well, parerile sunt impratite in functie de aplicatie , daca ceri parerea unui frigotechnist despre asa ceva , probabil se va "impusca singur in picior" ajungand in penibil precum si un electronist de meserie in fata unui banal volt mod
daca esti cel mai bun mecanic nu insemna ca vei fi si cel mai bun sofer si invers
acum vorbind de aplicatii si facand analogia la ce am scris mai sus , vorbim strict de OC condensing units ,se pot folosi diferite tipuri de compresoare volumice ,tipologia phase change nu este batuta in cuie si nu va fi niciodata ci vorbim de o adaptare( exclud reguliile de saefty la care trebuie sa existe o conformare obligatorie in prealabil precum si normele de executie a unei asemenea unitati dupa normele europene DIN), ne bazam pe feeling-ul builderilor amatori precum si performantele obtinute cu diferite tipuri de compresoare.
un compresor este o masinarie termica prin marirea presiunii( comprimare/presurizare) unui gaz inchis intr-un recipient( ermetic), prin micsorarea volumului sau
deci vorbim de compresoare volumice
pot fi:
-
cu piston( reciproacating)
- cu diafragma
- rotative ( rotary):
*cu surub
*cu palete in motor
* cu angrenaje
*dinamice
*axiale
toate buildurile mele ( si unele nu le-am postat
)au la baza un compresor tip rotativ( da , bucata aia verticala de "tubing" care ii iese o "tatza" dintr-o parte cu aspect de uger
) buildul de fata foloseste alt tip de compresor, dar cu acelasi main target
rotativul a fost introdus pe piata acum ~20 ani ,odata cu termenul de "aer conditionat" care a devinit atat de public si raspandit all over world ,deci vorbim de un design compresor relativ nou care s-a adeverit a fi extrem de eficient folosit in aplicatii LBP( low back pressure) si HBP( hight back pressure).
rotativul mi-a intrat la suflet din primul minut de folosire, vorbim strict de benchmark oc application :
-nu mai intereseaza nivelu de zgomot
-caldura degajata / de lucru
-consumul de energie electrica ..
temperatura de vaporizare , discharge pressure este mai constanta/permisiva la un rotativ vs reciprocating deci performanta /eficienta unui rotativ creste, vorbind de aplicatii HBP un rotativ cu design pt R410a este ceea ce trebuie pentru o cascada ( 2,3,4 stage) care foloseste hight pressure refrigerant( R410a , R23 , R1150 , R14 , R50
)
reciprocating-ul nu are suction acummulator inclus vs rotary care are din fabrica
suction acummulator previne
compressor liquid refrigerant floodback nightmare ( de aceea in specificatiile acestei unitati gasiti suction acummulator ( post1)..builderi vestiti pe XS nu folosesc la reciprocating condensing unit acummulator ....desi le vand la 1k $/€ )si distrugerea permanenta a compresorulu
i( probabil cei care aveti sau avut SS-uri reciprocating ati auzit cu siguranta zgomote in compresor ce se aseamana cu "pocnituri" sau cum ar "picura ceva" ..ei bine acela este refrigerant floodback return ...prin linia de aspiratie din evaporator out nu exista nici un device sa opreasca lichidul subracit sa intre in compresor , el va intra necontenit si va lovi direct capul pistonului fierbinte , care se va lasa cu o "respingere" o mica "explozie" asociata cu o pocnitura distrugand in timp angrenajul compresorului , de acceea se monteaza OBLIGAT pe suction line la intrare portul suction un acumulator , el va separa lichidul de vapor si introdus in compresor doar refrigerant vapor prevenind floodback-ul ) si multe alte aspecte de ordin technic acolo unde rotativul ii da bataie grava la un reciprocating , deci pe scurt NU ..un rotativ in aplicatii/condititii grele de functionare ( temperaturi ambientale extrem de ridicate /scazute )este indispersabil! pentru unitati de overclocking rotary all day long!!!
