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Srinivasa S Murthy - One of the best experts on this subject based on the ideXlab platform.

  • performance comparison of double effect parallel flow and series flow water lithium bromide absorption systems
    Applied Thermal Engineering, 2001
    Co-Authors: M. B. Arun, M.p. Maiya, Srinivasa S Murthy
    Abstract:

    The double-effect parallel flow absorption refrigeration cycle with water–lithium bromide as working fluid is analysed based on the concept of equilibrium temperature at the low Pressure Generator. Coefficient of performance (COP) and its sensitivity to operating conditions are compared with those for series flow cycle. Maximum attainable COP for parallel flow cycle is greater than that for series flow cycle throughout the range of operating conditions considered here. Performance of parallel flow system is more sensitive to the effectiveness of low Pressure heat exchanger than that of series flow system.

Marc A. Rosen - One of the best experts on this subject based on the ideXlab platform.

  • optimization and comprehensive exergy based analyses of a parallel flow double effect water lithium bromide absorption refrigeration system
    Applied Thermal Engineering, 2019
    Co-Authors: Safarnezhad B Bagheri, Reza Shirmohammadi, S M S Mahmoudi, Marc A. Rosen
    Abstract:

    Abstract In this paper, a parallel flow double-effect water-lithium bromide absorption refrigeration cycle is investigated using comprehensive exergy-based analyses. The exergy destruction of each device is calculated and used for further analysis. The performance of the system is optimized for maximum coefficient of performance and exergy efficiency, considering the distribution ratio as a variable using the Golden Section method. The maximum coefficient of performance, i.e. 1.295, is obtained at a high Pressure Generator temperature of 169.6 °C, and the maximum exergy efficiency, i.e. 0.225, is obtained at a high Pressure Generator temperature of 142.7 °C. Advanced exergy analysis, a state of the art thermodynamic method, is employed for diagnosing equipment and cycle malfunctions. Not only can the aforementioned analysis pinpoint the source of irreversibility, it also provides the avoidable irreversibility as well. The results show that the endogenous part of the exergy destruction is much larger than the exogenous part, implying it is better to focus on component efficiencies to improve system performance. Moreover, the unavoidable part of the total exergy destruction is much larger than the avoidable portion, indicating that exergy destruction cannot be decreased owing to technical limitations of equipment.

  • A comparative study of the performance characteristics of double‐effect absorption refrigeration systems
    International Journal of Energy Research, 2010
    Co-Authors: L. Garousi Farshi, S.m. Seyed Mahmoudi, Marc A. Rosen, M. Yari
    Abstract:

    SUMMARY Three classes of double-effect lithium bromide–water absorption refrigeration systems (series, parallel and reverse parallel) with identical refrigeration capacities are studied and compared thermodynamically. In order to simulate the performances of the systems, a new set of computationally efficient formulations is used for thermodynamic properties of Li-Br solutions at equilibrium. The simulation results are used to examine the influence of various operating parameters on the first and second law performance characteristics of the systems. In addition, the dependences are investigated of system performance on the effectivenesses of the solution heat exchangers, the Pressure drops between the evaporator and the absorber and between the low-Pressure Generator and the condenser, and the low-grade heat externally supplied to the low-Pressure Generator. The results reveal the advantages and disadvantages of different configurations of double-effect lithium bromide–water absorption refrigeration systems, and are expected to be useful in the design and control of such systems. Copyright © 2010 John Wiley & Sons, Ltd.

M. B. Arun - One of the best experts on this subject based on the ideXlab platform.

  • performance comparison of double effect parallel flow and series flow water lithium bromide absorption systems
    Applied Thermal Engineering, 2001
    Co-Authors: M. B. Arun, M.p. Maiya, Srinivasa S Murthy
    Abstract:

    The double-effect parallel flow absorption refrigeration cycle with water–lithium bromide as working fluid is analysed based on the concept of equilibrium temperature at the low Pressure Generator. Coefficient of performance (COP) and its sensitivity to operating conditions are compared with those for series flow cycle. Maximum attainable COP for parallel flow cycle is greater than that for series flow cycle throughout the range of operating conditions considered here. Performance of parallel flow system is more sensitive to the effectiveness of low Pressure heat exchanger than that of series flow system.

