• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.277-284
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• 2018

For the main variables to be selected by the designer for the heating and cooling load calculation in greenhouses, in order to evaluate the effect of these design values on the heating and cooling load, the simulations were carried out by varying the respective design values. Based on these results, we proposed the design values which should pay special attention to selection. The design values which have the greatest effect on the heating load were the overall heat transfer coefficient of the covering material and the design outdoor temperature was next. The effect of the design values according to the number of spans showed little difference. In the case of the single-span greenhouse, the effect of the design values related to the underground heat transfer can not be ignored. However, in the case of the multi-span greenhouse, the effect of the design values related to the underground heat transfer and the infiltration rate were insignificant. The design values which have the greatest effect on the cooling load were the solar radiation into the greenhouse and the evapotranspiration coefficient, followed by the indoor and outdoor temperature difference and the ventilation rate. The effect of the design values showed a great difference between the single-span greenhouse and the multi-span greenhouse, but there was almost no difference according to the number of spans. The effect of the overall heat transfer coefficient of the covering material was negligible in both the single-span greenhouse and the multi-span greenhouse. However, the effect of the indoor and outdoor temperature difference and the ventilation rate on the cooling load was not negligible. Especially, it is considered that the effect is larger in multi-span greenhouse.

• Journal of the Korean Solar Energy Society
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• v.29 no.4
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• pp.48-57
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• 2009

Energy demands for hotels in Korea are surveyed and statistically analyzed to develop calculation models for a simulation. Daily energy loads of 16 hotels located in Seoul, Busan, Daegu, Inchon, and Daejon are analyzed based on energy log sheets. Detailed hourly loads are field measured for 3 hotels that are carefully selected among the surveyed. One of the salient features for energy consumption by hotels is their weekly periodicity. Relatively large values of deviations are observed for both heat and electricity loads through the country. The mains factors are: location, hotel grade (luxuriousness) and insulation. Detailed quantitative information such are annual average, daily variation, and hourly patterns are provided.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.1
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• pp.1-13
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• 2022

In Korea, attention is being paid to the use of renewable energy in the livestock industry, and Ground Source Heat Pump (GSHP), which is advantageous for temperature control, is considered as one of the ways to reduce the use of fossil fuels. But GSHP is expensive to install, which proper capacity calculation is required. GSHP capacity is related to its maximum energy load. Energy loads are affected by climate characteristics and time, so dynamic analysis is required. In this study, the optimal capacity of GSHP was calculated by calculating the heating and cooling load of pig farms using BES (Building Energy Simulation) and economic analysis was performed. After designing the inside of the pig house using TRNSYS, one of the commercial programs of the BES technique, the energy load was calculated based on meteorological data. Through the calculated energy load, three heating devices and GSHP used in pig farms were analyzed for economic feasibility. As a result, GSHP's total cost of ownership was the cheapest, but the installation cost was the highest. In order to reduce the initial cost of GSHP, the capacity of GSHP was divided, and a scenario was created in which some of it was used as an auxiliary heating device, and economic analysis was conducted. In this study, a method to calculate the proper capacity of GSHP through dynamic energy analysis was proposed, and it can be used as data necessary to expand the spread of GSHP.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.302-310
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• 2011

A fluid in an enclosure can be heated by electric heating, chemical reaction, or fission heat. In order to remove the volumetric heat of the fluid, the walls surrounding the enclosure must be cooled. In this case, a natural convection occurs in the pool of the fluid, and it has a dominant role in heat transfer to the surrounding walls. It can augment the heat transfer rates tens to hundreds times larger than conductive heat transfer. The heat transfer by a natural convection in a regular shape such as a square cavity or semi-circular pool has been studied experimentally and numerically for many years. A pool of an inverted triangular shape with 10 degree inclined bottom walls has a good cooling performance because of enhanced boiling critical heat flux (CHF) compared to horizontal downward surface. The coolability of the pool is determined by comparing the thermal load from the pool and the maximum heat flux removable by cooling mechanism such as radiative or boiling heat transfer on the pool boundaries. In order to evaluate the pool coolability, it is important to correctly expect the thermal load by a natural convection heat transfer of the pool. In this study, turbulence models with modifications for buoyancy effect were validated for unsteady natural convections by volumetric heating. And natural convection in the triangular pool was evaluated by using the models.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1386-1391
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• 2008