bun , folosesc aici un compresor de 22,4ccm /1PH+( ca idee un LD sau Dimas Evo Beast are 10-11ccm compresor) ,deci o capacitate cilindrica DUBLA la unitatea de fata , va trebui sa faca fata unor loaduri extreme , eu zic ca va performa bine ,cu siguranta va fi cea mai SILENT unit care am proiectat-o / executat eu. initial am vrut sa fac o unitate silentioasa cu performante deosebite in load-uri de peste 400W
will see!!
pentru cei interesati de acest domeniu termodinamic rotary vs reciprocating
http://www.ries-gmbh.de/temp/explore...IPROCATING.pdf
punctez cateva fraze :
Rotary’s success is contributed to several factors: they are smaller and lighter, they are more efficient, more
resistant to liquid refrigerant presence and they tolerate higher working temperature. This has not been achieved
merely by the way the vapour gets compressed, but rather that the whole concept of a hermetic compressor has
been re-designed.
In
reciprocating type, returning gas enters the compressor housing and on its way to cylinder(s) it cools down the
casing, electric windings and oil. The vapour then gets sucked via suction reed(s) by a downward moving piston.
The compression begins with an upstroke and ends when the piston reaches TDC and the compressed gas gets
discharged into manifold and out to condenser.
Weakness of this design is its vulnerability for liquid refrigerant related damages. Especially floodback: during an
on-cycle when the amount of superheat is insufficient the droplets of non-evaporated refrigerant pour in
In rotary compressor: the returning gas first enters a suction line liquid accumulator that is fixed to the
compressor’s casing and from there it gets sucked directly into the compression chamber. The suction line liquid
accumulator’s primary function is to compensate during the reversed cycle for the volumetric difference between
the condensing and evaporating coils. However, it successfully doubles – like shown later, as a liquid inhibitor. In
the chamber, an eccentric shaft rotates a roller in a cylinder (Fig1). Extremely high tolerances - .01 mm made it
possible to do away with sealers. As the roller (also called an impeller or a rolling piston) revolves, the blade traps
quantity of vapour and compresses it into an ever-decreasing space, building up pressure and temperature. Finally
the vapour is discharged through the exhaust port into the compressor housing. Here the hot gas “cools down” the
electric windings and oil.
These components are designed to work happily in 100°C to 120°C.The practical
implication of the design is twofold:
revolving way of compression cause that the compressing mechanism is more
tolerant for the presence of liquid refrigerant and the high working temperature helps to make the compressor more
resistant against a floodback (More about this in the next chapter).
It is important to add that a new generation of oil had to be devised – Suniso, Clavus, etc, – to cope with these
demanding conditions: de-waxed oil, that allows it to work at 120°C or higher without braking down (Important:
though it will not carbonise at temperatures above 140°C, it will thin to the point of loosing its lubricating
properties).
The other important change that transpires from this design is a better oil management. Unlike in the reciprocating
compressor, where 3% of the total discharged volume is oil that gets pumped out with each stroke of the piston into
the system and then must be retuned back; the rotary lets very little oil out. This decreases lubrication-related
problems so often found in reciprocating compressors.
I am sorry to state that so far we do not have a liquid proof compressor. Only an improved degree of resistance to
liquid, as compared with the reciprocating design. Rotaries are no exception here. Though they can fight back a
mild floodback, their vulnerability lies in refrigerant migration and heavy floodback.
Rotary will endure higher discharge temperature and handle a presence of liquid refrigerant better. It is lighter and
smaller and more efficient. It also controls oil better.
Is it a better compressor then reciprocating type? Perhaps. But it is important to remember that a properly handled
recipe will happily work for 15 years or more. I know instances where they remain serviceable after 30 years.
Rotaries haven’t even being around for so long!
However, I believe, the rotaries construction make them more resistant to small human errors and system’s
mischief. And, yes, perhaps a rotary you have just installed, and done a good job on it, will still run in 2022!
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