  • Equilibrium low Pressure Generator temperatures for double-effect series flow absorption refrigeration systems
    Applied Thermal Engineering, 2000
    Co-Authors: M. B. Arun, M.p. Maiya, S. Srinivasa Murthy
    Abstract:

    Abstract The equilibrium temperatures at the low Pressure (LP) Generator for double-effect series flow lithium bromide–water vapour absorption chiller are evaluated and the system performance is estimated at these temperatures. Influence of temperatures at high Pressure (HP) Generator, evaporator, condenser and absorber, and the effectiveness of heat exchangers on equilibrium temperature and internal heat transfer at LP Generator, circulation ratio, and coefficient of performance are studied. Dual-heat mode of operation of the system is also investigated utilising low grade waste heat at the LP Generator. Correlations are presented for equilibrium LP Generator temperature, internal heat transfer at the low Pressure Generator, circulation ratio, coefficient of performance, optimum HP Generator temperature and optimum circulation ratio for maximum coefficient of performance in terms of operating temperatures, which are useful in the design and control of absorption system even at the off-design conditions.

  • Optimal performance of double‐effect series flow vapour absorption refrigeration systems with new working fluids
    International Journal of Energy Research, 1998
    Co-Authors: M. B. Arun, M.p. Maiya, S. Srinivasa Murthy
    Abstract:

    In a double-effect series flow vapour absorption refrigeration system (VARS), an optimum value of the low-Pressure Generator temperature exists at which all the vapour generated at the high-Pressure Generator is condensed. At these conditions, a comparative study of the performance of VARS using environment friendly refrigerants such as, R32, R134a, and R124 with N,N'-dimethyl acetamide (DMAC) as the absorbent is made. It is found that the system with R32-DMAC gives the best performance at high evaporator temperatures. R124-DMAC may be preferred at extreme operating conditions like low evaporator and high heat rejection temperatures. Influence of operating temperatures (high-Pressure Generator, evaporator, condenser and absorber) and the effectiveness of heat exchangers on the optimum low-Pressure Generator temperature, cut-off temperature, circulation ratio and coefficient of performance are studied.

M.p. Maiya - One of the best experts on this subject based on the ideXlab platform.

  • performance comparison of double effect parallel flow and series flow water lithium bromide absorption systems
    Applied Thermal Engineering, 2001
    Co-Authors: M. B. Arun, M.p. Maiya, Srinivasa S Murthy
    Abstract:

    The double-effect parallel flow absorption refrigeration cycle with water–lithium bromide as working fluid is analysed based on the concept of equilibrium temperature at the low Pressure Generator. Coefficient of performance (COP) and its sensitivity to operating conditions are compared with those for series flow cycle. Maximum attainable COP for parallel flow cycle is greater than that for series flow cycle throughout the range of operating conditions considered here. Performance of parallel flow system is more sensitive to the effectiveness of low Pressure heat exchanger than that of series flow system.

  • Equilibrium low Pressure Generator temperatures for double-effect series flow absorption refrigeration systems
    Applied Thermal Engineering, 2000
    Co-Authors: M. B. Arun, M.p. Maiya, S. Srinivasa Murthy
    Abstract:

    Abstract The equilibrium temperatures at the low Pressure (LP) Generator for double-effect series flow lithium bromide–water vapour absorption chiller are evaluated and the system performance is estimated at these temperatures. Influence of temperatures at high Pressure (HP) Generator, evaporator, condenser and absorber, and the effectiveness of heat exchangers on equilibrium temperature and internal heat transfer at LP Generator, circulation ratio, and coefficient of performance are studied. Dual-heat mode of operation of the system is also investigated utilising low grade waste heat at the LP Generator. Correlations are presented for equilibrium LP Generator temperature, internal heat transfer at the low Pressure Generator, circulation ratio, coefficient of performance, optimum HP Generator temperature and optimum circulation ratio for maximum coefficient of performance in terms of operating temperatures, which are useful in the design and control of absorption system even at the off-design conditions.

  • Optimal performance of double‐effect series flow vapour absorption refrigeration systems with new working fluids
    International Journal of Energy Research, 1998
    Co-Authors: M. B. Arun, M.p. Maiya, S. Srinivasa Murthy
    Abstract:

    In a double-effect series flow vapour absorption refrigeration system (VARS), an optimum value of the low-Pressure Generator temperature exists at which all the vapour generated at the high-Pressure Generator is condensed. At these conditions, a comparative study of the performance of VARS using environment friendly refrigerants such as, R32, R134a, and R124 with N,N'-dimethyl acetamide (DMAC) as the absorbent is made. It is found that the system with R32-DMAC gives the best performance at high evaporator temperatures. R124-DMAC may be preferred at extreme operating conditions like low evaporator and high heat rejection temperatures. Influence of operating temperatures (high-Pressure Generator, evaporator, condenser and absorber) and the effectiveness of heat exchangers on the optimum low-Pressure Generator temperature, cut-off temperature, circulation ratio and coefficient of performance are studied.

