• 한국연소학회:학술대회논문집
• /
• 2002.06a
• /
• pp.95-98
• /
• 2002

A numerical investigation on the flame propagation and extinction in a micro combustor is described. Previous measurements of $H_2-air$ flame propagation in a submilimeter scale combustor exhibited significance of wall effects on burning velocity and extinction. The heat transfer to wall becomes important not only in the cooling of burnt gases but also during the flame ropagation, which has be by and large ignored in macro scale combustor calculations. In order to take the heat loss into account the combustion calculation, we developed a numerical code with a heat transfer model that was determined empirically from measured data. PISO algorithm was used for differencing of conservation equations. $H_2-air$ reaction was modeled with 10 species - 16 steps. Comparison with measured data showed good agreement in flame propagation speed. Also the pressure decrease after flame extinction was accurately predicted by the model. A further study is desirable for a better quenching model that can predict the quenching location.

• Journal of computational fluids engineering
• /
• v.18 no.2
• /
• pp.9-16
• /
• 2013

The heat transfer enhancement of heat sink with mist flow is studied numerically by solving the conservation equations for mass, momentum and energy in the continuous and dispersed phases. A Lagrangian method is used for tracing dispersed water droplets in the heat sink and an Eulerian species transport model for air and steam mixture. The continuous and dispersed phases are interacted with the drag and evaporation source terms. The computed results show that addition of evaporating mist droplets enhances the cooling performance of heat sink significantly.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.9 no.2
• /
• pp.16-24
• /
• 2013

A multi-heat pump provides the benefits of comfort, energy conservation and easy maintenance. Recently, the multi-heat pump has been widely employed in small and medium-sized buildings. However, the control algorithm of the multi-heat pump are limited in the open literature due to complicated operating conditions. In this study, the MIMO control algorithm using integral optimum regulator was designed and the control performance of it was analyzed. In addition, system model of the control plant was developed by PRBS system identification scheme. The MIMO controller adopting the integral optimum regulator yielded satisfactory control performance results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.8
• /
• pp.711-716
• /
• 2000

A fuzzy defrost control algorithm for the multi-type heat pump system was developed. In the fuzzy defrost control algorithm, the air temperature difference at the outdoor unit and the refrigerant pressure difference at the compressor were used as input variables, and the defrost starting time and the defrost time interval were used as output variables. This fuzzy algorithm was applied to the multi-type heat pump system and tested in the five dynamic environmental chambers. Test results show that the newly developed control algorithm is more effective than the conventional control algorithm in the removal of frost formed at the outdoor unit of the heat pump.

• Journal of the Korean Solar Energy Society
• /
• v.37 no.1
• /
• pp.71-80
• /
• 2017

A Data center houses a large number of server computers, storage and etc in racks. With the rapid increase of heat generation rates per rack in a data center, energy consumption rates for cooling have been increased year by year. In this study, energy conservation effects of a MOA (multi-stage outdoor air enabled) cooling system in a data center has been investigated when it is applied to 5 different locations, Korea. As results, Energy conservation effects of the MOA cooling system was achieved at about 20% to 30%. Humidifier operation time was 40 to 55 days when supply air temperature was maintained at 13, and humidity condition was kept within the allowed range even though humidifier was off. Furthermore, humidification was not needed when supply air temperature was maintained at $25^{\circ}C$. In selected 5 locations in Korea, the difference of regional climatic conditions affected no more than 5% in cooling energy consumption rates.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.3
• /
• pp.228-234
• /
• 2007

Opening an ancient tomb interior can deal fair damage for preservation in long period because of high moisture. In this study, a duct-type HVAC system was installed to preserve an ancient tomb and temperature and humidity was measured to analyze heat environment. Armhole was measured to search whether an ancient tomb receives effects of vibration caused by a duct-type HVAC system. According to the measured data, temperature in an ancient tomb is kept adaptively in conservation regardless of a duct-type HVAC system installation when it rains in summer. The other side, humidity is kept adaptively in conservation when installed duct-type HVAC system. But when it is in natural state, a lot of humidity by dew condensation phenomena. So it needs a duct-type system for an ancient tomb conservation. In the case of vibration, measurement value of 3 satisfy control but Germanic DIN 4150 does not satisfy. Therefore, equip must be such that it can prevent vibration for safety.

• Journal of the Korean Solar Energy Society
• /
• v.30 no.3
• /
• pp.108-115
• /
• 2010

Global warming and heat island make the outdoor air temperature ascend. Tall office buildings are covered with glass window facades as a design aspect and the portion of window area to facade area is increasing. Hence, cooling load for solar radiation passing through glass window is rising. Cooling air to a certain room is supplied equally despite the face of the room in most office buildings. Especially, the west part of the office cannot maintain the required temperature that occupant needs because of the solar heat coming through windows.?In this study, we projected the water spray system to reduce the solar heat transfer and to reflect the solar ray through windows. We perform the experiments to evaluate the performance of the solar heat protection devices. We measured the room temperature of two separated office rooms for solar heat control devices. The investigation's results show that the water spray system is sufficient to the coated glass and the venetian blinds for the decrease of the solar heat inflow.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.215-220
• /
• 2006

Along with socioeconomic development and improving standard of living, the heat demand for heating and cooling in residential and commercial sectors is expected to expand rapidly, reaching over 43 million TOE by 2010 in Korea(about 80% increase compared with that in 1995). Since most of this heat demand is loop temperature below $60^{\circ}C$, the utilization of 'unused energy' is surely one of very effective measures to both environmental preservation and energy conservation. 'Unused energy' in this paper is implicated as 'temperature differential energy' available from treated sewage water, useful and abundant heat source for heat pump(cooler in summer and warmer in winter than outside air). An analysis was carried out to estimate the energy potential of treated sewage water for heat pump heat source. Some analysis were taken to study the characteristics of a heat pump system using the treated sewage water as heat source.

• Journal of Conservation Science
• /
• v.36 no.5
• /
• pp.430-439
• /
• 2020

This study focused on analyzing solid brown cosmetic residues that were excavated from the tomb of the Hwahyeop princess. The cosmetics had been buried in 1752 in Cheonghwa Baekja (small porcelain jars) within a Huigwakham (a stone box sealed with lime). A literature search and chemical analyses of the relics were conducted at the National Palace Museum of Korea. Based on the results of these analyses, raw materials and manufacturing methods for reproduction of the cosmetic were selected and then cream-form cosmetics were prepared. Aging tests using heat, ultraviolet (UV) radiation, and CO₂ were carried out to emulate the deterioration of the excavated cosmetics. Further chemical analyses and functionality tests were performed to evaluate changes from the tests and the effect as a cosmetic. As heat aging progressed, among the reproduced cosmetics, the one which has a high proposition of oil showed a color difference value of 32; the oxidation of oils involved chemical changes in O-H and C=C groups. As the cosmetic cream deteriorated under UV aging, the pH value became acidic. The result of the functional coverage test of the reproduced cosmetic cream was lower than the standard coverage ratio of modern cosmetics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.4
• /
• pp.189-196
• /
• 2010

U-factor and solar heat gain coefficient(SHGC) usually can be used as the index to evaluate the thermal performance. U-factor is a concept for heat loss by the temperature difference between inside and outside, so it's useful to be applied in heating season. But SHGC that indicates the fraction of heat from incident solar radiation that flows through a window by means of optical transmission, as well as absorption, re-radiation and convection is for cooling season. In other words, U-factor and SHGC of windows by cities have to be reflected to select the window of the energy conservation. The purpose of this research is to analyze the energy use impacts by SHGCs of windows for detached house in Inchon and Ulsan through energy simulation by eQUEST.