scholarly journals Performances of Transcritical Power Cycles with CO2-Based Mixtures for the Waste Heat Recovery of ICE

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1551
Author(s):  
Jinghang Liu ◽  
Aofang Yu ◽  
Xinxing Lin ◽  
Wen Su ◽  
Shaoduan Ou
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cycle Performance ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Power Cycles ◽  
Split Ratio ◽  
Turbine Inlet ◽  
Organic Fluids

In the waste heat recovery of the internal combustion engine (ICE), the transcritical CO2 power cycle still faces the high operation pressure and difficulty in condensation. To overcome these challenges, CO2 is mixed with organic fluids to form zeotropic mixtures. Thus, in this work, five organic fluids, namely R290, R600a, R600, R601a, and R601, are mixed with CO2. Mixture performance in the waste heat recovery of ICE is evaluated, based on two transcritical power cycles, namely the recuperative cycle and split cycle. The results show that the split cycle always has better performance than the recuperative cycle. Under design conditions, CO2/R290(0.3/0.7) has the best performance in the split cycle. The corresponding net work and cycle efficiency are respectively 21.05 kW and 20.44%. Furthermore, effects of key parameters such as turbine inlet temperature, turbine inlet pressure, and split ratio on the cycle performance are studied. With the increase of turbine inlet temperature, the net works of the recuperative cycle and split cycle firstly increase and then decrease. There exist peak values of net work in both cycles. Meanwhile, the net work of the split cycle firstly increases and then decreases with the increase of the split ratio. Thereafter, with the target of maximizing net work, these key parameters are optimized at different mass fractions of CO2. The optimization results show that CO2/R600 obtains the highest net work of 27.43 kW at the CO2 mass fraction 0.9 in the split cycle.

scholarly journals Parametric Investigation and Thermoeconomic Optimization of a Combined Cycle for Recovering the Waste Heat from Nuclear Closed Brayton Cycle

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Lihuang Luo ◽  
Hong Gao ◽  
Chao Liu ◽  
Xiaoxiao Xu
Keyword(s):  
Mass Fraction ◽  
Waste Heat ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet ◽  
Overall Efficiency ◽  
Economic Analyses

A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The combined cycle performance is also optimized based on a multiobjective function. Compared with the closed Brayton cycle, the optimized power output and overall efficiency of the combined cycle are higher by 2.41% and 2.43%, respectively. The optimized LEC of the combined cycle is 0.73% lower than that of the closed Brayton cycle.

Performance of N2O4 Gas Cycles for Solar Power Applications

1979 ◽  
Vol 193 (1) ◽  
pp. 313-320 ◽  
Author(s):  
G. Angelino
Keyword(s):  
Waste Heat ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Power Cycles ◽  
Average Temperature ◽  
Power Stations ◽  
Turbine Inlet ◽  
Compressor Inlet ◽  
Cycle Efficiency

The use of N2O4 as the working fluid in gas turbine power cycles is recognized as a potential instrument for improving cycle efficiency at moderate top temperatures while maintaining the technical advantages connected with the waste heat rejection at a comparatively high average temperature. Solar central receiver power stations, whose economic effectiveness is very sensitive to cycle efficiency and which must often reject their waste heat into the atmosphere, could usefully adopt this fluid. The thermodynamic reasons which explain the peculiar behaviour of N2O4 as the Brayton cycle working fluid are discussed. With respect to inert gas cycles, N2O4 permits, for a given efficiency, a reduction in turbine inlet temperature by 200-250°C. At a given turbine inlet temperature, the dissociating character of N2O4 allows overall efficiencies similar to those of steam cycles (at least for moderate plant capacities and provided N2O4 and steam cycles reject their waste heat at comparable temperatures). The relatively long relaxation time of the second step of the N2O4 dissociation can represent a problem mainly for the regenerator. A cycle is presented where regeneration at a pressure higher than the compressor inlet pressure can alleviate this problem.

Feasibility Study of a Supercritical Cycle as a Waste Heat Recovery System

2013 ◽  
Author(s):  
Antonio Agresta ◽  
Antonella Ingenito ◽  
Roberto Andriani ◽  
Fausto Gamma
Keyword(s):  
Power Systems ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Power Plants ◽  
Energy Savings ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Organic Fluids

Following the increasing interest of aero-naval industry to design and build systems that might provide fuel and energy savings, this study wants to point out the possibility to produce an increase in the power output from the prime mover propulsion systems of aircrafts. The complexity of using steam heat recovery systems, as well as the lower expected cycle efficiencies, temperature limitations, toxicity, material compatibilities, and/or costs of organic fluids in Rankine cycle power systems, precludes their consideration as a solution to power improvement for this application in turboprop engines. The power improvement system must also comply with the space constraints inherent with onboard power plants, as well as the interest to be economical with respect to the cost of the power recovery system compared to the fuel that can be saved per flight exercise. A waste heat recovery application of the CO2 supercritical cycle will culminate in the sizing of the major components.

