SERI/TP-253-1871 UC Cateaorv: 62
A Simple Energy Calculation Method for Solar Industrial Process Heat Steam Systems
Randy Gee
January 1983
To be presented at the ASME 6th Annual Solar Energy Division Conference Orlando, Florida 19-21 April1983
Prepared Under Task No. 1394.00 WPA No. 416
Solar Energy Research Institute A Division of Midwest Research Institute 1617 Cole Boulevard Golden, Colorado 80401
Prepared for the
U.S. Department of Energy Contract No. EG-77-C-01-4042 Printed in the United States of America Available from: National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 Price: Microfiche $3.00 Printed Copy $4.00
NOTICE
This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. SERI/TP-1871
A SDn'LE E1'IERGY CALCULATIOK M!THOD FO'R SOLAR INDUSTRIAL PllOCESS BEAT S'TlWI SYST!MS
Bandy Gee Solar Energy Research Institute Cole Boulevard 1617 Golden, COlorado 80401
H total expected daytime ho rs of Rprocess downtL�e u industrial process downtime an - annual �asis (hr yr 1) Designing a solar industrial process heat (IPH) system, I beam irradiation - ncirlent in col sizing its components and predicting its annual energy � le tor plane ) delivery requires a method for calculating solar system e (l·T m ?erformance. A calculation method that is accurate, long-term avera�e direct normal easy to use, accounts for the impact of all important irradiance - (�1 r.t �) system aramet r� and does not require use of a compu ? e , peak irradiance a'7ailable col ter is described in this paper. Only simple graphs and to lectors m-2) a hand calculator are required to predict annual col (W lector field perfo�nce and annual system losses. r annual incident-angle modifie cor1:ection The energy calculation method is applicable to a vari collector incident-angle �odifier ety of solar system configurations. However, this at x degrees paper describes the calculation method applied only to ?arabolic trough steam generation systems that do not latitude (de�rees) employ ther.ual storage. !loth flash tank and unfired collector length boiler steam systems are covered. 'Readers interested (m) in application of this calculation method to other col spillage �nd loss factor lector types and/or system configurations are referred eld fluid mass flow to Desilzn AJ)oroaches· for Solar Industrial Pl:'ocess Heat collector -ti Syste� (Kutscher at al. lqR2). rate (k� s ) f rate (kg :·Is steam mass l o w s-1) total col e tor fi�ld thermal (Mep)coll l c capacitance (J �c-1) t capacitance of s.:�lar total hermal collector area (�2) m t r sy'!te excl•Jding c,ollec�or he 1:1al it �aximum collector area for no �apac ance (J °C-1) storage system (m2) average number of collect:.i.on iays �1d,c ground rea covered own days) per r '!, by collector tcoold yea (days ::r- array (;u-) ) number collectc>r co�stant-pressure s c ic heat of parallel �OW\! � -1 pe if ( g " - 1 J c ) long-term average ene1:gy collec tion collectora, per concentrator fo a lengt� (m) rate of �ni: c l r collecto -�rea, during da�light "'' collector efficiency fac=cr ) hours (W m - unfired boiler factor long-term avera�e u ann al �n�r?Y flash steam syst� :ac=or l12c of system :-r- to tion solar (J collector heat removal factor ) long-term average ener3"J .