A simple model for falling film absorption on vertical tubes in the presence of non-absorbables

Marc Medrano, Mahmoud Bourouis, Horacio Perez-Blanco, Alberto Coronas

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    Most water-lithium bromide (LiBr) absorption chillers have a purge system to remove non-absorbable gases that cause a reduction in cooling capacity. Generally, the non-absorbables are originated in corrosion/passivation processes inside the machine, but leaks can also be a source of concern. However, since leaks must be corrected immediately to avoid machine deterioration, this study is mostly aimed at the non-absorbables evolved during operation. This paper analyses the effect of inlet non-absorbable air concentration, outlet purge velocity, absorber pressure and cooling water temperature on the falling film absorption process inside a vertical tube absorber, based on a simple transport coefficient model. This model consists of three ordinary differential equations solved with as method for initial-value problem, and a set of auxiliary equations. The study shows that the effect of non-absorbables can be significant, and furthermore provides a quantitative framework to aid in purge design. The nominal working conditions in this study were a solution Reynolds number of 100, an absorber pressure of 1.3 kPa, a cooling water temperature of 35 °C and an inlet solution concentration of 62% LiBr by weight. The results indicate that a minimum vapour velocity is required to sweep the non-absorbables along the absorber towards the purge, thus preventing reduced absorption fluxes. At a cooling water temperature of 35 °C, an inlet air concentration of 20% (by mole) resulted in a 61% reduction in mass absorption flux.

    Original languageEnglish (US)
    Pages (from-to)108-116
    Number of pages9
    JournalInternational Journal of Refrigeration
    Volume26
    Issue number1
    DOIs
    StatePublished - Jan 1 2003

    Fingerprint

    Cooling water
    Lithium
    Fluxes
    Initial value problems
    Air intakes
    Passivation
    Ordinary differential equations
    Temperature
    Deterioration
    Reynolds number
    Vapors
    Corrosion
    Cooling
    Air
    Gases
    Water

    All Science Journal Classification (ASJC) codes

    • Building and Construction
    • Mechanical Engineering

    Cite this

    Medrano, Marc ; Bourouis, Mahmoud ; Perez-Blanco, Horacio ; Coronas, Alberto. / A simple model for falling film absorption on vertical tubes in the presence of non-absorbables. In: International Journal of Refrigeration. 2003 ; Vol. 26, No. 1. pp. 108-116.
    @article{d224536aac37476190944a5a3b8457af,
    title = "A simple model for falling film absorption on vertical tubes in the presence of non-absorbables",
    abstract = "Most water-lithium bromide (LiBr) absorption chillers have a purge system to remove non-absorbable gases that cause a reduction in cooling capacity. Generally, the non-absorbables are originated in corrosion/passivation processes inside the machine, but leaks can also be a source of concern. However, since leaks must be corrected immediately to avoid machine deterioration, this study is mostly aimed at the non-absorbables evolved during operation. This paper analyses the effect of inlet non-absorbable air concentration, outlet purge velocity, absorber pressure and cooling water temperature on the falling film absorption process inside a vertical tube absorber, based on a simple transport coefficient model. This model consists of three ordinary differential equations solved with as method for initial-value problem, and a set of auxiliary equations. The study shows that the effect of non-absorbables can be significant, and furthermore provides a quantitative framework to aid in purge design. The nominal working conditions in this study were a solution Reynolds number of 100, an absorber pressure of 1.3 kPa, a cooling water temperature of 35 °C and an inlet solution concentration of 62{\%} LiBr by weight. The results indicate that a minimum vapour velocity is required to sweep the non-absorbables along the absorber towards the purge, thus preventing reduced absorption fluxes. At a cooling water temperature of 35 °C, an inlet air concentration of 20{\%} (by mole) resulted in a 61{\%} reduction in mass absorption flux.",
    author = "Marc Medrano and Mahmoud Bourouis and Horacio Perez-Blanco and Alberto Coronas",
    year = "2003",
    month = "1",
    day = "1",
    doi = "10.1016/S0140-7007(02)00015-4",
    language = "English (US)",
    volume = "26",
    pages = "108--116",
    journal = "International Journal of Refrigeration",
    issn = "0140-7007",
    publisher = "Elsevier Limited",
    number = "1",

    }

    A simple model for falling film absorption on vertical tubes in the presence of non-absorbables. / Medrano, Marc; Bourouis, Mahmoud; Perez-Blanco, Horacio; Coronas, Alberto.

