Design of a Test Rig for the Study of Methane Drying by Cooling Effect

Size: px

Start display at page:

Download "Design of a Test Rig for the Study of Methane Drying by Cooling Effect"

Chad Floyd
5 years ago
Views:

1 Availabl onlin at ProEnvironmnt ProEnvironmnt 7 (204) 23-3 Original Articl Dsign of a Tst Rig for th Study of Mthan Drying by Cooling Effct SAFIRESCU Călin Ovidiu* Tchnical Univrsity, Mmmorandumului St.., No. 28, 4004 Cluj-Napoca, Romania Rcivd 5 July 204; rcivd and rvisd form 3 August 2 04; accptd 22 August 204 Availabl onlin 23 Sptmbr 204 Abstract Th papr is prsnting th working principl of a tst rig for study of mthan drying in transport ducts by th cooling ffct followd by th mthan rhating. Th dsign principl of th hat xchangrs is also prsntd. Th thrmal calculation mthodology is basd on critria quations. Thr ar prsntd two constructiv variants of tubs and shll hat xchangrs, on in countr flow and on in cross flow. Th rsults of dsigning mthodology ar prsntd for both hat xchangrs: coolr dryr and hatr. Both hat xchangrs ar dimnsiond to fit with th tst rig. Kywords: mthan drying, cooling ffct, mthan transport, dsign, cooling cycl, thrmal alculation.. Introduction Th prsnc of humidity in th mthan transport systm is not dsird bcaus of th associatd ngativ ffcts. In practic thr ar implmntd thr drying mthods: Adsorption of humidity by solid matrials, Absorption of humidity by liquid solutions and rfrigration. In this papr it is prsntd a nw drying mthod by cooling ffct. Th novlty of th prsntd mthod consists in th rhating of th mthan immdiatly aftr th drying by cooling. Th papr is prsnting both th working principl of th proposd mthan drying mthod and th thrmal calculation principl for th cooling and hating hat xchangrs. Th thrmal calculations ar prformd for dimnsioning th coolr-dryr and th hatr, to fit with th xprimntal st-up. In th fram of th xprimnt, it was considrd th maximum flow rat of about 60m 3 /h. * Corrsponding author. Tl: Fax: mail: Tibriu.Rusu@imadd.utcluj.ro Th rfrigrating quipmnt was also spcially dsignd for this application and is providing both cooling and hating powr. Th goal of th papr is to prsnt th thrmal calculation procdur for both hat xchangrs in two constructiv variants: on in countr flow and on in cross flow. 2. Exprimntal St-Up Th schm of th tst rig is prsntd in fig.. Th tst rig is basd on a mthan circuit, whr humidity can b addd in a controlld mannr, (circuit of black color), a cooling circuit of cological antifrz (circuit of blu color) and a hating circuit of watr (circuit of rd color). Th pip diamtr of th mthan circuit was considrd: D = 2" 0.05 m Th flow spd was considrd (5 0) m/s. 23

2 3 2 Th rfrigration cycl working diagram is prsntd in fig. 3. lgp 4 3 B 2t 2 a b b a C H 5 A a b 4 Figur. Principl schm of th tst rig Coolr-dryr; 2 Hatr; 3 Rfrigrating quipmnt; 4 Mthan fan a Masurmnt point for tmpratur and humidity b Masurmnt point for tmpratur, humidity and flow rat Th maximum contnt of humidity is considrd of.5 g/m 3. Th schm of th rfrigrating unit is prsntd in fig. 2. 3/8" 0 mm VL /2" 2 mm FD IU 4 VEM 5 PRA in BL glycol out (gt) 4 Watr K 3 V Glycol out R34a T P PRG PT CS C glycol in (gr) a 2 /2" 2 mm 3/4" 20 mm Figur 2. Schm of th rfrigrating unit C Comprssor; VL Expansion valv; V Evaporator; K Condnsr; P Prssur connctr; T Thrmostatic bulb; VEM Solnoid valv; FD Filtr dryr; IU Humidity indicator; CS Chck valv; BL Liquid rcivr; RC Capacity rgulator; DA Liquid-gas mixtur PT Dual prssur control; PRG Glycol pump; PRA Watr pump Ovrhatd vapors; 2 Discharg vapors; 3 Saturatd liquid; 4 Sub coold liquid; 5 Humid vapors Figur 3. lgp-h working diagram 3. Thrmal Calculations 3.. Rqustd rfrigrating powr Th snsibl rfrigrating powr was calculatd with: Q 0 m cp t [kw] - m [kg/s] is th mthan flow rat; - c p [kj/kgk] is th spcific hat of mthan at th working prssur; - Δt [K] is th tmpratur diffrnc Th rfrigrating powr ndd to produc th condnsation is: - m w Q 0w m w lvw [kw] [kg/s] is th vacuatd humidity flow rat - l vw = 2490 kj/kg is th latnt hat of watr condnsation Th rfrigrating quipmnt was dsignd with variabl and controlld capacity (rfrigrating powr). Th chousd rfrigrant is R34a, bing adquat for rducd rfrigrating powr Thrmal rgim of hat xchangrs Th thrmal rgims of th hat xchangrs ar prsntd in th following figurs. h 24

