vfr by michael asham

7/24/2019 VFR by Michael Asham

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1jjhnpg. 0

enda University

houbra faculty of

engineering

Mech. Power

Variable RefrigerationFlow (VRF) Air Condition

System

Under Supervision:

Dr !A"# $%SA

Dire'ted y*+ ) ,-C!A$% AS!A, R-./

Se' Five


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Variable refrigerant ow !V"#$ syste%s& which

were introduced in 'apan %ore than (0 years ago&

have beco%e popular in %any countries& yet they

are relatively un)nown in the United States. *he

technology has gradually e+panded its %ar)etpresence& reaching ,uropean %ar)ets in 1-/& and

steadily gaining %ar)et share throughout the

world. n 'apan& V"# syste%s are used in

appro+i%ately 02 of %ediu%3si4ed co%%ercial

buildings !up to /0&000 ft( 5600 %(7$ and one3

third of large co%%ercial buildings !%ore than600 %(7$.

Variable refrigerant ow

(VRF)

s an air3condition syste% con8guration where

there is one outdoor condensing unit and %ultiple

indoor units. *he ter% variable refrigerant ow

refers to the ability of the syste% to control the

a%ount of refrigerant owing to the %ultipleevaporators !indoor units$& enabling the use of

%any evaporators of di9ering capacities and

con8gurations connected to a single condensing

unit. *he arrange%ent provides an individuali4ed


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co%fort control& and si%ultaneous heating and

cooling in di9erent 4ones.

Cooling type VRF system

Types of VRF

VRV/VRF systems can be used for cooling only, heat

pumping or heat recovery. On heat pump models there are

two basic types of VRF system: heat pump systems and

energyrecovery.

Appli'ations

V"# syste%s are generally best suited to buildings

with diverse& %ultiple 4ones re:uiring individual

control& such as o;ce buildings& hospitals& or


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hotels. < V"# syste% does not co%pete well with

rooftop syste%s in a large low3rise building such as

a big bo+ retail store.

Energy Savings

All VRFsystems provide energy savings by varying compressor

speed and matching the output of the system as closely as

possible to the load. In addition, VRF systems do not experience

the same energy losses as systems that move conditioned air

through ductwork. owever, differences in design in the

available outdoor units will influence the efficiency level that isachieved.

VRF ADVANTAGES

Comfort

*he %ain advantage of a variable refrigerantow syste% is its ability to respondindividually to uctuations in space loadconditions. *he user can set the a%bientte%perature of each roo% as per his=herre:uire%ents and the syste% willauto%atically adjust the refrigerant ow to

suit the re:uire%ent

V"# syste%s enable wide capacity %odulation

and bring roo%s to the desired te%peraturee+tre%ely :uic)ly and )eep te%perature


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uctuations to %ini%u%. *he technologyo9ers e+cellent dehu%idi8cation perfor%ancefor opti%al roo% hu%idity regardless ofoutside conditions.

V"# syste%s are capable of si%ultaneous

cooling and heating. ,ach individual indoor unitcan be controlled by a progra%%able

ther%ostat.

V"# syste%s can generate separate billing that

%a)es individuali4ed billing easier


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Reduced Noise Levelsndoor and outdoor units are so :uiet that they canbe placed just about anywhere& providing %oree+ibility on how to use indoor and outdoor space.ndoor ductless operating sound levels are as lowas (/dB !


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Maintenance and Commissioning

A V"# syste%s with their standardi4edcon8gurations and sophisticated electroniccontrols are ai%ing toward near plug3and3playco%%issioning. or%al %aintenance for a V"#syste% is si%ilar to that of any CD syste% andconsists %ainly of changing 8lters and cleaningcoils.

A Because there are no water pu%ps to %aintainor air ducts to be cleaned& less %aintenance isre:uired co%pared to other technologies.

Size of Units

!he si"e of the units selected must be considered for impact on

the design of the system# smaller units will provide flexibility of

"oning and re$uire less piping and less refrigerant per system.


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vfr by michael asham

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