    In: International Journal of Refrigeration, Vol. 26, No. 1, 01.01.2003, p. 108-116.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - A simple model for falling film absorption on vertical tubes in the presence of non-absorbables

    AU - Medrano, Marc

    AU - Bourouis, Mahmoud

    AU - Perez-Blanco, Horacio

    AU - Coronas, Alberto

    PY - 2003/1/1

    Y1 - 2003/1/1

    N2 - Most water-lithium bromide (LiBr) absorption chillers have a purge system to remove non-absorbable gases that cause a reduction in cooling capacity. Generally, the non-absorbables are originated in corrosion/passivation processes inside the machine, but leaks can also be a source of concern. However, since leaks must be corrected immediately to avoid machine deterioration, this study is mostly aimed at the non-absorbables evolved during operation. This paper analyses the effect of inlet non-absorbable air concentration, outlet purge velocity, absorber pressure and cooling water temperature on the falling film absorption process inside a vertical tube absorber, based on a simple transport coefficient model. This model consists of three ordinary differential equations solved with as method for initial-value problem, and a set of auxiliary equations. The study shows that the effect of non-absorbables can be significant, and furthermore provides a quantitative framework to aid in purge design. The nominal working conditions in this study were a solution Reynolds number of 100, an absorber pressure of 1.3 kPa, a cooling water temperature of 35 °C and an inlet solution concentration of 62% LiBr by weight. The results indicate that a minimum vapour velocity is required to sweep the non-absorbables along the absorber towards the purge, thus preventing reduced absorption fluxes. At a cooling water temperature of 35 °C, an inlet air concentration of 20% (by mole) resulted in a 61% reduction in mass absorption flux.

    AB - Most water-lithium bromide (LiBr) absorption chillers have a purge system to remove non-absorbable gases that cause a reduction in cooling capacity. Generally, the non-absorbables are originated in corrosion/passivation processes inside the machine, but leaks can also be a source of concern. However, since leaks must be corrected immediately to avoid machine deterioration, this study is mostly aimed at the non-absorbables evolved during operation. This paper analyses the effect of inlet non-absorbable air concentration, outlet purge velocity, absorber pressure and cooling water temperature on the falling film absorption process inside a vertical tube absorber, based on a simple transport coefficient model. This model consists of three ordinary differential equations solved with as method for initial-value problem, and a set of auxiliary equations. The study shows that the effect of non-absorbables can be significant, and furthermore provides a quantitative framework to aid in purge design. The nominal working conditions in this study were a solution Reynolds number of 100, an absorber pressure of 1.3 kPa, a cooling water temperature of 35 °C and an inlet solution concentration of 62% LiBr by weight. The results indicate that a minimum vapour velocity is required to sweep the non-absorbables along the absorber towards the purge, thus preventing reduced absorption fluxes. At a cooling water temperature of 35 °C, an inlet air concentration of 20% (by mole) resulted in a 61% reduction in mass absorption flux.

    UR - http://www.scopus.com/inward/record.url?scp=0037211753&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=0037211753&partnerID=8YFLogxK

    U2 - 10.1016/S0140-7007(02)00015-4

    DO - 10.1016/S0140-7007(02)00015-4

    M3 - Article

    AN - SCOPUS:0037211753

    VL - 26

    SP - 108

    EP - 116

    JO - International Journal of Refrigeration

    JF - International Journal of Refrigeration

    SN - 0140-7007

    IS - 1

    ER -