• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.37-43
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• 2015

A Beta-type Stirling engine is developed and tested on the operation stability and cycle performance. The flow rate for cooling water ranges from 300 to 1500 ml/min, while the temperature of heat source changes from 300 to $500^{\circ}C$. The internal pressure, working temperatures, and operation speed are measured and the engine performance is estimated from them. In the experiment, the rise in the temperature of heat source reduces internal pressure but increases operation speed, and overall, enhances the power output. The faster coolant flow rate contributes to the high temperature limit for stable operation, the cycle efficiency due to the alleviated thermal expansion of power piston, and the heat input to the engine, respectively. The experimental Stirling engine showed the maximum power output of 12.1 W and the cycle efficiency of 3.0 % when the cooling flow is 900 ml/min and the heat source temperature is $500^{\circ}C$.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.195-200
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• 2009

The objectives of this study are to analyze of energy consumption and operation conditions of each cooling system for gas and electric driven systems, and to compare operating cost for five different cooling systems; ice storage system, system air-condition, turbo chiller as the electric driven cooling systems, and absorption chiller and Gas driven Heat Pump (GHP) as the gas driven cooling systems. The sample designs are carried out based on the types of business, capacity, installation region and year.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.2
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• pp.33-41
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• 2012

The component cooling water heat exchangers are critical components in a nuclear power plant. As the operation years of the heat exchanger go by, the maintenance costs required for continuous operation also increase. Most heat exchangers have carbon steel shells, tube support plates and flow baffles. The titanium tube is susceptible to flow induced vibration. The damage on carbon steel tube support rod and titanium tube around cooling water entrance area is inevitable. Therefore, analysis of internal flow around the component cooling water entrance and tube channel is a good opportunity to seek for failure prevention practice and maintenance method. The numerical study was carried out by FLUENT code to find out the causes of tube failure and its location.

• 한국기계연구소 소보
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• s.16
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• pp.117-126
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• 1986

Trouble-free operation of cooling water systems is essential for efficient pro¬duction in most industrial facilities. Improper water treatments frequently cause such problems as corrosion, scaling, fouling and slime formation. Water quality, methods of cooling and materials of construction in the cooling circuit should be carefully studied before making selection of the water treatment programs. This paper reviewed cooling water problems encountered frequently in the open recirculating cooling systems and discussed the counter measures how to cope with them.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.852-858
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• 2011

This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4335-4349
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• 2023

Nuclear marine propulsion has been emerging as a next generation carbon-free power source, for which proper passive residual heat removal systems (PRHRSs) are needed for long-term safety. In particular, the characteristics of unlimited operation time and compact design are crucial in maritime applications due to the difficulties of safety aids and limited space. Accordingly, a compact and long-term-operable PRHRS has been proposed with the key design concept of using both air cooling and seawater cooling in tandem. To confirm its feasibility, this study conducted system design and a transient analysis in an accident scenario. Design results indicate that seawater cooling can considerably reduce the overall system size, and thus the compact and long-term-operable PRHRS can be realized. Regarding the transient analysis, the Multi-dimensional Analysis of Reactor Safety (MARS-KS) code was used to analyze the system behavior under a station blackout condition. Results show that the proposed design can satisfy the design requirements with a sufficient margin: the coolant temperature reached the safe shutdown condition within 36 h, and the maximum cooling rate did not exceed 40 ℃/h. Lastly, it was assessed that both air cooling and seawater cooling are necessary for achieving long-term operation and compact design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.401-413
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• 1999

An ice storage cooling facility with cooling capacity of 150㎾ has been constructed for the purpose of developing optimal design and control strategy for an ice storage system. As the first step to this purpose, a computer program has been developed to simulate the operation of the ice storage system and examined precisely by comparing the results with those measured from the test facility. With the simulation program verified from the comparison, a design procedure has been developed to determine the minimum capacity required for each operation strategy available commercially. It is shown that the minimum sizes of the chiller and the storage tank are strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1267-1273
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• 2009

Hot press forming can produce high-strength components by rapidly cooling between closed punch and die after hot forming using quenchable boron steel austenized in a furnace. In the hot press forming process, the cooling rate is influenced by the size, position and arrangement of the cooling channel and the file condition of cooling water in the die. Also, mechanical properties of the final components and operation time are related to cooling rate. Therefore, the design of optimized cooling channel is one of the most important works. In this paper, the effect of position and size of the cooling channel on the cooling rate was investigated by using design of experiment and FE analysis in hot press bending process. Therefore the optimum cooling channel ratio was presented in the HPB.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.979-986
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• 2003

The performance characteristics of heating and cooling operation for a heat pump system using seawater heat source and exhaust energy are presented. The heat pump system is made of a waste heat recovery system and a vapor compression refrigeration system. The working fluid is R-22. The heat pump system COPs are measured during heating and cooling operation modes, and the resultant COPs were 9.7 and 7.9, respectively, which are three times higher than those of the heat pump itself. Therefore, the performance of the heat pump system using exhaust energy is excellent compared to that of a general heat pump. The experimental data can be effectively used for the design of the high efficient heat pump using a seawater heat source.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.94-99
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• 2011

EMU(Electric Multiple Unit) of Seoul Metro are equipped with air conditioning and six line flow fans for air circulation. In summer, the air conditioning and line flow fans usually work at the same time. Recently, high oil price leads more people to use public transportation, which in turn makes them feel hotter inside the rolling stocks and complain about air conditioning state. In order to improve indoor air quality in summer, it is inevitable to increase the cooling capacity of air conditioners, which costs a lot of money. Thus, we need to raise cooling efficiency by rearranging existing devices effectively. In this study, we found a better way to improve refreshment inside the trains by changing the operation method of line flow fans and door opening systems. The results will help improve the cooling efficiency of EMU in summer. Also, more precise experiments and analyses of our data can lead to various methods to increase energy efficiency.