• Title/Summary/Keyword: LiBr

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Performance Analysis of New Working Solution for Absorption Refrigeration Machine using Treated Sewage (하수처리수이용 신용액 흡수식 냉동기의 성능해석)

  • 권오경;유선일;윤정인
    • Journal of Energy Engineering
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    • v.7 no.2
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    • pp.231-240
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    • 1998
  • The global environmental problems such as CFC, energy losses in heat recovery system as well as summer peak time power demands, the development of high efficiency absorption refrigeration systems is one of the most promising method in this problems. The absorption refrigeration system to utilize treated sewage is available for environmental protection and energy conservation. Simulation analysis on the double-effect absorption refrigeration cucles with parallel or series flow type has been performed. LiBr+LiI+LiCl+LiNO$_3$ solution was selected as the new working fluid. 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 other purpose of the present study is to determine the optimum designs and operating conditions based on the operating constraints and the coefficient of performance in the parallel or series flow type. In this study, we found out the characteristic of new working solution through the cycle simulation and compared LiBr solution to evaluate. The absorption refrigeration machine using the new working fluid was obtained better results COP rise and compactness of system by comparison with LiBr solution.

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Analysis of Thermodynamic Design Data of Double-Effect Absorption System for Heating using LiCl-water for Evaporator Heating Source of Solar Energy (흡수식 2중효용 시스템의 증발기 열원으로 태양열을 이용하는 LiCl 수용액 난방시스템 해석)

  • Won, Seung-Ho
    • Journal of the Korean Solar Energy Society
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    • v.24 no.3
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    • pp.39-46
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    • 2004
  • In this paper, thermodynamic design data for heating of double-effect absorption system using LiCl-water for evaporator heating source of sofar energy are investigated for the water-LiCl pair and a comparative study of the water-LiCl pair with the water-LiBr pair is given used for the computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water -LiCl pair than for the water-LiBr pair, and FR is lower for the water-LiCl pair than for the water LiBr pair.

An Experimental Study on the Effect of Low Fin Tube Geometry on Pool Boiling of a LiBr Solution (낮은 핀관의 형상이 LiBr 수용액의 풀 비등에 미치는 영향에 대한 실험적 연구)

  • Kim, Nae-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.7
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    • pp.591-598
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    • 2015
  • Pool boiling heat transfer coefficients of a LiBr solution were obtained for seven low fin tubes having different fin pitch and fin height. The test range covered saturation pressure from 7.38kPa to 101.3kPa, heat flux from $20kW/m^2$ to $40 kW/m^2$ and LiBr concentration from 0% to 50%. The optimum fin geometry for the present experimental range turned out to be 26 fpi with 0.18 mm fin height.The advantage of added heat transfer area and the disadvantage of slower bubble growth and departure appear to have yielded an optimum fin pitch. The heat transfer coefficient decreased as saturation pressure decreased and Libr concentration increased. The reason may be attributed to the low saturation pressure, which increased the bubble departure diameter and decreased the bubble departure frequency. As the LiBr concenreation increased, the saturation temperature increased and the mass diffusion rate decreased, which resulted in a reduced heat transfer coefficient. The heat transfer coefficients of the low fin tube were greater than those of the smooth tube. Correlations were developed based on the present data.

A Study on Heat and Mass Transfer Characteristics of LiBr-$H_2$O Solution with a Sufactant Flowing over a Cooled Horizontal Tube (계면활성제 첨가시 수평 냉각관 외부를 흘러내리는 LiBr수용액의 열 및 물질전달 특성에 관한 연구)

  • 김경희;설신수;이상용
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.4
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    • pp.341-349
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    • 2002
  • Heat and mass transfer characteristics of a surfactant-added LiBr-$H_2O$ solution flowing over a single horizontal tube were examined experimentally. The parameters considered were surfactant (2-ethyl-1-hexanol) concentration, solution temperature at the top of the tube and absorber pressure. Even with an amount of the surfactant below the solubility limit, heat and mass transfer performances were enhanced tremendously. The Nusselt and Sherwood numbers increased by about 70% and 340%, respectively, when 10 ppm of the surfactant was added. However, an excess amount of the surfactant in the solution did not bring a further enhancement. The absorption performance deteriorated when the non-condensable gases were extracted from the system (by a vacuum pump) since the vaporized surfactant was also extracted during the process. Therefore, it is desirable to add a sufficient amount of the surfactant (more than 10 ppm) to maintain high performance of absorption.