�ollec epe d nt heat exchan�e collectot"s system d n e tion rate of during a tor yl f c da ight hours (Y) 7 annual aharlin� loss fsctor for annual solar 3ystem c o shade �o :.d wn los midfield collectors ses (J :n--1) annual shading loss ctor for :1verilge annual energy fa long-tem 'shade, field collector field deli;;ery (J yr-1) solar system use factor a industrial process energy use r t a o ratio •Jf solar col ground c ver :�n lectC!r array o s industrial ;> l" ce s sn!".ual loac yr--) "liter latent :1eat of •Taporization (J 1 SERI/TP-1871 am�ient temperature (°C) Ideally, empirical correlations should be based on mea average yearly daytime temperature sured data from operating solar systems, but suitable (oC) data for solar IPH systems is not yet available. Instead, the empirical correlations that have been �ighest expected annual ambient developed are based on the results of a detailed, hour temperature (°C) by-hour IPH system computer model called SOLIPH. M average yearly nighttime ambient Another paper J.a,n in these proceedings descri�es the temperature (',C) computer model (Kutscher, 1983). Typical meteoro logical year tapes provided the hourly weather collector fluid temperature (!MY) (°C) and solar irradiation data base for the computer boiler feedwater temperature (°C) model. 'The Tlff data set is a COillt)OSite of months selected from the historical d ta base for each steam temperature so��! � (°C) of the 26 stations With long-term records. P'or these colle tor heat loss coefficient stations, thousands of runs were made to -2 1 so��T SOLIPH (l� m 0c- ) provide a large data base for developing empirical cor relations. With this large data base, a multivariable �odified collector heat loss coef regression analysis was used to generate empirical cor ficient (mod ied for pipe system -if 1 relations that closely matched the SOLIPH runs. Agree losses) (W m °C- ) ment between the empirical correlations and the SOLIPH 4% unfired boiler heat transfer coef runs is better than (t'IIIS error). Additionally, ficient, boiter surface area these empirical correlations were checked for accuracy product (W °C- ) against a larger weather and solar irradiation data base. runs for the sites (using overall heat loss coefficient of SOLIPH 208 ERSATZ tapes) were made and compared with the piping system co111ponents on outlet ERSATZ � empirical correlations. empirical correlation (hot) side of field (W 0c-l) Again, accuracy (rms error) was found to be better than 4%. overall heat loss coefficient of piping system components op inlet (cold) side of field (W °C- ) heat loss coefficilnt of entire piping system (H °C- ) A large amount of industrial process heat is utilized total solar svstem thet'lllal loss in the form of low-pressure saturated steam. A large fraction of this energy is utilized by industrial coefficient (W °C-1) plants that have daytime, 7 day/week loads. For these i:tcident angle 1110difier weighting lJX industrial plants, a no-storage, solar-steam .syst:em can factor for x degrees provide an attractive source of the�! energy. INTRODUCTIOR There are currently two principal configurations for solar system steam production *· 'l'l'!e first and most During t�e planning and design stages of an IPH solar widely used systent configuration is the unfired-boiler system, an annual energy calculation method is needed system (see Fig. t). This is the configuration used by for two principal reasons. First, a calculation method all five MISR program participants. In an anfired is needed to aid in the design of the ! 2 SERI/TP-1871 Existing Often parabolic trough efficiency is reported as: Parabotic Trougn Equ•oment Solar SYstem CheeK ----...... ! 2 Ta1 Steam I r f Header 1 1_.....;-.,r_;:.) I II Heat T:ansfer This efficiency form has no physical basis (Tabor, Flwd Loop I and should be modified to the suggesced . 