3 t [ C] t gaz,i =5 C mthan t gr =6 C t gaz, =3 C glycol 30% t gt = C S [m 2 ] Figur 4. Hat xchangr (Coolr-dryr): 5 kw 3.3. Calculation of rfrigrating cycl Th input data of th rfrigrating cycl thrmal calculation is prsntd in tabl. Tabl. Input data for rfrigrating cycl calculation Paramtr Valu U.M. Rfrigrating powr 4.4 kw Evaporating tmpratur -5 C Condnsing tmpratur 30 C Volumtric fficincy Isntropic fficincy Ovrhating 5 C Sub cooling 5 C t [ C] t gt = C t 5 =-5 C x 5 =0.2 glycol (30%) R34a (p=2.4 bar) t 0v =-5 C t gr =6 C t =0 C S [m 2 ] Th thrmal calculation of th rfrigrating cycl was ralizd with original softwar dvlopd basd on th Enginring Equation Softwar (EES) Thrmal calculation of hat xchangrs It was takn into considration two typs for ach of th hat xchangrs (coolr -dryr and hatr). Th principl schm for th horizontal pips hat xchangrs is prsntd in fig. 8. Th principl schm for th vrtical pips hat xchangrs is prsntd in fig. 9. Figur 5. Evaporator: 5 kw t [ C] Glycol (30%) Watr R34a (p=7.7 bar) t 2 =52 C t 4 =26 C t kl =30 C t kv =30 C t tur =25 C t rtur =20 C watr Condnsd Coolr - Dryr Mthan Hatr Mthan S [m 2 ] Figur 8. Schm for horizontal pips hat xchangrs Figur 6. Condnsr: 6 kw t [ C] Mthan watr t tur =25 C t rtur =20 C t gaz, =5 C Mthan Condnsd t gaz,i =3 C mthan S [m 2 ] Coolr - Dryr Glycol (30%) Hatr Watr Figur 7. Hat xchangr (Hatr) Figur 9. Schm for vrtical pips hat xchangrs 25

