• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.332-337
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• 2004

The use of gas absorption refrigeration machine has considerably increased because of the shortage of the electric power in the summer and the regulation of freon refrigerant. Gas absorption refrigeration machine consists of a condenser, a heat exchanger. supplying pipes, a radiator etc, This system is likely to be corroded by acid. dissolved oxygen and gases, Cavitation erosion-corrosion by flow velocity of cooling water may happen in absorption refrigeration machine. In these cases. erosion and corrosion occur simultaneously. Then, it makes a serious damage with synergy effect. Therefore, this paper was studied on the cavitation damage of cupronickel(70/30) tube for gas absorption refrigeration machine, In the $30^{\circ}C$ tap water, linear polarization test and anodic polarization test were carried out for copper(C1220T-OL) and cupronickel(70/30) tube. Also, cavitation erosion-corrosion behavior of cupronickel (70/30) tube was considered, The main results are as following: (1) In the linear test, the corrosion current density of cupronickel(70/30) is higher than that of copper. (2) The erosion-corrosion rate of cupronickel(70/30) displayed later tendency than that of copper by vibratory cavitation in cooling water. (3) In cooling water, the progress mechanism of erosion-corrosion rate of copper and cupronickel(70/30) follows a pattern of incubation, acceleration, attenuation and a steady state period.

• 한국가스학회지
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• 제6권1호
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• pp.92-97
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• 2002

가스흡수식 냉온수기의 작동매체로 사용되고 있는 LiBr 수용액 중에서 열교환기 세관용 재료인 동 세관 및 동합금재인 큐프로니켈 세관의 부식특성에 관한 연두를 하기 위하여 $62\%$ LiBr 수용액 중에서 각 재료에 대한 전기화학적 분극실험을 실시하여 부식특성을 고찰한 결과 다음과 같은 결론을 얻었다 1) 열교환기 세관재의 분극저항은 $30\%$ 큐프로니켈 세관 > $10\%$ 큐프로니켈 세관 > 동 세관의 순으로 높게 나타난다 2) 큐프로니켈 세관의 개로전위는 동 세관보다 귀전위화되면서 부식전류밑도는 더 억제된다 3) $30\%$ 큐프로니켈 세관의 부동태 영역은 $10\%$ 큐프로니켈 세관보다 전위구간이 더 크게. 나타나면서 부동태유지 전류밀도는 더 낮아진다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.714-720
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• 2003

Due to the electric power shortage in summer season and regulation of freon refrigerant, the application of gas absorption refrigeration and hot water systems are considerably increasing trend. But, this system consists of condenser, heat exchanger, supply pipe and radiator etc. which are easily corroded by acidity and dissolved oxygen and gases. In result, this system occurs scale attachment and corrosion damage like pitting and crevice corrosion. In this study, electrochemical polarization test of heat exchanger tubing material (copper, aluminium brass, 30% cupronickel(30% Cu-Ni)) was carried out in 60% lithium bromide solution at $95^{\circ}C$. As a result of polarization test, corrosion behavior by impressed potential and local corrosion. such as galvanic corrosion, pitting corrosion behavior, of tubing materials was investigated. The main results obtained are as follows: (1) The effect of pitting and crevice corrosion control of 30% cupronickel in 60% LiBr solution at $95^{\circ}C$ is very excellent. (2) Dissimilar metal corrosion of 30% cupronickel coupling to aluminium bronze is the most sensitive. (3) Current density behavior of tube materials by impressed potential is high in order of copper > aluminium brass > 30% cupronickel.

• 설비공학논문집
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• 제15권10호
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• pp.828-834
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• 2003

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (hydrogen or helium). In this study, experimental investigations have been carried out to examine the effects of charging conditions of working fluids on the evaporating temperature for diffusion absorption refrigerator. Experimental parameters considered in the present experiments are charging concentration, solution charge and system pressure determined by auxiliary gas charged. As a result, in the charging condition of 35% of concentration and 20 kg$_{f}$cm$^2$ of system pressure, the system has the lowest evaporating temperature. It was found that there exists a minimum value of solution charge for the operation of diffusion absorption refrigerator.r.

• 설비공학논문집
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• 제8권2호
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• pp.288-298
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• 1996

The gas-fired absorption refrigeration system to utilize treated sewage is available for environmental protection and energy conservation. Simulation analysis on the double-effect absorption refrigeration cycles with parallel or series flow type has been performed. The working fluid is Lithium Bromide and water solution. The main purpose of this study is evaluating the possibilities of effective utilization of treated sewage as a cooling water for the absorber and condenser. The efficiency of a couple of cycles has been studied and simulation results show that higher coefficient of performance could be obtained for parallel flow type. The other purpose of the present study is to determine the optimum designs and operating conditions based on the operating constraints and the coefficent of performance in the paralledl flow type.

