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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Solar Energy Society
Journal Basic Information
Journal DOI :
The Korean Solar Energy Society
Editor in Chief :
Volume & Issues
Volume 29, Issue 6 - Dec 2009
Volume 29, Issue 5 - Oct 2009
Volume 29, Issue 4 - Aug 2009
Volume 29, Issue 3 - Jun 2009
Volume 29, Issue 2 - Apr 2009
Volume 29, Issue 1 - Feb 2009
Selecting the target year
Building Energy Demand Models for Offices in Korea
Park, Hwa-Choon ; Chung, Mo ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 1~7
Energy demands for offices in Korea are surveyed and analyzed to generate communicational models for simulations. Daily energy loads of 13 office buildings scattered in the 6 largest cities in the country are surveyed and analyzed based on energy consumption log sheets. Detailed hourly loads that are frequently required when a detailed operation simulation is performed are measured using remote data acquisition processes for 3 offices. The complete load demand models of electricity, cooling, heating and hot water are established by combining the daily and hourly patterns based on the statistical behavior of the hourly patterns.
The Energy Performance & Economy Efficiency Evaluation of Micro Gas Turbine Installed in Hospital
Kim, Byoung-Soo ; Hong, Won-Pyo ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 8~13
Feasibilities of the application of a micro gas turbine cogeneration system to a large size hospital building are studied by estimating energy demands and supplies. The energy demand for electricity is estimated by surveying and sorting the consumption records for various equipment and devices. The cooling heating, and hot water demands are further refined with TRNSYS and ESP-r to generate load profiles for the subsequent operation simulations. The operation of the suggested cogeneration system in conjunction with the load data is simulated for a time span of a year to predict energy consumption and gain profile. The simulation revealed that the thermal efficiency of the gas turbine is about 30% and it supplies 60% of the electricity required by the building. The recovered heat can meet 56% of total heating load and 67% of cooling, and the combined efficiency reaches up to 70%.
The long-term operating evaluation of the grid connected photovoltaic system
Kim, Eui-Hwan ; Ahn, Kyo-Sang ; Lim, Hee-Chun ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 14~19
The 50 kWp grid connected photovoltaic system which was installed at KEPRI site in 1999 has been operated more than 10 years. In order to acquire long term operation characteristics of medium size photovoltaic system, the operation test data related on power generation electricity and capacity factor of 50 kWp system, which have been collected since 1999, were analysed. From the analysing results, 57.7 MWh in annual power generation electricity of 50 kWp photovoltaic system in 1999 has been decreased 49.1 MWh in 2005 and reached 41.9 MWh in 2008. In addition to, the capacity factor of 50 kWp photovoltaic system also showed 13.2 % in 1999, 11.2% in 2005 and finally reached 9.6% in 2008. The operation test data showed a trend of decreasing of generation electricity and capacity factor during the 10 years operation time and we guessed that was caused by solar cell performance degradation and decreasing of PCS system efficiency.
A Study of the Effect of Borehole Thermal Resistance on the Borehole Length
Lee, Se-Kyoun ; Woo, Joung-Son ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 20~27
The effect of borehole thermal resistance on the borehole length is studied. In performing this work a new concept BLRR(borehole length reduction rate) is developed based on the line source model. The solution of line source model is shown to be valid through the comparison with the data of thermal response test. It is shown that BLRR is a function of soil thermal conductivity(k) and borehole thermal resistance(
). The value of BLRR increases with increasing k, which means reducing
is more effective when k is high. The reduction of borehole length with change of
is easily estimated with BLRR. The validity of BLRR is also examined with EED analysis.
A Study on the Improvement of Thermal Environment by a method using thermometers and computer simulations on the Atrium
Lee, So-Yeun ; An, Jung-Soo ; Kim, Kang-Soo ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 28~34
The atrium in the building has many advantages including its aesthetic and functional effect. But the upper part of the atrium has the thermal problem of overheating due to insolation through the window. But natural ventilation aided buoyancy effect can be a solution to make comfortable indoor environment. Proper design of openings is very important to improve thermal environment in the atrium. In this study, thermal evaluations were performed to improve thermal environment in the atrium. Indoor thermal environment of an atrium at Seoul was measured in the field and simulated with Computational Fluid Dynamics( CFD) code. The turbulent flow model adopted is
model. The results of computer simulations are compared with the measurements at the point in the atrium. In order to improve the indoor ventilation environment of the atrium, thermal environment evaluations of six alternatives were conducted. After evaluations of the results, the design guidelines of an atrium are suggested.
Boiling Heat Transfer Coefficients of Nanofluids Using Carbon Nanotubes
Lee, Yo-Han ; Jung, Dong-Soo ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 35~44
In this study, boiling heat transfer coefficients(HTCs) and critical heat flux(CHF) are measured on a smooth square flat copper heater in a pool of pure water with and without carbon nano tubes(CNTs) dispersed at
. Tested aqueous nanofluids are prepared using multi-walled CNTs whose volume concentrations are 0.0001, 0.001, 0.01, and 0.05%. For dispersion of CNTs, polyvinyl pyrrolidone(PVP) is used in distilled water. Pool boiling HTCs are taken from
to critical heat flux for all nanofluids. Test results show that the pool boiling HTCs of the nanofluids are lower than those of pure water in entire nucleate boiling regime. On the other hand, critical heat flux is enhanced greatly showing up to 200% increase at volume concentration of 0.001% CNTs as compared to that of pure water. This is related to the change of surface characteristics by the deposition of CNTs. This deposition makes a thin CNT layer on the surface and the active nucleation sites of heat transfer surface are decreased due to this layer. The thin layer acts as the thermal resistance and also decreases the bubble generation rate resulting in a decrease in pool boiling HTCs. The same layer, however, maintains the nucleate boiling even at very high heat fluxes and reduces the formation of large vapor canopy at near CHF resulting in a significant increase in CHF.
