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Emerson
 
Definition of VRF systems
VRF systems refer to a system configuration where there is one outdoor condensing unit and multiple indoor units. In a typical Asian style of air-conditioning, there are multiple mini split units that are used in residential applications. Each mini split is used for each individual room and each machine can be turned on or off depending on the room needs. For commercial spaces, either chillers or ducted units are used and depending on the type of system, either cold air is blown through ducts or chilled water is circulated through fan coil units to cool the space. The key point is that the flow of refrigerant in the circuit is either full flow or no flow. The amount of refrigerant that flows is always a constant number. In a VRF system, the amount of refrigerant flow is variable and it depends on the room load. When the room load is high, a larger amount of refrigerant is delivered to the indoor units to provide more cooling/heating and conversely, when the room load is low, lesser refrigerant is provided. |
Imperial Palace Water Park Resort and Spa (Cebu, Philippines) - Air-conditioning systems powered by Copeland Digital Scroll compressor
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The above chart shows a typical VRF configuration – there is one
outdoor unit and it is connected to a variety of indoor units.
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The VRF market has been growing at twice the base market growth rates in most countries around the world. Obviously, there are end user benefits driving this market transition. Energy Savings, Better room temperature control, superior aethestics are the key to success of VRF Technology.
Energy savings: VRF systems deliver only the necessary amount of cooling or heating that is required inside the room. The output of the machine changes depending on the load and when the output is lower, the power consumption is also lower and that leads to energy savings.
Better room temperature control: in normal a/c systems, due to the inherent characteristics of the thermostat and also to prevent repeated cycling of the compressor, the room temperature range can be anywhere between 3 – 5 deg C. This limitation happens because the compressor can only deliver capacity in 2 steps – full capacity or zero capacity. In a VRF system, since the capacity output precisely matches the room load, the room temperature can be controlled very precisely (within 0.5 deg C) and this leads to better end user comfort.
Room by room temperature control: in VRF systems, there are electronic expansion valve mounted on each indoor unit and these valves can be regulated to control the right amount of refrigerant in each room to satisfy the cooling and heating demand. This means that each zone (where the individual indoor units are located) can be set and maintained at different temperatures.
Superior aesthetics: while air-conditioning the space, if several splits units are installed, there are several outdoor units that are mounted on the outside wall. These machines disfigure the aesthetics of the building and are not desirable. In a VRF system, since all the smaller outdoor machines are combined into one outdoor machine, this machine can be hidden while the building design is being made and louvers can be used to ensure that it does not damage the aesthetics of the building.
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VRF systems need a variable capacity compression technology and Digital Scroll is an easier to apply solution for VRF. Digital Scroll provides seamless capacity from 10 – 100% and has several other advantages – better dehumidification capability, zero electromagnetic interference, proven field reliability and above all, a very simple electronic and mechanical architecture to apply. The major limitation to the popularity of the VRF systems had been the complexity of the electronic controls and the valves/piping required. Digital Scroll has simplified the product design dramatically and has allowed OEMs to launch a VRF system reliably in a much shorter period of time.
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