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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Air-Conditioning and Refrigeration Engineering
Journal Basic Information
Journal DOI :
The Society of Air-Conditioning and Refrigerating Engineers of Korea
Editor in Chief :
Volume & Issues
Volume 23, Issue 12 - Dec 2011
Volume 23, Issue 11 - Nov 2011
Volume 23, Issue 10 - Oct 2011
Volume 23, Issue 9 - Sep 2011
Volume 23, Issue 8 - Aug 2011
Volume 23, Issue 7 - Jul 2011
Volume 23, Issue 6 - Jun 2011
Volume 23, Issue 5 - May 2011
Volume 23, Issue 4 - Apr 2011
Volume 23, Issue 3 - Mar 2011
Volume 23, Issue 2 - Feb 2011
Volume 23, Issue 1 - Jan 2011
Selecting the target year
Design of a Swash Plate Type of Steam Expander for Waste Heat Recovery
Kim, Hyun-Jae ; Kim, Hyun-Jin ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 313~320
DOI : 10.6110/KJACR.2011.23.5.313
For a steam Rankine cycle to recover waste heat from the exhaust gas of an Internal combustion engine, a swash plate type of expander as a power conversion unit has been designed. Numerical simulation has been carried out to estimate the performance of the designed expander. With the steam pressure and temperature of 35 bar and
at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 2.67 kW from the exhaust gas waste heat of 25.2 kW. The expander output increased almost linearly with the amount of exhaust gas waste heat in the range of from 5~40 kW, and the expander and Rankine cycle efficiencies showed gradual decreases in the ranges of 72.2%~69.5% and 10.8%~10.4%, respectively.
Numerical Analysis for the Effect of Ground and Groundwater Conditions on the Performance of Ground Source Heat Pump Systems
Nam, Yu-Jin ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 321~326
DOI : 10.6110/KJACR.2011.23.5.321
Recently, ground source heat pump (GSHP) systems have been introduced in many modem buildings which use the annually stable characteristic of underground temperature as one of the renewable energy uses. However, all of GSHP systems cannot achieve high level of energy efficiency and energy-saving, because their performance significantly depends on thermal properties of soil, the condition of groundwater, building loads, etc. In this research, the effect of thermal properties of soil on the performance of GSHP systems has been estimated by a numerical simulation which is coupled with ground heat and water transfer model, ground heat exchanger model and surface heat balance model. The thermal conductivity of soil, the type of soil and the velocity of groundwater flow were used as the calculation parameter in the simulation. A numerical model with a ground heat exchanger was used in the calculation and, their effect on the system performance was estimated through the sensitivity analysis with the developed simulation tool. In the result of simulation, it founds that the faster groundwater flow and the higher heat conductivity the ground has, the more heat exchange rate the system in the site can achieve.
Freeze Protection for Passive Solar Water Heating System
Kim, Jong-Hyun ; Hong, Hi-Ki ; Chung, Jae-Dong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 327~333
DOI : 10.6110/KJACR.2011.23.5.327
In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.
Study on the Development of Optimal Heat Supply Control Algorithm in Group Energy Apartment Building According to the Variation of Outdoor Air Temperature
Byun, Jae-Ki ; Lee, Kyu-Ho ; Cho, Young-Don ; Shin, Jong-Keun ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 334~341
DOI : 10.6110/KJACR.2011.23.5.334
In the present study, optimal heat supply algorithm which minimize the heat loss through the distribution pipe line in group energy apartment was developed. Variation of heating load of group energy apartment building in accord with the outdoor air temperature was predicted by the heating load-outdoor temperature correlation. Supply water temperature and mass flow rate were controlled to minimize the heat loss through distribution pipe line. District heating apartment building located in Hwaseong city, which has 1,473 households, was selected as the object building for testing the present heat supply a1gorithm. Compared to the previous heat supply system, 10.4% heat loss reduction can be accomplished by employing the present method.
