Trane trg-trc005-en manuale d’uso

Air Conditioning Clinic Refrigeration System Components One of the Fund amen tal Serie s TRG-TRC005-EN[...]

P erforation 5.5” from bottom/top P erforation 0.75” from edge Comment Card We want to ensure that our educational materials meet your ever -changing resource development needs. Please take a moment to comment on the effectiveness of this Air Conditioning Clinic. Refrigeration System Components Level of detail (circle one) T oo basic Just right[...]

NO POST AGE NECESSARY IF MAILED IN THE UNITED ST ATES BUSINES S REPL Y MAIL FIRST -CL ASS MAIL PERMIT NO. 11 LA CROS SE, WI POST AGE WILL BE P AID B Y ADDRESSEE THE TRANE COMP ANY Attn: Applications Engineering 3600 P ammel Creek Road La Crosse WI 54601-9985 NO POST AGE NECESSARY IF MAILED IN THE UNITED ST ATES BUSINES S REPL Y MAIL FIRST -CL ASS M[...]

Refr ig er ation S yst em Components One of the F undamen tal Ser ies A publication of The T rane Compan y— W orldwide Applied Sy stems Gr oup[...]

Pr ef ace © 1 999 Am erican Standard Inc. All rights reserved TRG-TR C0 05-EN ii The T rane Company belie ves that it is incumbent on manufacturers to serve the industry by regularly disseminating i nformation gathere d through laboratory researc h, testi ng programs, and field e x perienc e. The T rane A ir Conditioning Cli nic series is one mean[...]

TRG-TR C0 05-EN iii Cont ents Introduction .......... ......... ......... .......... ............ ......... 1 period one Refrige ration Cy cle ......... .......... ......... ............ ...... 2 period two Condensers ........ ......... ......... .......... ............ ......... ... 5 Air-Co oled Condens ers ........................ ..............[...]

iv TRG-TR C0 05-EN[...]

TRG-TR C0 05-EN 1 note s Intr oduction The major c omponents of a v apor -compres sion refrigerati on system include the compre ssor , conde nser , expa nsion devic e , and evaporato r . The latt er three will be d iscussed in this clinic — the compress or is discu ssed in a separate clinic. This cli nic will also discuss man y of th e common acc[...]

2 TRG-TR C0 05-EN note s peri od one Refr ig er ation Cy cle First, a brief re view of the vapor -co mpression refrigerat ion cycle will hel p to relate these comp onents. A diagram of a typical vapor -comp ression refrige ration cy cle can b e superimpos ed on a pressure-en thalpy (P - h ) c har t to demonstra te the function of eac h component in[...]

TRG-TR C0 05-EN 3 peri od one Refr ig er ation Cy cle note s The comp r ess or draws in t he superhea ted refrigeran t vapor ( B ) a nd compress es it to a pressure and temperature ( C ) high enough that it can rejec t heat to ano ther fluid. This hot, hig h-pressure refrigerant vap or then travels to the conde nser . Within the c ondenser , heat i[...]

4 TRG-TR C0 05-EN note s peri od one Refr ig er ation Cy cle Finally , the high-pressure l iquid refriger ant ( D ) flows through the expansion device, causing a large pres sure drop that reduces the pressu r e of t he refrigerant to th at of the evaporator . This pressure reduc tion cause s a sm all por tion of the liquid to bo il off , or flash, [...]

TRG-TR C0 05-EN 5 note s The first ma jor componen t to be discusse d is the condenser . The condenser is a heat ex chan ger that rejects h eat from the refriger ant to air , water , or som e othe r fl uid. The thre e common ty pes of condensers are ai r -cooled, w ater -cooled , and evapor ative. Air -Coole d Condensers A typical air -cooled conde[...]

6 TRG-TR C0 05-EN note s peri od t w o Condensers The air -co oled condenser is very popu lar in both residenti al and commercial applicati ons because of its c onveni ence. It requires very little mainten ance and does not re quire the fre eze prote c tion a nd water treatmen t that is necessary with a w ater -cooled co ndenser . Additionally , it[...]

TRG-TR C0 05-EN 7 peri od t w o Condensers note s An alternative air -c ooled conde nser uses a centrifug al fan to draw or bl ow air over th e condensing coil . The principa l advantage of this d esign is that the centrifug al fan is capab le of ov ercoming the highe r static-pres sure losses associ ated wi th ductwork. Therefore, if the co ndense[...]

