GEOHERMAL RAINING PROGRAMME Report 21 Orkutofnun, Grenávegur 9, Number 3 IS-18 Reykjavík, Iceland DESIGN OF SMALL GEOHERMAL HEAING SYSEMS AND POWER GENERAORS FOR RURAL CONSUMERS IN MONGOLIA Purevuren Dorj Renewable Energy Corporation, P.O.Box 479, Ulaanbaatar 21136, MONGOLIA puujeemoogii@yahoo.com ABSRAC Some of the rural conumer in Mongolia have no reliable electricity and heating. Geothermal energy i one of the renewable, clear and economical energy reource in the world. he uage of geothermal energy i developed in Iceland, and there i a long experience in it ue for heating and electrical production. Geothermal energy offer the poibility to upply electricity and heating for conumer cloe to geothermal reource in Mongolia. 1. INRODUCION According to geothermal tudie, Mongolia ha about 42 mall hot pring. he geothermal reource in Mongolia are not widely ued for heating and not for the upply of electricity. Now there i a good poibility to develop geothermal energy uage in Mongolia. he firt tage of geothermal energy application hould focu on heating and poibly production of electricity uing known geothermal reource. he preent tudy deal with thi and i preented in three main part: 1. Deign of geothermal heating ytem for the enher oum centre; 2. Feaibility tudy for electrification of the Shargaljuut area uing geothermal water; 3. Poibility of Ger (nomadic family houe heating and electrification uing geothermal water. he hot pring in Shargaljuut and enher have higher urface temperature and flow rate than other hot pring in Mongolia and the conumer are cloe to thee hot pring. Hence, thee hot pring are uitable for heating and electrical production for the nearet oum centre. he Kalina geothermal power cheme i uitable for a low-temperature geothermal field uch a the Shargaljuut hot pring. he Shargaljuut hot pring could produce 79 kw of electricity uing a Kalina power plant. he potential electricity production i more than enough for the preent electrical demand of the Shargaljuut area which i 589.5 kw. Future invetigation in thi area may lead to more geothermal water flow rate, and temperature higher than the preent 92/C. If the Shargaljuut area could produce 1-3 MW of electricity, upplying power to the Bayankhongor aimag centre would be a viable option for the future. he urface temperature in the enher hot pring i 86/C, o it can be ued for uppling geothermal heating ytem. he geothermal heating ytem ue hot water of about 8/C. Geothermal water can alo be ued to upply heat and electricity for Ger uing a geothermal floor heating ytem. In addition, a new technology thermoelectric generator could upply the mall electric demand of a Ger. 27
Dorj 28 Report 3 2. DESIGN OF A GEOHERMAL HEAING SYSEM FOR HE SENHER SOUM CENRE IN MONGOLIA he enher oum ha a potential a a ret area for tranit guet and tourit. hi oum centre i located 2 km from the enher hot pring and 3 km from the aimag centre of Arkhangai in the central part of Mongolia, far from the capital city Ulaanbaatar. he enher oum centre i located at the main road between the central and wetern part of Mongolia. In the lat year the Government of Mongolia decided to extend the tranportation main road ytem, o here will be the tranport connection between the wetern and eatern part of Mongolia a well. hi main road i named the Millennium Road. Preently, around 25 inhabitant are living in the enher oum centre. here i a good opportunity to tranport hot water from the hot pring and upply heat to the building, a well a hot water for wimming pool for tourit and guet. 2.1 Weather condition he load of heating ytem i cloely related to the influence from the heat dynamic of the building. hee influence can be divided into two group: he influence from the outdoor climate and thoe originating from ource inide the building. he latter group conit of heat from light, machine, peron and radiator (including the control ytem. he group involving the outdoor climate i compoed of (arranged in aumed decreaing importance for heating ytem: Air temperature, hort wave radiation (the un, wind peed and direction, and precipitation. Air temperature and olar radiation are the mot important factor affecting building dynamic. Hence weather data wa obtained for thee factor. he weather data wa collected and calculated from the meteorological compilation of Arkhangai Aimag (Meteorological Intitute of Mongolia, 199 and the MEEONORM V4. program (Remand and Lang, 1999. Meteorological data, except for olar radiation, i from the meteorological compilation of Arkhangai Aimag for the enher oum, while the olar radiation i calculated by MEEONORM. he annual mean wind peed i not o high, only 2.8 m/, and gut are 14-19 m/, Mean air temperature, C 2 15 1 5 2 4 6 8 1 12-5 -1-15 -2 ime, month FIGURE 1: Monthly average air temperature for the enher oum occurring on the average 13 time per year. Annual average precipitation i 332 mm. In the cold period between November and March precipitation i only 26.4 mm. he average monthly air temperature for the enher oum i hown in Figure 1. he MEEONORM V4. program include data for all the meteorological tation worldwide for the year 1961-199 (Remand and Lang, 1999. he weather data calculated for the enher oum i hown in three figure. Firtly, the hourly data for outide air temperature (Figure 2. he reult of the temperature profile hown in Figure 2 how the lowet temperature of -31.6/C in the enher oum. Secondly, hourly value for annual global olar radiation on the horizontal urface (Figure 3. Finally, Figure 4 how the outdoor temperature duration curve, and it how that the outdoor temperature i below 2/C for 8546 hour, almot the whole year.
Report 3 29 Dorj 4 1 Air temperature, C 2-2 Solar radiation on horizontal urface, W/m 2 8 6 4 2-4 2 4 6 8 ime, hour FIGURE 2: Air temperature profile for the enher oum 2 4 6 8 ime, hour FIGURE 3: Global olar radiation profile for enher oum -4 2.2 Geothermal heating ytem model In geothermal heating ytem water i uually taken directly from low-temperature geothermal area. Hot heating water i collected into torage tank. From the torage tank the water i then tranmitted to the conumer to heat up the building and for ue a tap water. Hot water temperature i about 8/C and it cool down to about 4/C in the radiator. Heat duty tranferred to building i controlled by the ma flow of water (Nappa, 2. Figure 5 how a chematic of a geothermal heating network. Outdoor temperature, C -2 2 Radiator. he radiator i conidered to be a heat exchanger between the heating water and the air of the room. he relative heat duty of a radiator can be written a: 4 2 4 6 8 ime, hour FIGURE 4: Outdoor air temperature duration curve m mo 3/ 4 (1 Logarithmic temperature difference m i defined a: m ( i ( r i i In r i ( r i In r i (2
Dorj 3 Report 3 o Hot water reervoir ap water 1 2 r i hermal hot water o drain FIGURE 5: Simple model of a geothermal heating network Inerting Equation 2 into Equation 1, it become: In ( In r i i r r i ( r i 3/4 (3 Water heat duty. he heat duty, which the heating water give away, when going through the radiator i: c m (4 p ( r Relative heat duty can be calculated on the water ide: m m r r (5 Building heat lo. Heat lo from the building can be defined a: lo k ( l i (6 where the building heat lo factor k l i taken a a contant. Relative heat lo i obtained a: lo i lo i o o (7 Pipe heat lo. Some heat lo will be in the pipe connecting the pumping tation and the building to be heated. he amount of the lo can be calculated by uing the pipe heat tranmiion effectivene parameter. he tranmiion effectivene τ i defined by the following equation (Valdimaron, 1993: τ l g g e U p mc p (8
Report 3 Dorj 31 p p c m U g l g e τ m m τ τ m m g g g 1 1 ( ( τ τ + + m m r g g r g 2 ( ( τ τ + + ( ( ( 1 ( 1 1 up k c m C C C t i l r p lo p net 4 3 / ( ln ln ( o io o i r i r i i r i r i z i n r e + + ( 1, 4 / 3, ln o i o i i r i r n r z he reference value, J, can be calculated from the reference flow condition: (9 he parameter U p and C p are aumed to be contant all over the ytem. Combining Equation 8 and 9 the tranmiion effectivene can be obtained a: (1 Combining Equation 8 and 1, the upply temperature to the houe can then be calculated a: (11 If the heating network circulate water, the return temperature at the pumping tation i obtained from Equation 12. (12 Building energy torage. When the heating for the building i turned off, the building doe not cool down immediately. he building ha heat capacity and it tore energy. he building energy torage model i: (13 All time derivative are et equal to zero in the teady-tate model. Steady-tate approach. When the heating ytem are aumed to be in teady-tate, no heat i accumulated in the building. Return temperature can then be calculated by combining Equation 3 and 7. (14 From Equation 14, r can be calculated with iteration. he fatet convergence of a fixed point iteration i obtained, when olved for r, found inide the logarithm, (Valdimaron, 1993. he equation for the n+1 iteration value i then (15 where z i
Dorj 32 Report 3 When outdoor temperature data i given, i i aumed to be contant and upply temperature i known, then r,n+1 can be found iteratively from Equation 15. In teady-tate, the heat lo from the building i the ame a the heat upplied: up p lo (16 mc p ( r k1( i o (17 Ma flow i obtained directly from Equation 17. k1( i o m C ( p r (18 he factor k i can be calculated from the reference condition: k 1 m c o p ( ( i o r (19 2.3 Geothermal heating ytem equipment hi chapter provide an overview of the variou component that are ued in mot geothermal direct-ue project and i mainly baed on Lund (1996. Four main type of equipment are decribed in more detail: well pump, piping, heat exchanger and pace heating equipment. Standard equipment i ued in mot direct-ue project, provided allowance are made for the nature of geothermal water and team. emperature i an important conideration; o i water quality. Corroion and caling caued by the ometime unique chemitry of geothermal fluid, may lead to operating problem with equipment component expoed to flowing water and team. In many intance, fluid problem can be deigned out of the ytem. One uch example concern diolved oxygen, which i abent in mot geothermal water, except perhap the lowet temperature water. Care hould be taken to prevent atmopheric oxygen from entering ditrict heating water; for example, by proper deign of torage tank. he iolation of geothermal water by intalling a heat exchanger may alo olve thi and imilar water quality derived problem. In thi cae, a clean econdary fluid i then circulated through the uer ide of the ytem a hown in Figure 6. he primary component of mot low-temperature direct-ue ytem are downhole and circulation pump, tranmiion and ditribution pipeline, peaking or back-up plant, and variou form of heat extraction equipment (Figure 6. Fluid dipoal i either urface or uburface (injection. A peaking ytem may be neceary to meet maximum load. hi can be done by increaing the water temperature or by providing tank torage (uch a i done in mot of the Icelandic ditrict heating ytem. Both option mean that fewer well need to be drilled. When the geothermal water temperature i low (below 5/C, heat pump are often ued. he equipment ued in direct-ue project repreent everal unit of operation. he major unit will now be decribed in the ame order a een by geothermal water produced for ditrict heating. 2.3.1 Downhole pump Unle the well i arteian, downhole pump are needed, epecially in large-cale direct utilization ytem. Downhole pump may be intalled not only to lift fluid to the urface, but alo to prevent the releae of ga and the reultant cale formation. he two mot common type are: linehaft pump ytem and ubmerible pump ytem.
Report 3 33 Dorj 55 C PLAE HEA EXCHANGER ENERGY 76 C USER SYSEM GEOHERMAL 82 C 6 C PRODUCION WELLHEAD EUIPMEN INJECION WELLHEAD EUIPMEN FIGURE 6: Geothermal direct utilization ytem uing a heat exchanger he linehaft pump ytem (Figure 7a conit of a multi-tage downhole centrifugal pump, a urface mounted motor and a long drive haft aembly extending from the motor to the pump. Mot are encloed, with the haft rotating within a lubrication column which i centred in the production tubing. A B FIGURE 7: Downhole pump (a linehaft pump detail, and (b ubmerible pump detail
Dorj 34 Report 3 hi aembly allow the bearing to be lubricated by oil, if the hot water doe not provide adequate lubrication. A variable-peed drive et jut below the motor on the urface can be ued to regulate flow intead of jut turning the pump on and off. he electrical ubmerible pump ytem (Figure 7b conit of a multi-tage downhole centrifugal pump, a downhole motor, a eal ection (alo called a protector between the pump and motor, and electric cable extending from the motor to the urface electricity upply. Both type of downhole pump have been ued for many year for cold water pumping and more recently in geothermal well (linehaft have been ued on the Oregon Intitute of echnology campu in 89/C water for 36 year (Lund, 1996. If a linehaft pump i ued, pecial allowance mut be made for the thermal expanion of variou component and for oil lubrication of the bearing. he linehaft pump are preferred over the ubmerible pump in conventional geothermal application for two main reaon: the linehaft pump cot le, and it ha a proven track record. However, for etting depth exceeding about 25 m, a ubmerible pump i required. 2.3.2 Piping he fluid tate in tranmiion line of direct-ue project can be liquid water, team vapour or a two-phae mixture. hee pipeline carry fluid from the wellhead to either a ite of application, or a team-water eparator. hermal expanion of pipeline heated rapidly from ambient to geothermal fluid temperature (which could vary from 5 to 2/C caue tre that mut be accommodated by careful engineering deign. he cot of tranmiion line and the ditribution network in direct-ue project i ignificant. hi i epecially true when the geothermal reource i located at great ditance from the main load centre; however, tranmiion ditance for hot water of up to 6 km have proven economical in Akrane, Iceland (Georgon et al., 1981, where abeto cement pipe inulated with rock-wool and covered with earth were ued uccefully (ee Figure 8 later. Carbon teel i now the mot widely ued material for geothermal tranmiion line and ditribution network, epecially if the fluid temperature i over 1/C. Other common type of piping material are fibregla reinforced platic (FRP and abeto cement (AC. he latter material, ued widely in the pat, cannot be ued in many ytem today due to environmental concern; thu, it i no longer available in many location. Polyvinyl chloride (PVC piping i often ued for the ditribution network, and for uninulated wate dipoal line where temperature are well below 1/C. Conventional teel piping require expanion proviion, either bellow arrangement or by loop. A typical piping intallation would have fixed point and expanion point about every 1 m. In addition, the piping would have to be placed on roller or lip plate between point. When hot water pipeline are buried, they can be ubjected to external corroion from groundwater and electrolyi. hey mut be protected by coating and wrapping. Concrete tunnel or trenche have been ued to protect teel pipe in many geothermal ditrict heating ytem. Although expenive (generally over $3/m, tunnel and trenche have the advantage of eaing future expanion, providing acce for maintenance, and a corridor for other utilitie uch a dometic water, wate water, electrical cable, phone line, etc. Supply and ditribution ytem can conit of either a ingle-pipe or a two-pipe ytem. he ingle-pipe i a once-through ytem where the fluid i dipoed of after ue. hi ditribution ytem i generally preferred when the geothermal energy i abundant and the water i pure enough to be circulated through the ditribution ytem. In a two-pipe ytem, the fluid i recirculated o the fluid and reidual heat are conerved. A two-pipe ytem mut be ued when mixing of pent fluid i called for, and when the pent cold fluid need to be injected into the reervoir.
Report 3 35 Dorj he quantity of thermal inulation of tranmiion line and ditribution network will depend on many factor. In addition to minimizing the heat lo of the fluid, the inulation mut be waterproof and water tight. Moiture can detroy the value of any thermal inulation, and caue rapid external corroion. Aboveground and overhead pipeline intallation can be conidered in pecial cae. Coniderable inulation i achieved by burying hot water pipeline. For example, burying bare teel pipe reult in a reduction in heat lo of about one-third a compared to aboveground in till air. If the oil around the buried pipe can be kept dry, then the inulation value can be retained. Carbon teel piping can be inulated with polyurethane foam, rock wool or fibregla. Belowground, uch pipe hould be protected with a polyvinyl (PVC jacket; aboveground, aluminum can be ued. Generally 2.5 to 1 cm of inulation are adequate. In two-pipe ytem, the upply and return line are uually inulated; wherea, in ingle-pa ytem, only the upply line i inulated. At flowing condition, the temperature lo in inulated pipeline i in the range of.1-1/c/km, but in uninulated pipe, the lo i 2-5/C/km for a approximately 5-15 l/ flow in a 15 cm diameter pipe. It i le for larger diameter pipe and for higher flow rate. A an example, le than 2/C lo i experienced in the aboveground 29 km long and 8-9 cm wide teel pipeline with 1 cm of rock wool inulation that run from Nejavellir to Reykjavik in Iceland. he flow rate i around 56 l/ and take even hour to cover the ditance. Un-inulated pipe cot about half of inulated pipe and thu, i ued where temperature lo i not critical. Pipe material doe not have a ignificant effect on heat lo; however, the flow rate doe. At low flow rate (off peak, the heat lo i higher than at greater flow. Several example of aboveground and buried pipeline intallation are hown in Figure 8. Steel piping i hown in mot cae; but FRP or PVC inulation can be ued in low-temperature application. Aboveground pipeline have been ued extenively in Iceland, where excavation in lava rock i expenive and difficult; however, in the USA, belowground intallation are mot common to protect the line from vandalim and to eliminate traffic barrier. FIGURE 8: Example of above and below ground pipeline: a aboveground pipeline with heet metal cover, b teel pipe in concrete tunnel, c teel pipe with polyurethane inulation and polyethylene cover, and d abeto cement pipe with earth and gra cover (Lund, 1996
Dorj 36 Report 3 2.3.3 Heat exchanger he principal heat exchanger ued in Example of above and below ground pipeline: a aboveground pipeline with heet metal cover, b teel pipe in concrete tunnel, c teel pipe with polyurethane inulation and polyethylene cover, and d abeto cement pipe with earth and gra cover (Lund, 1996 geothermal ytem are FIGURE 9: Plate heat exchanger (Lund, 1996 the plate, hell-and-tube, and downhole type. he plate heat exchanger conit of a erie of plate with gaket held in a frame by clamping rod (Figure 9. he counter-current flow and high turbulence achieved in plate heat exchanger provide for efficient thermal exchange in a mall volume. In addition, they have the advantage when compared to hell-and-tube exchanger, of occupying le pace, can eaily be expanded when additional load i added, and cot about 4% le. he plate are uually made of tainle teel; although, titanium i ued when the fluid are epecially corroive. Plate heat exchanger are commonly ued in geothermal heating ituation worldwide. Shell-and-tube heat exchanger may be ued for geothermal application, but are le popular due to problem with fouling, greater approach temperature (difference between incoming and outgoing fluid temperature, and the larger ize. Downhole heat exchanger eliminate the problem of dipoal of geothermal fluid, ince only heat i taken from the well. However, their ue i limited to mall heating load uch a the heating of individual home, a mall apartment houe or buine. he exchanger conit of a ytem of pipe or tube upended in the well through which econdary water i pumped or allowed to circulate by natural convection (Figure 1. In order to obtain maximum output, the well mut be deigned to have an open annulu between the well bore and caing, and perforation above and below the heat exchanger urface. Natural convection circulate the water down inide the caing, through the lower perforation, up into the annulu, and back inide the caing through the upper perforation (Culver and Reitad, 1978. FIGURE 1: Downhole heat exchanger he ue of a eparate pipe or promotor ha (typical of Klamath Fall, OR (Lund, 1996 proven ucceful in older well in New Zealand to increae the vertical circulation (Duntall and Freeton, 199. 2.3.4 Convector Heating of individual room and building i achieved by paing geothermal water (or a heated econdary fluid through heat convector (or emitter located in each room. he method i imilar to that ued in conventional pace heating ytem. hree major type of heat convector are ued for pace heating: 1 forced air, 2 natural air flow uing hot water or finned tube radiator, and 3 radiant panel (Figure 11. All three can be adapted directly to geothermal energy or converted by retrofitting exiting ytem.
Report 3 2.4 Conumer decription Population group in Mongolia. he total population of Mongolia i 2,65,952 (et. July 2. he annual population growth rate i now 1.45%. he ize of the country 1,564,619 km 2, 52% of the population live in the capital city Ulaanbaatar and aimag centre, 48% of population live in rural area. here are 21 aimag centre and 314 oum. Building type. he mot common building material until in the 197 wa brick. hen concrete aembled building took over a the mot common building type. he overall heat tranfer coefficient U for a concrete aembled building i equal to 1 W/m 2 /C. Overall heat tranfer coefficient U of building built before 197 i the ame a the European tandard. A very low percentage of the city population live in private building. he wall of a building are uually made of wood and a mixture of and and cement. A wall could be made of a number of material in a number of layer. Uually it i contructed of 15-2 cm of wood, and a mixture of and and cement on both ide of the wooden wall. On the inide, the wall i covered by a plater plate. he thickne of the plater plate i 5-8 mm. 37 Dorj Preent heating ytem in the capital city and aimag centre. Ditrict heating i a common heating ytem in the citie of Mongolia. he capital city Ulaanbaatar and the indutrial aimag centre, Erdenet, Darkhan, Choibalan and Dalanzadgad have a thermal power plant upplying heat in the winter eaon. he water upply temperature i 7-15/C, and the return temperature i 7-9/C. A temperature control ytem i placed in the central heating plant. Change in upply temperature depend on the weather condition. he heating eaon in Mongolia tart 15 th October and end on 15 th FIGURE 11: Convector: a forced air, b material convection (finned tube, c natural convection (radiator, and d floor panel April, when the heating ytem i turned off. he radiator ued to heat building are made of cat iron. Preent heating ytem and heat requet in oum centre. he intalled capacity of the heating ytem in the oum centre i.8-3. MW, and etimated peak heat load i.4-2. MW. he heating tation i located in the central part of the oum centre. Hot water i upplied from a team boiler to the conumer by underground inulated pipeline. All conumer have heating control ytem. he total population of the enher oum centre i 25. he main building in the oum centre are the chool houe, dormitory, hopital and adminitration building. here are 8 pupil in the chool. he heat lo from thi building i 3-45 kw. About 7 pupil are living in the dormitory, with a heat lo of 1-15 kw. he hopital i for only 15 peron, and the heat lo of the building i 1 kw.
Dorj 38 Report 3 ype of heating equipment. he building radiator ued in Mongolia are the ame a the Ruian tandard radiator (GOS 869-75. echnical characterization and a figure of the ectional cat-iron radiator i hown in able 1 and in Figure 12. ype of heating equipment ABLE 1: echnical characterization of heating equipment, ectional cat-iron radiator (GOS 869-75 Size of heating urface, A [m 2 ] Nominal heat flow, nhnf, [W (kkal/h] Structural ize, [mm] Weight [kg] t1 t2 t3 MC-14-18.244 185(159 5 588 14 18 7.62 MC-14-98.24 174(15 5 588 14 98 7.4 M-14 AO.299 178(153 5 582 14 96 8.45 M-14A.254 164(141 5 582 14 96 7.8 M-9.2 14(12 5 582 9 96 6.15 MC-9-18.187 15(129 5 588 9 18 6.15 Left pipe 1 1/4" Screw cork of pipe 1/2" or 3/4" t t1 t2 FIGURE 12: Sectional cat-iron radiator t3 Right pipe 1 1/4" 2.5 Deign of a geothermal heating ytem for the enher oum centre enher oum i at an elevation of 16 m above ea level, the location i 47/26 latitude and 11/45 longitude. he enher hot pring i located 15 km outhwet of enher oum centre, at location 47/2 latitude and 11/39 longitude, at an elevation 186 m above ea level. Figure 13 illutrate a topographical map of thi area, and clearly how the elevation difference between thee two place, with the enher hot pring lying 26 m higher than the enher oum. 2.5.1 ranmiion piping Piping i very important equipment for geothermal heating ytem. Until 1998 it wa common to ue Abeto Cement (AC pipe. Concern about the carcinogenic nature of abeto ha reulted in an impact on the availability of AC pipe (Lund, et al., 1998. Ductile iron pipeline are uitable for buried tranmiion piping ytem. Ductile iron piping i cot competitive with abeto cement material. In addition, it i commonly in ue in water upply ytem, which reult in wider familiarity with it intallation practice. However, ductile iron pipe i the heaviet material of thoe covered here. A a reult, additional handling cot are to be expected in comparion to the lighter weight material. able 2 outline cot for intallation of pre-inulated ditribution piping. Included are 11 cot categorie: aw cutting of exiting pavement, removal of pavement, hauling of pipe (local, trenching and backfill, pipe material, bedding, intallation and connection of piping, valve, fitting, traffic control, and paving.
Report 3 39 Dorj FIGURE 13: opographic map for enher oum and vicinity ABLE 2: Cot ummary ($/m of pre-inulated ductile iron ditribution piping (DUC Ductile iron (carrier, PVC - Polyvinyl chloride (jacket Carrier/Jacket Size (m Cot ($/m DUC/PVC.1 154.89 Several example of aboveground and buried pipeline intallation are hown in Figure 8. Buried or aboveground pipe intallation are option in the ytem deign that require evaluation. Aboveground intallation are more ubject to damage and vandalim. Buried piping ytem, the mot common type of tranmiion pipe line, are aethetically more pleaing than aboveground intallation and are deemed far uperior from the tandpoint of immunity to accidental or intentional damage. herefore, the buried pipe intallation of tranmiion piping i choen, ee Figure 8c. 2.5.2 Preure drop in tranmiion piping he preure drop, p, may be expreed in term of a friction factor, f (Holman, 1989: p f L D V ρ 2 2 (2 where f Friction factor; L Length of tranmiion pipe (m; D Pipe inner diameter (m; D Denity of geothermal water (kg/m 3 ; V Velocity (m/ of geothermal water in the piping, 4 V π * D 2 he modified Colebrook equation relate the friction factor f to the pipe inner urface roughne ε, the
Dorj 4 Report 3 pipe inner diameter D, and Reynold number Re: f 1.325 ε ln + 5,74 Re 3,7D.9 2 (21 We can write the Reynold number V Re D ν (22 and the kinematic vicoity can be calculated from the dynamic vicoity by: µ ν ρ (23 he relative roughne g / D in 4" diameter ductile iron piping equal.45. Hence the friction factor f equal.16. he temperature of the geothermal water in the enher hot pring i 86/C, and urface flowrate i 1 kg/. he propertie of water at 86/C are D 97.2 kg/m 3 k.673 W/m/C : 3.47 1-4 kg/m Pr 2.16 C p 4.195 kj/kg/c he propertie of the tranmiion piping are: L 2 m, D.1 m Figure 13 how the route of the geothermal water tranmiion piping between enher geothermal field and enher oum centre. he route of the tranmiion piping i along the valley of the river. he geothermal water can reach the conumer by gravity flow in the tranmiion pipe, a the altitude difference between thee two place i 26 m. he calculated preure drop equal 2456 Pa or 25 bar in 2 km length piping, which correpond almot exactly to the altitude difference of 26 m. 2.5.3 emperature drop in the tranmiion piping he upply water temperature to the conumer can be calculated by the following equation: U _ + + ( w o exp m C pipe p L (24 he heat tranfer coefficient U p can be defined: U p R in. 1 + R ground (25 where R in, R ground are determined a follow:
Report 3 41 Dorj R in. ro ri ln 2 π k in. R ground 2 D ri ln 2 π k ground (26 where k in hermal conductivity of inulation material, for gla wool,38, W/m/C, (Holman, 1989; k ground hermal conductivity of ground, 1 W/m/C (Holman, 1989; D Buried depth of pipe to it centre (m; r i Inide radiu of tranmiion pipe (m; Outide radiu of tranmiion pipe (m. r o Heat tranfer coefficient U p for.1 m diameter pre-inulated tranmiion pipeline i equal to.6255 W/m/C. Equation 21 i ued to calculate the upply temperature,, of the water at deign oil urface temperature 25/C. Figure 14 how upply water temperature a a function of the ditance from the hot pring. Supply water temperature, C 85 8 75 7 65 6 55 5 2.5.4 Deign of geothermal heating ytem for enher oum centre A mentioned in Chapter 2.4, the intalled capacity of the heating ytem in the oum centre i.8-3. MW, and etimated peak 5 1 15 2 ranmiion length, km FIGURE 14: emperature drop in hot water tranmiion line heat load i.4-2. MW. It i ummarized a follow: In the chool building heat lo i 45 kw, the dormitory ha heat lo of 15 kw and the hopital building ha heat lo of 1 kw. he additional adminitration building, kindergarten building, and cultural centre building have a total heat lo of 2 kw. herefore, the total heat required in the enher oum centre i 9 kw. 2.5.5 Radiator Intalled radiator data i a mentioned above in Chapter 2.4 _int 9/C r_int 7/C i_int 2/C he calculated geothermal upply water temperature i le than the deign upply temperature for the exiting radiator. herefore, we mut add radiator ection in order to increae the radiator ize. It i eaier to add radiator ection than to change the whole radiator ytem. Equation 22 define how many ection we need. increae ln( _ int _ int r _ int ln( i /( i _ int /( r _ int i _ int r r i 4 3 (27
Dorj 42 Report 3 where Deign upply water temperature in geothermal heating ytem, 8/C; i Deign inide temperature in geothermal heating ytem equal i_int ; r Deign return water temperature in geothermal heating ytem, 5/C. Radiator ize increae calculated from Equation 27 i hown in able 3 and Figure 15. ABLE 3: Increae in radiator ize FIGURE 15: Relationhip between and radiator ize increae Increae in radiator ize Supply water temperature ( /C 1.527 8 1.57 77.78 1.616 75.56 1.665 73.33 1.717 71.11 1.773 68.89 1.834 66.67 1.899 64.44 1.969 62.22 2.45 6 2.5.6 Supply and return water temperature calculation for geothermal heating ytem Above we have determined the deign of the tranmiion piping and the radiator ytem for a geothermal heating ytem intead of a boiler heating ytem. Now we define the needed upply water temperature and geothermal water ma flow for the whole geothermal ytem in the enher oum. he return water temperature of the geothermal heating ytem i calculated by the following equation: ( ln(( /( i o r i r i o ln(( i /( r i ( r i 4 3 (28 where i Deign inide temperature (boiler ytem, 2/C; o Deign outide temperature (boiler ytem, -25/C; Supply water temperature (boiler ytem, 9/C; r Return temperature (boiler ytem, 7/C; Deign upply water temperature (geothermal ytem, 82.5/C; i Deign inide temperature (geothermal ytem, 2/C; o Deign outide temperature (geothermal ytem, -25/C; Ma flow (geothermal ytem, 1 l/. m o Equation 28 give u the return water temperature r. We can find the ma flow in the geothermal heating ytem by the following equation: m m o r i r i o o (29 he calculation reult are hown in able 4 and Figure 16-18.
Report 3 43 ABLE 4: Calculation reult for o, and m Outide temperature (/C Supply temperature (/C -25 82.29 38.24-21.11 8 22.56-17.22 77.58 15.28-13.33 75 11.7-9.44 72.21 8.33-5.56 69.17 6.4-1.67 65.8 4.97 2.22 61.98 3.85 6.11 57.52 2.95 1 52.7 2.2 Ma flow, m (kg/ Dorj FIGURE 16: Relationhip between and FIGURE 17: Relationhip between m and able 4 how u a trong relationhip between the upply water temperature, the hot water ma flow and the outide air temperature. he outlet water temperature in the hot pring i 86/C, and the maximum flowrate i 1 kg/. At -9.4/C outide temperature, 8.3 kg/ hot water are required according to able 14. At thi outide temperature the water upply temperature in enher oum i 72.21/C. At -13.33/C, 11.7 kg/ are required, which i more than what i available from the hot pring. It mean that without drilling for more water we can upply enher oum with geothermal heating down to about -1/C outide air temperature. FIGURE 18: Relationhip between m and In order to upply enough water for the deign outide air temperature of -25/C, we will need four time more geothermal water than i available. In order to be able to upply geothermal heat under the deign condition, we need to drill one or two geothermal well in the area. Ele it i poible to ue an additional mall capacity boiler if the outide air temperature i le than -1/C.
Dorj 44 Report 3 3. FEASIBILIY SUDY FOR ELECRIFICAION OF SHARGALJUU AREA IN MONGOLIA USING GEOHERMAL WAER A 2 MW capacity Kalina power plant ha recently been taken into operation in Húavík town, N-Iceland. he following tudy i baed on the deign for thi power plant. It i etimated that the preent population of the Shargaljuut area total around 2,5 people and the demand for electricity in the area i around 2 kw. he nearet aimag centre, Bayankhongor, i 58 km from the Shargaljuut hot pring and if further invetigation confirm the availability of larger geothermal power potential (1-3 MW, upplying power to Bayankhongor would be a viable option for the future (Worley International, 1995. Now thi aimag centre i upplied with electricity from a dieel generator. 3.1 Preent ituation of electricity upply in Mongolia he main ource of electricity in Mongolia i a coal power plant with an intalled capacity of 764 MW, which upplie 4% of the total area and 5% of the population. According to recent etimate, 7 aimag, 197 oum, and 2, nomadic familie are not upplied by the central power upply line. hee are upplied with electricity from iolated dieel generator (aci ervice, 2. he main player in the electricity ector in Mongolia i the Energy Authority of Mongolia, which manage three ytem: -he Central Energy Sytem (CES -he Wetern Energy Sytem (WES, and -he power plant in the aimag centre of Choibalan he hitorical electricity balance of the country i hown in able 5. ABLE 5: Hitorical electricity balance in Mongolia Year 1975 198 1985 199 1993 1995 otal intalled capacity (MW 43 758 935 97 Gro generation (GWh 848.3 1531.7 2843.2 3347.3 273.2 2628.7 Import (GWh 263 153 228 198.2 381.2 Export (GWh 53 76 53.8 28.6 otal conumption (GWh 848.3 1794.1 2943.2 3499.9 2847.7 2981.3 he mot important tranmiion network of the country i that of the CES. he CES tranmiion ytem conit mainly of 22 kv overhead line. In ome cae, the ytem ha been extended to cover iolated aimag. Due to the very large ditance involved, thi ha reulted in very long feeder with ignificant loe. Only a fraction of the country i covered by the exiting tranmiion ytem (Figure 19. hu, 7 out of the 18 aimag of Mongolia are upplied with electricity through iolated dieel plant (and in one cae coal-fired CHP. Electricity upply data for each aimag Centre in 1995 i hown in able 6. ABLE 6: Aimag centre electricity upply for 1995 Aimag centre Generation (GWh Peak load (MW Hovd 8.8 3.2 Uliatai 11.5 n.a. Altai 6. 2.6 Murun 12.1 3.3 Bayankhongor 7.9 2.8 Dalanzadgad 7.5 1.9 Baruun-Urt 6.6 2.4 Choibalan 67. 13.3
Report 3 45 Dorj FIGURE 19: Scheme of the Mongolian centralized energy upply 3.2 Electrification by geothermal water in Shargaljuut area Mongolia, with a 1,564,619 km 2 total territory and a total population of 2,373,5 exhibit ignificant challenge in the electricity upply ector, impoed by a number of reaon, the mot important of them being the limited coverage of the country by the electricity network, the dependence on oil for the electrification of remote area, the (degradation of the exiting equipment and the very evere climatic condition in mot part of the country. Rural electrification in Mongolia. Currently, 197 Soum Centre in Mongolia are not connected to any electricity grid. From thee, about 5 are expected to be connected to the grid in future year, while there i not any uch plan for the remaining 15 Soum Centre. he main problem, which were identified concerning the oum centre electricity upply, are a follow: Lack of reource of rural population, and thu not adequate conumption of electricity. Mot of the electricity generating equipment i over 2 year old, manufactured in Ruia. In addition to low efficiency, thi alo caue frequent failure and difficultie in repair due to lack of pare part. he upply of fuel; tranportation of fuel for the dieel generator over the long ditance to the Soum Centre increae cot by about 1%. Furthermore, the lack oil reource in Mongolia create a dependence on foreign oil import. Renewable energy technologie preent a number of advantage for the electrification of remote area in Mongolia: hey favour the exploitation of local reource, thu reducing the import dependence a well a the tranportation problem aociated with fuel oil. hey remain economic and may operate efficiently on a mall cale.
Dorj 46 Report 3 hey utilie imple technology, with poibilitie for ome local production (geothermal turbine component, olar panel and wind turbine component. Due to their capability for implementation on a mall cale, but alo with world-wide awarene of their environmental advantage, they may prove eaier to finance than conventional, large cale electricity upply technologie. he Shargaljuut area ha geothermal water a one of it renewable energy reource. hu, Shargaljuut area ha the poibility of upplying electricity from the geothermal water of Shargaljuut hot pring. 3.3 Chemical content of the Shargaljuut hot pring Chemical compoition of urface pring water at Shargaljuut i reported (Worley International, 1995 a follow: K+Na 83.7 ppm Ca.4 ppm Mg 1.2 ppm Fe ppm Cl 14 ppm SO 4 75 ppm HNO 2 61 ppm NO 2 24 ppm Ph 8.4 Surface emp. 92/C Flowrate 25 l/ 3.4 Kalina cycle A Kalina cycle i principally a modified Rankine cycle. he tranformation tart with an important proce change to the Rankine cycle - changing the working fluid in the cycle from a pure component (typically water to a mixture of ammonia and water (Saad, 1997. he modification that complete the tranformation of the cycle from Rankine to Kalina conit of proprietary ytem deign that pecifically exploit the virtue of the ammonia-water working fluid. hee pecial deign, either applied individually or integrated together in a number of different combination, comprie a family of unique Kalina cycle ytem. hi i omewhat analogou to the Rankine cycle which, in fact, ha many deign option uch a reheat, regenerative heating, upercritical preure, dual preure etc., all of which can be applied in a number of different combination in a particular plant. Each Kalina cycle ytem in the family of deign ha a pecific application and i identified by a unique ytem number. For example - Kalina Cycle Sytem 5 (KCS5 i particularly applicable to direct (fuel fired plant, Kalina Cycle Sytem 6 (KCS6 i applicable to ga turbine baed combined cycle and Kalina Cycle Sytem 11(KCS11 i applicable to low-temperature geothermal plant. he Kalina cycle doe not require technological breakthrough in equipment deign. here i only a lack of experience with an ammonia-water working fluid in the power indutry. A uch, knockout rik aociated with the Kalina cycle are minimized. It i important to point out that the Kalina cycle combined higher efficiency and lower cot advantage hould make poible the exploitation of new energy reource. here i an abundant upply of low-temperature geothermal energy ource and wate heat proce tream that are not economically feaible to develop uing current technologie. he claim of the Kalina cycle technology have been upported by a 2 MW power plant in Húavík, Northern Iceland. hi plant utilize geothermal water at 125/C from a geothermal well. Kalina cycle are covered by approximately 3 patent in the US and internationally, which are hold by Exergy Inc., California (Exergy Inc., 21.
Report 3 47 Dorj A mixture of fluid ha been propoed to ubtitute team in a Kalina cycle, where a mixed working fluid variable compoition i ued to provide a better match between the temperature of hot and cold flow (Korobityn, 1998. he compoition of the fluid i changed in the cycle at different point. In mot Kalina cycle tudie a mixture of water and ammonia ha been ued. he ammonia in the mixture begin to vaporie firt, and a it boil off, the liquid mixture ammonia concentration decreae, and the boiling temperature of the liquid mixture increae. hi reduce the temperature mimatch between the topper wate heat and the fluid in the boiler, and allow an efficiency rie in the bottoming cycle. Figure 2 how a chematic diagram of heat utilization in a vaporizer in the Kalina cycle (Mlack, 1996 and 21. FIGURE 2: Heat utilization line in the Kalina cycle A baic Kalina cycle conit of a heat recovery vapour generator (HRVG, a team-ammonia turbine, and the ditillation condenation ubytem (DCSS, a hown in Figure 21. In the DCSS the tream from the turbine i cooled in the recuperator, and then mixed with a lean olution of ammonia in order to raie the condening temperature. he reulting baic olution i condened in the aborber and brought to the recuperator under preure. Part of the flow i ent to dilute the ammonia-rich tream coming from the eparator. he main flow pae the recuperator and i flahed in the eparator. he vapour i mixed with the baic olution, condened and preurized before entering the vapour generator. Heat Vapour turbine HRVG Separator Recuperator Working olution Baic olution Enriched vapour Lean olution Condener Aborber FIGURE 21: Flow cheme of the Kalina cycle 3.5 Deign of a Kalina power plant in Shargaljuut A Kalina power plant in the Shargaljuut i baed on the flow cheme hown in Figure 22. hi i the ame flow cheme a in the Húavík power plant. All calculation were carried out with the Engineering Equation Solver (EES program (Klein and Alvardo, 21. Program input variable are: x_bl.87 Ammonia - water mixture, % P_high 2 Preure on the high preure ide, bar P_low 5 Preure on the low preure ide, bar _high 92+273.1 Water inflow temperature, K
Dorj 48 Report 3 3 362.1 [K] 3 Re cupe r ator 2 362.1 [K] m w 25 [kg/] Vaporizer 2 high 365.1 [K] vapourizer 7532 [kw] x bl.87 1 1 316.4 [K] low 293.1 [K] Sepe rator m ga 5.69 [kg/] urbine m bl 7.496 [kg/] m liq 1.887 [kg/] 4 362.1 [K] 4 15 37.3 [K] Power out 789.7 [kw] Power turb 822.3 [kw] η.75 6 37 [K] 6 5 5 3.4 [K] Mixe r/ab orber brine 48 [kw] 11 7 7 36.2 [K] 11 33 [K] Reg enerator reg 76 [kw] P high 2 [bar] 8 8 297.5 [K] 1 1 281.4 [K] η p.5 Co n d en er Pum p Power pump 32.66 [kw] condener 6742 [kw ] 9 P low 5 [bar] 9 28.7 [K] FIGURE 22: Block diagram for a Kalina power plant in Shargaljuut _low 2+273.1 Water outflow temperature, K m_dot_w 25 Water flow rate, kg/ eta.75 urbine efficiency, % eta_p.5 Pump efficiency, % _brine 48 Recuperator heat exchange rate, kw _reg 76 Regenerator heat exchange rate, kw he calculation reult are hown in the following block diagram (Figure 22 and Figure 23-26. he diagram how all calculated variable, uch a each component inlet and outlet temperature, ammonia concentration in the mixture, turbine electricity production and pump power demand. FIGURE 23: Relationhip between geothermal water temperature and ammonia water mixture rate FIGURE 24: Relationhip between inlet thermal power and geothermal water flow rate
Report 3 49 Dorj FIGURE 25: Relationhip between pump preure and electricity production FIGURE 26: Relationhip between inlet thermal power and electricity production he Shargaljuut hot pring geothermal water could produce 79 kw electricity uing a Kalina power plant. he produced electricity i enough to upply the electric demand of the Sharagljuut area and it i poible to increae electric demand by 59 kw. If the geothermal water flow rate in thi area could be increaed, and higher temperature than 92/C temperature found, by invetigation and drilling, the Kalina power plant could produce the 1-3 MW needed for Bayankhongor aimag a well. 4. POSSIBILIY OF GER HEAING AND ELECRIFICAION USING GEOHERMAL WAER 4.1 Nomadic family life tyle A a nomadic nation, the Mongol have thouand of year of hitory and experience in raiing livetock. he life of the Mongol depended almot totally on thoe animal. hey ate the meat and the milk, even ditilled wine from the our cream; they made clothe from the kin and made the felt of the yurt from the wool; their tranportation were the big animal like hore, ox and camel. So the Mongol are very fond of the livetock and can recognize every ingle one. Mongol only raie five kind of livetock and only thee animal are conidered a livetock ( mal in Mongol language by them. hey are hore, heep, ox, camel and goat. he Mongol call them tavun huhuu mal. Ger (Figure 27 i the main houe for rural herdman and will be for the agricultural inhabitant in the coming foreeable year. Ger fulfil a very important role for the nomadic family. hee imple but very functional tent can eaily be dimantled and moved, yet are warm and comfortable. he Ger i heated with firewood or animal dung burned in a tove tanding in the centre. Nowaday 3% of the population in Mongolia live in modern apartment (reident and 7% live in Ger and mall building, Ger i a houe for the rural population a well a city and town reident becaue there i a lack of modern apartment Ger fulfill a very ueful purpoe in iolated rural area. here are everal advantage of the Ger. It i light weight, eay to tranport and intall, warm to live in. It can tand natural calamity uch a quicken, with good unlight and good ventilation. Mot Ger are deigned in imilar way, but they can have different wall dimenion: 4 wall, 5 wall, 6 wall. Figure 27 how the general deign of Mongolian Ger. he Ger with 5 wall are in common uage in Mongolia. he ize of floor for thi Ger i 36.3 m 2, inner volume i 47 m 3, light tranmiion and air convection top part meaure 2.27 m 2, ratio of the baic diameter of Ger D and the diameter of light tranmiion top part D equal D/D 4. Diameter D i the ame a the height of the door Hg (D Hg. he ratio between the height of the upport and wall i 1.5 (H p /H C 1.5. he data on the Ger i hown in able 7.
Dorj 5 Report 3 FIGURE 27: he general deign of Mongolian Ger. 1. op air ventilation and lighting through unhine wheel opening part, named toono ; 2. Felt cover for window; 3. Roof upport; 4. Wooden part of roof named uni ; 5. Several rev (two rev felt and between them paper; 6. Internal circle curtain iolated by cotton fabric; 7. Rope encircle wall; 8. Wall conit of everal wooden lattice named hana ; 9. Several covering (two covering egii and paper inulation; 1. Wall rope tighten and encircle felt cover; 11. Outide textile (white cotton fabric cover of Ger; 12. Outide rope girdle of Ger; 13. Floor made of board wood; 14. Sand foundation; 15. Door made of board wood; 16. he holding for rope ABLE 7: he main dimenion of a typical Ger Unit Size of Ger Diameter of foundation D, m Diameter of top part D, m Height of pot H, m Height of wall H C, m Height of Ger H I, m Size of main element of Ger Dimenion of each wall, m 2 Dimenion of total wall, m 2 General ize of a cover on top, m 2 Dimenion of a door, m 2 Dimenion 6.8 1.7 2.28 1.52 2.5 1.52 3.6 4.65 23.25 2.96 1.38 he top and upper part of the Mongolian Ger are different from the Kazakh Ger. 4.2 Heat requirement of the Ger he heat tranfer from the Ger to it environment can be calculated uing the following equation (Emeih, 21: (3
Report 3 51 Dorj where U he overall heat tranfer coefficient of the wall; A Area of the wall; i Inide deign temperature; Outide deign ambient temperature. o For our cae the overall heat tranfer coefficient and different area element of the Ger are hown in able 8. ABLE 8: Overall heat tranfer coefficient of different element of a typical Ger Element Material Area (m 2 hickne (m U value (W/m 2 /C Wall Wooden lattice covered by felt 23.25.15.35 Roof Wooden upport covered by felt 36.32+1.135/2.15.35 Floor Wood and concrete 36.32.1 and.55.92 Window (toono Wooden framework and gla 1.135/2.5 6.2 Door Wood and felt 1.38.3 and.5.94 he area of the window equal half of it total area a half of the window i covered by felt. herefore, half of the window area i added to the roof area. In the following calculation deign the inide temperature and outide ambient temperature were choen a the tandard Mongolian deign condition, at 2/C and -25/C. Now we can calculate the heat lo of the Ger from Equation 3 which at deign condition lead to Equation 31. q ger ( U wall Awall + U roof Aroof + U window Awindow + U door Adoor ( i o (31 he reult indicate a peak heat requirement of 1318 W. 4.3 Geothermal water needed for heating the Ger In the floor heating ytem, teel pipe were motly ued before, but now only platic pipe with high heat endurance are ued. Much progre ha been made in the production of platic pipe with high heat endurance and they will mot likely cot le in the future compared with other type of pipe. hee pipe are laid 15-45 mm apart, depending on the diameter of the pipe ued and how big a urface i to be heated. Leat ditance from floor urface to pipe i 4 mm. Deign have become better and there i much interet in utilizing 4-6/C hot water for heating (VEO, 2. Figure 28 how the 3 type of A: Concrete floor under carpet or PVC cover Cover Concrete 5 mm >7 mm >65 mm ile B: Concrete floor under tile Concrete > 3 mm >7 mm >4 mm C: Concrete floor under wooden floor Wooden floor < 1 mm Concrete >7 mm >55 mm Inulation 2-6 mm Inulation 2-6 mm Inulation 2-6 mm Concrete Concrete Concrete FIGURE 28: Different floor type for a Ger; ype A: At leat 3 mm of platic inulation i laid over the whole floor. On the inulation i laid a teel mat where PEX pipe are fatened. hen there i the concrete floor. he ditance from a pipe to the urface of the floor i 3-9 mm; ype B: Like A, except the concrete i thinner or 3-5 mm. On top of the cover i for example 2.5 mm cork; ype C: Like A, except now the concrete i thinner or 3-5 mm. On top of the cover i for example 13-23 mm wooden floor