Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented by Daikin Industries, Ltd. in 1982. Similar...

also invented by Daikin in 1982. Both were first sold in Japan. Variable refrigerant flow systems when compared with central plant cooling from an air handler...

A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they...

controls the amount of refrigerant released into the evaporator and is intended to regulate the superheat of the refrigerant that flows out of the evaporator...

be used to control the speed of the compressor motor to drive variable refrigerant flow in a refrigeration or air conditioning system to regulate system...

or refrigerant metering device (RMD) restricts the flow of the liquid refrigerant causing a pressure drop that vaporizes some of the refrigerant; this...

surface gradients are small. Darcy's law is used for flow in porous media, and works with variables averaged over several pore-widths. In rotating systems...

helps to secure the process while providing greater efficiency. Variable refrigerant flow (VRF) VRF units are very popular cooling or reversible systems...

a variable displacement compressor, its displacement; additionally, a secondary valve located on the suction side can throttle the refrigerant flow so...

over-cooling. The air blower's flow rate is variable. For a single VAV air handler that serves multiple thermal zones, the flow rate to each zone must be varied...

VRF may refer to: Variable refrigerant flow, for heating and cooling Verifiable random function, in cryptography Virtual routing and forwarding Vitiligo...

panels A parallel all air variable-air-volume (VAV) systems Packaged unitary water source heat pumps Variable Refrigerant Flow (VRF) systems Fan coil units...

Refrigerant reclamation is the act of processing used refrigerant gas which has previously been used in some type of refrigeration loop to meet the specifications...

refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and...

A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handler, or other air-handling equipment. A damper...

(also called metering device) regulates the refrigerant liquid to flow at the proper rate. The liquid refrigerant is returned to another heat exchanger where...

This type of compressor can compress a wide range of gases, including refrigerant, hydrogen, and natural gas. Because of this, it finds use in a wide range...

humidity control; a ground-source heat pump system (GSHP); and variable refrigerant flow systems with heat recovery. The building also serves as a live...

space conditioning unit from the conditioned space. A refrigerant valve that reverses refrigerant flow to determine whether system is heating or cooling On...

narrow tube; the bubbles of refrigerant gas push the refrigerant-depleted liquid into a higher chamber, from which it will flow by gravity to the absorption...

the refrigerant enters the compressor as a low pressure and low temperature vapor. In heat pumps, this refrigerant is typically R32 refrigerant or R290...

by evaporation of the refrigerant, and released at the other side, by condensation of the refrigerant. Condensed refrigerant flows by gravity to the first...

A gaseous refrigerant is compressed so its pressure and temperature rise. When operating as a heater in cold weather, the warmed gas flows to a heat exchanger...

automatic. Zone dampers provide automatic control in simple systems while variable air volume (VAV) allows control in sophisticated systems. Smoke dampers...

of conduction (heat diffusion) and advection (heat transfer by bulk fluid flow). Convection is usually the dominant form of heat transfer in liquids and...

moving parts made it more reliable; the introduction of Freon to replace refrigerant gases toxic to humans made it even less attractive commercially. The...

technical processes. While humidity itself is a climate variable, it also affects other climate variables. Environmental humidity is affected by winds and by...

height of the building and A is the flow area of the openings. For multi-floor, high-rise buildings, A is the flow area of the openings and h is the distance...

pumps: They can be used for heating and cooling, transferring heat using refrigerant and electricity, making them more efficient than other heating systems...

hoods can affect well-being, and may even contribute to hearing loss. Variable speed fans are generally noisier at higher speeds and different models...