Improving Efficiency by Thermodynamic and Gravitational Cycle

Abstract

The efficiency of Rankine cycle and its derivative cycles are severely affected by droplets condensed in the process of vapor expansion, which not only limit its maximum efficiency, but also cause extremely low efficiency around 3% when using low grade heat source. This paper introduces a new theory of Thermodynamic and Gravitational Cycle to explain the concept of MLC, and analyses the reasons MLC OTEC cannot be realized till now. Then The concept of Thermodynamic and Gravitational Closed-Cycle (TGCC) to overcome disadvantage of Rankine and MLC cycle are proposed, and its especial cycle process and efficiency model in detail are discussed. And then we propose a method of combining vapor with mist lift to improve efficiency further, and analyze the new ideal efficiency model (a maximum up to 18.17%) using carbon dioxide sample, indicate the dryness of liquid-vapor mixture is the key factor to improve efficiency. In conclusion, TGCC with mist lift has the potential to significantly improve efficiency and reduce the cost of electricity produced from low grade heat source, such as OTEC and industrial waste heat.