1980) form I� Treatment shown below. I Plant II ____ L ...J Circulating Pump where B • /I f a2 test - Fig. 1 Unfired Boiler Steam System I is the beam irradiance that was present during test the collector tes . I value is gi•ren, take f If no test I as W/m • �est 1000 Flash EJC1Sting Parabolic Trougn Va1ve Equtpment �row, the collector ?'1'1 and are given aa: Solar Svstem ----- 0 F'TJ Check l L Staam HaaaerlI I I Pressunzed I Water Flutd - I Evaluate F'Ut at aT 1"s a LOOP T , Treatment 1I I • Define land availability at proposed solar site. L __ _P�".!...J � - Configure collector field and enerl7 transport system. (Collector manufacturer recommendations as Circulattng well as references (8, 9, ll and 12) will aid in this Pumo step.) • Calc�late the maximum recommended collector area 2 - Fig. Steam Flash System A based on the process load energy use c ,malt rate assumin.g To prevent boil-ing within the collector, the water is Qload and no thermal stor"'ge is used pressurized by the recirculation pump. The pump is and that solar energy is never dumped. specified so that water exiting the collector field is under sufficient pressure to prevent boiling. The col lector field outlet temperature "liUSt be considerably • • r 3 SERI/TP-1871 t. - Step Calculate system dependent heat exchange fac .2 .4 .6 .8 tor Fs· 8 • For steam flash systems, calculate • Define expected dirt and dust optical loss �odi .3 3 f:!.er. l!ecause this loss is site specific it should 0 .2 .4 6 ,8 be based on observed material coupon degradation for 4 Intensity Ratio the particular site. (See Refs. and 10 for :llOre information.) FeU� (T,- ia) • Calculate incident-angle modifier annual correc Feil:, i;, • tion 'K,3 3 Intensity Fig. - Energy Collection Rate Cu�Jes vs. • W7.5K7.5 + 1122.5K22.S + l¥:37.5!<37.5 K + 11sz.sKs2.5 + 67.3 67.s in 1. Values of l{lt are found Table Values of JS.: are taken from · the collectors incident angle modifier c.urve.. • �1ultiply the normal incidence optical efficiency (F.,ll0 ) by both modifiers to arrive at the effective opti�al efficiency (FRn0). Step 5 - M"odify collector heat loss coefficient and effective optical efficiency to account for thermal transport energy losses. • Group energy tr ansport components (i.e., piping, •1al•tes, fittings, pipe anchors, circulation pum!J, flex hoses, and unfired boiler or Elash tank) into ei::her inlet (cold) components or outlet (hot) com �onents. r�lculate UiAi and U0A0• • Correct the effecti·te optical efficiency to account for steady-state pipe losses. Fig. F n·o 4 - Average Direct �o�l irradiance During __R ,. /M c Hours e - u o A o c p Daylight (1im-2) FRi"' 0 latitude, and collector orientation. • Correct the collector heat loss coefficient to • A used to evalu account for steady-state pipe losses. �nd calculator may �e "' " ' ate qc/[F9FRn; (lb + 50)] !.n3tead of the ;>raphical determination .._ :i c c U A • . R"L -'1 A c -U1A/t_ .• c o o /� cc !' o o /:i c p � e c p e p . ----- (e For east-west arabo ic troug s ·�- [ p l h : L Ac'RvL • ,•,t",'•>] qc/[75Fan� (fb + so)]"' '). 6688- 0.6745 • x- 0.3166 :�2 '-u For north-scu:h parabolic trou�hs: net ener�r Stery 7 - Calculate annual average collection � in q::iL='sF'1n�(T0 • �tak g into account thermal transport. losses) for +so): "'o.as1n- o.:n11 "<: � ,J. J:!n :·:- unsharl�d col�actors. O.C0391° • L + 0.003864 L � - O.J014R4 • • v� u ratio L • �2 Dete�in� l e of intensity L a latitude (degrees) F.,u; (�� c r.o��ere - 'fa )/(?.,n'� 0 Ih) and lo ate on :t-axis of Fig: 3.� �se ?ig. long-ta� avera�e direct 4 �o dete �ine no!":!al irr-�diance 'I,;,. • �f,.tltiply ::-a: 4 I SERI/TP-137l Step � - Calculate annual shading loss factor and • Correct qc for shading losses by multiplying by annual end loss factor. F shade, field' • Determine proposed ground cover ratio (GCR • collec- • Determine end-loss factor for specified row length tor aperture width/ row-to-row spacing). (see Fig.:. 7). • Calculate re�uired collector field size as A • • Correct for end loses by multiplying by L g qc end' GC . Ac/ R Step q - Calculate net annual energy collection (taking • Determine whether enough collector field area is �ccount thermal transport losses). available. If not, increase GCR or reduce A · c • Locate annual shading-loss factor ( F Multiply the-energy collection rate per unit col Fshade) on igs. 5 of or for specified and latitude of-site. 6 GCR lectOf area qc by the collector area Ac to cieter • Calculate field shading loss factor, accounting for mine Qc, the average annual energy collection rate of one unshaded row. the collector fiel�. . 1 + F • Since Q is an average collection rate (in W) bases (NR- l) c 1.5768 shade on all ciaytime hours, multiply by x F Qc 101 shade,field �R (the number of daylight seconds in a year) to obtain annual energy collection in Joules. Steo 10- Calculate annual overnight cool down losses. 1. • Calculate (Mcp) the total thermal capacitance of 0 sys system components including piping, valves, insula tion, and heat transfer fluid. Also, inclucie flash tank or unfired-boiler fluid inventory. Do not � include collector absorber tubes, flex hoses or their f contained fluid inventories. Ill 0.95 0 • Calculate ('!cp) the total thermal capacitance of "' oll 5 collector absorGer tubes, flex hoses, and their con tained fluid inventory . 0.7 0.8 -C1c ) sys /( (-:1A)sys � t] = iJ (T 0 [ 1 - e ] C1c ) - 'f ) ·o,sys p sys s a,n Lat1tucte (degrees) Use < � r 09J 0.95 North-Sourn j = t L 45° � 0.90 r 0.6 I ______J 85 __,:.._ __ ..:.._ ...:._ ...,:_ ...... :o 0.85 �.- 25 0 0.02 0.04 0.06 0.08 Latatua• (Cegreeal f/L, - :actor vs. Coll�ctor Focal Fig. 6 - �.;,nn�Jal Shading Loss �-!ulti.piier vs. ?ig. 7 End-Loss :�r Length to Collector Latitude XS Troughs Length Ratio 5 SERI/TP-1871 � 239 0.2 where � + T From this equation both 7'�0 and can be defined. d,c b r•u1 11 •.80 � .676 + .000334 SteP - Estimate the solar system use factor F'U �T Fuse• F'�0 and L 11°C ,. 19 4°C, e Esti�te the annual number of daylight hours that the or ·\c,max"' Oload/[F'�o I!!lax - F'UL(Ts - Ta,max>J 12 "' 1100 - 40°�· Ste? - r.alculate annual energy delivery and solar Using Im W m 2 and T m " �, , .,ax a, ax frac:ion. 6 • 3.203 10 /(.8(1100)- (205- 40)] "' A � x 10) c, x .741 • Subtract annual overnight losses (Step from the m2 4227 the �!ISi! annual energy collection determined in Step 9. • e value of 4227 m2 h. larger than Th Ac,�ax 2500 2500 collector field area of mz. Hence, t!!e m2 industrial :usR field is not too large for this pro cess. • '{ultiply annual energy total by the use factor esti 11. • The MIS system under consideration has: mated in Step This result is the solar system R annual energy delivery. a center feed piping layout, • �o obtain that fraction of the process load met by fourteen parallel collector rows, solar dnergy (neglecting electrical parasitics), two collector drive stri�gs per row, divide the annual energy delivered by the annual pro- load. cess north-south orientation, • Qd a total coll<:_ tor field !:lo;� rate (Therm:!.nol solar :ract!on ---- 17.64 l 6')) Qload of kg s f2?.0 gpm), a row-to-row spacing of I) .1 :n (20 ft) •:Ji th :1 collector aperture width m EXAMPLE CALCO'LAT!ON of 2.44 (� ft). IS ;:ollowin3 • The � R energy transport S?Stem has the A ;:ood processing ?lane near nenver, Colo. uses characteristics: (250 psia) of 1723 kPa saturated steam at a r:tte of 3-in. 40, 3-i::. 3000 24 :."'!let Header, sch. 150 m long, 1 • " s t'.lr i 28 collector row isolation val•:es, 1.:5-i!!., �3 :!O:"'Jc ( a at on temoerature at ZSO ps ia) insulated body, Tf d :s o 3 ee l20 C 5 m dxpansion tank, :'-i;;.:'•fiberglass L1sulat!on, • :II L 3°. 7"�r 18, 3-in. · isola cion valves, insulcrted C,ody, 11°c, • "fa ,. T'a,n soc 14, 1.25-1n. �ressure valves. ?sraholic rel!�f • trough efficiency = [ c • .so - .6i6 a�J. - • F :! _s_::_ , 2- _\. �refe ::-ed �fficiency equation, :1ssll!!1!ng �' - c F'T_T.,...... ��e ; I-::ast �f"J!j\1 H n-- is: l i .64 (230�1) = �T .:>fJ - .576 - :!5()0 ""' ( .7t.lj 6 SERI/TP-1871 '" F,..R·'o "R F'n o • .977 5 ( .80) '" .782 F' • All energy transport com-ponents used in the solar system are given in �able 2 along with their UA values. These trA values are based on data gi'1en in references 5 and 8. Stan 4 • Calculate FB, the unfired boiler factor. U A0 " 128.1 0 The �ISR system unfired boiler is specified to have a 0 W c-l U A value of -1 Btu -1 -1 b b 40,000 WOc (7 5,820 hr °F) . - u A /M c F �· - 0 c ] -l • R o e 0 P AoF>U L F + • • 128.1/[(17.64)(2300)] Fs B • c e . ( ub / :1c p [' H: c l e '\ c p -1) - .997 1 [ (2500)( .724) " .997 + F n� (.782) • .780 1 • • R 40,000 (1 64 2300)_ (17 .6 4)(2300) (e 1 Steo 5 • •97 4 • Reflective uteria1 samples were placed at the . proposed solar site as soon as the site was sel !1c c • • p ( Uo Ao /M cp -u A,/M• c ) ted. average specular reflectance loss of e c i c p ec An 5% AcFRU J per month has been measured. Since bimonthly con L centrator cleaning is anticipated for the solar [ system, average optical efficiency loss of is -163.2/[(1 7.64)(2300)] an 5% e + expected over the long term. Because receiver clean • .997 �1�7-�6�4�(�2�30�0�) ( 12�.11/[(17.64)(2300)] ing is a much easier operation than concentrator (.lz4) 2500 .e cleaning, the receiver '�ill be cleaned biweekly and )} only a loss in average 2% optical efficiency is - 163.2/[(17.64)(2300)] e:oected. e The tested incident angle modifier of the collector • - 1.153 �t incident angles of 7.5°, 22.5°, 37.5°, 52.5°, and n7.3° are given below. :<7 . - 1.00 Ksz. '" .88 s 5 .65 K :.:22.5 '" •99 67.5 '" K 7 " .96 3 .5 north-south troughs at latitudes near - For 40°, the F U'L !T. s Ta ) te sit Ratio R incident angle wei hting factors (from Tab1� 1) are: • In n y • g F -.n -I R o b ::7. s • . 35 33 ._ :> W ° - · �3- �-ZoC-l (�0 5 C - 11°�)� 2 ::zz.s = -? o. 396 "37.5 •22 .780 - (525 :< m ) Based :'lodifier on those valu'!s, the incident-angle annual cor�ection can now be calculated. • Using a hand • .35(1.00) + .33(.99) + .22(.96) + .10(.88) + .01(.65) calculator rather than the graphical u techniq e : = .9'124 • ':'ne f c � v __ e E� i e optical efficienc:- !.3: _;;qc�---- .8810 - .3117 (0.396) ' + "'• "' ::;-, (-I SO) = = .7 s·a o ') ��1" 0 .782 (.95)(.98)(.9824) 1 5 e :'able -· Angle d f r Annual g t �actor Incident l'!o i ie Correction l,' i h :.ng ��orth-S 0.24 0.47 • 0.'-3 0.35 0.2? 0.26 H - o .:.s t17 • .:> 0.23 0.30 0.29 0.28 0.33 0.38 0.40 .� ...,, - 0.12 0.:.6 0.18 0.22 o.:s 0.26 ..•;.;:-·� c-7. :> 0.17 0.20 0.88 0 .. 10 O.l2 •).10 0.07 0.07 �'t -., ,.. 0.15 0.00 0.00 0.00 0.01 0.02 0.0Z r..;;-.'J7.:> ·� 7 SERI/TP-1871 Table 2. Energy Transport System Component Loss Coefficients Quantity Component Inlet Side Components 150m 40 54.2 3 in. sch. piping with 3 in. fiberglass insulation 90m 1.25 in. sch. 40 piping with 1.5 in. fiberglass insulation 31.4 1 Unfired Boiler with 3 in. fiberglass insulation 11.3 1 Circulation pump, insulated, with seal cooling 13.8 1 2. Expansion tank, 3 in. fiberglass insulation 3 33 Pipe supports for 3 in. pipL�g using calcium silicate 5.3 14 Pipe supports for 1.25 in piping using calcium silicate 4.2 1 Pipe Anchor 0.6 28 Flexible hoses, 1.42m long 30.8 10 Insulated hand valves for 3 in. piping 5.7 14 1. in. 3 .1 Insulated hand valves for 25 piping A al63. t:i i ZWOc-1 Outlet Side Components 130m 3 in. sch. 40 piping with 3 in. fiberglass insulation 45.4 90m 1.25 in. sch. 40 piping with 1.5 in. fiberglass insulation 31.4 30 Pipe supports for 3 in. piping using calcium silicate 4.9 14 Pipe supports for 1.25 in. piping using calcium silicate 4.2 1 ?ipe anchor 0.6 28 Flexible hoses, 1.42m long 30.8 8 Insulated hand valves for 3 in. pipL�g 4.6 14 Insulated hand valves for 1.25 in. piping 3.1 14 Insulated pressure relief valves 3.1 � +.3130 (0.396)--.003919 (39.7) 2 _, + .003864 (39.7)(0.396) - .001484 (39. 7) (0.396) - .5046 - 0 - q 223 �; :n Q c c A c "' ';"' +SO) (.5046) • 557500 !1 a '"F F 1• (Ib ·;:. S R o • -2 • to Joules: •• (525 +50�� ) (.5046) Converting 974 (.780) 557500 107) s 10 2 (1,5768 X 8.791 X 1 J _, '" 239 - ',f 1ll Step 10 • :he total thermal c�pacitap�e of :he �ner�y trans?or: system is 1.8 10° J g n !able 3. 1 x 0c-- as ive in 0.::-1 • x .: 'l/20 • .40 (c!c ) 106 • c.c� "' p sys 11.9 '" s 2500 m2 - 6--7 m2) e Ag (.'0"' �0 • :he total theraal capacitance of the collector system Ac/GCR 6 acres. Since c es is 3.64 x 10 J in !able 4. 6250 �2 is just over 1.3 two a r is °C-l as givP.n • nll in the space a ailable , the :·I!SR system fit: v ..... allocated. • x o -t ''"!c ) coll 3.64 105 J is ? (:'or a latitude o 9. F • ::'rom n�. 6 f 3 7''), shace ) + tr.,.\ 0.95). e (trA sys " UiAi o field loss :3ctor calculated "ased on • che shading i; • 163.2 + - 291.3 � 1� rows. 128.1 "c-1 1 l) .95 F • + (14 - • .954 shade,field 1� Ta ' a) 2 228 'J m- r - ll.� X 106/(291.3(54000))] u.ax ,1- e J m long on en or to - • Four 6.1 c c trat s are mounted adjacent 10°(205 5) each other on each side of the drive assembly of each 9 1.245 " 10 row o Hence, • .. fo l length of ech Lc 24 4 !D.• The ca J • 24.4 .61 • 40, concentrator is I).61 !11· ror 0 Lc/f i • ) ate "' • 11o,coll - 7a,a �!g. 7 indic s L�nd .98. (�fep)coll (Ts (3.64 x 1 _,- • 106 °C- )(205° -:- " , s 223 Ul J - 5°�) • 0.�8 (223 ;1 :n--) !1 q::: SERI/TP-1871 Table 3. L�ergy Transport �ystem Thermal capac�tance Q uantity "Component Pump X 1 0.0 1066 ?6mm (3 in.) piping with 76mm (3 in.) insulation 6 280m 5.32 X 10 32mm (1.25 in.) piping with 38mm (1.5 in.) insulation 180m 0.94 X 10,6 l Unfired boiler with 76mm (3 in.) i�sulation 4.09 x lOb Insulated hand valves for 1.25 in. piping X 6 28 .16 10 Insulated hand valves for 3 in. piping .32 X 21 106 14 Pressure relief valves .1 X 10 l Expansion tank, insulated 6 .78 X 106 Table 4. Collector System Thermal Capacitance 5 l024m 32mm (1.25 in.) absorber tube, 3.27 x 10 including contained fluid 56 Flexible hoses, 1.42m long, .37 x 106 including contained fluid ° -l (HCp) "3.6 x l0 J°C coll 4 8 • Hultiply by the solar system use factor. " j .23 X 10 J 12 "(,954)(8,112 X 10 J) • �1. 239 + 2 Q d a,c 0, Ib 12 3 " 239 + 0.2 (525) " 344 days • 7.739 X 10 J (7.336 X 10 �Btu) • Calculate solar fraction. 9 [1,245 X 10 J + 7,28 X 103 Q 0 "344 Jj r Q " ';· 365 load Qload ( 24 �cay ( ' 6 For o a 3.203 x 10 ·load �.; , Ste� 11 3 nsi er g the past reliability of trough syste!DS • 9,769 X 1 J -1 • Co d in 0·load 10 yr and the av'lilability of an on-site maintenance crew 1 24 hr/ day, it is expected that the encire collector x 12 yr- s l r frac tion � Qd = 7.73'1 10 J s ste rarely be out-of-service. ?our days o a --- -1 y m tlill (4il Qload x yr daylight hours) of system downtime is estimated. o,75q 1013 J Additionally, one �rive string (out of 28) is esti " 0.079 (7 .9%) oated to be down two days (24 daylight hours) of each .'lont't or 238 daylight hours per year. 1lecause th re e detailed hour-by-h·:mr co ut r run was "-ade are drive strings, the entire collector system can A SOLil'H nrn a ZR as a compari�on to the ,;tap-by-step procedure he equi•talantly considered to be down 10.3 hours ( "' result. The nv er tape �as used as the ;;eather/ 2Ril/2R hrs). ?.ence, the total equivalent solar sys De Tiff irradiation ata b>1se. '!'he annua! .::nergy tem iowntime is 58.3 (= 48 + 10.3) daylight hours. d deli•1ery x �is result co o ras result was 7.637 1012 J yr-1 m a s a • t�e �� o l r iowntime S8.3 �r/yr. very closely (within 2�) of atep-�y-step pro cedure result and ttes s ccur cy t�e :he food process ng plant has a one week. holiday a t to ��e � a of • i si:nplified ner calcul.Hion methor!. shutdown in December and a five day shutdown in early e gy spring. This amounts to lost daylight hours 144 per year. HR process downtime = 1!>4 hr/yr. ACKNOWLEDGEMENT 18.3 - .;. 144 s s 0.954 are expressed t e r Des • Fu e = l �380 Thanks to the o � cc-au::hors of L:n Process t Anoroaches for Solar Industrial l'!ea S� Sten l2 and to Departnent i::nerg:' guppor::ing the U.S. of for w ork.. u r t ;�nnual losses. this .. • S bt ac •Jver-:Jight 1 c - ') d c ·o ris, ?_. (:a�eror.., P. Lewandowski, ;1.• .\., ,., 1. A.l .. L., C. , 3 t�e ':e?ar::nent B.l:2 X 10-- J "so:ar IP:t 3y�tecs Jeveloped J'nd�r 9 SERI/TP��871 of Energy �SR Project." Proceedings of the Sixth of the Sixth ��nual ASME Solar ��er� Division Con Annual AS!fE Solar Energy Division Conference, A5m::, 1&-21, 1983. ference, AS�, April April 19-21, 1983. }!eyer, R. D., "Energy TranSlllission System Heat 1981 R. SAND 1'12-1138, 1982, 2. ASHRAE Handbook, Fundamentals. New York, Losses." Oct. Sandia �tional NY: American Society of Heating, Refr!geratin�, Laboratories, Albuquerque, NM. and Air Conditioning Engineers, Inc. �rton, "Design of Collector Subsystem Piping 3. 9. R., Duffie, J. A. and 1!eckman, '"· A., Solar Ener'!y Layout." Proceedinss of the Line-Focus Solar The 1974, 146- mal Processes, Wiley, :�w York, l'P• Thermal Energy Technology Development Seminar, :48. Sandia National Laboratories, Albuquerque, NM, Sept. 1980. Freese, J. M., "Effects of Outdoor Exposure on the 4. 10. Solar Reflectance Properties of Silvered Glass Mir Morris, v. L., "Solar Collector Materials Exposure • 78-1649, 1978, rors. SAND Sept. Sandia National to the IPH Site Environment." SAND 81-7028, Jan. 191'12, Laboratories, Albuquerque, NM. :ields." SAND 81-1780, A5m:: Solar Energy Division Conference, April 1982, 1 Cl-21, 1983. ASME, April Sandia National Laboratories, Albuquerque, NM. May, E. 7. !{. and �!urphy, L. M., "Oirect Steam Genera 13. Tabor, H. 1980. Letter to the Edit:Jr, : ion in Line-Focus Solar Collectors." Proceedings 113-115. � Enerw, Vol. 24; PP• 10