8 TRG-TR C0 05-EN note s peri od t w o Condensers causing the refrigerant v apor within the tubes to condense . The remaining water t hen fal ls to the sum p to be r ecirc ulat ed an d used agai n. Subcooling of the refrigerant can be accomplished by piping the condense d liquid bac k through another few rows of coil t ubing, located either i n the[...]

TRG-TR C0 05-EN 9 peri od t w o Condensers note s A cooling tow er is a device commonly u sed to cool co ndensing w ater . In this design, w arm wa ter is spray ed over the fill inside th e cooling tower while a propeller fan draws outdoor air upw ard through the fill. The movement of air through t he spray ca uses some of the water to evapora te, [...]

10 TRG-TR C0 05-EN note s peri od t w o Condensers Condens er Contr ol The heat re jection capacity o f a condens e r is in fluenced by (1) the te mperature dif ference between the refrigerant and th e cooling media (air , water , or other fluid), (2) the flow rate of the cool ing media throu gh the condenser , and (3) the flow rate of the refriger[...]

TRG-TR C0 05-EN 11 peri od t w o Condensers note s A reduct ion in conde nsing pressure lessen s the powe r required to compres s the refrigerant. Unfortunately , if the condensing pressure falls too low , the expansio n valve may not be able to produce the flo w of liquid refri gerant needed to satisfy the dem and at the ev aporator . In some syst[...]

12 TRG-TR C0 05-EN note s peri od t w o Condensers It is more com mon, however , for a w ater -coole d conden ser to be conne cted to a cooling to wer . In this c ase, typic al methods fo r modulating the w ater flow thro ugh the condens er include ei ther using a variable-s peed drive on the condenser wa ter pump o r using a divertin g valve and p[...]

TRG-TR C0 05-EN 13 peri od t w o Condensers note s Common methods of modula ting this water tem perature include con trolling the cooling to wer fans or using a cool ing-tower bypass pipe. Controlli ng the cooling to wer fans, either by c ycling fans on and of f or by using a variable- speed drive on the fa ns, allows the system to control the temp[...]

14 TRG-TR C0 05-EN note s peri od t w o Condensers A common m e thod of c ontrolling the capac ity of an air -cooled conde nser is to vary the ai rflow across the co ndenser coi l. The heat-rejection ra te of a multiple- fan conde nser is of ten controlle d by cycling fans on and off to maintain accepta ble con densing pressu res. Alter natively , [...]

TRG-TR C0 05-EN 15 peri od t w o Condensers note s condens er is to flood the cond enser coil with liquid refrigerant. A conde nser coil tube that is filled with liq uid refrigerant no longer ac ts as a condens ing surface. Prog r ess ive flooding of the condenser coil tubes reduc es the capacity of the con denser and raises the c ondensing p ressu[...]

16 TRG-TR C0 05-EN note s period th ree Ev apor at ors The sec ond majo r compone nt to be discusse d is the e vaporator . The evapor ator is a hea t exc hanger that tra nsfer s heat from air , w ater , or some other fluid to the cool liquid refrigerant. T wo common types of evapora tors are the finne d-tube and the shell-and-tube. Finne d-T ube Ev[...]

TRG-TR C0 05-EN 17 period thre e Ev apor at ors note s The fins o f the coil are formed to p roduce turbulence as the air pas ses through them. This turbulence e nhances h eat transfer , preventing stratific a tion within the coil-le aving a irstream. T o p rovid e uniform heat transfer throughout the coil, th e liquid re frigerant is distributed t[...]

18 TRG-TR C0 05-EN note s period thre e Ev apor at ors Eac h distri butor has an a llow a ble rang e of refrigerant flow rates that define its stable op erating range. As the si ze of the eva porator coil increa ses, it ma y be necess ary to use more th an one d istributor to feed liquid refrig erant to th e coil. Inside the final length of tubes ?[...]

TRG-TR C0 05-EN 19 period thre e Ev apor at ors note s Shell-and- T ube Ev aporators Instead o f producing coole d air , a shell-and -t ube e vaporator is used to produce c hilled water . In this typ e of evaporator , the co ol liquid refrigerant flows throu gh the tub es and w ater fills the sh ell space su rrounding the tubes. As heat is trans fe[...]