As the time goes by, the energy use in buildings are increasing threateningly. So, it is important to have an accurate energy load calculation for buildings. The accurate energy simulation program carries numerous input data. So, our purpose of this study is to verify the application of simplify modeling method which eliminates coordinates of building components instead of using full coordinates by using DOE2. After comparing original modeling method with simplify modeling method, we applied PAF for daylighting control in the building to verify the application of daylighting control in simplify modeling method. The results shows that there are little difference between original modeling and simplify modeling. Also it showed that application of daylighting control has little difference between original modeling so it is feasible to adapt simplify modeling. These results reveals that the application of simplify modeling is possible to predict energy load and use of the building.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.184-189
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• 2008

These days, Apartment is altered oversized and high-rise through construction techniques development. Also, the cost of cooling and heating load would be expected by balcony expansion into inner space caused by legalization. In specially, HVAC systems of high-rise residential building almost apply to pre-existence techniques of middle and low residential building except for consideration and methods of the air inflow minimization into indoor through mechanical ventilation is used in ventilation system. From these cause, window systems of high-rise apartments stands high in estimation of components. Thus, purpose of this study is to make a comparative study through difference of window systems.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.549-552
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• 2012

Recently the world is trying to reduce carbon emissions for global warming. Reducing use of fossil fuels can decrease carbon emission. In this reason the construction field has tried to reduce the use of fossil fuels relating to heating and cooling of buildings. An energy loss through the window system is about 10 to 30 percent of energy consumption of the whole building. The use of window film insulation is increasing to control the heat loss at the windows. The window film insulation absorbs solar radiation and makes the surface temperature of windows high. In this study, window surface temperature is measured, and an impact on indoor air is identified after attaching window film insulation. Finally, we found that cooling load decreases through simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1262-1272
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• 1997

An experimental study on the frequency control of an inverter heat pump to get the desired indoor room temperature has been conducted for the performance characteristics during the steady, 4, 8, and 16 step frequency operations. The heat pump model used in this study was operated to meet the experimental conditions of ASHRAE standard. The performance of the system was tested by measuring the temperature and pressure of the refrigerant, and cooling capacity, power consumption, etc. of the system. As the controlling frequency steps increased, the running time of the compressor increased as well as the electric consumption of the system and the cooling energy due to the wall heating load. However, the average cooling COP was improved.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.14 no.1
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• pp.1-11
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• 1985

Solar/absorption cooling system was analyzed and its operating condition was examined. For the system, the optimum size of absorption refrigerator and collector area should be determined. As the temperature of water supplied to the generator increases, the collector efficiency decreases whereas the coefficient of performance of absorption refrigerator increases up to a certain point, and vice versa for decreasing of the temperature of water supplied to the generator . Thus if the reeling load is given, the appropriate operating condition can be determined between the two opposing trends by simulation program. As an example of the simulation, the case of Jejudo province was studied. Under the conditions (such as weather data and prices of components, etc.) given en the sample calculation, the result shows that the optimum temperature of water supplied to the generator turned out to be $80.3^{\circ}C$, and still shows a large economical disadvantage in present stage compared to the case of conventional vapor compression cooling/heating combined heat pump system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.645-650
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• 2006

The heat transfer performance and energy transport ability are relatively high due to higher specific heat. Therefore, it can be used in fields such as heating, ventilating, air-conditioning, refrigeration and heat exchangers. In this study, liquid-cooling heat exchangers were designed and tested by varying geometry and operating conditions. In addition, liquid-cooling heat exchangers were tested to provide performance data for MPCM slurry. The liquid-cooling heat exchangers had twelve rectangular channels with flow paths of 1, 2, 4 and 12. Silicon rubber heaters were used to control the heat load to the heat exchanger. Heat input ranged from 293 to 800 W, and inlet temperatures of working fluid varied from 15S to $27^{\circ}C$. The standard deviation of surface temperature was strongly affected by the coolant of MPCM Slurry, All MPCM-cooling heat exchangers showed higher cooling performance than the water-cooling heat exchanger except one path channel heat exchanger.