scholarly journals Performance Comparison of Advanced Transcritical Power Cycles with High-Temperature Working Fluids for the Engine Waste Heat Recovery

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5886
Author(s):  
Xinxing Lin ◽  
Chonghui Chen ◽  
Aofang Yu ◽  
Likun Yin ◽  
Wen Su
Keyword(s):  
High Temperature ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Performance Comparison ◽  
Design System ◽  
Working Fluids ◽  
Power Cycles ◽  
System Parameters ◽  
Pressure Cycle

To efficiently recover the waste heat of mobile engine, two advanced transcritical power cycles, namely split cycle and dual pressure cycle, are employed, based on the recuperative cycle. Performances of the two cycles are analyzed and compared through the development of thermodynamic models. Under given gas conditions, seven high-temperature working fluids, namely propane, butane, isobutane, pentane, isopentane, neopentane, and cyclopentane, are selected for the two cycles. At the design system parameters, the highest work 48.71 kW, is obtained by the split cycle with butane. For most of fluids, the split cycle has a higher work than the dual pressure cycle. Furthermore, with the increase of turbine inlet pressure, net work of the split cycle goes up firstly and then decreases, while the work of dual pressure cycle increases slowly. For the split cycle, there exists a split ratio to get the maximum network. However, for the dual pressure cycle, the larger the evaporation temperature, the higher the net work. On this basis, system parameters are optimized by genetic algorithm to maximize net work. The results indicate that the highest work 49.96 kW of split cycle is obtained by pentane. For the considered fluids, except cyclopentane, split cycle always has a higher work than dual pressure cycle. Due to the higher net work and fewer system components, split cycle is recommended for the engine waste heat recovery.

Effects of Steam Injection on the Performance of Gas Turbine Power Cycles

1979 ◽  
Vol 101 (2) ◽  
pp. 217-227 ◽  
Author(s):  
W. E. Fraize ◽  
C. Kinney
Keyword(s):  
Gas Turbine ◽  
Waste Heat ◽  
Steam Injection ◽  
Combined Cycle ◽  
Thermodynamic Efficiency ◽  
Inlet Temperature ◽  
Exhaust Gas ◽  
Turbine Inlet Temperature ◽  
Power Cycles ◽  
Determine Effect

The effect of injecting steam generated by exhaust gas waste heat into a gas turbine with 3060°R turbine inlet temperature has been analyzed. Two alternate steam injection cycles are compared with a combined cycle using a conventional steam bottoming cycle. A range of compression ratios (8, 12, 16, and 20) and water mass injection ratios (0 to 0.4) were analyzed to determine effect on net turbine power output per pound of air and cycle thermodynamic efficiency. A water/fuel cost tradeoff analysis is also provided. The results indicate promising performance and economic advantages of steam injected cycles relative to more conventional utility power cycles. Application to coal-fired configuration is briefly discussed.

Low grade waste heat recovery using heat pumps and power cycles

Energy ◽  
2015 ◽  
Vol 89 ◽  
pp. 864-873 ◽  
Author(s):  
D.M. van de Bor ◽  
C.A. Infante Ferreira ◽  
Anton A. Kiss
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pumps ◽  
Low Grade ◽  
Power Cycles

Evaluation of Design Performance of the Semi-Closed Oxy-Fuel Combustion Combined Cycle

2012 ◽  
Author(s):  
H. J. Yang ◽  
D. W. Kang ◽  
J. H. Ahn ◽  
T. S. Kim
Keyword(s):  
Co2 Capture ◽  
Gas Turbines ◽  
Fuel Combustion ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Design Parameters ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Separation Unit ◽  
Turbine Inlet

This study aims to present various design aspects and realizable performance of the natural gas fired semi-closed oxy-fuel combustion combined cycle (SCOC-CC). Design parameters of the cycle are set up on the basis of component technologies of today’s state-of-the-art gas turbines with a turbine inlet temperature between 1400°C and 1600°C. The most important part in the cycle analysis is the turbine cooling which affects the cycle performance considerably. A thermodynamic cooling model is introduced to predict the reasonable amount of turbine coolant to maintain the turbine blade temperature of the SCOC-CC at the levels of those of conventional gas turbines. Optimal pressure ratio ranges of the SCOC-CC for two different turbine inlet temperature levels are searched. The performance penalty due to the CO2 capture is examined. Also investigated are the influences of the purity of oxygen provided by the air separation unit on the cycle performance. A comparison with the conventional combined cycle adopting a post-combustion CO2 capture is carried out taking into account the relationship between performance and CO2 capture rate.

Sign in / Sign up

Export Citation Format

Share Document