PERFORMANCE OF OTEC RANKINE CYCE USING DIFFERENT WORKING FLUIDS

Transcription

1 PERFORMANCE OF OTEC RANKINE CYCE USING DIFFERENT WORKING FLUIDS Norazreen binti Samsuri Malaysia Japan International Institute of Technology Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia 1

2 OUTLINE OF PRESENTATION 1. Introduction Problem Statement Overview of the OTEC performance factor Objective Scope 2.Methodology Selection of tested working fluids Thermodynamic model of 1MW OTEC Rankine Cycle Techno-economic model Selection of pipe material 3. Result and Analysis Performance and cost evaluation of OTEC Rankine cycle with different working fluids 4. Discussion 5. Conclusion and Recommended Work 2

3 1.0 Introduction 1.1 Problem Statement OTEC Technology Major cost BUT component is the NO fuel for plant operation very substantial capital investment Estimated the capital cost of CC-OTEC plant by previous researchers Type of Plant Plant Size Estimated Cost Floating 10 MW $10,000/kW D. E. Lennard (1987) According to the literature review, the cost of the $18,000/kW L. plant A. Vega is and A. Land-based 1 MW based on ammonia as working fluid. This study R. Trenka is (1990) comparison for cost efficiency using different working fluids. Floating 100 MW $4200/kW L. A. Vega (2002) Floating 53.5MW $ 8430/kW L. A. Vega (2010) 3

4 1.0 Introduction 1.2 Overview of the OTEC performance factor Fig. 1. Pie chart of percentage of previous research focus on OTEC cycle from 1881 to

5 1.0 Introduction 1.3 Objective(s) 1. To assess the effects of using different working fluids on the efficiency of OTEC Rankine cycle; 2. To compare techno-economic efficiency of different working fluids on the OTEC Rankine cycle. 1.4 Scope(s) 1. This research lies within thermodynamic and technoeconomic analysis of 1MW OTEC Rankine Cycle (no desalinated water production); 2. The simulation using LabView, Refprop and PROPATH; 3. The working fluids: Ammonia, Ammonia-water mixture, Propane, R22, R32,R134a and R143a 5

6 2.0 Methodology 2.1 Selection of tested working fluids Fig 2. Latent heat-pressure diagram of pure fluid and pseudo-pure fluid Fig 3. Close up latent heat-pressure diagram of pure fluid and pseudo-pure fluid 6

7 2.0 Methodology 2.2 Thermodynamic model of 1MW OTEC Rankine Cycle Condition of calculation data based on Uehara, H and Ikegami, Y. (1990) : Warm seawater inlet temperature, T in(wsw) o C 28 Cold deep seawater inlet temperature, o C 6 T in(cdsw) Evaporator temperature, T e o C 25 Condenser temperature, T c o C 9.6 Turbine efficiency, η T Generator efficiency, η G Warm seawater pump efficiency, η pump,wsw Cold deep seawater pump efficiency, η pump,csw Working fluid pump efficiency, η wf

8 2.0 Methodology Evaporator analysis Heat added (kw) QE mwf ( h 3 h2) Heat transfer in warm seawater Qwsw mwswc p Tin wsw T wsw Condenser analysis Heat rejected (kw) Heat transfer in cold deep seawater Q Qcsw mcswc p Tin csw T csw Turbine work (kw) W m ( h 3 h4) C m wf T (, out, wsw ( h 4 h1) (, out, csw wf ) ) 8

9 2.0 Methodology Pumping power Working fluid P Warm seawater P wf wsw Cold deep seawater P csw m m wf m wsw H csw wf wf H wsw H csw wsw g csw g g Turbine generator power, P G P m ( h 3 h4) csw wf T G Net power, P N P n P G P wsw P csw P wf 9

10 2.0 Methodology Amount of working fluid in kg Mass flowrate m wf AV kg kg ( m 3 s m mass of working fluid m V kg kg ( 3 m m Ah 2 m ) s m 3 ) 10

11 2.0 Methodology 2.3 Techno economic model Total cost includes : 1) Cost of total amount working fluid 2) Piping cost of working fluid 3) Piping cost of seawater pipe 4) Cost of working fluid pump 5) Cost of warm seawater pump 6) Cost of cold seawater pump 7) Cost of evaporator 8) Cost of condenser 9) Cost of turbine-generator 10)O&M estimated cost (5%) by D. E. Lennard 11)Insurance 2% by D. E. Lennard 11

12 2.0 Methodology 2.4 Selection of pipe material for working fluids piping No. Material Consideration 1. Copper May be used with hot or cold water Lightweight and durable Fits easily in tight places Hard copper is used for water applications and is joined by soldering and brazing 2. Black Malleable, (aka Black Malleable Iron, Galvanized Malleable Iron, Cast Iron) Used to transport natural and propane gas from the street or a tank Usually comes in lengths of 10 or 20-feet in diameters of ½ to 1-inch 3. Stainless Steel High resistance to corrosion can be used to reduce material thickness, weight and cost 4. ASTM A106 (carbon steel pipe) May be used in power plants, boilers, oil and gas refineries, and ships the piping must transport fluids and gases that exhibit high pressures and temperatures Suitable for bending available widely 12

13 Cycle Efficiency Result and Analysis Ammonia-water Mixture (0.9) Propane Ammon R32 R22 R134a R410a R143a Capital Cost (USD)/ Net Power (kw) Fig 4. The effects of using different working fluids to the economic-efficiency for OTEC plant 13

14 Result and Analysis Working Fluids Capital Cost/Net Power ($/kw) Ammonia 2170 Ammonia-water mixture 1620 R410a 1790 Propane 1573 R R134a 2140 R143a

15 Net Power (kw) Result and Analysis Ammonia-water Mixture (0.9) Ammonia R22 R134a R32 Propane R410a R143a Work Pump, deep seawater (kw) Fig 5. The effects of using different working fluids to the work pump of deep seawater (kw) 15

16 Net Power (kw) Result and Analysis Ammonia-water Mixture (0.9) Ammonia R22 R134a R32 Propane R410a R143a Work Pump, surface seawater (kw) Fig 6. The effects of using different working fluids to the work pump of surface seawater (kw) 16

17 Result and Analysis 17

18 Discussion (R32) It has high specific heat at normal boiling point and abrupt dependence of saturated vapors pressure on the temperature and, as a result, R32 is characterized by the highest of all alternative refrigerants, except ammonia. R32 is characterized by high cold-productivity and energy effectiveness, but it is slightly inferior to R22 and R717. KRISO-20kW OTEC pilot test was using R32 as working fluids 18

19 Discussion (Propane) It is characterized by low cost and it is non-toxic. Propane is easily resolved in mineral oils. In the USA it is prohibited to use hydrocarbons in domestic refrigerators. American Environment Protection Agency is foreseeing up to fires per year in case of their use. In New Zealand hydrocarbons are allowed to use in commercial refrigeration equipment. 19

20 Conclusion Propane and R32 has a potential to economically satisfy the requirements of safety and environment protection Propane and R32 is likely the best candidate to become the refrigerant for the future OTEC working fluid to replace ammonia or ammoniawater mixture 20

21 THANK YOU 21