The Study of Optimized Combustion Tuning Method for Fossil Power Plant
Jung, Jae-Jin ; Song, Jung-Il ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 45~52
Fossil power plants firing lower grade coals or equipped with modified system for
controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases'
and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective rear pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess
and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing
emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.
A Study on the Analysis of Building Energy Rating considering the Region
Ahn, Byung-Lip ; Kim, Chi-Hoon ; Kim, Ji-Yeon ; Jang, Cheol-Yong ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 53~58
Entering in the time of high oil price, seriousness of an energy effect sector has given a huge impact and the importance of energy is growing. Especially, building energy occupying 24% of total demand of energy can be expected to reduce energy demand more than other section. To do this, the Building Energy Rating System is applied and implemented in Apartment houses on Jeju, South and Central region. This system calculates into energy saving rate, and certifies the building energy rating. This study evaluates the energy saving rate and rating and compares the difference in energy savings considering to each region and the thermal performance of the window. In result, the standard of the assessment house which is applied to the build energy rating system is demanded to distinguish the thermal performance of window according to regional variation.
A Study on the Evaluation of Building Energy Rating considering the Insulation Performance of the Building Envelope
Kim, Chi-Hoon ; Ahn, Byung-Lip ; Kim, Ji-Yeon ; Jang, Cheol-Yong ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 59~64
According to the building regulation U-value limitation of window is
in southern regions, while U-value limitation of wall is
. It means that the energy loss through windows is five times more than it through wall. Therefore, this study analyze how much it has affected building energy rating when the insulation performance of windows and walls is changed by building regulation. In conclusion, in order to obtain 2 rating thermal performance of windows is improved more than 10 percent of U-value limitation and it of wall is improved more than 20 percent. The thermal performance of windows is improved more than 20 percent of U-value limitation and it of wall is improved more than 30 percent to receive 1 rating.
High Speed Grid Voltage Detection Method for 3 Phase Grid-Connected Inverter during Grid Faults
Choi, Hyeong-Jin ; Song, Seung-Ho ; Jeong, Seung-Gi ; Choi, Ju-Yeop ; Choy, Ick ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 65~72
The new method is proposed to improve high speed detection of grid voltage phase and magnitude during a voltage dip due to a grid faults. Usually, A LPF(Low Pass Filter) is used in the feedback loop of PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. so, a new design method of the loop gain of the PI -type controller in the PLL system is proposed with the consideration of the dynamics of the LPF. As a result, a better transient response can be obtained with the proposed design method. The LPF frequency and PI controller gain are designed in coordination according to the steady state and dynamic performance requirement. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the lab-scale experiments.
Hydrodynamically Optimal Blade Design for 500kW Class Horizontal Axis Tidal Current Turbine
Ryu, Ki-Wahn ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 73~80
A tidal current turbine is designed and analyzed numerically by using blade element momentum theory. The rated power has a limitation because the diameter of the tidal current turbine cannot exceed the depth of sea water. This study investigates a horizontal axis tidal-current turbine with a rated power of 500 kW. NACA-6 series laminar foil shape is used for basic airfoil along the blade span. The distributions of chord length and twist angle along the blade span are obtained from the hydrodynamic optimization procedure. Prandtl's tip loss correction and angle of attack correction considering the three-dimensional effect are applied for this study. The power coefficient curve shows maximum peak at the rated tip speed ratio of 6.0, and the maximum torque coefficient is developed at the tip speed ratio of 4. The drag coefficient reaches about 0.85 at the design tip speed ratio.
Evaluation of hourly temperature values using daily maximum, minimum and average values
Lee, Kwan-Ho ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 81~87
Computer simulation of buildings and solar energy systems is being used increasingly in energy assessments and design.. Building designers often now predict the performance of buildings simulation programmes that require hourly weather data. However, not all weather stations provide hourly data. Climate prediction models such as HadCM3 also provide the daily average dry bulb temperature as well as the maximum and minimum. Hourly temperature values are available for building thermal simulations that accounts for future changes to climate. In order to make full use of these predicted future weather data in building simulation programmes, algorithms for downscaling daily values to hourly values are required. This paper describes a more accurate method for generating hourly temperature values in the South Korea that uses all three temperature parameters from climate model. All methods were evaluated for accuracy and stability in terms of coefficient of determination and cumulative error. They were compared with hourly data collected in Seoul and Ulsan, South Korea.
The Effect of the Ground Composition on Thermal Environment in Multi -residential Building Block
Hwang, Hyo-Keun ; Song, Doo-Sam ;
Journal of the Korean Solar Energy Society, volume 29, issue 5, 2009, Pages 88~97
In these days, it attracts our attention to create a green outdoor environment around the building block in urban area. Green space and permeable ground covering are increased by laws and regulations. According to these trends, variety researches for improving outdoor environment are accomplished at this moment. However, the problems for outdoor environment such as heat island effect and air contaminant in urban area are still reported. The purpose of this study is to examine the variables to affect the formation of outdoor thermal environment by quantitative analysis. As a initial study, in this paper, the effect of ground composition on changes of surface temperature and heat flux in multi-residential building were analyzed by field measurement and numerical simulation. Through field measurement, the surface temperature and heat flux of artificial ground in multi-residential building in Suwon city were measured. The result showed that the surface temperature was decreased by about
with afforestation of artificial ground compared with those of concrete covering. Moreover, the inner temperature of artificial ground was changed as same behaviors of outdoor temperature changes to depths of 20cm. In simulation, the effect of soil types and depth of artificial ground on the changes of the surface temperature and heat flux were analyzed. As results, the natural soil ground was more effective against lowering the surface temperature than any other cases in the analyzed cases.