• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.106-111
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• 2001

The performance characteristics of heat pump system using the new refrigerant subcooling system were investigated. The new heat pump system has the ice storage tank to accumulate the latent heat of the refrigerant during the night-time. The heat is released to subcool the saturated refrigerant liquid at the outlet of a condenser in the daytime. The experimental apparatus is a well-instrumented heat pump which consisted of a refrigerant loop and a coolant loop. The test sections(condenser and evaporator) were made of tube-in-tube heat exchanger with the horizontal copper tube of 12.7[mm] outer diameter and 9.5[mm] inner diameter. The evaporating temperatures ranged from $-5[^{\circ}C]$ to $0[^{\circ}C]$ and the subcooling degrees of the refrigerant varied from $15[^{\circ}C]$ to $25[^{\circ}C]$. The test of the ice storage was carried out at evaporating temperature of $-10[^{\circ}C]$ and the ice storage mode is an ice-on-coil type. The main results were summarized as follows ; The refrigerant mass flow rate and compressor shaft power of the heat pump system were independent of the subcooling degrees. The cooling capacity o the heat pump system increases as the evaporating temperature and subcooling degree increases. The cooling capacity of the heat pump system is about 25 to 30% higher than that of normal heat pump system. The COP of the heat pump system which subcooled the refrigerant liquid at the outlet of the condenser is about 28% higher than that of the normal heat pump system.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.6
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• pp.790-796
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• 2003

As a fluid machinery for piping liquid in the reactor cooling system, multi-stage centrifugal pump requires the structural dynamic stability against external dynamic excitation. This paper is concerned with the finite element analysis of its eigen behavior and seismic response to RRS(Required Response Spectrum) curves in the case of SSE (Safe Shutdown Earthquake). Through the finite element analysis, the major vibration characteristics of multi-stage centrifugal pump(MSCP) are investigated and seismic qualification based on the IEEE codes is executed. The numerical results show that the MSCP used in this study has enough seismic strength.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.455-460
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• 2008

The flammable gas monitoring system is to be provided in cargo pump rooms of tankers in accordance with the requirements of SOLAS regulations, and flammable gas detectors are to be arranged in a proper position. In this paper, simulation tests and CFD analysis are carried out under the actual ventilation conditions of pump rooms in the ship in service. Based on the results, a new guidelines for an arrangement of flammable gas detectors are suggested.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.341-346
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• 2010

In this paper, viscous flow calculation of pump-jet that is used as underwater propulsor was made by using RANS equation. For the validation, calculation for DTRC4119 marine propeller was made and reasonable agreements were obtained between the present results and the experiment. An unstructured overset mesh technique is used for analysis of relative motion between rotor and stator in pump-jet propulsor. Results for pump-jet propulsor were compared with computational results of another researcher.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.685-692
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• 2006

In a general centrifugal pump, if it is operated in a two-phase flow the activity of the impeller usually degrades and occasionally losses its function. However, the effect of break down of centrifugal pump due to entrained air has not been clarified yet. This paper shows the air-water two-phase flow characteristics of closed type and semi-open type impellers. In a sing1e-phase flow, closed-type impeller has higher efficiency and head. But in air-water two-phase flow semi-open type impeller's rates of decreases of efficiency and head are decreased.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.89-94
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• 2002

A commercial CFD code is used to calculate the 3-D viscous flow field within the centrifugal pump impeller. Design conditions are changed by impeller inlet(9.3mm, 12.2mm) and outlet breadth(6.65mm, 6.85mm). Numerical calculation was performed by changing flow rate from 8 to 26m$^{3}$/hr. Computation results shows that total head is increased at the larger inlet and outlet breadth than the others. And when the flow rate is increasing, the total head was decreased. The maximum efficiency of pump is shown at the design flow rate(16m$^{3}$/hr). In this study shows that the calculated results are good agreements with analysis results of design condition.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.218-224
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• 2011

The fresh water and sea water in present ships is used as cooling water for marine engine. Therefore, corrosion damage in seawater system is frequently occurred. In particular, in the impeller of pump, the performance and material span due to the corrosion and cavitation erosion has adverse effects. Most of the pump impellers in vessels are used Cu-Al alloy. Cu-Al alloy which having the excellent mechanical properties and corrosion resistance is widely used in marine environments. However, despite the excellent characteristics, the periodic replacement parts due to the cavitation damage in seawater is vulnerable to economic viewpoint. In this study, Cu-Al alloy used with impeller for centrifugal pump were conducted various experiments to evaluate its characteristics in seawater and fresh water solutions. As an electrochemical result, the dynamic conditions that exposed to the cavitation environment presented high corrosion current density with collapse of the cavity compared with the static conditions. Cavitation test results, the weightloss and weightloss rate in fresh water are observed more than those of seawater.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.624-629
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• 2008

The problem was derived from a simple process in solar water heating system. In a new designed electro less separated system we involved a kind of bubble pump. Beside experiment analysis, numerical simulation of the core of bubble pump is also very important. In this paper we investigated the motion of bubbles in vertical tube in two dimensions. The heat and mass transfer was simulated. The result of numerical simulation give a significant help of optimize design of bubble pump.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.2
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• pp.252-258
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• 1999

As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.195-201
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• 2010

In this paper, a cooling system of high-power propulsion motor with Energy Saving System(ESS) is described. Normally, the cooling system for ship consists of fresh water pump, sea water pump, 3-way valve and cooler. In the cooling system, F.W(Fresh Water) and S.W(Sea Water) pump is operated on rated rpm, and the 3-way valve is controlled for preventing over-cooling. So, the consumption power of pump's motor is changed according to a sea water temperature. In the proposed cooling system, F.W. pump and S.W pump is controlled by inverter, and it is can be reduced the consumption power. Also, it is proved with simulation.