VARIABLE REFRIGERATE FLOW
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Variable refrigerant flow (VRF) systems allow for individual temperature control of multiple indoor units connected to a single outdoor unit. VRF systems can operate in cooling-only mode, heat pump mode for both heating and cooling, or heat recovery mode which allows simultaneous heating and cooling. VRF systems offer advantages like energy savings, precise temperature control, and zoning capabilities. However, their initial costs are high compared to conventional HVAC systems. VRF technology provides an energy efficient option for heating and cooling buildings with varied internal loads like hotels, schools, and offices.
VARIABLE REFRIGERATE FLOW
- 1. BUILDING SERVICES SEMESTER – VII VARIABLE REFRIDGERANT FLOW (VRV) SYSTEM SUBMITTED BY:- RIDDHESH RAJENDRA VARIK 15SA31 4TH YEAR B.ARCH ST.WILFRED’S INSTITUTE OF ARCHITECTURE SUBMITTED TO:- AR.SIDDHARTH SHARMA SIR
- 2. SR.NO TOPIC PAGE.NO 1 INTRODUCTION 1 2 MULTIPLE SPLIT SYSTEMS 2 3 SPLITAIR CONDITIONERS 3 4 VARIABLE REFRIDGERATE FLOW SYSTEMS 4 5 VRF HEAT PUMP SYSTEMS 5 6 HEAT RECOVERYVRF SYSTEM 6 7 APPLICATIONS 7 8 ADVANTAGESAND LIMITATIONS 8 9 CONCLUSION 9 INDEX
- 3. INTRODUCTION • CONTROLLED REFRIGERANT IS SUPPLIED IN THE EVAPORATOR UNIT AS PER LOAD REQUIREMENT. • NO INTERMEDIATE MEDIUM FOR THE HEAT EXCHANGE WHICH MAKES IT EFFICIENT. • IN A VRF SYSTEM, MULTIPLE INDOOR FAN COIL UNITS MAY BE CONNECTED TO ONE OUTDOOR UNIT. HISTORY: • VARIABLE REFRIGERANT FLOW (VRF), ALSO KNOWN AS VARIABLE REFRIGERANT VOLUME (VRV), IS INVENTED IN JAPAN BY DAIKIN COMPANY IN 1982. • DAIKIN HAD REGISTERED THE VRV TERM AS AN OFFICIAL TRADEMARK. ALL OTHER COMPANIES USE VRF FOR THEIR SIMILAR HVAC SYSTEMS. • EVENTUALLY, VRF IS THE MORE COMMON TERM FOR THESE TYPES OF SYSTEMS, AND THIS IS THE TERM THAT WILL BE USED FOR THE REST OF THE ARTICLE. 1
- 4. MULTI SPLIT SYSTEMS • THERE ARE MULTIPLE EVAPORATOR UNITS CONNECTED TO ONE EXTERNAL CONDENSING UNIT. THESE TYPE OF SYSTEMS WERE DESIGNED MAINLY FOR SMALL TO MEDIUM COMMERCIAL APPLICATIONS. • EACH INDOOR UNIT HAS ITS OWN SET OF REFRIGERANT PIPE WORK CONNECTING IT TO THE OUTDOOR UNIT. ADVANTAGES OF MULTI-SPLITS: • NO NEED OF DUCT WORK INSTALLATION. • SYSTEM EFFICIENCY IMPROVES THEN INDIVIDUAL SPLIT UNIT. • MULTI-SPLITS ARE SUITABLE FOR SINGLE THERMAL ZONE APPLICATIONS I.E. EITHER FOR COOLING MODE OR HEAT MODE. DRAWBACKS: • MAIN DRAWBACK IS THAT INDIVIDUAL SYSTEM CONTROL NOT POSSIBLE. • IN THIS SYSTEMS WHOLE SYSTEM WILL TURN OFF OR ON COMPLETELY IN RESPONSE TO A SINGLE THERMOSTAT. THESE SYSTEMS ARE THEREFORE NOT SUITABLE FOR AREAS/ROOMS WITH VARIABLE HEAT GAIN/LOSS CHARACTERISTICS 2