4 Th critria quation usd to calculat th Nusslt (Nu) numbr in th cas of a fluid flow ovr a bank of horizontal tubs (for th mthan) can b calculatd with th quation of Zukauskas [], according with [2]: / 4 m 0.36 Pr Nu C C2 Rmax Pr Pr s Nu [-] - Nusslt numbr at th outsid of tubs R max [-] - th maximum valu of Rynolds numbr, in th minimum flow sction Pr [-] - Prandtl numbr at th avrag tmpratur of th fluid (mthan) Pr s [-] - Prandtl numbr at th tubs surfac tmpratur also for mthan C [-] - constant C 2 [-] - constant m [-] - cofficint Th valus of constant C and of cofficint m, ar prsntd in tabl blow. Tabl 2.Th valus of constant C and of cofficint m Disposal R max C m Alignd Alignd Isolatd cylindr Alignd Alignd Staggrd Staggrd Isolatd cylindr Staggrd (s T/s L) /5 0.6 Staggrd Th valus of constant C 2, function of numbr of rows (n t) and typ of disposal, ar prsntd in tabl blow. For n t > 20 => C2 =. Tabl 3. Th valus of constant C 2 n t Alignd Staggrd Th critria quation usd to calculat th Nusslt (Nu) numbr in th cas of a fluid that flow insid th tubs (glycol or watr), according to [2] is: 4 / 5 n Nui C3 Ri Pri C 3 [-] - a constant. In th cas of fluid hating (glycol) C 3 = In th cas of fluid cooling (watr) C 3 = R i [-] - Rynolds numbr at th tubs insid Pr i [-] - Prandtl numbr at th tubs insid at th avrag fluid tmpratur N [-] - a constant. In th cas of fluid hating (glycol) n = 0.4. In th cas of fluid cooling (watr) n = 0.3. Th critria quation usd to calculat th Nusslt (Nu) numbr in th cas of a fluid fl ow along a bank of vrtical tubs (for th mthan) can b calculatd with th quation according with [2]: Nu C R Pr s R [-] - Rynolds numbr for mthan Pr [-] - Prandtl numbr for mthan µ [Pa s] - dynamic viscosity of mthan at avrag tmpratur µ s [Pa s] - dynamic viscosity of mthan at tubs surfac tmpratur 0.6 C [-] constant, C.6 d ch d ch [m] - quivalnt hydraulic diamtr of tubs Th critria quation usd to calculat th Nusslt (Nu) numbr in th cas of a fluid that flow insid th vrtical tubs (glycol or watr) ar th sam with th quation for horizontal tubs. Th global cofficint of hat transfr is calculatd with th rlation: Th avrag hat transfr cofficint at th outr sid of th bank of tubs ( α ) can b dtrmind with th quation of dfinition for Nusslt numbr: k tv tv i 2 [W /(m K)] Nu d Nu α [W/(m 2 K)] - th cofficint of convction d [m] - th outr diamtr of tubs λ [W/(m K)] - th thrmal conductivity of th fluid in flow outsid th tubs (mthan). d α [(W/m 2 K)] - cofficint of convction on th tubs outsid α i [(W/m 2 K)] - cofficint of convction on th tubs insid δ tv = mm - th tub thicknss λ tv = 43 W/(m K) - th thrmal conductivity of th tubs matrial (stl). 26

4. Rsults and Discussions Th rsults of snsibl rfrigration powr calculation ar indicatd in tabl4. Tabl 4. Valus of snsibl rfrigrating powr [kw] Mthan tmp. diffrnc [K] 2 6 0 4 5 0.27 0.80.34.88 6 0.

5 4. Rsults and Discussions Th rsults of snsibl rfrigration powr calculation ar indicatd in tabl4. Tabl 4. Valus of snsibl rfrigrating powr [kw] Mthan tmp. diffrnc [K] Th rsults of latnt rfrigrating powr calculation ar prsntd in tabl 5. Tabl 7. Calculatd valus of th flow rats Flow rat Valu U.M. Mass flow rat kg/s Mass flow rat 27.2 g/s Mass flow rat 97.9 kg/h Volumic flow rat 8.74 m 3 /h Tabl 8. Powrs of th main componnts and cofficint of prformanc Powr Valu U.M. Evaporator 4.50 kw Condnsr 5.6 kw Comprssor. kw COP In fig. 0 ar prsntd th rsults of th thrmal calculation of th rfrigration cycl, with th Slct Softwar. Tabl 5. Valus of latnt rfrigrating powr [kw] Humidity flow rat Q ow [kg/s] [kg/h] [g/h] [kw] 5.30E E E E E E E E E E E E-02 Du th low valus of latnt rfrigrating powr, comparing to th snsibl rfrigrating powr but also to th non stationary charactr of th latnt hat xtraction of humidity, th maximum rfrigrating powr was considrd by incrasing th snsibl rfrigrating powr by 5%. Q kw Th calculatd valus of th thrmal paramtrs ar prsntd in tabl 6. Tabl 6. Thrmal paramtrs Stat t[ C] p[bar] h[kj/kg] x[-] t A B H Th calculatd valus of th flow rats ar prsntd in tabl 7. Th powrs of th main componnts and th global cofficint of prformanc ar prsntd in tabl 8. Figur 0. Rsults of thrmal calculation using Slct It can b obsrvd that th rsults obtaind with th original softwar and with EES ar in good agrmnt. Th rsults of thrmal calculation of hat transfr on th mthan sid in th cas of crossing flow ovr a bank of horizontal tubs ar prsntd in tabls 0,, 2, and 3. Tabl 0. Rsults of hat transfr calculation for mthan - cross flow ovr bank of horizontal tubs [m 3 /s] Nusslt (Nu ) [-] Cof. of convction (α ) [W/(m 2 K)] Th rsults of thrmal calculation of hat transfr on th liquid sid in th cas of cooling insid horizontal tubs ar prsntd in tabls, 2, and 3. 27