Cycle Analysis of Air-Cooled Double-Effect Absorption Cooling System Using H2O/LiBr+HO(CH2)3OH (H2O/LiBr+HO(CH2)3OH계 공냉형 이중효용 흡수식 냉방시스템의 사이클 해석)

  • Kwon, Oh-Kyung;Moon, Choon-Geun;Yoon, Jung-In
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.2
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    • pp.272-280
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    • 1999
  • A cycle analysis was achieved to predict the characteristics by comprehensive modeling and simulation of an air-cooled, double-effect absorption system using a new $H_2O/LiBr+HO(CH_2)_3OH$ solution. The simulation results showed that the new working fluid may provide the crystallization limit 8% higher than the conventional $H_2O/LiBr$ solution. With a crystallization margin of 3wt%(weight%), the optimal solution distribution ratio was found in the range of 36 to 40%. Variation of cooling air Inlet temperature has a sensitive effect on the cooling COP and corrosion problem. The simulation of heat exchangers with UA value revealed that the absorber and the evaporator are relatively important for an air-cooled system compared with the condenser and the low temperature generator. The effect of cooling air flow rate, circulation weak solution flow rate and chilled water inlet temperature were also examined. The new working fluid may provide the COP approximately 5% higher than the conventional $H_2O/LiBr$ solution.

Simulation of the First Kind LiBr-H2O Absorption Heat Pump (제1종 LiBr-H2O 흡수식 열펌프의 시뮬레이션)

  • Huh, J.Y.;Choi, Y.D.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.2 no.1
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    • pp.11-26
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    • 1990
  • The first kind LiBr -$H_2O$ absorption heat pump system was simulated and the performances of it were predicted. The elements of heat pump system, evaporator, absorber and generator were analysed by solving the energy balance equations and concentration equations which describe the reactions between working fluids. The results show that the temperature gain of absorber and condenser and the COP of the system are affected considerably by the operating conditions of heat pump system.

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The characteristics of heat transfer coefficient for falling-film evaporation on a horizontal tube with aqueous LiBr solution (LiBr 수용액의 수평관 유하액막 증발에 있어서의 열전달계수 특성)

  • Ji, Yong-Hae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.2
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    • pp.294-302
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    • 1997
  • Falling-film evaporation experiments for aqueous solution of lithium bromide (LiBr) were performed on a horizontal smooth 19.05-mm-dia copper tube. Average heat transfer coefficients were obtained with varied film Reynolds numbers, system pressures, LiBr concentrations and degrees of wall superheat. Heat transfer coefficients increase with increasing system pressure and decreasing concentration. For degrees of wall superheat, the heat transfer coefficient did not't show the distinct trend. For this experimental ranges, heat transfer coefficients showed maximum values at an optimal film Reynolds number. The results of this work were compared with pool boiling data reported previously, and it was shown that the heat transfer performance is superior to the pool boiling.

The Effect of Temperature on Corrosion of Absorption Refrigeration Systems Using $LiBr-H_2O$ Working Fluids ($LiBr-H_2O$계 흡수식냉동기의 부식에 미치는 온도의 영향)

  • 임우조;정기철
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.1
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    • pp.125-131
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    • 2002
  • This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using $LiBr-H_2O$ working fluids. In the fresh water and 62 % lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(C1220T-OL) and Al-Ni bronze was carried out. And polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: (1) As the experimental temperature increase, the change of corrosion rate of Al-Ni bronze become duller than SS 400 and Cu in 62% lithium bromide solution. (2) According as corrosion environment is changed from fresh water to 62% lithium bromide solution, potential change of Cu and Al-Ni bronze become less noble than SS 400. (3) The corrosion sensitivity of Al-Ni bronze was duller than that of Cu and SS 400 in 62% LiBr solution.

Analysis of LiBr-H$_{2}$O Film Absorption on a Horizontal Tube (수평원관상의 LiBr-H$_{2}$O 액막흡수현상 해석)

  • Park, Il-Seok;Choe, Do-Hyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.2
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    • pp.670-679
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    • 1996
  • A numerical study for vapor absorption into LiBr-H$_{2}$O solution film flowing over horizontal circular tubes has been carried out. The momentum, energy and diffusion equations, which are parabolized by the boundary- layer approximation, are solved simultaneously for various mass-flow rates and inlet conditions. The results for the velocity, temperature and concentration fields, as well as the heat and mass flux at the free surface are presented. The effects of inlet conditions, i.e., flow rate, temperature and concentration, on the absorption process are also examined and discussed.

An investigation of absorption phenomena in the horizontal staggered tube absorber for various LiBr solution flow rates (LiBr용액량 변화에 따른 수평다관 흡수기의 특성 연구)

  • Kwon, Yul;Yoon, Sang-Guk
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.3
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    • pp.332-338
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    • 1999
  • An experimental study of absorption phenomena of water vapor into LiBr solution was carried out to find out the optimum solution flow rate. The staggered bundle of horizontal absorption tubes, which are the same configuration as the commercial heat pump, were tested. The results showed that the heat transfer and absorption rate were enhanced with the increase of LiBr solution flow rate. Those values for different absorber pressures showed the same qualitative trends. The optimum flow rate of solution was obtained as three times of the designed flow rate.

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