scholarly journals Numerical Investigation of Working Fluid Effect on Stirling Engine Performance

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Distributed Generation ◽  
Heat Engine ◽  
Engine Performance ◽  
Volume Ratio ◽  
Stirling Engine ◽  
Working Fluid ◽  
Prime Mover ◽  
Thermal Generation ◽  
Swept Volume ◽  
Engine Power

The Stirling engine is achieving great concern in the actual energy area since it has many advantages such as its cleanness and quietness. It is also considered a flexible prime mover for useful for several applications such as micro- cogeneration, solar thermal generation and other micro-distributed generation conditions. Theoretically, the Stirling cycle engine can efficiently convert heat into the mechanical work at the Carnot efficiency. The importance of the choice of working fluid is also demonstrated in the literature. In fact, the Stirling engine power can be increased ten times by changing the working fluid from air to hydrogen for example. This paper represents an evaluation of the on working fluid of a solar-dish Stirling heat engine. Thermal efficiency, exergetic efficiency and the rate of entropy generation corresponding to the optimum value of the output power are also evaluated. Numerical results demonstrate that the swept volume ratio is independent of the choice of working fluid.

CFD Simulation of an Alfa-Stirling Engine to Study the Geometrical Parameters on the Engine Performance

2019 ◽  
Author(s):  
Ana C. Ferreira ◽  
Senhorinha F. C. F. Teixeira ◽  
Ricardo F. Oliveira ◽  
José C. Teixeira
Keyword(s):  
Heat Exchanger ◽  
Power Output ◽  
Cfd Simulation ◽  
Engine Performance ◽  
Stirling Engine ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Cold Temperatures ◽  
Temperature Heat

Abstract An alpha-Stirling configuration was modelled using a Computational Fluid Dynamic (CFD), using ANSYS® software. A Stirling engine is an externally heated engine which has the advantage of working with several heat sources with high efficiencies. The working gas flows between compression and expansion spaces by alternate crossing of, a low-temperature heat exchanger (cooler), a regenerator and a high-temperature heat exchanger (heater). Two pistons positioned at a phase angle of 90 degrees were designed and the heater and cooler were placed on the top of the pistons. The motion of the boundary conditions with displacement was defined through a User Defined Function (UDF) routine, providing the motion for the expansion and compression piston, respectively. In order to define the temperature differential between the engine hot and the cold sources, the walls of the heater and cooler were defined as constant temperatures, whereas the remaining are adiabatic. The objective is to study the thermal behavior of the working fluid considering the piston motion between the hot and cold sources and investigate the effect of operating conditions on engine performance. The influence of regenerator matrix porosity, hot and cold temperatures on the engine performance was investigated through predicting the PV diagram of the engine. The CFD simulation of the thermal engine’s performance provided a Stirling engine with 760W of power output. It was verified that the Stirling engine can be optimized when the best design parameters combination are applied, mostly the regenerator porosity and cylinders volume, which variation directly affect the power output.

Design and Evaluation of a MEMS-Based Stirling Microcooler

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Dongzhi Guo ◽  
Jinsheng Gao ◽  
Alan J. H. McGaughey ◽  
Gary K. Fedder ◽  
Matthew Moran ◽  
...  
Keyword(s):  
Volume Ratio ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Dead Volume ◽  
Working Fluid ◽  
Cooling Power ◽  
Phase Lag ◽  
Power Losses ◽  
Cold Side ◽  
Swept Volume

A new Stirling microrefrigeration system composed of arrays of silicon MEMS cooling elements has been designed and evaluated. The cooling elements are to be fabricated in a stacked array on a silicon wafer. A regenerator is placed between the compression (hot side) and expansion (cold side) diaphragms, which are driven electrostatically. Air at a pressure of 2 bar is the working fluid and is sealed in the system. Under operating conditions, the hot and cold diaphragms oscillate sinusoidally and out of phase such that heat is extracted to the expansion space and released from the compression space. Parametric study of the design shows the effects of phase lag between the hot space and cold space, swept volume ratio between the hot space and cold space, and dead volume ratio on the cooling power. Losses due to regenerator nonidealities are estimated and the effects of the operating frequency and the regenerator porosity on the cooler performance are explored. The optimal porosity for the best system coefficient of performance (COP) is identified.