6 Tabl. Valus of flow rats, spd ad Rynolds for fluids insid th horizontal tubs Fluid Mass flow Vol. flow Rynolds [m [kg/s] [kg/h] /s] (R i) [-] x 0-4 [m 3 /h] Glycol Watr Tabl 6. Rsults of thrmal calculation for fluids insid th vrtical tubs Fluid Cof. of Rynolds Nusslt convction [-] [-] [W/(m 2 K)] Glycol Watr Tabl 2. Rsults of hat transfr calculation for fluids insid th horizontal tubs Fluid Nusslt Cof. of convction (Nu i) [-] (α i) [W/(m 2 K)] Glycol Watr Tabl 3. Global hat transfr cofficints for glycol and watr for horizontal tubs hat xchangrs Global hat transfr Global hat transfr cof. (glycol) (k glicol) [W/(m 2 K)] cof. (watr) (k w) [W/(m 2 K)] Th rsults of thrmal calculation of hat transfr on th mthan sid in th cas of flow along a vrtical bank of tubs ar prsntd in tabls 4, 5, 6, and 7. Tabl 7. Global hat transfr cofficints for glycol and watr for vrtical tubs hat xchangrs Global hat transfr Global hat transfr cof. (glycol) (k glicol) [W/(m 2 K)] cof. (watr) (k w) [W/(m 2 K)] Th lmnts of gomtry for both coolrdryr and hatr, with horizontal tubs wr also calculatd and prsntd blow (tabls 9 2). Tabl 8. Elmnts of gomtry for horizontal tubs coolr-dryr (I) Surfac (S) [m 2 ] No. of tubs [-] Rows no. long. dir [-] Tabl 4. Rsults of Rynolds max. calculation for mthan - flow along bank of vrtical tubs Transport spd in HX Rynolds [-] E E E E E E+05 Tabl 9. Elmnts of gomtry for horizontal tubs coolr-dryr (II) No. of pass. (glycol) [buc] Lngth [m] Tabl 5. Rsults of hat transfr calculation for mthan - flow along bank of vrtical tubs Transport spd Nusslt [-] Cof. of convction [W/(m 2 K)] Tabl 20. Elmnts of gomtry for horizontal tubs hatr (I) Rows no. Surfac (S) No. of tubs [m 2 long. dir ] [-] [-]

Tabl 2. Elmnts of gomtry for horizontal tubs hatr (II) No. of pass. (glycol) [buc] Lngth [m] 5 3.6 5.42 6 2.5 5.0 7.7 4.70 8. 4.45 9 0.6 4.25 0 0.2 4.

7 Tabl 2. Elmnts of gomtry for horizontal tubs hatr (II) No. of pass. (glycol) [buc] Lngth [m] Th lmnts of gomtry for both coolrdryr and hatr, with vrtical tubs wr also calculatd and prsntd blow (tabls 22 and 23). Th tubs wr considrd of Ø0x and wr considrd 7 tubs in th tubular plats. Figur. Opration point in th nvlop of th comprssor Tabl 22. Elmnts of gomtry for vrtical tubs coolrdryr Coolr-dryr (glycol) Surfac Lngth [m2] [m] Tabl 23. Elmnts of gomtry for vrtical tubs hatr Hatr (watr) Surfac Lngth [m2] [m] Figur 2. Tchnical laf of th Condnsr 5. Slction of Componnts Basd on thrmal calculation of th rfrigration cycl and on th thrmal rgim of th hat xchangrs, wr slctd th main componnts. In fig. is prsntd th opration point in th nvlop of th Emrson Copland ZR40K3E- PFJ scroll comprssor. Th tchnical data of th Sondx SL23-BR25-20-TL-COND condnsr and SL32-BR25-20-TLA- EVAPDX vaporator, providd by th slction softwar (in Romanian) ar prsntd in fig. 2, and fig. 3. Th tchnical data of th Emrson Alco TX3-M25 xpansion valv ar prsntd in fig. 4. Figur 3. Tchnical laf of th Evaporator 29

