• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.123-132
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• 2016

The importance of energy saving technology for managing greenhouse was recently highlighted. For practical use of energy in greenhouse, it is necessary to simulate energy flow precisely and estimate heating/cooling loads of greenhouse. So the main purpose of this study was to develope and to validate greenhouse energy model and to estimate annual/maximum energy loads using Building Energy Simulation (BES). Field experiments were carried out in a multi-span plastic-film greenhouse in Jeju Island ($33.2^{\circ}N$, $126.3^{\circ}E$) for 2 months. To develop energy model of the greenhouse, a set of sensors was used to measure the greenhouse microclimate such as air temperature, humidity, leaf temperature, solar radiation, carbon dioxide concentration and so on. Moreover, characteristic length of plant leaf, leaf area index and diffuse non-interceptance were utilized to calculate sensible and latent heat exchange of plant. The internal temperature of greenhouse was compared to validate the greenhouse energy model. Developed model provided a good estimation for the internal temperature throughout the experiments period (coefficients of determination > 0.85, index of agreement > 0.92). After the model validation, we used last 10 years weather data to calculate energy loads of greenhouse according to growth stage of greenhouse crop. The tendency of heating/cooling loads change was depends on external weather condition and optimal temperature for growing crops at each stage. In addition, maximum heating/cooling loads of reference greenhouse were estimated to 644,014 and $756,456kJ{\cdot}hr^{-1}$, respectively.

• Advances in Energy Research
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• v.5 no.4
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• pp.277-287
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• 2017

This study examines the risk of overheating of a school building, under extreme hot weather conditions, in 14 locations in the United Kingdom using the overheating criteria defined in Building Bulletin 101 (BB101). The building was modelled as naturally ventilated, mechanically ventilated and in mixed mode and was simulated both for the current and the projected weather conditions of the 2050s. Under the current weather conditions, results of the simulations show that when naturally ventilated, the school building fulfils the BB101 criteria only in the areas of Edinburgh and Glasgow. In the simulations of the building as mechanically ventilated and in mixed mode, mechanical cooling was provided in order for the building to comply with the overheating criteria. A comparison of the required cooling loads between the two scenarios shows that application of mixed mode ventilation results in less cooling loads.

• Wind and Structures
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• v.28 no.5
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• pp.299-313
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• 2019

In order to examine the effects of different wind deflectors on the wind load distribution characteristics of extra-large cooling towers, a comparative study of the distribution characteristics of wind pressures on the surface of three large cooling towers with typical wind deflectors and one tower without wind deflector was conducted using wind tunnel tests. These characteristics include aerodynamic parameters such as mean wind pressures, fluctuating wind pressures, peak factors, correlation coefficients, extreme wind pressures, drag coefficients and vorticity distribution. Then distribution regularities of different wind deflectors on global and local wind pressure of extra-large cooling towers was extracted, and finally the fitting formula of extreme wind pressure of the cooling towers with different wind deflectors was provided. The results showed that the large eddy simulation (LES) method used in this article could be used to accurately simulate wind loads of such extra-large cooling towers. The three typical wind deflectors could effectively reduce the average wind pressure of the negative pressure extreme regions in the central part of the tower, and were also effective in reducing the root of the variance of the fluctuating wind pressure in the upper-middle part of the windward side of the tower, with the curved air deflector showing particularly. All the different wind deflectors effectively reduced the wind pressure extremes of the middle and lower regions of the windward side of the tower and of the negative pressure extremes region, with the best effect occurring in the curved wind deflector. After the wind deflectors were installed the drag coefficient values of each layer of the middle and lower parts of the tower were significantly higher than that without wind deflector, but the effect on the drag coefficients of layers above the throat was weak. The peak factors for the windward side, the side and leeward side of the extra-large cooling towers with different wind deflectors were set as 3.29, 3.41 and 3.50, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.10
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• pp.1046-1052
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• 2007

Elastic-plastic structural analysis for regenerative cooling chamber of gas generator was performed. Uniaxial tension test was conducted for STS316L at room and high temperature conditions to get the material data necessary for the structural analysis of the chamber which was operated under thermal load and high internal pressure. Physical properties including thermal conductivity, specific heat and thermal expansion were also measured. The structural analysis for four different types of regenerative cooling chamber of gas generator revealed that increased cooling performance decreased the thermal load and strain of the cooling channel structure. The results propose that in order for the regenerative cooling gas generator chamber to have high structural stability with endurance to high mechanical and thermal loads, it is important for the chamber to be designed to have high cooling performance.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.802-807
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• 2007

Elastic-plastic structural analysis for regenerative cooling chamber of gas generator was performed. Uniaxial tension test was also conducted for STS316L at room and high temperature conditions to get the material data necessary for the structural analysis of the chamber which is operated under thermal load and high internal pressure. Physical properties including thermal conductivity, specific heat and thermal expansion data were also measured. The structural analysis for four different types of regenerative cooling chamber of gas generator revealed that increased cooling performance decreases the thermal load and strain of the cooling channel. The results propose that in order for the regenerative cooling gas generator chamber to have high structural stability with endurance to high mechanical and thermal loads, it is important for the chamber to be designed to have high cooling performance.