scholarly journals INVALIDITY OF ISOTHERMAL ANALYSIS IN ESTIMATING THE THERMAL PERFORMANCE OF STIRLING ENGINE AND CRYOCOOLER

2021 ◽  
Vol 21 (4) ◽  
pp. 274-288
Author(s):  
Hailaa Jabbar Kareem ◽  
Ali A. F. Al-Hamadani ◽  
Ali Noaman Ibrahim
Keyword(s):  
Heat Exchangers ◽  
Heat Engine ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Low Noise ◽  
Stirling Engine ◽  
Isothermal Model ◽  
Working Space ◽  
Isothermal Analysis ◽  
Noise Vibration

The Stirling engine is an external heat engine, which is considered as the best option for extracting work from concentrated solar power applications. The most prominent characteristics of the engine are low noise, vibration, and emissions besides reflexivity of usage with any kind of heat source such as solar, biomass, industrial heat, etc. In the present paper, the STE-1008 gamma-type Stirling engine had been analyzed by using an isothermal model to demonstrate the failure of the model in analyzing the STE-1008 considering it firstly as an engine and secondly as a cryocooler. The energy equation had been used to demonstrate the disability of the isothermal model in achieving a successful thermal analysis for engine performance. In addition, a MATLAB code had been developed to check the credibility of the isothermal model in the estimation of the engine thermal parameters. The findings of the isothermal analysis revealed that the heat exchangers are unnecessary. But, in reality; all the necessary heat transfer occur within the heat exchangers rather than in the working space boundaries. Therefore, that is invalid conclusion. However, Schmidt's theory is capable of capturing the essential engine features superbly. In particular, it is capable of capturing the fundamental interplay between the mechanically restricted movement of the engine components as well as the thermodynamic cycle which is obtained from this theory.

Valved Heat Engine Working on Modified Atkinson Cycle

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
C. V. Ramesh
Keyword(s):  
Thermal Efficiency ◽  
Heat Engine ◽  
Engine Performance ◽  
Inertial Force ◽  
Expansion Ratio ◽  
Stirling Engine ◽  
Performance Criteria ◽  
Stirling Cycle ◽  
Heat Engines ◽  
Atkinson Cycle

There is immense scope for the development of heat engines that can directly convert solar and biochemical renewable sources of thermal energy to high-grade energy. Regenerative Stirling cycle heat engine with its performance criteria of highest thermal efficiency and high mean effective pressure is theoretically the best engine for small capacity reciprocating heat engine. However, the practical Stirling engine performance is far from the ideal. As an alternative, practical heat engines based on thermodynamic cycles (without regeneration) other than the Stirling cycle have been suggested. This paper deals with a new concept in the design of reciprocating heat engine working on modified Atkinson cycle. In the Atkinson cycle, expansion ratio being higher than compression ratio, the thermal efficiency is better than that of the standard Otto cycle. Heat engine design based on the suggested modified Atkinson cycle can be an alternative to the practical Stirling engine. In the conceptual mechanical design of the engine suggested here, apart from utilizing the principle of Atkinson cycle for achieving higher thermal efficiency, the mechanical configuration of the reciprocating engine ensures a high degree of inertial force balancing. This can result in reduced vibrations in the mountings of the power units.

scholarly journals A Study of Mesh Sheets of 3-kW Stirling Engine

2021 ◽  
Vol 313 ◽  
pp. 05001
Author(s):  
Takeshi Enomoto ◽  
Atsushi Matsuguchi ◽  
Noboru Kagawa
Keyword(s):  
Low Temperatures ◽  
High Performance ◽  
High Efficiency ◽  
Heating Temperature ◽  
Engine Performance ◽  
Stirling Engine ◽  
Working Fluid ◽  
Heat Engines ◽  
Exhaust Heat ◽  
Regenerator Material

