마이크로채널 증발기의 모델링

윤린(Rin Yun), 최창선(Changsun Choi), 김용찬(Yongchan Kim) 대한설비공학회 2002 대한설비공학회 학술발표대회논문집 Vol.2002 No.-

낮은 오일 농도에서 CO₂-PEC9 혼합물의 밀도와 점성예측

윤린(Rin Yun) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.11

Due to environmental concerns CO₂ has been reintroduced as a potential candidate to replace HFCs in refrigeration systems. Oils are always required in a vapor-compression cycle, and thus it is necessary to precisely estimate the thermodynamic mixture properties of CO₂-lubricant oil. In the present study, the density and the viscosity of the mixture was calculated by the Redlich and Kwong type EoS and the modified Peng and Robinson type viscosity EoS, respectively. The viscosity model was based on the similarity between P-v-T and T-u-P relationships. The predicted results were compared with the experimental data of Pensado et al. whose test conditions were 100~650 bar of pressure and 303 K ~353 K of temperature with the CO₂-POEs mixtures under 92.2 wt.% and 83.3 wt.% of CO₂ concentration. The mean deviations of the mixture density were 7.93% and 8.32% for 92.2 wt.% and 83.3 wt.% of CO₂ concentration, respectively. Concerning the viscosity, the mean deviations were 4% and 10% for 92.2 wt.% and 83.3 wt.% of CO₂ concentration under the Pensado et al.'s test conditions.

수열시스템 통합설계 플랫폼 개발연구

윤린(Rin Yun), 안문기(Mungi Ahn), 정광진(Gwangjin Jeong) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

초임계조건에서 CO₂-PEC9 혼합물의 물성예측을 통한 냉각 열전달특성 연구

윤린(Rin Yun) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

Due to environmental concerns CO₂ has been reintroduced as a potential candidate to replace HFCs in refrigeration systems. Oils are always required in a vapor-compression cycle, and thus actual working fluid in the system is CO₂-oil mixtures even though the oil concentrations are low at the heat exchangers and the expansion device. The cooling heat transfer coefficients for CO₂-oil mixtures under supercritical condition are required to designing of the gas cooler in the CO₂ refrigeration system properly. In the present study, the gas cooling heat transfer coefficients for CO₂-PEC9 was estimated by using the Gnileinski correlation, and the Kim and Ghajar model through the previous prediction models for the thermo-physical properties of CO₂-oil mixture. The Gnileinski correlation was used when the oil wt.% in the mixture is less than 1.0, and for the higher oil concentration the Kim and Ghajar model was applied. The estimated results agree with the experimental results conducted by the Dang et al.

슈퍼마켓용 CO₂/NH₃ 캐스케이드 시스템과 CO₂ 2단 시스템의 성능평가

윤린(Rin Yun), 조용(Yong Cho) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6

Due to environmental concerns the natural refrigerants of CO₂ and NH₃ has been reintroduced as replacements of the chemical refrigerants of R404A in supermarket refrigeration. Possible system configurations for the natural refrigerants are the CO₂-NH₃ cascade system and the CO₂ two-stage system. In this study, the comparison of the system performance between the CO₂-NH₃ cascade system and the three-different CO₂ two-stage systems are conducted. The suction line heat exchanger and the internal heat exchanger are added to improve the performance of the CO₂ two stage system. The COP of the cascade system is highest among the present simulated systems due to the improvement of the low stage system performance of the CO₂ cycle.

CO₂-Hydrate와 CO₂ 가스 혼합물의 전달물성과 관내측 열전달계수 및 압력강하 예측

윤린(Rin Yun) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.5

The Thermophysical properties of thermal conductivity, viscosity, and heat capacity for CO₂ slurry (CO₂ gas and CO₂-hydrate mixture) having a high gas phase volume fraction were predicted using the conventional mixture models and the TRAPP model under hydrate formation conditions. Based on the calculated thermophysical properties, the heat transfer coefficient and pressure drop of the CO2 slurry in the tube were predicted. The thermal conductivity of CO₂ slurry ranged from 0.02 to 0.2 W/m-K, and the mixture viscosity was larger than that of pure CO₂ by 1.9~2.7 times. The heat capacity of CO₂ slurry ranged from 63 to 68% of that for pure CO₂. The predicted heat transfer coefficient of CO2 slurry was 6 times higher than that of pure CO₂. In the separate model, the estimated pressure drop increased with an increase of CO₂-hydrate mole fraction, and was 60% of that of pure CO₂.

수열에너지 활용이 수온에 미치는 영향

윤린(Rin Yun), 이광빈(Kwangbin Lee) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

The heat transfer characteristics of CO₂ and CO₂-oil mixture in tubes

Rin Yun(윤린) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

The heat transfer characteristics of CO₂ and CO₂-oil mixture in tubes including convective flow boiling, gas cooling, and condensation are investigated. Two-phase flow patterns are thoroughly investigated based on physical phenomena, which show the early flow transition to intermittent or annular flow especially for small diameter tube. The physical phenomena for nucleate boiling of CO₂ follow the same trends with other organic fluids under the same reduced pressure. The gas cooling heat transfer is critically dependent on the turbulent diffusivity related with buoyancy force due to the large density difference. Under the oil presence conditions, the interaction of oil rich layer and bubble formation is the physical mechanism for the CO₂-oil mixture convective boiling. Besides, the gas cooling phenomena with oil should be investigated based on the flow patterns formed by CO₂ and oil, and the oil rich layer, whose thickness are depends on the solubility of CO₂ to oil explains the physical mechanisms of heat transfer. The thermodynamic properties of CO₂-oil were estimated by the general model based on EOS, and they are utilized to estimate the properties for oil rich layer and oil droplet vapor core. Through these predicted properties, the convective boiling and gas cooling heat transfer coefficients and pressure drop theoretically estimated. Condensation of CO₂ is not so different from the existing one, so the heat transfer coefficients and pressure drop are well estimated by the existing one developed for other fluids.

가스-하이드레이트 기반 이산화탄소 수송 및 포집

윤린(Rin Yun), 베네딕트 프라(Benedict Prah) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.5

CHP Capacity Optimizer를 이용한 건물 열병합 시스템의 경제성 평가

윤린(Rin Yun) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.5

This paper presents and analyzes the effects of on-grid electricity cost, fuel price and initial capital cost of a CHP system, on the optimum DG and AC capacity and NPV, by using the ORNL CHP Capacity Optimizer, which was applied to a library in a university. By considering the current domestic energy cost and initial capital cost, it is shown that the installation and operation of the CHP system is not economical. However, with the current domestic CHP installation cost and fuel price, the NPV achieved by the installation of CHP system is greater when the on-grid electricity price is a factor of x1.5 the present value. Regarding the initial capital cost of the CHP system, the reduction of the DG cost is much more economical than that of the AC cost, with respect to NPV. Electricity cost and fuel price have opposite effects on NPV, and NPV is more sensitive to an increase of the electricity cost than an increase of the fuel price.