In the new type thermodynamic cycle for the ocean thermal energy conversion system, the Guohai cycle, a lean ammonia solution and the steam extraction of the turbine heat recovery branch on the basis of the Kalina cycle are adopted in order to increase the thermodynamic efficiency. This paper applies the principle of the energy conservation and the equation of the heat balance to calculate the efficiency of the Guohai cycle under different steam pressures at the turbine inlet, in warm and cold water temperatures, and with various concentrations of the working fluid. The results show that the concentration of the ammonia and water mixture has a significant effect on the efficiency. When the temperatures of the cold and warm source are fixed, there is an optimal concentration of the ammonia and water mixture, with a higher cycle efficiency. If the temperatures of the surface warm water and the deep cold water are 26 and 5℃, respectively, the maximum efficiency of the system is 4.56% as the concentration of the ammonia and water is 92%. The cycle efficiency first increases and then decreases with the increase of the steam pressure at the turbine inlet, with a maximum value in-between. The deep cold water temperature has an influence on the cycle efficiency, while that of the surface warm water has little effect on the cycle efficiency.

ocean thermal energy conversion  /  thermodynamic cycle  /  cycle efficiency