In recent years, the interest in low-pollution and high-efficiency heat engines has been increasing due to the growing awareness of environmental protection, and power generation at relatively low temperatures, such as use of exhaust heat and sunlight, has been attracting attention. Compared with other heat engines, Stirling engine is very important because it can be driven by any heat source at low temperatures, such as exhaust heat, and it does not emit exhaust gas. In order to realize a more efficient Stirling engine, it is essential to design a heat exchange system that is suitable for each component. Performance measurement and analysis on a new mesh regenerator material at low temperature difference using a 2-piston alpha-type 3-kW Stirling engine, NS03T are carried out. Mesh sheets developed for high performance Stirling engines can be designed with CAD and CAM technologies by etching process. For this study, M5 and M7 mesh sheets which are thin sheets of stainless steel with square holes in a grid arrangement, are used. With nitrogen and helium as the working fluid, the engine performance is measured by changing the charge pressure, heating temperature, and engine speed to clarify the flow resistance and heat transfer characteristics of the M5 and M7.

scholarly journals Modeling dynamics of the spacecraft power plant consisting of Stirling engine and external thermal circuit

2021 ◽  
Vol 313 ◽  
pp. 12002
Author(s):  
Aigiz Valiullin ◽  
Vladimir Zenkin
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Thermal State ◽  
Engine Performance ◽  
Electrical Energy ◽  
Stirling Engine ◽  
Working Fluid ◽  
Plant Model ◽  
Thermal Circuit ◽  
Wide Range

Modern space programs cover a wide range of missions, including both near-earth missions and those affecting areas of deep space. In the second case, power plants based on the conversion of thermal energy into electrical energy are often considered for the power supply of spacecraft. One of the possible thermoelectric converters is the Stirling engine. To be able to design modern power plants of spacecraft built based on Stirling engines, it is necessary to use calculation tools to simulate their operation in a wide range of modes, to take into consideration the influence of subsystems on each other and the final characteristics of the power plant. As part of the work, a thermodynamic model of an external thermal circuit was created, consisting of heat pipes, heat exchangers and radiator cooler panels. The hot thermal circuit is consisted of two parts: primary and secondary, the cold thermal circuit is consisted of only one part. A mathematical model of the free-piston Stirling engine of the first order has been also implemented. The working fluid in the engine is helium. The developed models were independently debugged and then integrated into a single model of the power plant. For each type of model, the corresponding mathematical models are presented and the basic assumptions are described. The model is implemented in an open simulation environment of xcos/scilab, examples of power plant model implementation are presented. Numerical experiments were carried out to study the dynamics of the heating of the contour elements (with independent, and then with integrated modeling) and the effect of the non-stationary thermal state on the engine performance. The article presents the basic equations and the design schemes for the power plant model, as well as some results of numerical simulation, including the dynamics of hot and cold circuit temperature changes and the dynamics of changes in the indicator diagram of the engine when the external thermal circuit is heated. The developed model can be used in the early stages of spacecraft design for a preliminary assessment of the main indicators of the power plant, its dimensions and thermal loads.

Parametric analysis of a beta Stirling engine – A prime mover for distributed generation

2018 ◽  
Vol 145 ◽  
pp. 693-704 ◽  
Author(s):  
Wojciech Uchman ◽  
Leszek Remiorz ◽  
Krzysztof Grzywnowicz ◽  
Janusz Kotowicz
Keyword(s):  
Distributed Generation ◽  
Parametric Analysis ◽  
Stirling Engine ◽  
Prime Mover

scholarly journals A new compact heat engine

2002 ◽  
Vol 6 (1) ◽  
pp. 45-51
Author(s):  
Miodrag Novakovic
Keyword(s):  
Heat Engine ◽  
Volume Ratio ◽  
The Other ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Thermodynamic Cycles