20 TRG-TR C0 05-EN note s period thre e Ev apor at ors Ev apora tor Contr ol The rate of heat exc hange within an evaporator is go verned by (1) th e temperature d ifference between the refrigerant and the air or w ater being cooled, (2 ) the flow rate of the air or w ater through the ev aporator , and (3) the flow rate of the refrigera nt through [...]

TRG-TR C0 05-EN 21 period thre e Ev apor at ors note s T ypically , an e x pan sion valve is used to control the flo w rate of refrigerant through the e vaporator to maintain the proper amount of superhe at, ensuring that the liqu id refrigerant will be c ompletely vaporize d. W orking in conjunc tion with the u nloading or cycli ng compress or s, [...]

22 TRG-TR C0 05-EN note s period thre e Ev apor at ors The face-split coil configuration, a lso called ho r iz ontal-split or paral lel-flow, is split into p a rallel s ections. A por tion of the air passes th rough the to p section, the remaind er passes through the botto m section, and the two airstreams mix downstrea m of the coil. At lower loa [...]

TRG-TR C0 05-EN 23 period thre e Ev apor at ors note s The intertwined coil c onfigurati on splits th e coil section s by alternating the tubes fed in eac h row betw een two distributors. At lower loa ds, liquid refrigerant is fed t o every other tu be of the coil an d, therefore, it b ehaves like a coil with s ubstantially greater fin surface. At [...]

24 TRG-TR C0 05-EN note s period thre e Ev apor at ors Finally , the ro w-split coil configurat ion, also c alled ver tical-split or se ries-flow, places the independently -controlled coil s ections in series in the airstream. All of the air pa sses through both coil s ections, one before the other . T ypically , the first few upstream row s of the[...]

TRG-TR C0 05-EN 25 period thre e Ev apor at ors note s four rows for the downstream section . This is a n atte mpt to ensure near -equa l loading of t he two coil se ctions whe n both are active. A second concern in volves the control of superhe at. The coo ler temperatures leaving th e upstream section of coil hamper the abil ity of the downstream[...]

26 TRG-TR C0 05-EN note s peri od f o ur Expansion Devices The final m ajor component to be d iscussed is the expansion device. An expansion de vice is used to maintain a pressure difference be tween the high-press ure (condenser) a nd low-pressure (e vaporator) sides of the system establis hed by the c ompressor . This pres sure dif ference allow [...]

TRG-TR C0 05-EN 27 peri od f ou r Expansion Devices note s In addi tion to maintai ning a pressure d if ference, the t hermost atic expans ion valv e controls the qua ntity of li quid refrigerant e ntering the evaporator . It ensure s that th e refriger ant wi ll be comple tely vaporiz ed within the evaporator ( A ) and ma intains the proper amount[...]

28 TRG-TR C0 05-EN note s peri od f ou r Expansion Devices On the other hand, if too muc h liquid refrigeran t enters the evaporator , not all of it will be vaporized. As a result, so me liquid refrigerant gets into the compress or suction l ine. Since the compre ssor is design ed to compress vap or and not liqu id, liquid refrigerant can cause exc[...]

TRG-TR C0 05-EN 29 peri od f ou r Expansion Devices note s por tion of the liqui d to boil of f , or flash, an d has the effe ct of cooling the remaining li quid refrigerant to the desired eva porator temp erature. Th e resulting pres sure of the refrigeran t is 85 psia [0.59 MP a], whic h cor responds to 41 °F [5 °C]. Inside the evaporator tubes[...]

30 TRG-TR C0 05-EN note s peri od f ou r Expansion Devices In a typic a l TX V application , the outlet of the valv e is connected to the distributor . A remote bulb is at tac hed to the s uction line, whe re it se nses the refrigeran t vapor temper ature le aving t he evapor ator . This bulb is c harged with refrigeran t and as heat is trans ferre[...]

TRG-TR C0 05-EN 31 peri od f ou r Expansion Devices note s Using th e conditions from the pr evious example, the 49 °F [9.4 °C] refrigerant vapor leav ing the evaporator boils the refrigerant in the bulb , generating 97 psia [0.67 MP a] of pressu re within the r emote bulb. This pressure is transmit ted to the top si de of the valve diaphragm , c[...]

