Performance analysis of an Open Cycle OTEC power module on laboratory scale

Necessities like water, electricity and a clean environment are essential for the sustainable development of society. The demand for electricity and fresh water is increasing day by day, especially in small islands. Hence desalination of seawater and alternative new renewable energy becomes essential to cope with the demand in islands. To mitigate these issues, the low temperature thermal desalination (LTTD) for freshwater and ocean thermal energy conversion (OTEC) for electricity generation is one of the best future alternative solutions. NIOT has also set up a laboratory in its Chennai campus in order to carry out studies on OTEC and desalination systems. It is India's first-of-kind facility to carry out research in field of OTEC. The facility is equipped with a state-of-the-art complete system.This paper presents performance of an indigenously developed power module with a single stage axial flow turbine tested in the open cycle OTEC setup of the laboratory. It discusses evaluation methodology, parametric studies on complete system and performance characteristics of the power module obtained from experiments. The turbines with tip diameter of 196 mm generate power from the ultra-low pressure water vapour. The turbine’s stator and rotor were made using additive manufacturing technique. The system was tested at different combinations of temperatures and flow rates of warm and cold water streams. The power module successfully generated electricity in all conditions. Also non-dimensional parameters like turbine efficiency and flow coefficient are used to study the behavior of turbine under different operating conditions. These studies are beneficial for understanding process parameters for the open cycle OTEC-based desalination plant and setting up a large-scale OTEC and self-sustained OTEC-based desalination plant in India.