A detachable plate falling film generator and condenser coupling using lithium bromide and water as working fluids

Mathematical model of conjugated heat and mass transfer in absorption on the entrance region of the semi-infinite liquid film of lithium bromide water solution is investigated for different values of Froude number. The calculations shown that larger values of Froude number corresponds to a smaller thickness of the falling film. It was demonstrated that for large values of the Froude number the heat transfer from the surface is greater than for smaller values.

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Effects of a Nonabsorbable Gas on Interfacial Heat and Mass Transfer for the Entrance Region of a Falling Film Absorber

Journal of Solar Energy Engineering ◽

10.1115/1.2847928 ◽

1996 ◽

Vol 118 (1) ◽

pp. 45-49 ◽

Cited By ~ 10

Author(s):

T. A. Ameel ◽

H. M. Habib ◽

B. D. Wood

Keyword(s):

Mass Transfer ◽

Water Vapor ◽

Analytical Solution ◽

Liquid Film ◽

Heat And Mass Transfer ◽

Vertical Wall ◽

Lithium Bromide ◽

Entrance Region ◽

Falling Film ◽

Aqueous Lithium Bromide

An analytical solution is presented for the effect of air (nonabsorbable gas) on the heat and mass transfer rates during the absorption of water vapor (absorbate) by a falling laminar film of aqueous lithium bromide (absorbent), an important process in a proposed open-cycle solar absorption cooling system. The analysis was restricted to the entrance region where an analytical solution is possible. The model consists of a falling film of aqueous lithium bromide flowing down a vertical wall which is kept at uniform temperature. The liquid film is in contact with a gas consisting of a mixture of water vapor and air. The gas phase is moving under the influence of the drag from the falling liquid film. The governing equations are written with a set of interfacial and boundary conditions and solved analytically for the two phases. Heat and mass transfer results are presented for a range of uniform inlet air concentrations. It was found that the concentration of the nonabsorbable gas increases sharply at the liquid gas interface. The absorption of the absorbate in the entrance region showed a continuous reduction with an increase in the amount of air.

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Effect of Ejector Location in Absorption Refrigeration Cycles Using Different Binary Working Fluids

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132519500032 ◽

2019 ◽

Vol 27 (01) ◽

pp. 1950003 ◽

Cited By ~ 2

Author(s):

Salem Yosaf ◽

Hasan Ozcan

Keyword(s):

Performance Enhancement ◽

Water Solution ◽

Lithium Bromide ◽

Cycle Performance ◽

Refrigeration Cycle ◽

Absorption Refrigeration ◽

Working Fluids ◽

Steam Ejector ◽

Thermodynamic Performance ◽

Chloride Water

In this study, three novel modifications of ejector-absorption refrigeration cycles (E-ARC) are investigated to evaluate the effect of ejector location on cycle performances. In the first modification (triple pressure level absorption refrigeration cycle TPL-ARC), the ejector is located at the evaporator inlet. In the second modification (double ejector absorption refrigeration cycle DE-ARC), two ejectors are used; one is located at the evaporator inlet and the other at the absorber inlet, which are coupled to each other. In the third modification (low pressure condenser absorption refrigeration cycle LPC-ARC), the steam ejector is installed at the downstream of the vapor generator discharging line. An additional flow splitter is integrated to the steam ejector outlet and part of the vapor is extracted and returned to the absorber at a pressure equal to the diffuser pressure. Effect of ejector location on thermodynamic performances are evaluated considering three different working fluids, namely ammonia–water solution (NH3–H2O), lithium bromide-water solution (H2O–LiBr), and lithium chloride–water solution (H2O–LiCl). Even though all three configurations enhance the conventional absorption refrigeration cycle (C-ARC) performances, the LPC-ARCs work at high temperature and improve the cycle performance. The TPL-ARC proves to improve the COP and exergy efficiency up to 9.14% and 7.61%, respectively, presenting the highest thermodynamic performance enhancement and lowest operating temperature.

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ABSIM: Modular Simulation of Advanced Absorption Systems

10.1115/imece1999-0824 ◽

1999 ◽

Author(s):

Gershon Grossman ◽

Abdi Zaltash

Keyword(s):

Lithium Bromide ◽

Computer Code ◽

Operating Conditions ◽

Working Fluid ◽

Main Program ◽

Governing Equations ◽

Working Fluids ◽

State Point ◽

Simulation Results ◽

Cycle Diagram

Abstract The computer code ABSIM has been developed for simulation of absorption systems in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. Based on a user-supplied cycle diagram, working fluid specification and given operating conditions, the program calculates the temperature, flowrate, concentration, pressure and vapor fraction at each state point in the system and the heat duty at each component. The modular structure of the code is based on unit subroutines containing the governing equations for the system’s components. A main program calling these subroutines links the components together according to the cycle diagram. The system of equations for the entire cycle is thus established, and a mathematical solver routine is employed to solve them simultaneously. Property subroutines contained in a separate database serve to provide thermodynamic properties of the working fluids. The paper describes the current capabilities and recent improvements made to ABSIM along with examples of simulation results for several rather complex cycles, including lithium bromide-water double-, triple- and quadruple-effect cycles and ammonia-water GAX, branched GAX and vapor exchange (VX) cycles.

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