32 TRG-TR C0 05-EN note s peri od f ou r Expansion Devices For exam ple, assu me that an increa sing syste m load causes th e refrigerant within the coil to vaporiz e at a fas ter rate than desired. Th is moves the p oint at whic h the refrige rant becomes completel y vaporiz ed from A tow ard B . This increase in coil surface us ed for su perheati[...]

TRG-TR C0 05-EN 33 peri od f ou r Expansion Devices note s A typical re commended superheat set ting is from 8 to 1 2 ° F [4.4 to 6.7 °C]. T oo li ttl e superheat is ris k y because it presents a dange r of allowing refrigerant to leave th e evaporator in the liquid s tate. As mentioned earlier , the compress or is design ed to compres s vapor , [...]

34 TRG-TR C0 05-EN note s peri od fiv e A ccess or ies This peri od discusse s several acc essories used in comfor t-cooling refrigeration syste ms. S o le noid V al ve A solenoid v alv e is used to stop the flow of refrigerant within the s yste m. These va lves are magnetica lly operated, and an electric winding controls the opening an d closing o[...]

TRG-TR C0 05-EN 35 peri od fiv e A ccess or ies note s One com m on use of a s olenoid valve is to control the flow of liquid refrigeran t to multiple sections of the evaporator . In this applicatio n, a valve is i nstalled in the liquid l ine, upstream of the ex pansion valve for ea ch in di vidually controlled section of the evapora tor coil. Usi[...]

36 TRG-TR C0 05-EN note s peri od fiv e A ccess or ies When the c ompressor is shut of f, the e vaporator contains a large qua ntity of liquid re frigerant. This can presen t a problem if some of the refrigerant drai ns into the su ction line and slugs the compressor when it starts u p again. T o prevent this from occur ring, man y systems pump the[...]

TRG-TR C0 05-EN 37 peri od fiv e A ccess or ies note s act as a catalyst in ch emical reactions th at result in the form ation of acid s. These ac ids can cor rode system comp onents and cau se the oil to sludge. The filt er drier should be installed cl ose to the s olenoid valve to provide the most pr otection for the solenoid and expa nsion valve[...]

38 TRG-TR C0 05-EN note s peri od fiv e A ccess or ies Moisture-Indicating Sig ht Glass A moisture-indicating sight glass is installed in the liqu id line, upstream of the expan s io n valve, and permits the opera tor to observe t he condition of the refrigerant prio r to entering the expansi on valve. The v alue of the sigh t glass is in its mois [...]

TRG-TR C0 05-EN 39 peri od fiv e A ccess or ies note s Suction Lin e Filter Similar to the l iquid-line filter drier , the su ct i on line filter performs the ta sk of removi ng foreign mat ter from the refrigeratio n system. It is instal led in the suction l ine, just upstream of the compressor . The suc tion filter conta ins filter media to remo [...]

40 TRG-TR C0 05-EN note s peri od fiv e A ccess or ies R eplaceabl e core suct ion filters are c ommonly installed a f ter a com pressor failure has occurred . The core is replaced a fter the foreign m atter or ac id has been remo ved from the system. Additionally , suction filt ers should be ins talled in all field-as sembled systems . Hot Gas Muf[...]

TRG-TR C0 05-EN 41 peri od fiv e A ccess or ies note s Shutof f V alve Shutof f val ves are used t o isolate on e part of the refrigeratio n system from the rest. Add itionally , they can be u sed to trap the refrigerant c harge in one componen t of the system, the c ondenser for exa mple, to per mit se rvice or repair to ano ther part of th e syst[...]

42 TRG-TR C0 05-EN note s peri od fiv e A ccess or ies Ac cess P or t An access port is u sed to add refrigera nt to the system or for m easurement. An acces s por t is typically installed in the liquid line in a con venient location and is us ed to c harge the system with liq uid refrigerant. It is also used to measure s ubcooling. The suc tion li[...]

TRG-TR C0 05-EN 43 note s W e will no w review the main conc epts that were co vered in this clinic ab out the componen ts in a vapor -com pression r efrigerati on system. P eriod One rev iewed the vapor -co mpression ref rigeration c ycle using the P - h ch a rt . A cool, low -pressure mix ture of liq uid and vapo r refrige r ant e nters the evapo[...]