Kenan Saka - One of the best experts on this subject based on the ideXlab platform.

  • Üç Kademeli Soğurmalı Soğutma Sisteminin Enerji ve Ekserji Analizi
    Bitlis Eren Üniversitesi Fen Bilimleri Dergisi, 2019
    Co-Authors: Kenan Saka
    Abstract:

    Absorption refrigeration systems offer the most effective way of cooling by using waste heat. In this study, energy and exergy analysis is performed on a triple effect absorption refrigeration system. The system is series flow and it works with water – lithium bromide solution. In addition, three different heat exchangers are used to achieve heat recovery within the system. Triple effect absorption refrigeration systems are more efficient than double and single effect absorption refrigeration systems. Also the systems have more system components and they are more complex in terms of thermodynamics. In the analysis performed exergy destruction of the components and changes of total exergy destruction of the system are shown due to the low Pressure Generator temperature. It is also been added to the analysis results in the change in efficiency of the first and second laws. As a result, there is decreasing in the total exergy destruction of the system with increasing of the low Pressure Generator temperature. The decreasing in the total exergy destruction of the system is reflected to the first and second laws efficiency as increasing. Within the system components, there is decreasing in the exergy destruction of the high and low Pressure Generator and there is increasing in the exergy destruction of the absorber. The decreasing in exergy destruction of heat exchangers providing heat recovery is observed.

  • Performance Assessment and Solution Procedure for Series Flow Double-Effect Absorption Refrigeration Systems Under Critical Operating Constraints
    Arabian Journal for Science and Engineering, 2019
    Co-Authors: Ibrahim Halil Yilmaz, Kenan Saka, Ömer Kaynaklı, Önder Kaşka
    Abstract:

    In this study, the effects of critical operational constraints on the operational domain of a double-effect lithium bromide/water absorption refrigeration system and its performance were investigated. These constraints were determined as the equivalence state of concentrations, the thermal unbalance between the system components of high-Pressure condenser and low-Pressure Generator, freezing and crystallization risk of lithium bromide/water solution. For the system analysis, a simulation program was developed, and its detailed solution procedure was presented. The program outputs were initially validated with the literature. Subsequently, parametric studies were conducted for broad ranges of the component temperatures. The results demonstrate that the considered constraints were essential for acceptable design and the operational control of double-effect absorption refrigeration systems. The simulations will help to figure out under which operating conditions a double-effect absorption refrigeration system functions effectively and what kind of control strategies are essentially required to increase the coefficient of performance. Based on the operation scenario of fixed high-Pressure Generator temperature, the proposed system can enhance the coefficient of performance up to 31% and 84% as compared to its counterparts which function under the variable high-Pressure Generator temperature and the pinch point temperature difference (5 K between the high-Pressure condenser and the low-Pressure Generator), respectively.

  • A Thermodynamic View of Triple-effect Absorption Refrigeration Systems
    2017
    Co-Authors: Kenan Saka, Ibrahim Halil Yilmaz, Taha Tuna Goksu
    Abstract:

    Today, the need for energy is at the forefront of the most important problems of mankind. The increasing energy security problem has even brought about system designs that have negative effects on the environment, the clean energy requirement has come out the systems operating with waste heat or solar energy. Absorption refrigeration systems are energy-saving systems, which reduce the electricity consumption to a minimum compared to vapor compression systems. There are many different designs on absorption refrigeration systems in the literature. The developed designs are advancing as single, double and triple effects as the system performance is considered. The increase in the number of effects increases the performance of absorption systems, as well as the number of system components used, which leads to more complicated and more precisely controlled systems. In this study, the thermodynamic analysis of a triple effect series flow lithium bromide-water absorption refrigeration system was made using the Engineering Equation Solver (EES) program, and the obtained simulation results was verified with the literature. Moreover, the effect and effectiveness of heat exchangers on the system performance were shown based on the capacity variations of the system components. It was shown that the coefficient of performance (COP) increases with the increase of the low Pressure Generator temperature and decreases with the increase of the high Pressure Generator and medium Pressure Generator temperatures. The increase in the condenser and absorber temperatures was found to have an adverse effect on the COP.