• 설비공학논문집
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• 제14권10호
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• pp.817-824
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• 2002

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (typically hydrogen). This system has no moving parts and the associated noise and vibration. In this study, the operating characteristics of diffusion absorption refrigerator are investigated through cycle modeling and simulation. System parameters considered in this study are the charged concentration of ammonia aqueous solution, the concentration difference between absorber inlet and outlet and the system pressure determined by the amount of auxiliary gas charged. It was found that there exists a critical value of concentration difference that maximizes the refrigerating capacity. And the lower the system pressure, the higher the refrigerating capacity.

• 한국가스학회지
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• 제5권4호
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• pp.33-39
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• 2001

흡수식냉동기의 작동매체로 사용되고 있는 LiBr수용액 중에서 각 구성재료인 일반구조용 압연강재, 동 및 동합금재인 Ai-Ni bronze의 부식거동에 관한 연구를 하기 위하여, 여러 가지 농도의 LiBr 수용액 중에서 각 재료에 대한 분극실험을 실시하여 부식거동을 고찰한 결과 다음과 같은 결론을 얻었다. 1) 수용액의 LiBr 농도가 증가할수록 각 재료의 분극저항은 낮아지고, 개로전위는 비전 위화되면서 부식전류밀도는 높게 배류된다. 2) 일반구조용 압연강재의 개로전위는 동 및 Al-Ni bronze의 개로전위보다 비전위화되면서 부식전류밀도는 더 높게 배류된다. 3) 동 및 Al-Ni bronze에 대한 $62\%$ LiBr 수용액 중에서의 양극분극은 활성태로 지속되지만, 천연해수 중에서의 양극분극은 활성태가 지속되다가 부동태화전류가 나타난다.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.792-799
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• 1998

Further improvement of existing $H_{2}O/LiBr$ absorption refrigeration machine is absolutely neces-sary to promote the utilization of gas-cooling system Among various methods to improve the per-formance of the absorption refrigeration machine this research has focused on the use of a new working fluid that has better properties than the existing $H_{2}O/LiBr$ working fluid. In the series of the research, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ system was selected as the most promisable candidate. The absorption refrigeration machine is water-cooled double-effect, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ sys-tem with series flow type. In this study we found out the characteristic of new working solution through the cycle simulation and compared the result with that of LiBr solution to evaluate. Theoptimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance. Results demonstrate that new working fluid subsrantially increases COP by as much as 10% and has a wider working range with 8% higher crystallization limits compared to the conventional $H_{2}O/LiBr$.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1998년도 추계학술발표회 논문집
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• pp.249-254
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• 1998

This paper describes the study of developing air-cooled absorption system which uses a new working solution instead of LiBr solution to improve the performance of system. The absorption chiller-heater considered was an air-cooled, double-effect, $H_2O/LiBr+HO(CH_2)_3$ system of parallel flow type. In this study, we found out the characteristic of new working solution through the cycle simulation and compared the result that of LiBr solution to evaluate. The new working fluid has a wider working range with $8\%$ higher crystallization limit at the saturated refrigerant pressure of 0.8kPa. The optimum designs and operating conditions of air-cooled absorption system were suggested based on this cycle simulation analysis. It was demonstrated that new working fluid substantially improves the performance of the absorption refrigeration machine and is expected to increase the COP by as much as $5\%$.

• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.56-66
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• 1998

The absorption process of water vapor in a liquid film is an important process in LiBr-Water absorption system. The composition of the gas phase, in which a non-absorbable gas is combined with the absorbate, influences the transport characteristics. In the present work, the absorption processes of water vapor into aqueous solutions of lithium bromide in the presence of non-absorbable gas are investigated. The continuity, momentum, energy and diffusion equations for the solution film and gas are formulated in integral forms and solved numerically. It is found that the mass transfer resistance in gas phase increases with the concentration of non-absorbable gas. However the primary resistance to mass transfer is in the liquid phase. As the concentration of non-absorbable gas in the absorbate increases, the interfacial temperature and concentration of absorbate in solution decrease, which results in the reduction of absorption rate. The reduction of mass transfer rate is found to be significant for the addition of a small amount of non-absorbable gas to the pure vapor, especially at the outlet of tube where the non-absorbable gas accumulates. At higher non-absorbable gas concentration, the decrease of absorption rate seems to be linear to the concentration of non-absorbable gas.