• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.567-573
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• 2015

Commercial buildings account for significant portions of the total building energy in Korea, and thus, a variety of research on chiller operation has been carried out. However, most of the studies were carried out on the chiller itself, i.e., the part load ratio characteristics and the corresponding electricity energy consumption patterns were not analyzed in existing studies. In this study, the part load ratio and the operating characteristics of the vapor compression chiller were analyzed within an office building equipped with the conventional variable air volume system. As a result, significant portions of total operating hours, cooling load, and energy consumption turned out to be in the part load ratio range of 0 through 50%. Thus, energy consumption was significantly affected by the chiller COP at low part load conditions, indicating that chiller operation at the part load is an important factor in commercial buildings.

• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.541-552
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• 1997

In this paper the ultimate strength of the R/C cooling towers, which have initial imperfection and pre-cracked elements, is analyzed. The initial geometric imperfections arise from the unavoidable inaccuracies under the construction and the pre-cracks are assumed to be produced by the temperature stress gradients or cyclic loading under wind pressure and/or earthquake load. Both effects are strongly influenced on the strength of the R/C cooling tower shell structures. The reinforcing ratio is also the important factor to evaluate the ultimate strength of the R/C cooling tower shells. However we could not analyze these structures experimentally because of their large, analyses are the powerful schemes to evaluate the safety and reliability of these structures. The analyzed model is Port Gibson cooling tower shell. In the numerical analysis the geometric and material nonlinearities are taken into account.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1277-1282
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• 2009

The main objective of this prototype is to control resonance frequency of DTL system through the temperature control of cooling water. It is to resonant frequency of the drift tube cavities to 350 MHz. This paper describes the design of a prototype cooling water skid required for the temperature control of the DTL cavities, focusing in the modeling and simulation of the cooling system, the sizing of water pumping skid component.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.411-415
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• 2008

This paper presents on design factor considered in an altitude test cell facility to determine the best sizing to optimize exhaust diffuser pressure recovery and the exact cooling load required to be supplied under transient operation. Engine simulation was performed to analyse the exhaust gas temperature, exit mass flow rate, specific fuel consumption and exhaust velocity helpful in determining secondary mass air flow and the mixed air temperature entering the ejector. based on this, the amount of cooling load was deduced. It was found that improved pressure recovery reduces operational cost(air supply facility, cooling water).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.15-20
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• 2017

The summer climate is very hot and humid in Korea. The humidity is an important factor in determining thermal comfort. Recently, the research for dehumidification device development has been attempted to save energy that is required for the operation of the current dehumidifiers on the market. Existing dehumidification systems have disadvantages such as wasting energy to drive a compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature so it doesn't have to consume cooling energy. In this paper, the cooling energy savings was studied when a dehumidification system was applied in a model building instead of a chiller. The sensible heat load was almost the same result, but the latent heat load was decreased by 38.9% and the total heat load was decreased by 8.5%. As a result, electric energy used to drive the compressor in a chiller was saved by applying a membrane air-conditioning system instead.

• Wind and Structures
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• v.28 no.4
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• pp.215-224
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• 2019

Because of the particularity and complexity of direct air-cooling structures (ACS), wind parameters given in the general load codes are not suitable for the wind-resistant design. In order to investigate the wind loads of ACS, two 1/150 scaled three-span models were designed and fabricated, corresponding to a rigid model and an aero-elastic model, and wind tunnel tests were then carried out. The model used for testing the wind pressure distribution of the ACS was defined as the rigid model in this paper, and the stiffness of which was higher than that of the aero-elastic model. By testing the rigid model, the wind pressure distribution of the ACS model was studied, the shape coefficients of "A" shaped frame and windbreak walls, and the gust factor of the windbreak walls were determined. Through testing the aero-elastic model, the wind-induced dynamic responses of the ACS model was studied, and the wind vibration coefficients of ACS were determined based on the experimental displacement responses. The factors including wind direction angle and rotation of fan were taken into account in this test. The results indicated that the influence of running fans could be ignored in the structural design of ACS, and the wind direction angle had a certain effect on the parameters. Moreover, the shielding effect of windbreak walls induced that wind loads of the "A" shaped frame were all suction. Subsequently, based on the design formula of wind loads in accordance with the Chinese load code, the corresponding parameters were presented as a reference for wind-resistant design and wind load calculation of air-cooling structures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.159-166
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• 2018

The Korean fenestration energy consumption efficiency rating system only considers thermal performance of the heat transfer coefficient (U-value) and airtightness excluding optical characteristics of the solar heat gain coefficient (SHGC). This study analyzed annual heating and cooling energy requirements on the middle floor of apartment by optical and thermal performance of windows to evaluate the suitability of the rating system. One hundred and twenty-eight windows were analyzed using THERM and WINDOW 7.4, and energy simulation for a reference model of an apartment house facing south was performed using TRNSYS 17. The results showed that window performance was the main factor in the heating and cooling load. The heating load of the reference model was 539 kWh to 2,022 kW, and the cooling load was 376 kWh to 1,443 kWh. The coefficient of determination ($R^2$) of the heating and cooling loads driven from the SHGC were 0.7437 and 0.9869, which are more compatible than those from the U-value, 0.0558 and 0.4781. Therefore, it is not reasonable to evaluate the energy performance of windows using only the U-value, and the Korean fenestration energy consumption efficiency rating system requires a new evaluation standard, including SHGC.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.1
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• pp.7-16
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• 2016

This paper presents the measurement and analysis results for the cooling performance of ground-coupled heat pump (GCHP) system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from May 1 to October 30, 2014. The results showed that the entering source temperature of brine returning from the ground heat exchanger was in a range of design target temperature. Leaving load temperatures to building showed an average value of $11.4^{\circ}C$ for cooling season. From the analysis, the daily performance factor (PF) of geothermal heat pumps ranged from 4.4 to 5.2, while the daily PF of hybrid GCHP system varied from 3.0 to 4.0 over the entire cooling season.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.9
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• pp.496-504
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• 2009

In order to investigate the feasibility of a direct ice slurry transporting system for the purpose of district cooling, a case study of field application is performed. The research aims include the field measurement of ice packing factor, the performance of coldness delivery, and the branching characteristics of ice slurry. Two representative types of pipe branch are dealt with in this work. For the slurry flow with ice volume fraction of 0.16 or less, the pipe blocking due to aggregation is not observed. Based on the time-wise variation of temperature in the storage tank, a calculating method of ice packing factor is newly developed, which seems to be useful when the brine concentration is unknown. It is confirmed that the mass flow rate of ice slurry per unit cooling load is markedly reduced with increasing the ice content. The pumping power also decreases, but remains unchanged for high ice fractions. The distribution of ice particle before and after branching shows a good uniformity within the range of 5% difference, but yields a unique trend depending on the flow rate.

• KIEAE Journal
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• v.11 no.4
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• pp.71-78
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• 2011

The goal of this study is to analyze the impact of load factors on building energy consumption by using EnergyPlus program. We selected a campus building and monitored energy consumption from January 2009 to November 2010. First, we simulated energy consumption basically with weather data, building heat gain and EHP performance data. And then we simulated energy consumption with three additional parameter(infiltration, OA control and schedule). Simulation results are verified by MBE and Cv(RMSE) proposed by M&V guideline 3.0. Simulated total energy consumption was 104.3% of measurements, 4.33% of MBE, and 13.62% of Cv(RMSE). Results show infiltration and schedule were revealed as the most dominant factor of heating energy consumption and of cooling energy consumption, respectively.