Second law analysis of a natural gas-fired gas turbine cogeneration system

2009 ◽  
Vol 33 (8) ◽  
pp. 728-736 ◽  
Author(s):  
B. V. Reddy ◽  
Cliff Butcher
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Second Law ◽  
Second Law Analysis ◽  
Cogeneration System

Performance Evaluation of Selected Combustion Gas Turbine Cogeneration Systems Based on First and Second-Law Analysis

1990 ◽  
Vol 112 (1) ◽  
pp. 117-121 ◽  
Author(s):  
F. F. Huang
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Decision Makers ◽  
Utilization Efficiency ◽  
Second Law ◽  
Pinch Point ◽  
Combustion Gas ◽  
Second Law Analysis ◽  
Industrial Gas Turbines

The thermodynamic performance of selected combustion gas turbine cogeneration systems has been studied based on first-law as well as second-law analysis. The effects of the pinch point used in the design of the heat recovery steam generator, and pressure of process steam on fuel-utilization efficiency (first-law efficiency), power-to-heat ratio, and second-law efficiency, are examined. Results for three systems using state-of-the-art industrial gas turbines show clearly that performance evaluation based on first-law efficiency alone is inadequate. Decision makers should find the methodology contained in this paper useful in the comparison and selection of cogeneration systems.

A Simplified Method to Predict Energy Cost Savings in Office Buildings Using a Hybrid Desiccant, Absorption Chiller, and Natural Gas Turbine Cogeneration System With Thermal Storage

2007 ◽  
Author(s):  
James McNeill ◽  
Jon Previtali ◽  
Moncef Krarti
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Energy Cost ◽  
Cost Savings ◽  
Thermal Storage ◽  
Analysis Tool ◽  
Conventional System ◽  
Absorption Chiller ◽  
Cogeneration System ◽  
Simplified Analysis

This paper provides a simplified analysis tool to predict the energy savings associated with the usage of a hybrid air conditioning system that combines liquid desiccant, absorption chiller, natural gas turbine cogeneration system with thermal storage (hereafter hybrid cogeneration system) versus a watercooled centrifugal chiller with a natural gas boiler (hereafter conventional system). The hybrid cogeneration system is controlled to track both electrical and thermal loads. The simplified analysis method is formulated from detailed energy simulation models. A direct correlation has been determined between the energy cost savings of using the hybrid cogeneration system instead of the conventional system and the cogeneration capacity, peak electricity rate, and natural gas rate for five U.S. cities: Atlanta, Chicago, Denver, New York, and San Francisco.

“Lost Available IMEP”: A Second-Law-Based Performance Parameter for IC Engines

2016 ◽  
Author(s):  
H. Mahabadipour ◽  
K. K. Srinivasan ◽  
S. R. Krishnan
Keyword(s):  
Natural Gas ◽  
Performance Parameter ◽  
Second Law ◽  
Dual Fuel ◽  
Effective Pressure ◽  
Closed Cycle ◽  
Indicated Mean Effective Pressure ◽  
Second Law Analysis ◽  
Ic Engines ◽  
Engine Size

The second law of thermodynamics is a powerful tool for investigating thermodynamic irreversibilities and to identify pathways for improving efficiencies of energy systems, including IC engines. In the present work, second law analysis is applied to quantify irreversibilities in diesel-ignited natural gas dual fuel low temperature combustion (LTC), which utilizes diesel to ignite natural gas to simultaneously reduce emissions of oxides of nitrogen and particulate matter. A previously validated multi zone thermodynamic model of dual fuel LTC was used as the basic framework to perform the second law analysis. The multi-zone model, which simulates closed cycle processes between intake valve closure (IVC) and exhaust valve opening (EVO), divides the cylinder contents into four main zones: (i) an unburned zone containing a premixed natural gas-air mixture, (ii) a pilot fuel zone (or “packets”) containing diesel vapor and entrained natural gas-air mixture, (iii) a flame zone, and (iv) a burned zone. By applying the second law systematically to each zone, the total entropy generated over the closed cycle (Sgen) and the lost available work (Wlost = T0*Sgen) were quantified. Subsequently, the lost available work was divided by the displaced volume to calculate a new engine performance parameter labeled “lost available indicated mean effective pressure” (LAIMEP). Proceeding analogously from the definition of indicated mean effective pressure (IMEP) as an engine-size-normalized measure of indicated work, the LAIMEP may be interpreted as an engine-size-normalized measure of available work that is lost due to thermodynamic irreversibilities. Since LAIMEP is independent of engine size, it can be used to compare thermodynamic irreversibilities between engines of various displaced volumes as well as between different engine combustion strategies. Two additional second-law-based parameters: fuel conversion irreversibility (FCI) as the ratio of Wlost to total fuel chemical energy input and normalized LAIMEP as the ratio of LAIMEP to IMEP, were also defined. Parametric studies were performed at different diesel injection timings (SOI ∼ 300–340 CAD), intake temperatures (Tin ∼ 50°–150°C), and intake boost pressures (Pin ∼ 1–2.4 bar) to characterize their impact on LAIMEP and FCI. It was determined that both LAIMEP and FCI increased with SOI advancement (from 340 to 300 CAD) and decreased with increasing Tin and Pin. These trends were explained using predicted combustion parameters, especially burned mass fraction and average in-cylinder temperature at EVO. While the present work focused on diesel-natural gas dual fuel LTC (as an example), the overall methodology adopted for the second law analysis as well as the conceptual definitions of LAIMEP, FCI, etc., are generally applicable to any IC engine operating on any combustion strategy (e.g., SI, CI, LTC, etc.).

A Decomposition Strategy for Thermoeconomic Optimization

1989 ◽  
Vol 111 (3) ◽  
pp. 111-120 ◽  
Author(s):  
Y. M. El-Sayed
Keyword(s):  
Objective Function ◽  
Gas Turbine ◽  
Point Of View ◽  
Thermal Design ◽  
Second Law ◽  
System Configuration ◽  
Power Cycle ◽  
Design Variables ◽  
Second Law Analysis ◽  
Optimal Values

An optimal thermal design of a considered system configuration is conveniently decided when the system is modeled as made up of one thermodynamic subsystem and of the essential number of design subsystems. The thermodynamic subsystem decides the performance of the components and the design subsystems decide their best matching geometry and costs. An optimizer directs all decisions to an extremum of a given objective function. This decomposition strategy is illustrated by investigating the optimal values of seven decision design variables for a regenerative gas turbine power cycle when a cost-objective function is minimized. The results seen from the point of view of second law analysis and costing are discussed.

Energy and Exergy Analyses of a Natural Gas Fired Combined Cycle Cogeneration System

2007 ◽  
Author(s):  
B. Law ◽  
B. V. Reddy
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Operating Variables ◽  
Energy And Exergy ◽  
Cogeneration System ◽  
Multiple Process ◽  
Process Heat

Combined cycle cogeneration systems have the ability to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. In the present work the performance of a natural gas fired combined cycle cogeneration unit with multiple process heaters is investigated to study the effect of operating variables on the performance. The operating conditions investigated include, gas turbine pressure ratio, process heat loads and process steam extraction pressure. The gas turbine pressure ratio significantly influences the performance of the combined cycle cogeneration system. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. The exergy analysis is conducted to identify the exergy destruction and losses in different components of the combined cycle cogeneration unit.

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