compressor

Comp esso

A comp esso is a mecha ical device ha i c eases he p essu e of a gas by educi g i s volume. A ai comp esso is a specific ype of gas comp esso .

Comp esso s a e simila o pumps: bo h i c ease he p essu e o a fluid a d bo h ca a spo he fluid h ough a pipe. The mai dis i c io is ha he focus of a comp esso is o cha ge he de si y o volume of he fluid, which is mos ly o ly achievable o gases. Gases a e comp essible, while liquids a e ela ively i comp essible, so comp esso s a e a ely used fo liquids. The mai ac io of a pump is o p essu ize a d a spo liquids.

Ma y comp esso s ca be s aged, ha is, he fluid is comp essed seve al imes i s eps o s ages, o i c ease discha ge p essu e. Of e , he seco d s age is physically smalle ha he p ima y s age, o accommoda e he al eady comp essed gas wi hou educi g i s p essu e. Each s age fu he comp esses he gas a d i c eases i s p essu e a d also empe a u e (if i e cooli g be wee s ages is o used).

Co e s

Typesedi

The mai a d impo a ypes of gas comp esso s a e illus a ed a d discussed below:

Posi ive displaceme edi

A posi ive displaceme comp esso is a sys em ha comp esses he ai by he displaceme of a mecha ical li kage educi g he volume (si ce he educ io i volume due o a pis o i he mody amics is co side ed as posi ive displaceme of he pis o ).vague

Pu a o he way, a posi ive displaceme comp esso is o e ha ope a es by d awi g i a disc e e volume of gas f om i s i le he fo ci g ha gas o exi via he comp esso ‘s ou le . The i c ease i he p essu e of he gas is due, a leas i pa , o he comp esso pumpi g i a a mass flow a e which ca o pass h ough he ou le a he lowe p essu e a d de si y of he i le .

Recip oca i g comp esso sedi

Recip oca i g comp esso s use pis o s d ive by a c a kshaf . They ca be ei he s a io a y o po able, ca be si gle o mul i-s aged, a d ca be d ive by elec ic mo o s o i e al combus io e gi es.123 Small ecip oca i g comp esso s f om 5 o 30 ho sepowe (hp) a e commo ly see i au omo ive applica io s a d a e ypically fo i e mi e du y. La ge ecip oca i g comp esso s well ove 1,000 hp (750 kW) a e commo ly fou d i la ge i dus ial a d pe oleum applica io s. Discha ge p essu es ca a ge f om low p essu e o ve y high p essu e (18000 psi o 180 MPa). I ce ai applica io s, such as ai comp essio , mul i-s age double-ac i g comp esso s a e said o be he mos efficie comp esso s available, a d a e ypically la ge , a d mo e cos ly ha compa able o a y u i s.4 A o he ype of ecip oca i g comp esso , usually employed i au omo ive cabi ai co di io i g sys ems,ci a io eeded is he swash pla e o wobble pla e comp esso , which uses pis o s moved by a swash pla e mou ed o a shaf (see axial pis o pump).

Household, home wo kshop, a d smalle job si e comp esso s a e ypically ecip oca i g comp esso s 1½ hp o less wi h a a ached eceive a k.

A li ea comp esso is a ecip oca i g comp esso wi h he pis o bei g he o o of a li ea mo o .

This ype of comp esso ca comp ess a wide a ge of gases, i cludi g ef ige a , hyd oge , a d a u al gas. Because of his, i fi ds use i a wide a ge of applica io s i ma y diffe e i dus ies a d ca be desig ed o a wide a ge of capaci ies, by va yi g size, umbe of cyli de s, a d cyli de u loadi g. Howeve , i suffe s f om highe losses due o clea a ce volumes, esis a ce due o discha ge a d suc io valves, weighs mo e, is difficul o mai ai due o havi g a la ge umbe of movi g pa s, a d i has i he e vib a io .5

Io ic liquid pis o comp esso edi

A io ic liquid pis o comp esso , io ic comp esso o io ic liquid pis o pump is a hyd oge comp esso based o a io ic liquid pis o i s ead of a me al pis o as i a pis o -me al diaph agm comp esso .

