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박한빛(Hanvit Park),윤린(Rin Yun) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.11
In-tube convective heat transfer coefficient and pressure drop of the CO₂-hydrate and gas/water mixture was investigated in this study. The CO₂-hydrate was formed by injecting water to high pressure gas-state CO₂, and the CO₂-hydrate and water mixture went through double-tube type test section. The test tube was made of stainless steel, and length of test section and diameter of inner tube was 4.0 m, 9.52 mm, respectively. The inlet pressure of CO₂ before mixing part was maintained around 2.0 MPa, and mole fraction of CO₂-hydrate in the mixture was controlled by amount of water injection. The CO₂-hydate mole fraction at test section inlet ranged from 0.4 to 0.65. The formation of CO₂-hydrate was verified by rising temperature of the mixture after mixing under adiabatic condition. Phase equilibrium of CO₂-hydrate was checked by inlet pressure and temperature of the mixture too. The in-tube heat transfer coefficient of the mixture ranged from 2400 to 3000 W/m2K, and the pressure drop was from 30 to 50 kPa.
박한빛(Hanvit Park),윤린(Rin Yun),김영득(Young Deug Kim) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.4
Middle-sized CO<sub>2</sub> water heater having compressor power of 7.45 kW was designed, and its performances were experimentally tested. Besides, optimum design of the CO<sub>2</sub> water heater was conducted by cycle simulation. When ambient temperature of 7℃ and hot water outlet temperature of 80℃ the CO<sub>2</sub> water heater showed the COP of 3.2. As hot water temperature increased the COP is getting decreased due to significant increase of compressor power consumption compared to increasing rate of heating capacity. When ambient temperature increased from -3℃ to 12℃ the COP increased by 30%. The optimum components design of a gas cooler, an internal heat exchanger, and an evaporator were conducted, and the experimental correlation between amount of EEV opening and ambient temperature, and hot water temperature was suggested.