Modeling of Hybrid Solar Pond - Ocean Thermal Energy Conversion for Power Generation

Transcription

1 Modeling of Hybrid Solar Pond - Ocean Thermal Energy Conversion for Power Generation Nur Hidayah Nong Nazari a,b,tohru Suwa a a Malaysia-Japan International Institute of Technology,Universiti Teknologi Malaysia,Kuala Lumpur, Malaysia b Ocean Thermal Energy Centre, Universiti Teknologi Malaysia,Kuala Lumpur, Malaysia 3 rd International OTEC Symposium 2015 Universiti Teknologi Malaysia Kuala Lumpur, Malaysia 1

2 Outline Introduction Design of the System Analysis of the system Modeling of the system Result Conclusions 2

3 Introduction [1] Advantages Sustainable energy Requires no fossil fuels Less environment impact Limitation Low energy conversion efficiency Solutions Optimization of Rankine based cycle.[2] Increase temperature difference.[3] Combination of OTEC and solar pond[4] 3

4 Introduction Solar Pond: What and Why? A body of water with salinity gradient used to collect and store solar energy The high density of saltwater at the bottom gives a lower buoyancy effect which limits the upward convective flow of the water, thereby trapping some of the heat Hybrid OTEC-Offshore Solar Pond(OSP) system is said to be cost competitive due to its low cost OSP collector and higher thermal efficiency compared to conventional OTEC.[4] Figure 1: mechanism of solar pond 4

5 Design Of The System Figure 2: proposed design of the hybrid OTEC Solar Pond 5

6 Analysis of The System The system is performed under thermodynamic analysis on each component to predict the thermal performance of the system. The efficiency OTEC solar pond was further calculated by varying the required temperature of superheated working fluid that entering turbine. Component Heat Balance Cycle Efficiency Evaporator Condenser Q=ṁCpΔT Super Heater Solar Pond Q=ṁ(hout hin ) Turbine Pump W=ṁ(hout hin ) Ƞ=Wnet/Qin 6

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8 Analysis of The System ipumping Power,Wp{KW} Pumping Power OTEC OTEC-SP (T=30ᴼC) OTEC-SP (T=40ᴼC) OTEC-SP (T=50ᴼC) OTEC-SP (T=60ᴼC) OTEC-SP (T=70ᴼC) superheater cold seawater warm seawater working fluid Figure 4:Comparison of pumping power of OTEC cycle and OTEC-SP with various superheating temperature 8

9 Modeling of The System Designing of solar pond Figure 5: Solar Pond Configuration Pipe diameter= 0.025m Surface Area=1120 m 2 Velocity= 1.75 m/s 33m Figure 6 : Solar Pond Configurations(Top View) 9

10 Modeling of The System MODELING OF SOLAR POND Finite Element Software-COMSOL 0.3m 1.2m 1.5m Figure 7 :Transient 2D asymmetrical solar pond 10

11 Modeling of The System Boundary condition and assumption : The solar pond is modeled as solid There is heat loss due to conduction, radiation and evaporation at the surface of solar pond Heat loss by conduction at the bottom of solar pond The heat loss through the wall is neglected No natural convection inside the solar pond Measured KL data was used as the solar radiation data 11

12 Result Temperature Gradient Figure 9: temperature gradient of solar pond in function of depth. 12

13 Conclusions OTEC solar pond has higher efficiency compared to the conventional OTEC. High temperature at the turbine inlet increases the OTECsolar pond system efficiency. Solar Pond Finite Element model was developed. 13

14 THE END Q&A 14

15 References 1. Pub.L ,Sec. 9, July17, 1980, 94 Stat.946.] 2. Kim, N. J., Ng, K. C., & Chun, W. (2009). Using the condenser effluent from a nuclear power plant for Ocean Thermal Energy Conversion (OTEC). International Communications in Heat and Mass Transfer, 36(10), doi: /j.icheatmasstransfer Yamada, N., Hoshi, A., & Ikegami, Y. (2009). Performance simulation of solar-boosted ocean thermal energy conversion plant. Renewable Energy, 34(7), doi: /j.renene Straatman, P. J. T., & van Sark, W. G. J. H. M. (2008). A new hybrid ocean thermal energy conversion-offshore solar pond (OTEC-OSP) design: A cost optimization approach. Solar Energy, 82, doi: /j.solener