• Journal of the Korea Institute of Building Construction
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• v.10 no.2
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• pp.97-104
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• 2010

This study evaluated the energy efficiency of a windows system using built-in blinds, with regard to their insulation performance and their blocking of solar radiation. The study took advantage of the "Physibel Voltra" program as a physical simulation of heat transfer. To simulate the "Physibel Voltra" program, I practiced a mock-up test to determine heating quality and translation condition. I analyzed the propensity to annual energy consumption, the annual quantity of heat transfer, and the annual cooling and heating cost through a computer simulation for one general household in an apartment building. In the test, it was found that compared to a general windows system, a windows system with built-in blinds reduced the annual heat transfer by 10% in cooling states and by 11% in heating states when the blind was up. When the blind was down, the windows system with built-in blinds reduced the annual heat transfer by 25% in cooling states and 30% in heating states. When a windows system with built-in blinds is compared with a general windows system, the quantity of cooling and heating loads is reduced by 283.3kw in cooling states and 76.3kw in heating states. This leads to a reduction in the required cooling and heating energy of 359.6kw per house. It is thus judged that the use of a windows system with built-in blinds is advantageous in terms of reducing greenhouse gas emissions, because the annual TOE (tons of oil equivalent) per house is reduced by 0.078TOE, while $tCO_2$ is reduced by $0.16tCO_2$. In addition, compared with a general windows system, the cost of cooling and heating loads in the system reduces the annual cooling cost by 100,000won, and the annual heating cost by 50,000won. Ultimately, this means that cooling and heating loads are cut by 150,000won per year.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.202-207
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• 2008

Measures for coping with energy shortage are being sought all over the world. Following such a phenomenon, effort to use less energy in the design of buildings and equipment are being conducted. In particular, a program to evaluate the performance of a building comes into the spotlight. However. indispensable standard wether data to estimate the exact energy consumption of a building is currently unprepared. Thus, after appling standard weather data for four weather factors which were used in previous researches to Visual DOE 4.0, we compared it with the result of the existing data and evaluated them. For the monthly cooling and heating load of our target building, we used revised data for June, July, August, and September during which cooling load is applied. When not the existing data but the revised data was used, the research shows that an average of 14.9% increased in June, August, and September except for July. Also, in a case of heating load, the result by the revised data shows a reduction of an average of 11.9% from October to April during which heating load is applied. In particular, the heating loads of all months for which the revised data was used were more low than those of the existing data. In the maximum cooling and heating load according to load factors, the loads by residents and illumination for which the revised data was used were the same as those of the existing data, but the maximum cooling loads used by the two data have a difference in structures such as walls and roofs. Through the above results, the research cannot clearly grasp which weather data influences the cooling and heating load of a building. However, in the maximum loads by the change of weather data in four factors (dry-bulb temperature, web-bulb temperature, cloud amount, and wind speed) among 14 weather factors, the research shows that 5.95% in cooling load and 27.56% in heating load increased, and these results cannot be ignored. In order to make weather data for Performing energy performance evaluation for future buildings, the flow of weather data for the Present and past should be obviously grasped.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.91-101
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• 2007

The purpose of this study is to provide fundamental cooling design data for the large public enclosures as gymnasium. This study executed indoor thermal environment verification of the existing gymnasium by measuring temperature distribution with and without cooling the space in summer. Colling loads from human body was not considered. We examined various indoor thermal environment factors of the large enclosed space in this study which include vertical and horizontal temperature distribution, supply and return air flow feature, thermal comfort environment feature, amount of ventilation and etc.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.81-87
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• 2014

According to the domestic construction business will continue stagnant, many domestic construction companies are expanding their business into foreign countries. As results, building design guidelines including HVAC design for foreign countries considering the regional climate conditions are needed. Also, green building design strategies to minimize the heating and cooling load are key issue to win a contract in construction business in the world. In this study, peak heating and cooling loads were calculated for the representative cities in the world : Seoul, St. Petersburg, Singapore and Mecca. The analyzed building was a typical high-rise office building and the building envelope properties, indoor heat gain, residence and operating schedules were same in all cases. Only the weather conditions were different by cases.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.30-33
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• 2006

Several crucial issues are discussed in the design of cryogenic cooling system for high field magnets. This study is mainly motivated by our ongoing program to develop a 21 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The magnets of this system will be built horizontally to accomplish the requirement of user friendliness and reliability, and the replenishment of cryogen will not be necessary by a closed-loop cooling concept. The initial cool-down and safety are basically considered in this paper. The effects of the helium II volume and the gap distance of the weight load relief valve (or safety valve) on the cool-down time and temperature rising during an off-normal state are discussed. The total amount of cryogenic cooling loads and the required helium flow rate during cool-down are also estimated by a relevant heat transfer analysis. The temperatures of cryogen-free radiation shield are finally determined from the refrigeration power of a cryocooler and the total cryogenic loads.