Thermodynamic Cycles

2017 ◽  
pp. 45-58
Author(s):  
Bahman Zohuri ◽  
Patrick McDaniel
Keyword(s):  
Thermodynamic Cycles

On Thermodynamic Cycles for Detonation Engines

2012 ◽  
pp. 287-292 ◽  
Author(s):  
R. Vutthivithayarak ◽  
E. M. Braun ◽  
F. K. Lu
Keyword(s):  
Thermodynamic Cycles

Recuperators in Gas Turbine Systems

1998 ◽  
Author(s):  
Esa Utriainen ◽  
Bengt Sundén
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Cross Sections ◽  
Heat Exchangers ◽  
Power Plants ◽  
Pressure Ratio ◽  
Compact Heat Exchangers ◽  
Thermodynamic Cycles ◽  
Large Pressure ◽  
Gas Turbine Cycle

The application of recuperators in advanced thermodynamic cycles is growing due to stronger demands of low emissions of pollutants and the necessity of improving the cycle efficiency of power plants to reduce the fuel consumption. This paper covers applications and types of heat exchangers used in gas turbine units. The trends of research and development are brought up and the future need for research and development is discussed. Material aspects are covered to some extent. Attempts to achieve compact heat exchangers for these applications are also discussed. With the increasing pressure ratio in the gas turbine cycle, large pressure differences between the hot and cold sides exist. This has to be accounted for. The applicability of CFD (Computational Fluid Dynamics) is discussed and a CFD–approach is presented for a specific recuperator. This recuperator has narrow wavy ducts with complex cross-sections and the hydraulic diameter is so small that laminar flow prevails. The thermal-hydraulic performance is of major concern.

H2/O2 Cycles: Thermodynamic Potentialities and Limits

2003 ◽  
Author(s):  
M. Gambini ◽  
G. L. Guizzi ◽  
M. Vellini
Keyword(s):  
Production Systems ◽  
Renewable Energy Sources ◽  
H2 Production ◽  
Thermodynamic Cycles ◽  
A Value ◽  
Overall Performance ◽  
Definition Of ◽  
Working Parameters ◽  
O2 Production

In this paper, the thermodynamic potentialities and limits of the H2/O2 cycles are investigated. Starting from the conventional gas turbine and steam turbine technology, the paper qualitatively tackles problems related to a change of oxidizer and fuel: from these considerations, an internal combustion steam cycle (ICSC) is analyzed where steam, injected in the combustion chamber together with oxygen and hydrogen, is produced in a regenerative way and plays the important role of inert. A proper parametric analysis is then performed in order to evaluate the influence of the main working parameters on the overall performance of H2/O2 cycles. All the results are carried out neglecting the energy requirements for O2 and H2 production systems, but taking into account their work compression only. This choice permits great freedom in the definition of these thermodynamic cycles and allows general considerations because there is no need of any specification about H2 and/or O2 production systems and their integration with thermodynamic cycles. Therefore this paper can be framed in a context of oxygen and hydrogen centralized production (by nuclear or renewable energy sources for example) and in their distribution as pure gases in the utilization place. Adopting realistic assumptions, TIT of about 1350°C, the potentialities of H2/O2 cycles are very limited: the net efficiency attains a value of about 50%. Instead, adopting futurist assumptions, TIT = I700°C, a different H2/O2 cycle scheme can be proposed and more interesting performance is attained (a net efficiency value over 60%). The thermodynamic and technological aspects are completely addressed in the paper, underlining the great importance of the choice of the main working parameters.

Using Excel for the Thermodynamic Analysis of Air-Standard Cycles and Combustion Processes

2009 ◽  
Author(s):  
Amir Karimi
Keyword(s):  
Engineering Students ◽  
Solution Process ◽  
Ideal Gas ◽  
Power Cycles ◽  
Thermodynamic Cycles ◽  
Specific Heats ◽  
Property Evaluation ◽  
Difficult Time ◽  
Parametric Studies ◽  
Combustion Processes

In an undergraduate course or a course-sequence in thermodynamics mechanical engineering students are introduced to air-standard power cycles, refrigeration cycles, and the fundamentals of combustion processes. The analysis of air-standard thermodynamic cycles or solving problems involving combustion processes requires the evaluation of thermodynamic properties either from ideal gas tables or equations developed based on the assumption of constant specific heats. Many students have a difficult time to distinguish the differences between the two property evaluation methods. Also, solving problems involving power and refrigeration cycles or parametric studies of combustion processes involve several steps of property evaluation and some steps require interpolation of data listed in the thermodynamic property tables. Also solution to problems requiring trial and error iterative procedure makes the solution process tedious and time consuming, if it is done manually. This paper provides several examples to demonstrate the effectiveness of Excel in solving problems involving air-standard cycles and combustion processes.

scholarly journals Influence of evaporating rate on two-phase expansion in the piston expander with cyclone separator

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2077-2088 ◽  
Author(s):  
Weifeng Wu ◽  
Qi Wang ◽  
Zhao Zhang ◽  
Zhijun Wu ◽  
Xiaotian Yang ◽  
...  
Keyword(s):  
Low Grade ◽  
Cyclone Separator ◽  
Expansion Process ◽  
Two Phase ◽  
Kalina Cycle ◽  
Thermodynamic Cycles ◽  
Heat Utilization ◽  
Inlet Stream ◽  
Organic Rankine Cycles ◽  
Low Grade Heat

The trilateral flash cycle shows a greater potentiality in moderate to low grade heat utilization systems due to its potentiality of obtaining high exergy efficiency, compared to the conventional thermodynamic cycles such as the organic Rankine cycles and the Kalina cycle. The main difference between the trilateral flash cycle and the conventional thermodynamic cycles is that the superheated vapor expansion process is replaced by the two-phase expansion process. The two-phase expansion process actually consists of a flashing of the inlet stream into a vapor and a liquid phase. Most simulations assume an equilibrium model with an instantaneous flashing. Yet, the experiments of pool flashing indicate that there is a flash evaporating rate. The mechanism of this process still remains unclear. In this paper, the flash evaporating rate is introduced into the model of the two-phase expansion process in the reciprocating expander with a cyclone separator. As such, the obtained results reveal the influence of evaporating rate on the efficiency of the two-phase expander.

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