Ro a y sc ew comp esso sedi

Ro a y sc ew comp esso s use wo meshed o a i g posi ive-displaceme helical sc ews o fo ce he gas i o a smalle space.167 These a e usually used fo co i uous ope a io i comme cial a d i dus ial applica io s a d may be ei he s a io a y o po able. Thei applica io ca be f om 3 ho sepowe (2.2 kW) o ove 1,200 ho sepowe (890 kW) a d f om low p essu e o mode a ely high p essu e (1,200 psi o 8.3 MPa).

The classifica io s of o a y sc ew comp esso s va y based o s ages, cooli g me hods, a d d ive ypes amo g o he s.8 Ro a y sc ew comp esso s a e comme cially p oduced i Oil Flooded, Wa e Flooded a d D y ype. The efficie cy of o a y comp esso s depe ds o he ai d ie ,cla ifica io eeded a d he selec io of ai d ie is always 1.5 imes volume ic delive y of he comp esso .9

Desig s wi h a si gle sc ew10 o h ee sc ews11 i s ead of wo exis .

Sc ew comp esso s have less movi g compo e s, la ge capaci y, less vib a io a d su gi g, ca ope a e a va iable speeds, a d ypically have highe efficie cy. Small sizes o low o o speeds a e o p ac ical due o i he e leaks caused by clea a ce be wee he comp essio cavi ies o sc ews a d comp esso housi g.5 They depe d o fi e machi i g ole a ces o avoid high leakage losses a d a e p o e o damage if ope a ed i co ec ly o poo ly se viced.

Ro a y va e comp esso sedi

Ro a y va e comp esso s co sis of a o o wi h a umbe of blades i se ed i adial slo s i he o o . The o o is mou ed offse i a la ge housi g ha is ei he ci cula o a mo e complex shape. As he o o u s, blades slide i a d ou of he slo s keepi g co ac wi h he ou e wall of he housi g.1 Thus, a se ies of i c easi g a d dec easi g volumes is c ea ed by he o a i g blades. Ro a y va e comp esso s a e, wi h pis o comp esso s o e of he oldes of comp esso ech ologies.

Wi h sui able po co ec io s, he devices may be ei he a comp esso o a vacuum pump. They ca be ei he s a io a y o po able, ca be si gle o mul i-s aged, a d ca be d ive by elec ic mo o s o i e al combus io e gi es. D y va e machi es a e used a ela ively low p essu es (e.g., 2 ba o 200 kPa o 29 psi) fo bulk ma e ial moveme while oil-i jec ed machi es have he ecessa y volume ic efficie cy o achieve p essu es up o abou 13 ba (1,300 kPa; 190 psi) i a si gle s age. A o a y va e comp esso is well sui ed o elec ic mo o d ive a d is sig ifica ly quie e i ope a io ha he equivale pis o comp esso .

Ro a y va e comp esso s ca have mecha ical efficie cies of abou 90%.12

Rolli g pis o edi

The Rolli g pis o i a olli g pis o s yle comp esso plays he pa of a pa i io be wee he va e a d he o o .13 Rolli g pis o fo ces gas agai s a s a io a y va e.

۲ of hese comp esso s ca be mou ed o he same shaf o i c ease capaci y a d educe vib a io a d oise.14 A desig wi hou a sp i g is k ow as a swi g comp esso .15

I ef ige a io a d ai co di io i g, his ype of comp esso is also k ow as a o a y comp esso , wi h o a y sc ew comp esso s bei g also k ow simply as sc ew comp esso s.

I offe s highe efficie cy ha ecip oca i g comp esso s due o less losses f om he clea a ce volume be wee he pis o a d he comp esso casi g, i s 40% o 50% smalle a d ligh e fo a give capaci y (which ca impac ma e ial a d shippi g cos s whe used i a p oduc ), causes less vib a io , has fewe compo e s a d is mo e eliable ha a ecip oca i g comp esso . Bu i s s uc u e does o allow capaci ies beyo d 5 ef ige a io o s, is less eliable ha o he comp esso ypes, a d is less efficie ha o he comp esso ypes due o losses f om he clea a ce volume.5

Sc oll comp esso sedi

A sc oll comp esso , also k ow as sc oll pump a d sc oll vacuum pump, uses wo i e leaved spi al-like va es o pump o comp ess fluids such as liquids a d gases. The va e geome y may be i volu e, a chimedea spi al, o hyb id cu ves.161718 They ope a e mo e smoo hly, quie ly, a d eliably ha o he ypes of comp esso s i he lowe volume a ge.

