Second Law Analysis of a Combined Cycle With Integrated Compressor Inlet Air Cooling

2001 ◽  
Author(s):  
A. Razani ◽  
M. Patterson ◽  
K. J. Kim
Keyword(s):  
Combined Cycle ◽  
Second Law ◽  
Air Cooling ◽  
Refrigeration Cycle ◽  
Power Cycle ◽  
System Parameters ◽  
Second Law Analysis ◽  
Compressor Inlet ◽  
Environmental Air ◽  
Topping Cycle

Abstract A gas/ammonia combined cycle is proposed in which exhaust gases from a Brayton gas topping cycle are used to produce superheated ammonia in a Heat Recovery Ammonia Generator (HRAG). To increase the power of the gas turbine in the combined cycle, when the environmental air temperature is high, inlet air to the compressor is cooled in the evaporator of an ammonia refrigeration cycle added to the combined air/ammonia power cycle. In this integrated combined power cycle a small fraction of high-pressure ammonia liquid, from the exit of the ammonia pump, is used in the ammonia refrigeration cycle to cool the air. The second law analysis and optimization of the above combined cycle is presented. The effect of important system parameters on the irreversibility of components in the cycle and the exergy of exhaust streams are evaluated. Reasonable constraints for system components are assumed. The power and efficiency of the cycle are evaluated and their dependences on system parameters are presented.

scholarly journals Dry-Cooled Supercritical CO2 Power for Advanced Nuclear Reactors

2014 ◽  
Author(s):  
T. M. Conboy ◽  
M. D. Carlson ◽  
G. E. Rochau
Keyword(s):  
Power Systems ◽  
Nuclear Energy ◽  
Energy Systems ◽  
Air Cooling ◽  
Brayton Cycle ◽  
Heat Rejection ◽  
Ambient Temperatures ◽  
Power Cycle ◽  
Dry Air ◽  
Compressor Inlet

Currently, waste heat rejection from electrical power systems accounts for the largest fraction of water withdrawals from the US fresh water table. Siting of nuclear power plants is limited to areas with access to a large natural supply of fresh or sea water. Due to a rise in energy needs and increased concern over environmental impact, dry air cooling systems are poised to play a large role in the future energy economy. In practice, the implementation of dry air-cooled condensing systems at steam plants has proven to be capital-intensive and requires the power cycle to take a significant efficiency penalty. These shortcomings are fundamental to dry-air steam condensation, which must occur at a fixed temperature. Closed-cycle gas turbines are an alternative to the conventional steam Rankine plant that allow for much improved dry heat rejection compatibility. Recent research into advanced nuclear energy systems has identified the supercritical CO2 (s-CO2) Brayton cycle in particular as a viable candidate for many proposed reactor types. The s-CO2 Brayton cycle can maintain superior thermal efficiency over a wide range of ambient temperatures, making these power systems ideally suited for dry air cooling, even in warm climates. For an SFR operating at 550°C, thermal efficiency is calculated to be 43% with a 50°C compressor inlet temperature. This is achieved by raising CO2 compressor inlet pressure in response to rising ambient temperatures. Preliminary design studies have shown that s-CO2 power cycle hardware will be compact and therefore well-matched to near-term and advanced integral SMR designs. These advantages also extend to the cooling plant, where it is estimated that dry cooling towers for an SFR-coupled s-CO2 power cycle will be similar in cost and scale to the evaporative cooling tower for an LWR. The projected benefits of the s-CO2 power cycle coupled to dry air heat rejection may enable the long-awaited rise of next-generation nuclear energy systems, while re-drawing the map for siting of small and large nuclear energy systems.

