Maoqing Li

Experimental Evaluation of the Regenerative and Basic Organic Rankine Cycles for Low-Grade Heat Source Utilization

AbstractThe present paper conducts the experimental evaluation of the performance of a regenerative organic Rankine cycle (ORC) system working with refrigerant R123 and generating 10-kW-level power. The ORC system consists of an axial-flow single-stage turbine, a regenerator, an evaporator, a condenser, and a pump. The regenerative ORC and the basic ORC system efficiency are evaluated under the same conditions. The degree of superheat of the turbine inlet vapor is controlled by the evaporating temperature. The cooling water flow rate is controlled by adjusting the opening of the valve. The experiment results show that the thermal efficiency of the regenerative ORC is higher than that of the basic ORC by about 25%. The thermal efficiency of basic ORC with saturated vapor at turbine inlet is higher than that with superheated vapor by 3.2%, and the thermal efficiency of the regenerative ORC with saturated vapor at turbine inlet is higher than that with superheated vapor by 4.36%. The enthalpy drop across the...

Experimental Study and Numerical Simulation of a Regenerative ORC Utilizing Low-Grade Heat Source

AbstractIn this paper, the performance of the regenerative organic rankine cycle (ORC) working with R123 is experimentally analyzed at different heat source temperatures of approximately 85, 95, 110, and 130°C. The higher heat source temperature leads to higher turbine inlet temperature, turbine inlet pressure, and turbine rotation speed. The regenerator and the increment of turbine inlet temperature can both increase the efficiency of the system. The experimental data of ORC are compared with that of the conventional Rankine cycle (CRC), which employs water as the working fluid. The results indicate that the thermal efficiency and the turbine isentropic efficiency of the ORC are higher than that of the CRC by approximately 5.9 and 24%, respectively. A numerical model is built by interconnecting different submodels: a turbine model, a volumetric pump model, and the heat exchanger models. The numerical results show a good agreement with the experimental data in terms of system efficiency. The model is fina...

Modeling and Simulation of Micro-Grid System Coupled With Small Wind Turbine

Wind energy has been examined as a clean and economic resource, however, the intermittent and fluctuate feature of which makes it necessary to couple with an energy storage system for compensating the wind energy curtailments. A micro-grid with a compressed air energy storage (CAES) system may help to eliminate the problem resulted from high wind power penetration in the power grid. What is more, it can reduce the network losses. A micro-grid system coupled with small wind turbine presented in this paper. Off-peak power from the wind turbine is used to drive the compressor which serves for the storage vessel. The compressed air supercharges the gas turbine directly when wind energy is not sufficient to guarantee the required load. A dynamic model is built to test the behavior of the system. A statistical model based on stochastic weather data is used to simulate the output of the wind turbine for one day at quarter-hour intervals. An accurate model of CAES includes a compressor, a high pressure vessel and a gas turbine is built in details. A control system is developed to achieve outstanding system’s characteristics like great control performance, stable operation and fast starting. The simulation results show that the CAES can compensate the wind turbine and make the most of wind energy.Copyright