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اريد المساعدة الفرق بين vrv and multi system

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  1. [1]
    experts
    experts غير متواجد حالياً

    عضو فعال

    تاريخ التسجيل: Mar 2009
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  2. [2]
    م/زيكو تك
    م/زيكو تك غير متواجد حالياً
    عضو متميز
    الصورة الرمزية م/زيكو تك


    تاريخ التسجيل: Nov 2007
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    لا فرق عمليا ولكن نظريا الانظمه الصغيره منها تعرف بmulti system وتختلف عدد الوحدات الداخليه لها حسب المنتج او المصنّع فمنها 4 ومنا 8
    وهذا شرح لها من ashrea 2008

    VARIABLE-REFRIGERANT-FLOW HEAT PUMPS
    A variable-refrigerant-flow (VRF) system typically consists of a
    condensing section housing compressor(s) and condenser heat
    exchanger interconnected by a single set of refrigerant piping to
    multiple indoor direct-expansion (DX) evaporator fan-coil units.
    Thirty or more DX fan coil units can be connected to a single condensing
    section, depending on system design, and with capacity
    ranging from 0.5 to 8 tons.
    The DX fan coils are constant air volume, but use variable refrigerant
    flow through an electronic expansion valve. The electronic
    expansion valve reacts to several temperature-sensing devices such
    as return air, inlet and outlet refrigerant temperatures, or suction
    pressure. The electronic expansion valve modulates to maintain the
    desired set point.
    Application
    VRF systems are most commonly air-to-air, but are also available
    in a water-source (water-to-refrigerant) configuration. They
    can be configured for simultaneous heating and cooling operation
    (some indoor fan coil units operating in heating and some in cooling,
    depending on requirements of each building zone).
    Indoor units are typically direct-expansion evaporators using
    individual electronic expansion devices and dedicated microprocessor
    controls for individual control. Each indoor unit can be controlled
    by individual thermostat. The outdoor unit may connect
    several indoor evaporator units with capacities 130% or more than
    the outdoor condensing unit capacity.
    Categories
    VRF equipment is divided into three general categories: residential,
    light commercial, and applied. Residential equipment is singlephase
    unitary equipment with a cooling capacity of 65,000 Btu/h or
    less. Light commercial equipment is generally three-phase, with
    cooling capacity greater than 65,000 Btu/h, and is designed for
    small businesses and commercial properties. Applied equipment
    has cooling capacity higher than 135,000 Btu/h and is designed for
    large commercial buildings.
    Refrigerant Circuit and Components
    VRF heat pump systems use a two-pipe (liquid and suction gas)
    system; simultaneous heat and cool systems use the same system, as
    well as a gas flow device that determines the proper routing of
    refrigerant gas to a particular indoor unit.
    VRF systems use a sophisticated refrigerant circuit that monitors
    mass flow, oil flow, and balance to ensure optimum performance.
    This is accomplished in unison with variable-speed compressors
    and condenser fan motors. Both of these components adjust their
    frequency in reaction to changing mass flow conditions and refrigerant
    operating pressures and temperatures. A dedicated microprocessor
    continuously monitors and controls these key components to
    ensure proper refrigerant is delivered to each indoor unit in cooling
    or heating.
    Heating and Defrost Operation
    In heating mode, VRF systems typically must defrost like any
    mechanical heat pump, using reverse cycle valves to temporarily
    operate the outdoor coil in cooling mode. Oil return and balance
    with the refrigerant circuit is managed by the microprocessor to
    ensure that any oil entrained in the low side of the system is brought
    back to the high side by increasing the refrigerant velocity using a
    high-frequency operation performed automatically based on hours
    of operation.


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  3. [3]
    م علي حسن
    م علي حسن غير متواجد حالياً
    جديد


    تاريخ التسجيل: Apr 2010
    المشاركات: 4
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    والله أنت رائع يا م / زيكو

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