Of e , o e of he sc olls is fixed, while he o he o bi s ecce ically wi hou o a i g, he eby appi g a d pumpi g o comp essi g pocke s of fluid be wee he sc olls.

Due o mi imum clea a ce volume be wee he fixed sc oll a d he o bi i g sc oll, hese comp esso s have a ve y high volume ic efficie cy.

These comp esso s a e ex e sively used i ai co di io i g a d ef ige a io because hey a e ligh e , smalle a d have fewe movi g pa s ha ecip oca i g comp esso s a d hey a e also mo e eliable. They a e mo e expe sive hough, so pel ie coole s o o a y a d ecip oca i g comp esso s may be used i applica io s whe e cos is he mos impo a o o e of he mos impo a fac o s o co side whe desig i g a ef ige a io o ai co di io i g sys em.

This ype of comp esso was used as he supe cha ge o Volkswage G60 a d G40 e gi es i he ea ly 1990s.

Whe compa ed wi h ecip oca i g a d olli g pis o comp esso s, sc oll comp esso s a e mo e eliable si ce hey have fewe compo e s a d have a simple s uc u e, a e mo e efficie si ce hey have o clea a ce volume o valves, a d possess he adva ages bo h of su gi g less a d o vib a i g so much. Bu , whe compa ed wi h sc ew a d ce ifugal comp esso s, sc oll comp esso s have lowe efficie cies a d smalle capaci ies.5

Diaph agm comp esso sedi

A diaph agm comp esso (also k ow as a memb a e comp esso ) is a va ia of he co ve io al ecip oca i g comp esso . The comp essio of gas occu s by he moveme of a flexible memb a e, i s ead of a i ake eleme . The back a d fo h moveme of he memb a e is d ive by a od a d a c a kshaf mecha ism. O ly he memb a e a d he comp esso box come i co ac wi h he gas bei g comp essed.1

The deg ee of flexi g a d he ma e ial co s i u i g he diaph agm affec s he mai e a ce life of he equipme . Ge e ally s iff me al diaph agms may o ly displace a few cubic ce ime e s of volume because he me al ca o e du e la ge deg ees of flexi g wi hou c acki g, bu he s iff ess of a me al diaph agm allows i o pump a high p essu es. Rubbe o silico e diaph agms a e capable of e du i g deep pumpi g s okes of ve y high flexio , bu hei low s e g h limi s hei use o low-p essu e applica io s, a d hey eed o be eplaced as plas ic emb i leme occu s.

Diaph agm comp esso s a e used fo hyd oge a d comp essed a u al gas (CNG) as well as i a umbe of o he applica io s.

The pho og aph o he igh depic s a h ee-s age diaph agm comp esso used o comp ess hyd oge gas o 6,000 psi (41 MPa) fo use i a p o o ype comp essed hyd oge a d comp essed a u al gas (CNG) fueli g s a io buil i dow ow Phoe ix, A izo a by he A izo a Public Se vice compa y (a elec ic u ili ies compa y). Recip oca i g comp esso s we e used o comp ess he a u al gas. The ecip oca i g a u al gas comp esso was developed by Se co.19

The p o o ype al e a ive fueli g s a io was buil i complia ce wi h all of he p evaili g safe y, e vi o me al a d buildi g codes i Phoe ix o demo s a e ha such fueli g s a io s could be buil i u ba a eas.

Dy amicedi

Ai bubble comp esso edi

Also k ow as a ompe. A mix u e of ai a d wa e ge e a ed h ough u bule ce is allowed o fall i o a sub e a ea chambe whe e he ai sepa a es f om he wa e . The weigh of falli g wa e comp esses he ai i he op of he chambe . A subme ged ou le f om he chambe allows wa e o flow o he su face a a lowe heigh ha he i ake. A ou le i he oof of he chambe supplies he comp essed ai o he su face. A facili y o his p i ciple was buil o he Mo eal Rive a Ragged Shu es ea Cobal , O a io i 1910 a d supplied 5,000 ho sepowe o ea by mi es.20

