Exergy analysis of a combined power cycle using low-grade heat source and LNG cold energy

2015 ◽  
Vol 17 (3) ◽  
pp. 374 ◽  
Author(s):  
Kyung Chun Kim ◽  
Jong Man Ha ◽  
Kyoung Hoon Kim
Keyword(s):  
Heat Source ◽  
Exergy Analysis ◽  
Low Grade ◽  
Power Cycle ◽  
Cold Energy ◽  
Low Grade Heat

Working Fluid and Parametric Optimization of a Two-Stage ORC Utilizing LNG Cold Energy and Low Grade Heat of Different Temperatures

2017 ◽  
Author(s):  
Zhixin Sun ◽  
Shujia Wang ◽  
Fuquan Xu ◽  
Tielong Wang
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Low Grade ◽  
Two Stage ◽  
Cold Energy ◽  
Low Grade Heat

Natural gas is considered as a green fuel due to its low environmental impact. LNG contains a large amount of cold exergy and must be regasified before further utilization. ORC (Organic Rankine Cycle) has been proven to be a promising solution for both low grade heat utilization and LNG cold exergy recovery. Due to the great temperature difference between the heat source and LNG, the efficiency of one-stage ORC is relatively small. Hence, some researchers move forward to a two-stage Rankine cycle. Working fluid plays a quite important role in the cycle performance. Working fluid selection of a two-stage ORC is much more challenging than that of a single-stage ORC. In this paper, a two-stage ORC is studied. Heat source temperatures of 100,150 and 200°C are investigated. 20 substances are selected as potential candidates for both the high and low Rankine cycles. The evaporating, condensing and turbine inlet temperatures of both Rankine cycles are optimized by PSO (Particle Swarm Optimization). The results show that the best combination for heat source temperature of 100°C is R161/R218 with the maximum exergy efficiency of 35.27%. The best combination for 150°C is R161/RC318 with the maximum efficiency of 37.84% and ammonia/ammonia with the maximum efficiency of 39.15% for 200°C. Fluids with intermediate critical temperature, lower triple point temperature and lower normal boiling temperature are good candidates.

scholarly journals The CO2 Transcritical Power Cycle for Low Grade Heat Recovery: Discussion on Temperature Profiles in System Heat Exchangers

2011 ◽  
Author(s):  
Y. Chen ◽  
P. Lundqvist
Keyword(s):  
Carbon Dioxide ◽  
Heat Source ◽  
Temperature Profile ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Low Grade ◽  
Power Cycle ◽  
Low Grade Heat ◽  
Cycle Efficiency ◽  
Better Than

Carbon dioxide transcritical power cycle has many advantages in low-grade heat source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO2’s temperature profile can match the heat source temperature profile better than other pure working fluids and its heat transfer performance is better than the fluid mixtures, which enables a better cycle efficiency. Moreover, the specific heat of supercritical CO2 will have sharp variations in the region close to its critical point, which will create a concave shape temperature profile in the heat exchanger that used for recovering heat from low-grade heat sources. This brings more advantage to carbon dioxide transcritical power systems in low-grade heat recovery. This study discusses the advantage of carbon dioxide power system in low-grade heat source recovery by taking this effect into account. A basic carbon dioxide transcritical power system with an Internal Heat Exchanger (IHX) is employed for the analysis and the system performance is also compared with a basic Organic Rankin Cycle (ORC). Software Engineering Equation Solver (EES) and Refprop 7.0 are used for the cycle efficiency and working fluid properties calculations.

Thermodynamic analysis of a Kalina-based combined cooling and power cycle driven by low-grade heat source

2017 ◽  
Vol 111 ◽  
pp. 8-19 ◽  
Author(s):  
Liyan Cao ◽  
Jiangfeng Wang ◽  
Hongyang Wang ◽  
Pan Zhao ◽  
Yiping Dai
Keyword(s):  
Heat Source ◽  
Thermodynamic Analysis ◽  
Low Grade ◽  
Power Cycle ◽  
Low Grade Heat ◽  
Combined Cooling
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