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OST-4B: Ocean Energy
HIGH PERFORMANCE COMPACT HEAT EXCHANGERS FOR THE 1 MW INDIAN OTEC DEMONSTRATION PLANT
Raju Abraham1, M. Ravindran1, Haruo Uehara2 and Yasuyuki Ikegami3
1National Institute of Ocean Energy Chennai, INDIA
abraham@niot.res.in
2Saga University Saga, JAPAN
3Institute of Ocean Energy, Saga University Saga, JAPAN
The heat exchangers in an OTEC power plant is significant as they exchange large quantity (nearly 40-50 times of the gross power) of heat energy due to the low thermal efficiency of the power cycle. Nearly 30-40% of the total cost of the plant should be allotted to this single component. For the present 1 MW OTEC plant plate heat exchangers are used for both evaporator and condenser. The heat energy is exchanged between seawater and ammonia with phase change through corrugated titanium plates of 0.7 mm thickness with CR gaskets. The evaporator and condenser consist of 4 modules arranged in parallel. The ammonia side of the evaporator is coated with stainless steel powder to enhance the heat transfer co-efficient. The coating or thermal spraying is expected to increase the heat transfer co-efficient by 30-50 percent. The evaporator makes use of low angle plates and condenser medium angle plates. The heat transfer co-efficient and pressure drop in the plate heat exchanger is related to the plate angles. In this paper, it is presented the performance of the evaporator using ammonia as working fluid on the condition for the 1MW OTEC.
OST-4B: Ocean Energy
EFFECTIVENESS AND ECONOMIC ADVANTAGES OF HYDROGEN PRODUCTION USING OTEC
Yasuyuki Ikegami1, Kenji Fukumiya1, Kiyonori Okura1, Sadayuki Jitsuhara2 and Haruo Uehara3
1Institute of Ocean Energy, Saga University Saga, JAPAN
ikegami@ioes.saga-u.ac.jp
2Xenesys Inc. Tokyo, JAPAN
3Saga University Saga, JAPAN
Ocean Thermal Energy Conversion (known as OTEC) is an advanced technology to generate electricity from seawater and, at the same time, it can also provide us with fresh water from the seawater upwelled for OTEC power generation system. Therefore, OTEC technology is quite suitable for production of hydrogen by use of related device based on electrolysis method. This paper deals with multiple-product for hydrogen production (OTEC) system and its design method in relation to required electric energy, volume of fresh water.
In this paper, we have observed the hydrogen production system based on OTEC technology and proposed the design method for the purpose. Effectiveness and economic advantage of hydrogen production by the method are reviewed with a case study of 10[MW] OTEC.
OST-4B: Ocean Energy
EFFECTS OF MASS FRCTION OF AMMONIA/WATER MIXTURES ON PERFORMANCE OF OTEC SYSTEM USING UEHARA CYCLE
Tetsuya Nishida1, Yasuyuki Ikegami2 and Haruo Uehara2
1Department of Ocean Mechanical Engineering, National Fisheries University Yamaguchi, JAPAN
nishida@fish-u.ac.jp
2Institute of Ocean Energy, Saga University Saga, JAPAN
An Ocean Thermal Energy Conversion (OTEC) system using the Uehara cycle is proposed. The Uehara cycle utilizes ammonia/water mixtures as the working fluid. Parametric performance analysis of OTEC System using the Uehara cycle is carried out. The parameters in the performance analysis consist of the warm inlet and outlet temperature, the cold inlet and outlet temperature, the mass fraction of ammonia, the extraction rate from the turbine 1 and the heat transfer performance o the evaporator, condenser, heater and regenerator. In this paper, effects of the mass fraction of ammonia on performance of OTEC system using Uehara cycle are clarified by using this analysis.
Thermodynamic physical properties of ammonia/water mixtures are calculated using an improved version of the modified Benedict-Webb-Rubin (BWR) equation of state.
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