Study on Effects of Compressor Inlet Air Cooling on GTCC System Performance Under Different Environmental Conditions

2020 ◽  
Author(s):  
Duan Liqiang ◽  
Guo Yaofei ◽  
Pan Pan ◽  
Li Yongxia
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Output Power ◽  
Environmental Conditions ◽  
System Performance ◽  
Combined Cycle ◽  
Air Cooling ◽  
Compressor Inlet ◽  
Cooling Technology

Abstract The environmental conditions (air temperature and relative humidity) have a great impact on the power and efficiency of gas turbine combined cycle (GTCC) system. Using the intake air cooling technology can greatly improve the performance of GTCC system. On the base of the PG9351FA gas turbine combined cycle system, this article builds the models of both the GTCC system and a typical lithium bromide absorption refrigeration system using Aspen Plus software. The effects of compressor inlet air cooling with different environmental conditions on the GTCC system performance are studied. The research results show that using the inlet air cooling technology can obviously increase the output powers of both the gas turbine and the combined cycle power. When the ambient humidity is low, the efficiency of GTCC changes gently; while the ambient humidity is high, the GTCC system efficiency will decline substantially when water in the air is condensed and removed with the progress of cooling process. At the same ambient temperature, when the relative humidity of the environment is equal to 20%, the gas turbine output power is increased by 35.64 MW, with an increase of 16.32%, and the combined cycle output power is increased by 39.57 MW, with an increase of 11.34%. At an ambient temperature of 35°C, for every 2.5 °C drop in the compressor inlet air, the thermal efficiency of the gas turbine increases by 0.189% compared to before cooling.

Performance optimization for an open-cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling. Part 1: Thermodynamic modelling

2009 ◽  
Vol 223 (5) ◽  
pp. 505-513 ◽  
Author(s):  
L Chen ◽  
W Zhang ◽  
F Sun
Keyword(s):  
Power Plant ◽  
Pressure Drop ◽  
Power Output ◽  
Working Fluid ◽  
Air Cooling ◽  
Refrigeration Cycle ◽  
Mixing Chamber ◽  
Compressor Inlet ◽  
Gas Turbine Power Plant ◽  
Flow Resistances

A thermodynamic model of an open cycle gas turbine power plant with a refrigeration cycle for compressor inlet air cooling with pressure drop irreversibilities is established using finite-time thermodynamics in Part 1 of this article. The flow processes of the working fluid with the pressure drops of the working fluid and the size constraints of the real power plant are modelled. There are 12 flow resistances encountered by the working fluid stream for the cycle model. Three of these, the friction through the blades, vanes of the compressor, and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in the flow cross-section at the mixing chamber inlet and outlet, the compressor inlet and outlet, the combustion chamber inlet and outlet, the heat exchanger inlet and outlet, and the turbine inlet and outlet. These resistances associated with the flow through various cross-sectional areas are derived as functions of the mixing chamber inlet relative pressure drop, and they control the air flowrate and the net power output. The analytical formulae about the power output, efficiency, and other coefficients are derived with the 12 pressure drop losses. The numerical examples show that the dimensionless power output reaches its maximum at the optimal value and that the dimensionless power output and the thermal efficiency reach their maximum values at the optimal values of the compressor fore-stages pressure ratio of the inverse Brayton cycle.

Analysis of a Combined Power and Refrigeration Cycle Working on Solar Energy

2008 ◽  
Author(s):  
Bijan Kumar Mandal ◽  
Kousik Sadhukhan ◽  
Achin Kumar Chowdhuri ◽  
Arup Jyoti Bhowal
Keyword(s):  
Solar Energy ◽  
Working Conditions ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Cooling Effect ◽  
Second Law ◽  
Carnot Cycle ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
The Ideal

Thermodynamic analysis of a combined cycle producing power and refrigeration (cooling) effect simultaneously using solar energy has been analyzed. The working substance of the cycle is a binary mixture of ammonia and water. The effect of variation of absorber pressure, boiler pressure, boiler temperature and superheater temperature on the turbine work, refrigeration (cooling) effect and net output has been investigated. For different conditions of the above variables, the first law efficiency, the second law efficiency and the exergy efficiency of the cycle have been investigated. Since the ammonia water mixture boils at varying temperatures, Lorenz cycle instead of Carnot cycle is considered as the ideal cycle for this analysis. It is observed that the first law and the second law efficiencies are maximum under the same working conditions, but the exergy efficiency is maximum at some other working conditions. The maximum values of the first law, the second law and the exergy efficiencies are found to be 21.72%, 27.30% and 62.53% respectively.