Figur 8. Slction chart of th coil cabl Figur 4. Tchnical data of th xpansion valv Th tchnical data of th Emrson Alco ADK 032 filtr dryr ar prsntd in fig. 5.

Tchnical data of th filtr dryr Figur 9. Slction chart of th coil supply transformr Figur 20.

8 Figur 8. Slction chart of th coil cabl Figur 4. Tchnical data of th xpansion valv Th tchnical data of th Emrson Alco ADK 032 filtr dryr ar prsntd in fig. 5. Th tchnical data of th Emrson Alco 200 RB 3 T3 solnoid valv ar prsntd in fig. 6. Th slction chart of th Emrson Alco 2 ASC 24V/50Hz coil for th solnoid valv is prsntd in fig. 7. Figur 5. Tchnical data of th filtr dryr Figur 9. Slction chart of th coil supply transformr Figur 20. Slction chart of th moistur indicator Th tchnical data of th Danfoss KVC 2 capacity rgulator ar prsntd in fig. 2. Th tchnical data of th Danfoss LG 2-6 liquid distributor ar prsntd in fig. 22. Th tchnical data of th Emrson Alco PS2-W7A dual prssur control ar prsntd in fig. 23. Figur 2. Tchnical data of th capacity rgulator Figur 6. Tchnical data of th solnoid valv Figur 22. Tchnical data of th liquid distributor Figur 7. Slction chart of th coil for th solnoid valv Th slction chart of th Emrson Alco 2 ASC-N30 coil cabl is prsntd in fig. 8. Th slction chart of th Emrson Alco ECT 323 coil supply transformr is prsntd in fig. 9. Th slction chart of th Emrson Alco AMI- TT 3 moistur indicator is prsntd in fig. 20. Figur 23. Tchnical data of th dual th prssur control Th tchnical data of th Klimal EFM 2.3 liquid rcivr of 2.3 l and 28 bar maximum oprating prssur ar prsntd in fig

Th thrmal calculation of hat xchangrs is basd on critria quations and th thrmal calculation of th rfrigrating unit was ralizd using an original computing program and comprssors slction softwar.

9 Th thrmal calculation of hat xchangrs is basd on critria quations and th thrmal calculation of th rfrigrating unit was ralizd using an original computing program and comprssors slction softwar. Th slctd componnts of th rfrigrating unit ar also prsntd. Figur 24. Tchnical data of th liquid rcivr 6. Conclusions It was dsignd an xprimntal tst rig for th study of mthan drying in transport ducts by using th cooling ffct followd by th mthan rhating. Th papr prsnts th working principl and th dsign principl of th hat xchangrs and of th rfrigration unit. Rfrncs [] Zukauskas A. Hat transfr from tubs in cross flow, 972,in J.P. Hartntt and T.F. Irvin, Jr., Eds. Advancs in hat transfr, Vol. 8, Acadmic Prss, Nw York. [2] Incropra F.P., D.P. Dwitt, T.L. Brgman, A.S. Lavin, 2006, Fundamntals of hat and mass transfr, 6th dition, John Wily & Sons, USA. [3] Ştfănscu D., M. Marinscu, A. Dănscu, 98, Transfrul d căldură în thnică. Culgr d problm pntru inginri, Vol., Ed. Thnică, Bucurşti. 3

WASTE HEAT RECOVERY USING DIRECT THERMODYNAMIC CYCLE

Bulltin of th Transilvania Univrsity of Braşov Vol. 8 (57) No. 2-2015 Sris I: Enginring Scincs WASTE HEAT RECOVERY USING DIRECT THERMODYNAMIC CYCLE I. COSTIUC 1 L. COSTIUC 2 S. RADU 3 Abstract: For wast