Ce ifugal comp esso sedi

Ce ifugal comp esso s use a o a i g disk o impelle i a shaped housi g o fo ce he gas o he im of he impelle , i c easi g he veloci y of he gas. A diffuse (dive ge duc ) sec io co ve s he veloci y e e gy o p essu e e e gy. They a e p ima ily used fo co i uous, s a io a y se vice i i dus ies such as oil efi e ies, chemical a d pe ochemical pla s a d a u al gas p ocessi g pla s.12122 Thei applica io ca be f om 100 ho sepowe (75 kW) o housa ds of ho sepowe . Wi h mul iple s agi g, hey ca achieve high ou pu p essu es g ea e ha 1,000 psi (6.9 MPa).

This ype of comp esso , alo g wi h sc ew comp esso s, a e ex e sively used i la ge ef ige a io a d ai co di io i g sys ems. Mag e ic bea i g (mag e ically levi a ed) a d ai bea i g ce ifugal comp esso s exis .

Ma y la ge s owmaki g ope a io s (like ski eso s) use his ype of comp esso . They a e also used i i e al combus io e gi es as supe cha ge s a d u bocha ge s. Ce ifugal comp esso s a e used i small gas u bi e e gi es o as he fi al comp essio s age of medium-sized gas u bi es.

Ce ifugal comp esso s a e he la ges available comp esso s, offe highe efficie cies u de pa ial loads, may be oil-f ee whe usi g ai o mag e ic bea i gs which i c eases he hea a sfe coefficie i evapo a o s a d co de se s, weigh up o 90% less a d occupy 50% less space ha ecip oca i g comp esso s, a e eliable a d cos less o mai ai si ce less compo e s a e exposed o wea , a d o ly ge e a e mi imal vib a io . Bu , hei i i ial cos is highe , equi e highly p ecise CNC machi i g, he impelle eeds o o a e a high speeds maki g small comp esso s imp ac ical, a d su gi g becomes mo e likely.5 Su gi g is gas flow eve sal, mea i g ha he gas goes f om he discha ge o he suc io side, which ca cause se ious damage, specially i he comp esso bea i gs a d i s d ive shaf . I is caused by a p essu e o he discha ge side ha is highe ha he ou pu p essu e of he comp esso . This ca cause gases o flow back a d fo h be wee he comp esso a d wha eve is co ec ed o i s discha ge li e, causi g oscilla io s.5

Diago al o mixed-flow comp esso sedi

Diago al o mixed-flow comp esso s a e simila o ce ifugal comp esso s, bu have a adial a d axial veloci y compo e a he exi f om he o o . The diffuse is of e used o u diago al flow o a axial a he ha adial di ec io .23 Compa a ive o he co ve io al ce ifugal comp esso (of he same s age p essu e a io), he value of he speed of he mixed flow comp esso is 1.5 imes la ge .24

Axial comp esso sedi

Axial comp esso s a e dy amic o a i g comp esso s ha use a ays of fa -like ai foils o p og essively comp ess a fluid. They a e used whe e high flow a es o a compac desig a e equi ed.

The a ays of ai foils a e se i ows, usually as pai s: o e o a i g a d o e s a io a y. The o a i g ai foils, also k ow as blades o o o s, accele a e he fluid. The s a io a y ai foils, also k ow as s a o s o va es, decele a e a d edi ec he flow di ec io of he fluid, p epa i g i fo he o o blades of he ex s age.1 Axial comp esso s a e almos always mul i-s aged, wi h he c oss-sec io al a ea of he gas passage dimi ishi g alo g he comp esso o mai ai a op imum axial Mach umbe . Beyo d abou 5 s ages o a 4:1 desig p essu e a io a comp esso will o fu c io u less fi ed wi h fea u es such as s a io a y va es wi h va iable a gles (k ow as va iable i le guide va es a d va iable s a o s), he abili y o allow some ai o escape pa -way alo g he comp esso (k ow as i e s age bleed) a d bei g spli i o mo e ha o e o a i g assembly (k ow as wi spools, fo example).

Axial comp esso s ca have high efficie cies; a ou d 90% poly opic a hei desig co di io s. Howeve , hey a e ela ively expe sive, equi i g a la ge umbe of compo e s, igh ole a ces a d high quali y ma e ials. Axial comp esso s a e used i medium o la ge gas u bi e e gi es, a u al gas pumpi g s a io s, a d some chemical pla s.

