VRV, VAV, VWV, KRV Concepts and Differences
DATE:2024-07-02
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MRV: fully variable multi-connected central air conditioning, the realization is also a variable refrigerant flow system (there are some manufacturers named MDV, GMV, etc.)
VRV: variable refrigerant flow system air conditioning, VRV technology is represented by Daikin, so this name was registered by Daikin. And now we as refrigeration HVAC people, need to pay attention to the usual for the variable refrigerant flow system of English abbreviation, that is, VRF.
1, VRV terminology
VRV system for variable refrigerant flow multi-connected system, that is, control the refrigerant flow and through the direct evaporation of refrigerant or direct condensation to achieve cooling or heating of the air conditioning system.
VRV was invented by Daikin in the 1980s as a variable refrigerant flow system. Since the VRV system only delivers refrigerant to the split unit in each room, there is no need to design a separate air duct (the fresh air system arranges a separate air duct), which achieves miniaturization and quietness of the equipment. The system structure is similar to the split air conditioning unit, using an outdoor unit corresponding to a group of indoor units (generally up to 16 units). The control technology adopts frequency conversion control mode, which controls the speed of the scroll compressor in the outdoor unit according to the number of indoor units opened to control the refrigerant flow.
VRV air-conditioning system and all-air system, all-water system, air - water system, compared to meet the user's individual requirements for the use of equipment occupying a smaller building space, and more energy-efficient.
VRV air conditioning system design contains two parts: 1) air conditioning equipment selection and air conditioning piping design; 2) air conditioning system control design.
2, VAV terminology
VAV Variable Air Volume Air Conditioning System, like Constant Air Volume Air Conditioning System, Variable Air Volume Air Conditioning System is also a kind of air conditioning of the whole air system, which controls and regulates the temperature of a certain air conditioning area by changing the volume of the air supply instead of the temperature of the air supply, so as to adapt with the change of the load of the air conditioning area.
The working principle is that when the load of the air-conditioning zone changes, the end device of the system automatically adjusts the air supply into the room to ensure that the indoor temperature stays within the design range, which makes the air handling unit's air supply drop in low load, and the air handling unit's air blower speed decreases accordingly to achieve the purpose of energy saving. Variable air volume (VAV) systems are usually composed of air handling units, air supply (return) systems, end devices (variable air volume boxes) and air supply outlets and automatic control instruments.
Generally, VAV system is suitable for the following systems: 1) In the same air-conditioning air system, the air-conditioning zones have large differences and changes in heat and cold, load, low load operation time is longer, and need to control the air-conditioning zones temperature separately. 2) Cold air needs to be sent throughout the year to the inner area of the building.
3, VWV terminology
VWV air conditioning variable water volume system, design compared to the variable air volume system (VAV), domestic and foreign research earlier and more mature technology, VWV and VAV have many similar or even the same characteristics, in specific engineering practice, and even can be used "the same" control strategy.
For example: VWV system of variable frequency static pressure control and VAV system of variable frequency static pressure control on the same reason; and if the automated control system can easily "capture" to the VWV system valve opening (just add a valve sensor), then the same can be realized in the VWV system of variable static pressure control. And then if the automatic control system can be timely "measure" the flow of the VWV system at each end, then we can also realize the VWV system of total water control.
4, KRV terminology
KRV fresh air ventilator - total heat exchanger. The core device of KRV is the total heat exchanger, the dirty air discharged indoors and the fresh air sent in from outdoors exchange temperature through the heat transfer plate, and at the same time exchange humidity through the microporous exchange of the plate, so as to achieve the effect of both ventilating and maintaining the stability of indoor temperature and humidity. This is the total heat exchange process.
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VRV: variable refrigerant flow system air conditioning, VRV technology is represented by Daikin, so this name was registered by Daikin. And now we as refrigeration HVAC people, need to pay attention to the usual for the variable refrigerant flow system of English abbreviation, that is, VRF.
1, VRV terminology
VRV system for variable refrigerant flow multi-connected system, that is, control the refrigerant flow and through the direct evaporation of refrigerant or direct condensation to achieve cooling or heating of the air conditioning system.
VRV was invented by Daikin in the 1980s as a variable refrigerant flow system. Since the VRV system only delivers refrigerant to the split unit in each room, there is no need to design a separate air duct (the fresh air system arranges a separate air duct), which achieves miniaturization and quietness of the equipment. The system structure is similar to the split air conditioning unit, using an outdoor unit corresponding to a group of indoor units (generally up to 16 units). The control technology adopts frequency conversion control mode, which controls the speed of the scroll compressor in the outdoor unit according to the number of indoor units opened to control the refrigerant flow.
VRV air-conditioning system and all-air system, all-water system, air - water system, compared to meet the user's individual requirements for the use of equipment occupying a smaller building space, and more energy-efficient.
VRV air conditioning system design contains two parts: 1) air conditioning equipment selection and air conditioning piping design; 2) air conditioning system control design.
2, VAV terminology
VAV Variable Air Volume Air Conditioning System, like Constant Air Volume Air Conditioning System, Variable Air Volume Air Conditioning System is also a kind of air conditioning of the whole air system, which controls and regulates the temperature of a certain air conditioning area by changing the volume of the air supply instead of the temperature of the air supply, so as to adapt with the change of the load of the air conditioning area.
The working principle is that when the load of the air-conditioning zone changes, the end device of the system automatically adjusts the air supply into the room to ensure that the indoor temperature stays within the design range, which makes the air handling unit's air supply drop in low load, and the air handling unit's air blower speed decreases accordingly to achieve the purpose of energy saving. Variable air volume (VAV) systems are usually composed of air handling units, air supply (return) systems, end devices (variable air volume boxes) and air supply outlets and automatic control instruments.
Generally, VAV system is suitable for the following systems: 1) In the same air-conditioning air system, the air-conditioning zones have large differences and changes in heat and cold, load, low load operation time is longer, and need to control the air-conditioning zones temperature separately. 2) Cold air needs to be sent throughout the year to the inner area of the building.
3, VWV terminology
VWV air conditioning variable water volume system, design compared to the variable air volume system (VAV), domestic and foreign research earlier and more mature technology, VWV and VAV have many similar or even the same characteristics, in specific engineering practice, and even can be used "the same" control strategy.
For example: VWV system of variable frequency static pressure control and VAV system of variable frequency static pressure control on the same reason; and if the automated control system can easily "capture" to the VWV system valve opening (just add a valve sensor), then the same can be realized in the VWV system of variable static pressure control. And then if the automatic control system can be timely "measure" the flow of the VWV system at each end, then we can also realize the VWV system of total water control.
4, KRV terminology
KRV fresh air ventilator - total heat exchanger. The core device of KRV is the total heat exchanger, the dirty air discharged indoors and the fresh air sent in from outdoors exchange temperature through the heat transfer plate, and at the same time exchange humidity through the microporous exchange of the plate, so as to achieve the effect of both ventilating and maintaining the stability of indoor temperature and humidity. This is the total heat exchange process.