44 TRG-TR C0 05-EN note s peri od six Review of the refrigera nt vapor causes it to de superheat, condense in to liquid, and furthe r subc ool be fore leavi ng th e cond ense r ( D ) for the e xpansion d evice. Finally , the high-p ressure liquid refrigerant flow s through the expansion device, causing a large press ure drop (the line fro m D to A [...]

TRG-TR C0 05-EN 45 peri od six Review note s P eriod Three presented th e different types of evaporators and me thods of evapor ator con trol. The evaporator transfers heat from air , water , or some othe r fluid to the cool liquid refrigeran t. The two common types of evaporators are finned- tube and shell-and-tub e. P eriod Four reviewed the oper[...]

46 TRG-TR C0 05-EN note s peri od six Review P erio d Fiv e discu ssed se veral ac cessor ies com monly used in comfort-co oling applicati ons, including: sol enoid valve , liquid-line filter d rier , moisture- indicating sight glass, suc tion line filter , hot g as muf fler , shutoff v alve, and access port. The sole noid valve is used to stop the[...]

TRG-TR C0 05-EN 47 peri od six Review note s For m ore information, refer to the following references: ■ Tr a n e Air Conditionin g Manua l ■ Tr a n e R eciprocati ng R efrigeration Ma nual ■ “The DX R efrigerant Cooling Coi l Conundrum” (T rane Engineers New slet ter , 1 988 — vo lume 17 , numb er 1) ■ A SHRAE Handbook – Fundamenta[...]

48 TRG-TR C0 05-EN Questions f o r P er iod 1 1 Using th e pressure–enth alpy c hart in F igure 68, wh ic h two poin ts cor respond to superh eating the refrig erant vapor inside the evaporator? 2 Again using Figure 68, wh ich two points cor respond to subc ooling the liquid re frigerant insid e the condenser? Questions f o r P er iod 2 3 List t [...]

TRG-TR C0 05-EN 49 Quiz Questions f o r P er iod 4 10 What are the two pr imary pu r pose s of a thermostatic expa nsion valve? 11 What are th e risks of to o muc h super heat in the s ystem? Questions f o r P er iod 5 12 During a pump -down cycle, the comp res sor p umps the refrigerant from th e ____ _ (low or high)-p ressu re side of the sys tem[...]

50 TRG-TR C0 05-EN 1 B to C 2 F to G 3 Air -cooled, e vaporative, and w ater -cooled 4 A decreas e in syste m load and a reduction in the outdoo r air te mperature 5 V arying the airflow through the condense r coi l or flooding the co ndenser coil with liqu id refrigerant 6 A dis tri butor 7 T o dire ct the w ater in a rising and fall ing flow path[...]

TRG-TR C0 05-EN 51 access port A device th at allows a tec hnician to g ain access to the refrigeration s y stem for cha rging or measurement. air -coole d condens er A type of condenser where refrigera nt flows through the tubes and rejects hea t to air that is drawn acros s the tubes . ASHRAE A merican S ociety of H eating, R efrigerating a nd Ai[...]

52 TRG-TR C0 05-EN Glossary fa c e -s p l i t A type of finned -tube evaporator ar rangement that splits the coil into paralle l air paths. fill The hea t transfer surface ins ide a cooling tower . finned- tube ev apora tor A type of evapo rator where refrige rant flows through the tubes and air blows acros s the tubes and fins. flash The process o[...]

TRG-TR C0 05-EN 53 Glossary subcoole r The lower po rti on of the condenser th at fur ther cools the saturate d liquid refrigerant. suction he ader A section of pipe used to collec t the refrigerant vapor wh en it leaves the tubes of a finned-tu be evaporator coil . suction li ne filter A device installed in the suction line to r emo ve foreign mat[...]

The T rane Compa n y Wo rldwi d e Ap plied Syste ms Group 3600 Pammel C reek Road La Crosse, WI 5460 1-7599 ww w .t ran e.co m An American S tand ard Company Literature Or der Number TRG-TRC 005-EN File Number E/A V -FND-TRG-TRC005-11 99-EN Supersedes 2803-3-784 and 2803-5-1284 Stocking Location Inland-La Cro sse Since Th e T rane Company has a p o[...]