scholarly journals Supercritical Rankine Cycle Coupled with Ground Cooling for Low Temperature Power Generation

2014 ◽  
Vol 57 ◽  
pp. 524-532 ◽  
Author(s):  
Rachana Vidhi ◽  
D. Yogi Goswami ◽  
Elias Stefanakos
Author(s):  
Jixiang Liao ◽  
Qun Zheng

The performances of the transcritical Rankine cycles using R41 and CO2 as working fluids for power generation with lower temperature renewable energy are analyzed respectively and presented in this paper. The results show that the R41 cycle displays better comprehensive performance than that of the CO2 cycle. Compared with the CO2 cycle under the same specified conditions, the average value of the maximum net power output increased by more than 52.6%, the optimum inlet pressure decreased by over 41.6% and the second law efficiency increased by 24.8%. Moreover, the system thermal efficiency of R41 cycle is slightly higher than that of the CO2 cycle.


Author(s):  
Jahar Sarkar ◽  
Souvik Bhattacharyya

This study presents the potential of ammonia as a working fluid in transcritical Rankine cycle for power generation using both high and low temperature heat sources. Higher heat capacity value and superior heat transfer properties of ammonia compared to water are the motivating factors behind its use as a working fluid. A thermodynamic analysis for the ammonia based transcritical Rankine cycle and its comparison with the water based Rankine cycle is presented. Analyses with several cycle modifications are also presented to study the thermal efficiency augmentation. It is observed that an optimum high side pressure exists for near critical operation. In case of low temperature heat sources such as solar energy or waste heat, where water based systems are not suitable, ammonia based Rankine cycle is applicable with attractive thermal efficiency, although cycle modification is not possible. The results with high temperature heat source such as boiler or nuclear reactor, where the turbine outlet is in superheated zone, show that simple ammonia systems yield lower efficiency than water, although a recompression cycle with regenerative heat exchangers exhibits higher efficiency than water. Significant thermal efficiency improvement can be achieved by increasing the high side cycle pressure. Recompression Rankine cycle can be a potential alternative with proper design measures taken to avoid toxicity and flammability.


2011 ◽  
Vol 383-390 ◽  
pp. 6614-6620
Author(s):  
Xin Ling Ma ◽  
Xiang Rui Meng ◽  
Xin Li Wei ◽  
Jia Chang ◽  
Hui Li

This paper presents energy analysis, thermodynamic calculation and exergy analysis for waste heat power generation system of Organic Rankine Cycle based on the first and second laws of thermodynamics. In order to improve system performance, for low-temperature waste heat of 120°C and R245fa organic working fluid, using Aspen Plus software conducted simulation, optimization and improvement. Results from these analyses show that decreasing the expander inlet temperature, increasing inlet pressure of the expander, and adding regenerative heater can increase thermal and exergy efficiencies, at the same time reduce system irreversibility.


Author(s):  
Zemin Bo ◽  
Zhenkun Sang ◽  
Qianqian Zhang ◽  
Yiwu Weng

The radial turbine is a key component of the Organic Rankine Cycle (ORC) power generation system. In order to improve the performance of ORC system for low temperature heat sources, a 150kW radial turbine using R600a has been designed and analyzed. First, the aerodynamic calculation of the radial turbine was conducted and one-dimensional aerodynamic parameters were obtained. Then three-dimensional CFD numerical analysis has been conducted to optimize the geometric design of the radial turbine. The results show the distribution of the flow field around the blades at different height and streamline distribution from leading edge to the trailing edge. At last, the effect of rotation speed on the performance of radial turbine was analyzed. The results can provide basic data for the design of radial turbine of ORC power generation system for low temperature heat sources.


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