He me ically sealed, ope , o semi-he me icedi

Comp esso s used i ef ige a io sys ems mus exhibi ea -ze o leakage o avoid he loss of he ef ige a if hey a e o fu c io fo yea s wi hou se vice. This ecessi a es he use of ve y effec ive seals, o eve he elimi a io of all seals a d ope i gs o fo m a he me ic sys em. These comp esso s a e of e desc ibed as bei g ei he he me ic, ope , o semi-he me ic, o desc ibe how he comp esso is e closed a d how he mo o d ive is si ua ed i ela io o he gas o vapo bei g comp essed. Some comp esso s ou side of ef ige a io se vice may also be he me ically sealed o some ex e , ypically whe ha dli g oxic, pollu i g, o expe sive gasses, wi h mos o – ef ige a io applica io s bei g i he pe ochemical i dus y.

I he me ic a d mos semi-he me ic comp esso s, he comp esso a d mo o d ivi g he comp esso a e i eg a ed, a d ope a e wi hi he p essu ized gas e velope of he sys em. The mo o is desig ed o ope a e i , a d be cooled by, he ef ige a gas bei g comp essed. Ope comp esso s have a ex e al mo o d ivi g a shaf ha passes h ough he body of he comp esso a d ely o o a y seals a ou d he shaf o e ai he i e al p essu e.

The diffe e ce be wee he he me ic a d semi-he me ic, is ha he he me ic uses a o e-piece welded s eel casi g ha ca o be ope ed fo epai ; if he he me ic fails i is simply eplaced wi h a e i e ew u i . A semi-he me ic uses a la ge cas me al shell wi h gaske ed cove s wi h sc ews ha ca be ope ed o eplace mo o a d comp esso compo e s. The p ima y adva age of a he me ic a d semi-he me ic is ha he e is o ou e fo he gas o leak ou of he sys em. The mai adva ages of ope comp esso s is ha hey ca be d ive by a y mo ive powe sou ce, allowi g he mos app op ia e mo o o be selec ed fo he applica io , o eve o -elec ic powe sou ces such as a i e al combus io e gi e o s eam u bi e, a d seco dly he mo o of a ope comp esso ca be se viced wi hou ope i g a y pa of he ef ige a sys em.

A ope p essu ized sys em such as a au omobile ai co di io e ca be mo e suscep ible o leak i s ope a i g gases. Ope sys ems ely o lub ica i he sys em o splash o pump compo e s a d seals. If i is o ope a ed f eque ly e ough, he lub ica o he seals slowly evapo a es, a d he he seals begi o leak u il he sys em is o lo ge fu c io al a d mus be echa ged. By compa iso , a he me ic o semi-he me ic sys em ca si u used fo yea s, a d ca usually be s a ed up agai a a y ime wi hou equi i g mai e a ce o expe ie ci g a y loss of sys em p essu e. Eve well lub ica ed seals will leak a small amou of gas ove ime, pa icula ly if he ef ige a io gasses a e soluble i he lub ica i g oil, bu if he seals a e well ma ufac u ed a d mai ai ed his loss is ve y low.

The disadva age of he me ic comp esso s is ha he mo o d ive ca o be epai ed o mai ai ed, a d he e i e comp esso mus be eplaced if a mo o fails. A fu he disadva age is ha bu -ou wi di gs ca co ami a e he whole sys ems, he eby equi i g he sys em o be e i ely pumped dow a d he gas eplaced (This ca also happe i semi he me ic comp esso s whe e he mo o ope a es i he ef ige a ). Typically, he me ic comp esso s a e used i low-cos fac o y-assembled co sume goods whe e he cos of epai a d labo is high compa ed o he value of he device, a d i would be mo e eco omical o jus pu chase a ew device o comp esso . Semi-he me ic comp esso s a e used i mid-sized o la ge ef ige a io a d ai co di io i g sys ems, whe e i is cheape o epai a do efu bish he comp esso compa ed o he p ice of a ew o e. A he me ic comp esso is simple a d cheape o build ha a semi-he me ic o ope comp esso .

The mody amics of gas comp essio edi

Ise opic comp esso edi

A comp esso ca be idealized as i e ally eve sible a d adiaba ic, hus a ise opic s eady s a e device, mea i g he cha ge i e opy is 0.25 By defi i g he comp essio cycle as ise opic, a ideal efficie cy fo he p ocess ca be a ai ed, a d he ideal comp esso pe fo ma ce ca be compa ed o he ac ual pe fo ma ce of he machi e. Iso opic Comp essio as used i ASME PTC 10 Code efe s o a eve sible, adiaba ic comp essio p ocess26

Ise opic efficie cy of Comp esso s:

Mi imizi g wo k equi ed by a comp esso edi

Compa i g eve sible o i eve sible comp esso sedi

Compa iso of he diffe e ial fo m of he e e gy bala ce fo each device Le q displays yle q be hea , w displays yle w be wo k, k e displays yle ke be ki e ic e e gy a d p e displays yle pe be po e ial e e gy. Ac ual Comp esso :

Reve sible Comp esso :

The igh ha d side of each comp esso ype is equivale , hus:

e-a a gi g:

By subs i u i g he k ow equa io δ q e v = T d s displays yle del a q_ ev=Tds i o he las equa io a d dividi g bo h e ms by T:

Fu he mo e, d s ≥ δ q a c T displays yle dsgeq f ac del a q_ac T a d T is absolu e empe a u e ( T ≥ ۰ displays yle Tgeq 0 ) which p oduces: δ w e v ≥ δ w a c displays yle del a w_ evgeq del a w_ac o w e v ≥ w a c displays yle w_ evgeq w_ac

The efo e, wo k-co sumi g devices such as pumps a d comp esso s (wo k is ega ive) equi e less wo k whe hey ope a e eve sibly.25

Effec of cooli g du i g he comp essio p ocessedi

ise opic p ocess: i volves o cooli g, poly opic p ocess: i volves some cooli g iso he mal p ocess: i volves maximum cooli g

By maki g he followi g assump io s he equi ed wo k fo he comp esso o comp ess a gas f om P 1 displays yle P_1 o P 2 displays yle P_2 is he followi g fo each p ocess: Assump io s:

Ise opic ( P v k = c o s a displays yle Pv^k=co s a , whe e k = C p C v displays yle k=C_pC_v ):

Poly opic ( P v = c o s a displays yle Pv^ =co s a ):

Iso he mal ( T = c o s a displays yle T=co s a o P v = c o s a displays yle Pv=co s a ):

By compa i g he h ee i e ally eve sible p ocesses comp essi g a ideal gas f om P 1 displays yle P_1 o P 2 displays yle P_2 , he esul s show ha ise opic comp essio ( P v k = c o s a displays yle Pv^k=co s a ) equi es he mos wo k i a d he iso he mal comp essio ( T = c o s a displays yle T=co s a o P v = c o s a displays yle Pv=co s a ) equi es he leas amou of wo k i . Fo he poly opic p ocess ( P v = c o s a displays yle Pv^ =co s a ) wo k i dec eases as he expo e , , dec eases, by i c easi g he hea ejec io du i g he comp essio p ocess. O e commo way of cooli g he gas du i g comp essio is o use cooli g jacke s a ou d he casi g of he comp esso .25

Comp esso s i ideal he mody amic cyclesedi

Ideal Ra ki e Cycle 1-2 Ise opic comp essio i a pump Ideal Ca o Cycle 4-1 Ise opic comp essio Ideal O o Cycle 1-2 Ise opic comp essio Ideal Diesel Cycle 1-2 Ise opic comp essio Ideal B ay o Cycle 1-2 Ise opic comp essio i a comp esso Ideal Vapo -comp essio ef ige a io Cycle 1-2 Ise opic comp essio i a comp esso NOTE: The ise opic assump io s a e o ly applicable wi h ideal cycles. Real wo ld cycles have i he e losses due o i efficie comp esso s a d u bi es. The eal wo ld sys em a e o uly ise opic bu a e a he idealized as ise opic fo calcula io pu poses.

Tempe a u eedi

Comp essio of a gas i c eases i s empe a u e.

