Flash Gas Bypass (FGB) was implemented in an R134a mobile air conditioning (MAC) system with a single pass microchannel evaporator. An experimental comparison to a conventional direct expansion system was conducted using the same components and under the same operating conditions. At the same compressor speed, the cooling capacity in FGB mode increased about 13%-18% over DX mode while COP increased about 4%-7%. When the cooling capacity is matched by adjusting the compressor speed, the COP improvement was 37%-58% higher when compared to the DX mode. The primary reason for the improved performance of this system in the FGB mode is due to more uniform refrigerant distribution. Superheated zone in the evaporator is reduced and the heat transfer rate is higher than that in the DX mode, which results in higher cooling capacity, higher evaporating temperature and thus higher efficiency (COP). Another benefit is reduced refrigerant pressure drop across the evaporator. Although due to the low pressure drop in the DX mode this contribution for this evaporator is relatively small when compared to the improved heat transfer, this will be more beneficial when using a compact microchannel evaporator with high pressure drops. The magnitude of performance improvement due to the improved refrigerant distribution and the reduced refrigerant-side pressure drop strongly depends on the evaporator design, quality and relative size of the components of the system. Systems with relatively small evaporator compared to condenser and compressor will benefit more from FGB and vice versa is true: systems with oversized evaporators and good distribution will see less effect.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Flash gas bypass in mobile air conditioning system with R134a


    Beteiligte:
    Tuo, Hanfei (Autor:in) / Hrnjak, Pega (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2012


    Format / Umfang :

    9 Seiten, 12 Bilder, 2 Tabellen, 18 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch