Nonconventional Technologies Review no. 3/2009

Transcription

1 Nonconventional Tecnologies Review no. /2009 CONSTRUCTIVE AND FUNCTIONAL UPGRADING OPPORTUNITIES FOR THE HEAT SECTION FROM UNIVERSITY OF ORADEA Cercetător ştiințific III Cristian VANCEA, Centrul de cercetări Geotermale Universitatea din Oradea, România Profesor Doctor Inginer Mircea GORDAN, Facultatea de Inginerie Electrică şi Tenologia Informaţiei Universitatea din Oradea, România drd. ing. Tania-Mariana POPA, Universitatea din Oradea Abstract: Te paper deals wit toretical and paractical considerations. Te eat section of te University of Oradea ensures te efficient, termal energy needed for te current eat users. Te disadvantage is tat te geotermal water temperature, out of te point, is of 50 C, temperature wic is made iger, bot for te reinjection and also for te discarge. It was found tat altoug te eat excangers were replaced on te circuit to prepare domestic ot water, electric valve regulating te flow of geotermal water is called CV due to large fluctuations recorded in domestic ot water consumption. If te geotermal water temperature output drops to about 0 C, sould be available eat, eat tat could be used for district eating and providing domestic ot water eat prospective users listed in te development plan University of Oradea, analysis tat we intend to perform furter. Keywords:.primary users, eat pump, efficiency, friendly to te environment 1. BENEFITS OF GEOTHERMAL HEAT PUMPS In tis paper, we suggest a different approac, different from te existing one, namely ug cascaded geotermal eat pump ug vapor compression. Heat pump as some notable advantages [ suc as: - efficiency, - friendly to te environment, - responsibility towards te environment, Heating efficiency areas: In te first case, coose a conventional eating system. Tis will consume 100% energy to cover te eat. In te second case, it cooses te eat pump. Tis will consume only 0% as muc energy as to acieve te same result as te remaining energy for eating will be taken from te natural environment for free. In oter words, wen a conventional eating system uses an energy unit, eat pump uses only 0. wic allows eating of financially accessible. Friendly to te environment: Fig 1. Functional diagram of a eat pump Q & 0 - Amount of eat taken, V - evaporator; Rg - regenerative; C Compressor, Q & k termal capacity of te pump; K - condenser; Vl - rolled valve. A source of renewable and clean energy. Since te eat pump consumes less energy,it reduces suc pollution resulting from te use of conventional fuels. 1 because conventional fuels are polluting emissions suc as carbon dioxide, nitrogen oxides and sulfur dioxide. Nitrogen oxides and sulfur dioxide are particularly unpleasant - tey are a part of te cause of acid rain and some breating problems. Tese gases are carefully monitored by te European autorities. To acieve te same result, eating a ouse on a eat pump can reduce nitrogen oxide pollution by 70% compared wit a conventional fuel-based boiler. If sulfur dioxide, reducing pollution tat substance can 9

2 Nonconventional Tecnologies Review no. /2009 be up to 0%. Carbon dioxide is a gas and "important" and is te subject of te tird Responsibility towards te environment: An effective metod to combat te greenouse effect Carbon dioxide is one of te gases responsible for te "greenouse effect". Tis is already well known today, namely tat increag greenouse effect climate canges our planet. You need to be taken in tis regard and still very urgent. Kyoto International Conference triggered te alarm and set targets for reducing gases for various countries involved. Heat pump is fully part of te policy to combat te greenouse effect - Instead, it is an ally in tis figt. For example: in France, were eat 1kW resulting product gas equivalent of 70g of carbon dioxide, eat 1kW same product wit a eat pump produces only 60g of carbon dioxide, ie 6 times less! Examples of notable advantages for te use of eat pump (kw costs of various systems to produce eat, eat oug costs, investment costs, al costs of eating after 20 years) are given by: [WWW. Germanrenewable-energy.com] 2. SIZING CALCULATIONS Te academic campus includes a series of buildings wit a developed area of approximately 70,000 m2 (built Vcl. volume 155,000 m). Some existing buildings may be considered old. Te al area of tese old buildings is approximately 2,000 m2 (Vcl.veci 125,000 m) and area of buildings constructed in November (Vcl.noi 0,000 m) is 7600 m2. In tese buildings are furnised educational facilities, teacing and researc laboratories, researc and design offices, sports alls, administrative offices, two student ostels, university canteen, etc. In te extension plan of te University of Oradea we intend, among oter tings, to build a new library, wit a developed area of 5900 m2 (Vcl.bibl. 2,000 m), some student ostels wit a al capacity of 400 seats, wit an area undertaken by 9900 m2 (Vcl.cămin. 0,000 m), a swimming pool wit geotermal water, a greenouse designed for te students from te Faculty of Horticulture. According to DIN 4701 on conditions to be met by eated buildings present, te values of termal caracteristics of unit: 2 qu W / m² (0,4-0,57 kcal/mk) new construction (regulation of 2002) qu W / m² (0,48-0,57 kcal/mk) new construction (regulation 1995) qu W / m² (0,67-0,86 kcal/mk) construction completed before 1995 qu 120 W / sqm (1.15 kcal/mk) old buildings made witout regulations Primary users For te primary users ere are presented, te next eating calculations, based on te equations of eat transfer and termal balance. Te calculations were made in detail, bot for te primary users and for te secondary ones, being obtained ye next results: al volume: Vcl m efficient ollow brick walls (7.5 cm tick), wooden double glazing; feature coupled termal unit: air temperature in rooms: outdoor temperature calculation: eating period: 172 days a year (15/10 15 / 4) Total ourly eat consumption for eating (power required):.1 Qinc + Qvent 1,15 1,15 qu Vcl. ( ti te ) kcal / (4.650 kw ) Temperature Round trip for secondary agent is cosen from 70 C or 40 C, te required flow of secondary agent is: sec.1 c t t m / 7,5 l / s Temperature Round trip geotermal water is coose 85 C and 50 C, te required flow of geotermal water is: prm.1 c t t m / 2 l / s - geotermal water temperature: 85 C - for eating circuit: Primary agent: geotermal water flow: 115 m / (2 l / s ) temperatures (round trip): 85 / 50 C pressure (round trip): 2.5 / 0.8 bar Secondary Agent: ot water flow: 15 m / (7.5 l / s) temperatures (round 94

3 Nonconventional Tecnologies Review no. /2009 trip): 70 / 40 C pressure (round trip):,5 / 1,5 bar Secondary users of geotermal energy In te extension plan of te University of Oradea we intend, among oter tings, to build a new library, wit a developed area of 5900 m2 (Vcl.bibl. 2,000 m), some student ostels wit a al capacity of 400 seats, aving a developed area of 9900 m2 (0,000. Vcl.cămin m), a swimming pool wit geotermal water, emissions to te practice of students from te Faculty of Horticulture. For te secondary users are presented below, termal calculations, based on te equations of eat transfer and termal balance. Te calculations were made in detail, bot for te primary users and for te secondary ones, aving te next results: al volume: 62,000 m Vcl. efficient ollow brick walls (7.5 cm tick), wooden double glazing coupled feature termal unit: air temperature in rooms: outdoor temperature calculation: eating period: 172 days a year (15/10 15 / 4) Total ourly eat consumption for eating (power required):.2 Qinc + Qvent 1,15 1,15 qu Vcl. ( ti te ) kcal / (1.40 kw ) Temperature Round trip for secondary agent is cosen from 60 C, respectively 45 C, te required flow of secondary agent is: sec c t t m / 21,4 l / s COP 4 te required flow of geotermal water is: Q m 4 0, & înc c t t m / 6,1 l / s Taking te value of a eat pump, geotermal water flow required is al ourly eat consumption for cooking water domestic ot (power required): average domestic ot water needs: m / required for domestic ot water temperature: 50 C water temperature supply: 10 C. Total ourly eat consumption for domestic ot water (power required): Q c ( te ti ) ( 50 10) kcal / ( 1.070kW ) Considering te value of a eat pump, geotermal water flow required iscop 4 temperature geotermal water discarge resulting from te mixture: Q m 4 0, & c t t m / 4,8 l / s Termal power still available for space eating or oter domestic ot water ug eat pumps is: tgeo. dev 5 C 109 Volume of buildings tat can be eated: built area available: Q& c Δt disp ( ) ( kw ) kcal / t Volume of buildings tat can be eated: Q& disp Vdisp 1,15 q t t 1,15 0,5 2 u ( ) int m Built surface available: Vdisp 2 Sdisp m H Main parameters of te eating plants are: installed capacity 6,000,000 kcal / (7000 kw); Built to be eated volume: 217,000 m; domestic ot water flow 2 m / ; annual amount of eat delivered for space eating: Gcal; annually for te amount of eat delivered. domestic ot water: 8600 Gcal; ourly consumption of geotermal water: 115 m / (2 l / s) annual consumption of geotermal water: 525,000 m; geotermal water discarge temperature: 5 C. power available for eating ug eat pumps: kcal / ext 95