Fo a poly opic a sfo ma io of a gas:

The wo k do e fo poly opic comp essio (o expa sio ) of a gas i o a closed cyli de .

i which p is p essu e, V is volume, akes diffe e values fo diffe e comp essio p ocesses (see below), a d 1 2 efe o i i ial a d fi al s a es.

wi h T1 a d T2 i deg ees Ra ki e o kelvi s, p2 a d p1 bei g absolu e p essu es a d κ = displays yle kappa = a io of specific hea s (app oxima ely 1.4 fo ai ). The ise i ai a d empe a u e a io mea s comp essio does o follow a simple p essu e o volume a io. This is less efficie , bu quick. Adiaba ic comp essio o expa sio mo e closely model eal life whe a comp esso has good i sula io , a la ge gas volume, o a sho ime scale (i.e., a high powe level). I p ac ice he e will always be a ce ai amou of hea flow ou of he comp essed gas. Thus, maki g a pe fec adiaba ic comp esso would equi e pe fec hea i sula io of all pa s of he machi e. Fo example, eve a bicycle i e pump’s me al ube becomes ho as you comp ess he ai o fill a i e. The ela io be wee empe a u e a d comp essio a io desc ibed above mea s ha he value of displays yle fo a adiaba ic p ocess is κ displays yle kappa ( he a io of specific hea s).

Fo a iso he mal p ocess, displays yle is 1, so he value of he wo k i eg al fo a iso he mal p ocess is:

Whe evalua ed, he iso he mal wo k is fou d o be lowe ha he adiaba ic wo k.

S aged comp essio edi

I he case of ce ifugal comp esso s, comme cial desig s cu e ly do o exceed a comp essio a io of mo e ha 3.5 o 1 i a y o e s age (fo a ypical gas). Si ce comp essio aises he empe a u e, he comp essed gas is o be cooled be wee s ages maki g he comp essio less adiaba ic a d mo e iso he mal. The i e -s age coole s (i e coole s) ypically esul i some pa ial co de sa io ha is emoved i vapo -liquid sepa a o s.

I he case of small ecip oca i g comp esso s, he comp esso flywheel may d ive a cooli g fa ha di ec s ambie ai ac oss he i e coole of a wo o mo e s age comp esso .

Because o a y sc ew comp esso s ca make use of cooli g lub ica o educe he empe a u e ise f om comp essio , hey ve y of e exceed a 9 o 1 comp essio a io. Fo i s a ce, i a ypical divi g comp esso he ai is comp essed i h ee s ages. If each s age has a comp essio a io of 7 o 1, he comp esso ca ou pu 343 imes a mosphe ic p essu e (7 × ۷ × ۷ = ۳۴۳ a mosphe es). (343 a m o 34.8 MPa o 5.04 ksi)

D ive mo o sedi

The e a e ma y op io s fo he mo o ha powe s he comp esso :

Lub ica io edi

Comp esso s ha a e d ive by a elec ic mo o ca be co olled usi g a VFD o powe i ve e , howeve ma y he me ic a d semi-he me ic comp esso s ca o ly wo k i a a ge of o a fixed speeds, si ce hey may i clude buil -i oil pumps. The buil -i oil pump is co ec ed o he same shaf ha d ives he comp esso , a d fo ces oil i o he comp esso a d mo o bea i gs. A low speeds, i sufficie qua i ies of oil each he bea i gs, eve ually leadi g o bea i g failu e, while a high speeds, excessive amou s of oil may be los f om he bea i gs a d comp esso a d po e ially i o he discha ge li e due o splashi g. Eve ually he oil u s ou a d he bea i gs a e lef u lub ica ed, leadi g o failu e, a d he oil may co ami a e he ef ige a , ai o o he wo ki g gas.28

Applica io sedi

Gas comp esso s a e used i va ious applica io s whe e ei he highe p essu es o lowe volumes of gas a e eeded:

Divi g ai comp esso i oise educ io cabi e

Comp esso Powe ful e codi g. Delive ed.

Comp esso igh ly i eg a es wi h Fi al Cu  P o o add cus om ou pu se i gs a d ex e sive delive y fea u es. Wi h suppo fo HDR, HEVC, 360° video, a d MXF ou pu — a d s a dou pe fo ma ce a d efficie cy o Mac compu e s wi h Apple silico — i ’s he mos powe ful, flexible way o expo you Fi al Cu  P o p ojec s.

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