A New Heat Engine and its Applications in Concentrating Solar Power (CSP)

2012 ◽  
Author(s):  
Yiding Cao
Keyword(s):  
Heat Source ◽  
Internal Combustion Engines ◽  
Solar Power ◽  
Combustion Engine ◽  
Heat Engine ◽  
Working Fluid ◽  
Concentrating Solar Power ◽  
Time Duration ◽  
Combustion Gas ◽  
External Combustion

This paper introduces a new heat engine using a gas, such as air or nitrogen, as the working fluid that extracts thermal energy from a heat source as the energy input. The heat engine is to mimic the performance of an air-standard Otto cycle. This is achieved by drastically increasing the time duration of heat acquisition from the heat source in conjunction with the timing of the heat acquisition and a large heat transfer surface area. Performance simulations show that the new heat engine can potentially attain a thermal efficiency above 50% and a power output above 100 kW under open-cycle operation. Additionally, it could drastically reduce engine costs and operate in open cycles, effectively removing the difficulties of dry cooling requirement. The new heat engine may find extensive applications in renewable energy industries, such as concentrating solar power and geothermal energy power. Furthermore, the heat engine may be employed to recover energy from exhaust streams of internal combustion engines, gas turbine engines, and various industrial processes. It may also work as a thermal-to-mechanical conversion system in a nuclear power plant, and function as an external combustion engine in which the heat source is the combustion gas from an external combustion chamber.

Development of Scaling Model for a MEMS-Based Micro Heat Engine

2010 ◽  
Author(s):  
H. Bardaweel ◽  
B. S. Preetham ◽  
R. Richards ◽  
C. Richards ◽  
M. Anderson
Keyword(s):  
Combustion Engine ◽  
Heat Engine ◽  
Working Fluid ◽  
Thin Membranes ◽  
Micro Heat Engine ◽  
Heat Of Evaporation ◽  
Major Factors ◽  
Engine Components ◽  
External Combustion ◽  
Thermal Physical Properties

In this work we investigate issues related to scaling of a MEMS-based resonant heat engine. The engine is an external combustion engine made of a cavity encapsulated between two thin membranes. The cavity is filled with saturated liquid-vapor mixture working fluid. We use both model and experiment to investigate scaling of the MEMS-based resonant heat engine. The results suggest that the performance of the engine is determined by three major factors: geometry of the engine, speed of operation, and thermal physical properties of engine components. Larger engine volumes, working fluids with higher latent heat of evaporation, slower engine speeds, and compliant expander structures are shown to be desirable.

A Study of Supercritical Carbon Dioxide Power Cycle for Concentrating Solar Power Applications Using an Isothermal Compressor

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Jin Young Heo ◽  
Jinsu Kwon ◽  
Jeong Ik Lee
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Thermal Efficiency ◽  
Solar Power ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Power Cycle ◽  
Compressor Inlet ◽  
Supercritical Carbon

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including high cycle efficiencies, reduced component sizing, and potential for the dry cooling option. More research is involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems for CSP applications. In this study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced, up to 50%, compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the simple recuperated and recompression Brayton cycle layouts using s-CO2 as a working fluid are evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the recompression Brayton cycle using an isothermal compressor has 0.2–1.0% point higher cycle thermal efficiency compared to its reference cycle. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency for a wider range of CIT than the reference cycle. Adopting an isothermal compressor in the s-CO2 layout can imply larger heat exchange area for the compressor which requires further development.

Rubber Heat Engines, Analyses and Theory

1979 ◽  
Vol 52 (1) ◽  
pp. 159-172 ◽  
Author(s):  
R. J. Farris
Keyword(s):  
Heat Source ◽  
Atmospheric Pressure ◽  
Heat Engine ◽  
Working Fluid ◽  
Thermodynamic Behavior ◽  
The Past ◽  
Heat Engines ◽  
Pressure Steam ◽  
The Subject ◽  
Power Densities

Abstract It has long been known that elastomeric solids could be used as the working “fluid” in engines designed to convert heat into mechanical work. In the past rubber heat engine cycles were not given serious consideration since energy alternatives were not in demand and the majority of the scientific community is unaware of their gas-like thermodynamic behavior. Consequently, past work has dealt with the subject primarily as a novelty or as a demonstrative proof of thermodynamic behavior. This paper provides an idealized mechanical and thermodynamic analysis of the rubber cycle and compares it to an equivalent cycle wherein a gas is the working fluid. Experimental data on a small rubber fiber engine are included which confirms the high power potential of these engines when they are designed using modern elastomeric fibers. These materials have remarkable properties and can respond rapidly to cyclic thermal disturbances. Power densities of roughly one watt/g of rubber have been attained using only a 30°C difference between the heat source and heat sink. Engine speeds well over 1000 rpm have also been attained when atmospheric pressure steam was used as the heat source. The analyses demonstrate that elastomers are ideally suited for energy conversion when only small temperature differences are available.

Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Saeb M. Besarati ◽  
D. Yogi Goswami
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Solar Power ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Working Fluids ◽  
Supercritical Carbon

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose; however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.

scholarly journals OPTIMIZATION OF MECHANICAL STRENGTH OF ROTARY-VANE ENGINE

2017 ◽  
Vol 3 ◽  
pp. 357
Author(s):  
Yury Zhuravlev ◽  
Andrey Perminov ◽  
Yury Lukyanov ◽  
Sergey Tikhonov ◽  
Alexander Ilyin ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Heat Engine ◽  
Fluid Pressure ◽  
Internal Combustion ◽  
Working Fluid ◽  
Drive Torque ◽  
Cam Mechanism ◽  
Inertial Moment ◽  
Engine Components ◽  
External Combustion

The article discusses a rotory-vane heat engine with a lever-cam mechanism motion conversion (an engine may be an internal combustion or external combustion). The output shaft of the engine adds drive torque from the working fluid pressure forces acting on the blade and the inertial moment of the forces of inertia of engine components. The mechanical strength of the motor is dependent on the magnitude and phase of these two torque. The purpose of the article is to determine the conditions under which mechanical strength is minimized.

Applying Thermodynamics in Search of Superior Engine Efficiency

2005 ◽  
Vol 127 (3) ◽  
pp. 670-675 ◽  
Author(s):  
Charles A. Amann
Keyword(s):  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Heat Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Closed Cycle ◽  
Engine Efficiency ◽  
Operating Cycles ◽  
Thermodynamic Processes

Historically, a succession of thermodynamic processes has been used to idealize the operating cycles of internal combustion engines. In this study, the 256 possible combinations of four reversible processes—isentropic, isothermal, isochoric, and isobaric—are surveyed in search of cycles promising superior thermal efficiency. Regenerative cycles are excluded. The established concept of the air-standard cycle, which mimics the internal combustion engine as a closed-cycle heat engine, is used to narrow the field systematically. The approach relies primarily on graphical interpretation of approximate temperature-entropy diagrams and is qualitative only. In addition to identifying the cycles offering the greatest efficiency potential, the compromise between thermal efficiency and mean effective pressure is addressed.

Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications

2013 ◽  
Author(s):  
Saeb M. Besarati ◽  
D. Yogi Goswami
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Solar Power ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Working Fluids ◽  
Supercritical Carbon

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose, however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.

scholarly journals Analysis of a second order thermodynamic model for the performance analysis of a Stirling engine prototype

2018 ◽  
Author(s):  
Miguel Torres García ◽  
Elisa Carvajal Trujillo ◽  
José Antonio Vélez Godiño ◽  
David Sánchez Martínez
Keyword(s):  
High Efficiency ◽  
Combustion Engine ◽  
Numerical Models ◽  
Operational Reliability ◽  
Stirling Engine ◽  
Working Fluid ◽  
Simple Type ◽  
Engine Model ◽  
External Combustion ◽  
External Combustion Engine

The Stirling engine is a simple type of external-combustion engine with an external combustion engine based on cyclic compression and expansion of gas at different temperature levels. It has high efficiency; low vibration levels, simple structure and can run on any combustible fuels. It has been the object of numerous studies. This paper presents an analysis of a Stirling engine model GENOA 03 for electric power generation, of 3 KW of nominal power with pressurized air as working fluid, currently under development. To improve its performance and ensure a good operational reliability, it is necessary to carry out a modelling of the engine in all its operating range. This requires complex numerical models that simulate the behaviour of any element of the engine in a cycle. Two typologies of thermodynamic models are developed in this work: isothermal and adiabatic. The main benefits and shortcomings of each model are mentioned. The geometry and conditions of the engine have been adapted through the Matlab ® tool, in order to obtain the operative conditions of the cooler that you want to replace, as well as an approximation to the expected behaviour.

scholarly journals Maximum work output of multistage continuous Carnot heat engine system with finite reservoirs of thermal capacity and radiation between heat source and working fluid

2010 ◽  
Vol 14 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jun Li ◽  
Lingen Chen ◽  
Fengrui Sun
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Heat Sink ◽  
Heat Engine ◽  
Thermal Capacity ◽  
Working Fluid ◽  
Work Output ◽  
Maximum Work ◽  
Engine System ◽  
Maximum Work Output

Optimal temperature profile for maximum work output of multistage continuous Carnot heat engine system with two reservoirs of finite thermal capacity is determined. The heat transfer between heat source and the working fluid obeys radiation law and the heat transfer between heat sink and the working fluid obeys linear law. The solution is obtained by using optimal control theory and pseudo-Newtonian heat transfer model. It is shown that the temperature of driven fluid monotonically decreases with respect to flow velocity and process duration. The maximum work is obtained. The obtained results are compared with those obtained with infinite low temperature heat sink.

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