• Solar Energy
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• v.18 no.1
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• pp.57-67
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• 1998

A study on a buoyancy effect by the temperature difference between a inner room air and a inflowing cool air and also by Inlet velocity can contribute greatly to enhance performance of air conditioning system, so the study on the distribution characteristics of inflowed cool air is important to analyze the cool air storage in a room. For this study, in the real-sized model room, the temperature differences between inflowing cool air and inner room air are 10, 20, $30^{\circ}C$, and the inlet velocities of inflowing cool air are 1, 2, 3m/s respectively as dynamic parameters. Also, a anemos and a vane type diffuser are used as inlet geometric conditions. Following conclusions have been obtained through this study. 1) In case of the anemos type diffuser, it is found that a dimensionless temperature profile is low and the distribution of the inflowed cool air is uniform. and also, all diffuusers have a low temperature of the inner room as increasing the inlet velocity. 2) A mixing takes place rapidly in case of the anemos type diffuser when the temperature difference is low ${\Delta}T=10^{\circ}C$ and the inletvelocity is high V=3m/s. and the mixing degree is higher with the anemos type diffuser than the vane.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.2
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• pp.85-91
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• 2016

The Positive Temperature Coefficient (PTC) is used for cabin air heating of a battery electric vehicle, which is different from conventional vehicles. Since the PTC heater consumes a large quantity of power in a parasitic manner, many valuable studies have been reported in the field of alternative heat pumps. In this study, a model for an R134a heat pump taking into account the thermal environment of the cabin was developed for a MATLAB/SIMULINK(R) platform. Component and cabin models are validated with reference values. Results show that the heat pump is more competitive for parasitic power consumption over all ambient temperature conditions. Additionally, the method of waste heat recovery to overcome disadvantages when temperatures are below zero is applied to efficiently operate the heat pump.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.437-444
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• 2012

This paper describes the experimental characteristics on cooling and heating performance of the coil deposition type heat pump using geothermal energy to optimize the design for the operating parameters of this system. The operating parameters considered in this study include subcooling degree, evaporation and condensation temperature in the coil deposition type heat pump using geothermal energy. The main results are summarized as follows : As the evaporation temperature and subcooling degree of the coil deposition type heat pump using geothermal energy increases, and the condensation temperature decreases, the COP of this system increases. The subcooling degree, evaporation and condensation temperature of the coil deposition type heat pump have an effect on cooling and heating COP of this heat pump. Therefore, it is a necessary to determine the optimum operation conditions for the highest COP of this heat pump presented in this study.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.301-305
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• 2006

An electrical bill is one of the various factors that influence on energy use of residents. This study focused on electrical bills and searched that whether electrical bills affect resident behavior of operating air conditioner and their controlled indoor climate. We surveyed two groups for field study ; the one is residents who live in a studio apartment in Seoul and they are charged for electric as energy consumption they used, and the other is residents who live in a university dormitory and they are not charged for their energy consumption. We measured how long they used the air conditioner for cooling, on/off temperature of air conditioner and room temperature for these two groups. Residents were interviewed about their cooling needs, decisions about when to turn on their air conditioner and so on. We found that dormitory group has much amount of time used the air conditioner than studio apartment group and there are differences of room temperature between two groups when they turn on or off air conditioner. The result shows that perception of money affects resident behavior of operating air conditioner and their acceptable thermal range.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.3
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• pp.297-304
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• 2014

The purpose of this study is to evaluate the experimental performance characteristics of a water-to-water geothermal heat pump featuring a vapor refrigerant injection for the production of hot water. The performance of geothermal heat pump with a vapor injection was evaluated by comparing with that of a conventional geothermal heat pump without a vapor injection. For heating operation, the geothermal heat pump with a vapor injection is superior in COP and heating capacity. The vapor injection was more effective for supplying hot water while overloading. The vapor injection was effective for the improvement of the cooling capacity. However, the vapor injection was not effective for the increasing of COP according to the increased input of a compressor. The advantage of vapor injection in water-to-water geothermal heat pump become disappeared while cooling operation with lower part loading.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.11
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• pp.72-77
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• 2010

The fatigue characteristic of a material or a structure is derived from fatigue tests of standard specimens. However, many test results of standard specimens are very different from those of real structures. One reason for this difference is the constraint effects according to the geometrical difference. Therefore, to calculate more accurate fatigue life, the constraint effect must be considered by comparing test results of standard specimens with those of real structures. In this study, a blade of an air-conditioner was evaluated by both the test and the analysis. The results showed that a standard specimen is conservative, compared with a structure specimen. And fatigue life of an air-conditioner's blade was predicted from those.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.223-230
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• 1998

Energy consumption statistics have been surveyed for 50 large commercial buildings with high energy consumption records in Seoul City. The buildings were classified into three different groups for data analysis: hospitals, hotels, and department stores/office buildings. The analysis was focused on identifying installed boiler and refrigerator data, energy consumption rates, and energy load distribution throughout the year. Refrigerating electricity was confirmed again to affect most on the formation of the summer electricity load peak as expected. Replacing the refrigerator electricity peak in the summer with co-generation in large commercial buildings. However, overall heat load distribution in a single building is still considered not large enough for economically feasible co-generation and thus joint co-generation for multiple neighboring buildings are preferred and the Electric Power Law and LNG pricing policy should be revised favorably for co-generation in advance.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1857-1862
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• 2003

The air-side particulate fouling in the heat exchangers of HVAC applications degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. Indoor and outdoor air contaminants foul heat exchangers. The purpose of this study is to investigate the fouling characteristics trough accelerated tests. The fouling characteristics are analyzed as functions of a dust concentration (1.28 and 3.84 $g/m^3$), a face velocity (0.5, 1.0, and 1.5 m/s), and a surface condition. The cooling capacity in the slitted finned-tube heat exchangers at the face velocity of 1 m/s decreases about 2% and the pressure drop increases up to 57%. The rate of build-up of fouling is observed to be 3 times slower for this three-fold reduction of dust concentration whilst still approaching the same asymptotic level.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.337-344
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• 2012

Today, the number of super tall buildings are under construction or being planed in Middle East and Asian Countries. For example the burj Khalifa, the tallest building in the world, is completed in 2008 and the height of that is about 800m. Also, Lotte World Tower is under construction in Korea. External environmental conditions such as wind speed, air temperature, humidity and solar radiation around the super tall building differs according to the building height due to the vertical micro climate change. However, the meteorological information used for AC design of building is obtained typically from standard surface meterological station data(~2m above the ground). In this paper the effect of the building envelope on heating and cooling load in super tall building considering the meteorological changes with height was analyzed with simulation method. As results of this research, the guideline to select the building envelop alternatives for super tall building will be suggested in this paper.