4 Nonconventional Tecnologies Review no. /2009 Fig 5. Teoretical cycle of a eat pump Fig 2.Te cost of eating a ouse of 175mp wit various systems to produce eat Calculation of eat pump Operation eat pump Te operating system of a eat pump is similat to te operating system of a refrigerator. In te case of te refrigerator, te refrigerant evaporator removes te eat troug te condenser, and ten it is transferred into te room. Fig. Work processes in te diagram LGP-. t0 - temperature vapor tk - Dewpoint vapor overeat vapor compression process condeng vapor - - subcooling liquid te process of rolling. Fig. 4. Te principle sceme of eat pump In te case of te eat pump, te eat is taken from te environment (soil, water, air) and leaded to te eater. Te eat circuit cooling unit is made according to pysical laws. Agency work, a liquid as reaced boiling point at low temperature, it leads in a circuit and running, evaporate, compresses, condenses and rebound. Te evaporator 5 is an agent working under reduced pressure. Te temperature level of environmental eat te evaporator is iger tan te corresponding boiling temperature field agent working pressure. Tis difference in temperature leads to a eat transfer agent working on environmental and working agent boil and vaporizes. Vapors displaced from tis agent are continuously witdrawing te compressor and compresses. During compression increases te vapor pressure and te temperature. Te vapor reaces te compressor eat into te condenser, wic is surrounded by eat. Te eat temperature is lower tan te condensation temperature of te agent working, so tat vapors are cooled and liquefies. Te eat taken in evaporator and additional electricity transferred by compression, condensation is released in te condenser and eat transfer. te working agent is recirculated troug te evaporator valve rolling. Staff working at ig pressure passes to te condenser, te low pressure evaporator. On entering te evaporator to reac te new pressure and initial temperature. Te circuit is closed. In a subrăcitorul regenerative eat excange occurs between te vapor produced in evaporator and te liquid resulting from condensation. Following te excange of eat, te liquid found in a ig temperature, vapor eat yields suffered a subrăcire. Vapor due to te fact tat tey receive an additional quantity of eat, is overeating. 96

5 Nonconventional Tecnologies Review no. /2009 Secondary users of geotermal energy ug eat pumps Hourly al eat requirement for eating (power required): Q inc kcal / (1.40 kw ) Te PDC will use 20 units of ground-water type WPF STIEBEL-EL TRON 66 in parallel or series modular 400kW four units, connected in parallel. Total time needed for domestic ot water eat (power required): Q c ( te ti ) ( 50 10) kcal / ( 1.070kW ) 9 PDC will use 16 units of ground-water type WPF STIEBEL-EL TRON 66 in parallel or series modular tree 400kW units, connected in parallel. Constructive-functional parameters of ground-water type PDC WPF 66 STIEBEL-EL TRON (as Product Manufacturing Program STIEBEL-Eltron ): - H x L x W [mm] 1160x1250x870, - weigt [kg] 600, 6 - temperature cold source (solution of te probe) from -5 to 20 [degrees Celsius] - maximum temperature on lap 60 [degrees Celsius], - te required flow of cold source (te probe solution) 16. [m³ / ] at 20 [p] - required flow of te eating circuit (eat) 12.5 [m³ / ] to 280 [Pa]; - now coupling te eating circuit and te circuit G 2 ½ cold outside source -- R410A refrigerant - te temperature of 0 [degrees C] te solution of te probe and te temperature 5 [degrees C] te eat on Tour (W0/W5): - 66 al termal power [kwt] - electric power absorbed 14. [kwel] - COP 4.6. Use te eat pump module in te eat section of te University of Oradea is acieved by coupling teir form of "battery eat pump" modules consist of PDC connected in parallel (20 units ground-water type PDC WPF 66 STIEBEL-EL TRON or four modular units range 400kW eating system, and 16 units of type ground-water PDC WPF 66 STIEBEL-EL TRON or tree units range 400kW modular system domestic ot water preparation. REFERENCES 1. Abbado D., (1998), Abbado D., Orlando V., Minisale A., Tassi F., Magro G., Segedi I., Ioane D., Szakacs AL, Coradossi N. Origin and evolution of te fluids from te Eastern Carpatians, Proceed. XVI-t Carpatian-Balkan Geological Association Congress, p 7, Viena. 2. Antal,C., Gavrilescu,O., ş.a., (2000): Utilizarea energiei geotermale. Conversia energiei geotermale în energie electrică, Editura Universităţii din Oradea, Astrom K.J., Wittenmark B. (1984): Computer Controlled Systems. Teory and Design, Prentice Hall, Atanasovici, V. (1981): Termoenergetică industrială şi termoficare, Editura Didactică şi Pedagogică,