Analysis of Energy Consumption and Research on Energy Saving of Lighting and Coo1ing Energy of a Superstore
Bae, Chang-Hwan ; Kim, Young-Il ; Chung, Kwang-Seop ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 342~348
DOI : 10.6110/KJACR.2011.23.5.342
This study analyzes the current and after retrofit energy consumption of lighting and cooling system of a superstore in Seoul. Energy consumption data were measured and collected with a measurement system. Annual energy consumption was calculated using TRNSYS program. After replacing lighting and chiller with higher efficiencies, annual TOE consumption decreased from 1,066 before retrofit to 832 after retrofit, saving 234 TOE (22%) in total. Similarly, total annual
consumption decreased from 2,214 to 1,721, reducing 493
(22%) during this pilot study.
Indoor Ventilation Efficiency Depending on Diffuser Inlet Angle
Jeon, Hyun-Jun ; Jang, Yong-Jun ; Yang, Kyung-Soo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 349~355
DOI : 10.6110/KJACR.2011.23.5.349
In this study, numerical simulation has been conducted to investigate dispersion of a pollutant released from a new furniture, a kind of Sick Building Syndrome (SBS). A sofa which generates formaldehyde is implemented by using an immersed boundary method. Large Eddy Simulation (LES) is employed to obtain time-dependent velocity and concentration fields. It is shown that the ventilation efficiency in this room can be improved by changing inlet angle of diffuser, even though other conditions still remain unchanged. Both active diffusion near a sofa and air flow pattern are important parameters to enhance the ventilation efficiency.
Thermal Diffusivity Evaluation of Backfilling Materials for Horizontal Ground Heat Exchanger Using Single-Probe Method
Sohn, Byong-Hu ; Choi, Hang-Seok ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 356~364
DOI : 10.6110/KJACR.2011.23.5.356
Storage and transfer heat in soils is governed by the soil thermal properties and these properties are therefore needed in many engineering applications, including horizontal ground heat exchanger for ground-coupled heat pumps. This paper presents the evaluation results of the thermal diffusivity of soils (silica, quartzite, limestone, sandstone, granite, and two masonry soils used for the trench backfilling materials of the horizontal ground heat exchanger. To assess this thermal property, we (i) measure the soil thermal conductivities using single-probe method and (ii) use the de Vries method of summing the heat capacities of the soil constituents. The results show that the thermal diffusivity tends to increase as dry soil begins to wet, but it approaches a constant value or even decreases as the soil continues to wet. Combined algorithm with and improved model for the thermal conductivity of soils and the constituent equation provides accurate estimates of the soil thermal diffusivity.
Measurements of Velocity Distribution Function in Circular Open Channel Flows by Stereoscopic PIV
Yoon, Ji-In ; Sung, Jae-Yong ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 365~374
DOI : 10.6110/KJACR.2011.23.5.365
For the first time, the present study has measured the velocity distribution function in circular open channel flow in a three-dimensional shape using a stereoscopic PIV system. For a given channel slope, water depth was varied from 30% to 80% of the channel diameter. Then, the characteristics of the velocity distribution function was compared according to the change of the water depth. Unlike a rectangular channel, the present experiment exhibited quite different shapes in the velocity distribution function whether the water depth is higher than 50% or not. Especially, the position of maximum velocity in the central and side wall changes in a different manner for the water depth above 50%. By differentiating the velocity distribution function, local wall friction coefficient was evaluated as a function of wall position. If the water depth goes down, the difference between the maximum and minimum values in the local wall friction coefficient increases, and the averaged value a1so increases.
Consideration of Measurement Method for SVOCs Emission Rates
Seo, Jang-Hoo ;
Korean Journal of Air-Conditioning and Refrigeration Engineering, volume 23, issue 5, 2011, Pages 375~382
DOI : 10.6110/KJACR.2011.23.5.375
Semi volatile organic compounds (SVOCs) are used as plasticizers in building materials, interior materials, furniture, consumer electronics. etc. In the home, these SVOCs mix together with house dust. There is thus concern over the health effects of SVOCS in the home, there is a risk that they ini1uence childhood asthma and allergies. It is difficult to measure SVOCs emission rates from building materials or household appliances utilizing the usual test chamber methods, because the boiling points of SVOCs are higher and they are apt to adhere to the surface of the test chamber used. In this study, we introduce FLEC chamber method, passive sampler method and micro chamber method, which are used in Germany and Japan in order to measure SVOCs emission rates. Characteristic, merits and demerits of test methods are also considered.