The Differential Cylinder Heat Engine (DCHE) reported consists of two different size cylinders with pistons where four passages (channels) enable fluid communications between cylinders. The pistons are connected in opposition to share the work. As the channels are open and closed by movement of pistons the working fluid passing through the adequate channel is heated, cooled or let adiabaticaly flown from one cylinder to the other. The arrangement enables different thermodynamic cycles to be performed. Here the Brayton cycle is chosen by adequate choice of volume ratio and by positioning the channel apertures. During isobaric parts of the cycle the gas is adequately heated or cooled when passing through corresponding channel. During these process temperatures remain constant (and different) in each cylinder. The performance of the engine is analyzed and the parameters and efficiency determined.

scholarly journals Action and Entropy in Heat Engines: An Action Revision of the Carnot Cycle

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 860
Author(s):  
Ivan R. Kennedy ◽  
Migdat Hodzic
Keyword(s):  
Heat Engine ◽  
Working Fluid ◽  
Field Energy ◽  
Carnot Cycle ◽  
Gibbs Potential ◽  
Atmospheric Gases ◽  
Temperature Dependent ◽  
Expansion Phase ◽  
Heat Engines ◽  
The Difference

Despite the remarkable success of Carnot’s heat engine cycle in founding the discipline of thermodynamics two centuries ago, false viewpoints of his use of the caloric theory in the cycle linger, limiting his legacy. An action revision of the Carnot cycle can correct this, showing that the heat flow powering external mechanical work is compensated internally with configurational changes in the thermodynamic or Gibbs potential of the working fluid, differing in each stage of the cycle quantified by Carnot as caloric. Action (@) is a property of state having the same physical dimensions as angular momentum (mrv = mr2ω). However, this property is scalar rather than vectorial, including a dimensionless phase angle (@ = mr2ωδφ). We have recently confirmed with atmospheric gases that their entropy is a logarithmic function of the relative vibrational, rotational, and translational action ratios with Planck’s quantum of action ħ. The Carnot principle shows that the maximum rate of work (puissance motrice) possible from the reversible cycle is controlled by the difference in temperature of the hot source and the cold sink: the colder the better. This temperature difference between the source and the sink also controls the isothermal variations of the Gibbs potential of the working fluid, which Carnot identified as reversible temperature-dependent but unequal caloric exchanges. Importantly, the engine’s inertia ensures that heat from work performed adiabatically in the expansion phase is all restored to the working fluid during the adiabatic recompression, less the net work performed. This allows both the energy and the thermodynamic potential to return to the same values at the beginning of each cycle, which is a point strongly emphasized by Carnot. Our action revision equates Carnot’s calorique, or the non-sensible heat later described by Clausius as ‘work-heat’, exclusively to negative Gibbs energy (−G) or quantum field energy. This action field complements the sensible energy or vis-viva heat as molecular kinetic motion, and its recognition should have significance for designing more efficient heat engines or better understanding of the heat engine powering the Earth’s climates.

Performance of a Stirling Engine Regenerator Having Finite Mass

1986 ◽  
Vol 108 (4) ◽  
pp. 669-673 ◽  
Author(s):  
J. D. Jones
Keyword(s):  
Finite Element ◽  
Pressure Variation ◽  
Stirling Engine ◽  
System Model ◽  
Finite Mass ◽  
Element System ◽  
The Matrix ◽  
Cyclic Variations ◽  
Good Agreement ◽  
Engine Power

The performance of a Stirling engine regenerator subjected to sinusoidal mass flow rate and pressure variation is analyzed. It is shown that cyclic variations in the temperature of the matrix due to its finite mass lead to an increase in the apparent regenerator effectiveness, but a decrease in engine power. Approximate closed-form expressions for both of these effects are deduced. The results of this analysis are compared with the predictions of a finite-element system model, and good agreement is found.

Sign in / Sign up

Export Citation Format

Share Document