Effects of Intake Air Cooling Performance Improvement on a Two-Shaft Laboratory-Scale Gas Turbine Unit

2007 ◽  
Author(s):  
Hussain Al-Madani ◽  
Teoman Ayhan ◽  
Omar Al-Abbasi
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Thermal Efficiency ◽  
Performance Test ◽  
Second Law ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Proposed Model ◽  
Compressor Inlet

The present study deals with the thermodynamically modelled two-shaft gas turbine system consisting of a cooling unit at the compressor inlet. The system is used to investigate the generated power, thermal efficiency and second law efficiency. The parametric study using this model shows effect of ambient conditions, compressor inlet temperature, and pressure ratios on power output, thermal efficiency and second law efficiency. Theoretical results using the proposed model show that when the compressor inlet temperature is decreased by some kind of cooling systems, the net power output and thermal efficiency increases up to 30% and 23%, respectively. Also, the second law efficiency of the proposed system increases in compression to the specified reference state. It shows that the proposed model is thermodynamically viable. A comparison of the performance test results of the model and the experimental results are in good agreement. The results provide valuable information regarding the gas turbine system and will be useful for designers.

On Evaluating Efficiency of a Combined Power and Cooling Cycle

2003 ◽  
Vol 125 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Sanjay Vijayaraghavan ◽  
D. Y. Goswami
Keyword(s):  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Second Law ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Cooling Cycle ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient

A combined power and cooling cycle is being investigated. The cycle is a combination of the Rankine cycle and an absorption refrigeration cycle. Evaluating the efficiency of this cycle is made difficult by the fact that there are two different simultaneous outputs, namely power and refrigeration. An efficiency expression has to appropriately weigh the cooling component in order to allow comparison of this cycle with other cycles. This paper develops several expressions for the first law, second law and exergy efficiency definitions for the combined cycle based on existing definitions in the literature. Some of the developed equations have been recommended for use over others, depending on the comparison being made. Finally, some of these definitions have been applied to the cycle and the performance of the cycle optimized for maximum efficiency. A Generalized Reduced Gradient (GRG) method was used to perform the optimization. The results of these optimizations are presented and discussed.

Economic Analysis on the Combined Power/ Refrigerating Cycle for Power Plant Air Cooling System

2012 ◽  
Vol 433-440 ◽  
pp. 7436-7442 ◽  
Author(s):  
Li Jun Chen ◽  
Li Jun Mi ◽  
Chao Xu ◽  
Shan Rang Yang
Keyword(s):  
Economic Analysis ◽  
Energy Saving ◽  
Emission Reduction ◽  
Cooling System ◽  
Combined Cycle ◽  
Air Cooling ◽  
Analog Computation ◽  
Power Cycle ◽  
Air Cooling System ◽  
New Situation

At present, the development of power industry is facing the pressure of energy saving and emission reduction. This paper reviewed briefly the strategy for development in optimizing power cycle and improving comprehensive utilization of heat energy. A economic analysis was made to the combined power cycle/refrigerating cycle air cooling system (hereinafter called ‘combined cycle air cooling system’ or ‘CCACS’) which presented previously and estimated its contribution to energy saving and emission reduction in this paper. An analog computation example shows that the combined cycle air cooling system based on the compression refrigeration is feasible and effective. Finally this paper pointed out that the air-cooling system is facing the re-selection under the new situation, the indirect air-cooling system will be of importance to the development, and the combined cycle air cooling system will become a kind of new options.

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