- 5. SPLIT AIR CONDITIONING • IT CONSISTS OF ONE INDOOR UNIT ALONG WITH AN OUTDOOR UNIT CONSTITUTE A SINGLE SPLIT AC. SOURCE-CARRIER ADVANTAGES : • THESE AC’S HAVE LOW INITIAL COST • EASE OF INSTALLATION • NO DUCTING REQUIRED • EACH SYSTEM HAVE OWN CONTROL. DISADVANTAGES : • DISTANCE BETWEEN INDOOR AND OUTDOOR UNIT SHOULD NOT BE GREATER THAN 100- 150 FT OTHERWISE THE PERFORMANCE WILL SUFFER. • LIMITED AIR THROW 3
- 6. VARIABLE REFRIGERANT FLOW SYSTEM • ADJUST COOLING AND HEATING BY ADJUSTING REFRIGERANT FLOW AND VARIABLE SPEED COMPRESSOR . INDOOR UNITS CAN BE IN DIFFERENT MODES . • VRF SYSTEMS ARE EQUIPPED WITH ENHANCED FEATURES LIKE INVERTER DRIVES, PULSE MODULATING ELECTRONIC EXPANSION VALVES AND DISTRIBUTED CONTROLS. TYPES OF VRF SYSTEMS : • COOLING ONLY SYSTEMS : THOSE SYSTEMS CAN ONLY COOL. HEATING IS NOT AVAILABLE. FAN AND DRY MODES ARE AVAILABLE FOR EACH INDOOR UNIT INDEPENDENTLY. • HEAT PUMP SYSTEMS : ALL THE INDOOR UNITS CAN EITHER HEAT OR COOL . FAN AND DRY MODES ARE AVAILABLE FOR EACH INDOOR UNIT INDEPENDENTLY. • HEAT RECOVERY SYSTEMS : THESE SYSTEMS ARE THE MOST SOPHISTICATED ONES, WHERE COOLING AND HEATING MAY BE AVAILABLE BY EACH INDOOR UNIT, INDEPENDENTLY, AT THE SAME TIME. 4
- 7. VRF HEAT PUMP SYSTEMS • VRF HEAT PUMP SYSTEMS PERMIT HEATING OR COOLING IN ALL OF THE INDOOR UNITS BUT NOT SIMULTANEOUS HEATING AND COOLING. • WHEN THE INDOOR UNITS ARE IN THE COOLING MODE, THEYACT AS EVAPORATORS; WHEN THEYARE IN THE HEATING MODE, THEYACT AS CONDENSERS. • THESE ARE ALSO KNOWN AS TWO-PIPE SYSTEMS. 5
- 8. HEAT RECOVERY VRF SYSTEM 6
- 9. APPLICATIONS • VRF SYSTEMS MAY BE A PARTICULARLY GOOD OPTION FOR BUILDINGS WITH MULTIPLE ZONES OR WIDE VARIANCE HEATING/COOLING LOADS ACROSS MANY DIFFERENT INTERNAL ZONES. • THESE SYSTEMS PROVIDE INDIVIDUAL CONTROL AND ARE THE MOST VERSATILE OF THE MULTI- SPLIT SYSTEMS. HOTELS, SCHOOLS AND OFFICE BUILDINGS ARE GOOD EXAMPLES. 7
- 10. ADVANTAGES : • ENERGY SAVING CLAIMED UP TO 40 %. • SPACE SAVING • LESSER NOISE • PRECISE TEMPERATURE CONTROL • SIMULTANEOUS HEATING AND COOLING (THREE-PIPE VRF HEAT RECOVERY SYSTEM ONLY) • HEAT RECOVERY • ZONED COMFORT LIMITATIONS : • INITIAL COST IS HIGH ,SINCE ADDITIONAL BACKUP UNIT IS NEEDED • SEPARATE VENTILATION SYSTEM • REFRIGERANT PIPING • ENVIRONMENTAL CONCERNS • FOR HIGH RISE BUILDING THE SYSTEM CANNOT BE USED 8
- 11. CONCLUSION • THE VARIABLE REFRIGERANT FLOW SYSTEM IS CONSIDERED TO BE ONE OF THE MOST PROMISING ENERGY SAVING TECHNOLOGIES GAINING ITS MOMENTUM IN RECENT YEARS. • A VIABLE ENERGY EFFICIENT TECHNOLOGY IS NEEDED TO CONSERVE ENERGY AS WELL AS TO ACHIEVE BETTER HUMAN COMFORT. • SO THIS IS BEEN RELATIVELY NEW AND EFFICIENT WAY TO DESIGN HVAC SYSTEM WITH VRF TECHNOLOGY. 9