibiting a relatively high temperature distribution due to the temperature effect of the inner fluid in the duct.

    3. The temperature distribution that occurred in the duct volume according to a change in the convective heat transfer coefficient showed that as the convective heat transfer coefficient increased, heat transfer was facilitated, thereby decreasing the temperature.

    Figure

    KSMPE-17-23_F1.gif
    Air conditioning duct for marine offshore
    KSMPE-17-23_F2.gif
    Analysis model
    KSMPE-17-23_F3.gif
    Control volume shape for CFD analysis
    KSMPE-17-23_F4.gif
    Control volume for fluid and solid
    KSMPE-17-23_F5.gif
    Sensing positions at length and radial direction
    KSMPE-17-23_F6.gif
    Result of temperature distributions in Fluid region
    KSMPE-17-23_F7.gif
    Comparison of temperature distributions at positions
    KSMPE-17-23_F8.gif
    Result of temperature distributions at solid region
    KSMPE-17-23_F9.gif
    Result of heat transfer distribution at duct surface
    KSMPE-17-23_F10.gif
    Result of temperature distribution at duct

    Table

    Reference

    1. Yi, C. S. , Chin, D. H. , “ Numerical Analysis of the Development of an Air Conditioning Duct for Marine and Oil Drilling Ships ”, Journal of the Korean Society of Manufacturing Process Engineers, Vol. 16, No. 2, pp. 50-55, 2017.
    2. Park, J. Y , C., Yi, C. S., Chin, D. H., “Numerical Analysis on the Development of Shut off Damper for Tsunami at Nuclear Plant ”, Jorunal of KSMTE, Vol. 23, No. 5, pp. 471-477, 2014.
    3. Yi, C. S. , " Numerical Analysis of the Kitchen Hood Ventilation System for MarineEnvironment ", Journal of the Korean Society of Manufacturing Process Engineers, Vol. 14, No. 5,pp. 96-101, 2015.
    4. Yi, C. S. , Jang, S. C. , Choi, J. H. , " Numerical Analysis on Hood Shape Improvement of Local Ventilation System ", Journal of ACRE, Vol. 21, No. 4, pp. 260-265, 2009.
    5. Jang, S. C. , Jung, W. B. , Yi, C. S. , "A Study on Performance Improvement of Gear Type Vane Damper in Marine/Offshore FD Fan", Journal ofKSMPE, Vol. 14, No. 2, pp. 7-13, 2015.
    6. Seo, J. H. , Kim, B. T. , Chin, D. H. , Yoon, M. C. Kwak, J. S., "Comparison of the Contact Characteristics for Sealing strips of the Tsunami Damper ", Journal of the Korean Society of Manufacturing Process Engineers, Vol. 14, No. 1,pp. 21-28, 2015.
    7. Lim, K. B. , Lee, K. S. and Lee, C. H. , " A Numerical Study on the Characteristics of Flow Field, Temperature and Concentration Distribution According to Changing the Shape of SeparationPlate of Kitchen Hood System " Journal of KSME B, Vol. 30, No. 2, pp. 177-185, 2006.