Adiabatic Analysis of Rotary Displacer Stirling Engine

2018 ◽  
Author(s):  
AmirHossein Bagheri ◽  
William C. Mullins ◽  
Phillip R. Foster ◽  
Huseyin Bostanci
Keyword(s):  
Ideal Gas ◽  
Stirling Engine ◽  
Analytical Models ◽  
Working Fluid ◽  
Power Cylinder ◽  
Significant Difference ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
The Cost ◽  
The Ideal

Utilizing analytical models at the initial stages of Stirling engine (SE) development is a common approach since the cost could be excessive when experimental (i.e., building prototypes) or even numerical (i.e., using Computational Fluid Dynamics (CFD)) approaches are taken first. One of the well-known analyses in this area is the adiabatic analysis that assumes working fluid to be an ideal gas, and adiabatic expansion and compression processes in the power cylinder. Although adiabatic analysis neglects pressure loss in the cycle, it still predicts operating envelope and performance with a better accuracy compared to isothermal (Schmidt) analysis. This study considers the adiabatic analysis that was originally developed for conventional, reciprocating displacer SE configuration, and aims to adapt it for an innovative, rotary displacer SE configuration. The analysis enables to present pressure-volume diagrams, and estimates the amount of generated work and the efficiency. The results, when compared to that of the ideal Schmidt analysis, indicate up to 4.6% lower values of the generated work, suggesting a significant difference between the two ideal assumptions.

Design and Fabrication of Stirling Engine for Solar Power Application

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Muhammad Hassan ◽  
Hussain Ahmed Tariq ◽  
Muhammad Anwar ◽  
Talha Irfan Khan ◽  
Asif Israr
Keyword(s):  
Computer Aided Design ◽  
Peak Power ◽  
Stirling Engine ◽  
Working Fluid ◽  
Cad Model ◽  
Stroke Length ◽  
And Performance ◽  
Power Application ◽  
Aided Design ◽  
Alpha Type

Abstract This paper showcases the designing, fabrication, and performance evaluation of 90-deg alpha-type Stirling engine. The diameters of the hot and cold cylinder are 50 mm and 44 mm, respectively, with a stroke length of 70 mm. The computer-aided design (CAD) model is developed by keeping in mind the ease of manufacturing, maintenance, bearing replacements, and lubrication. After fabrication, the engine is tested by heating the hot cylinder with air as a working fluid. The engine delivered peak power of 155 watts at the temperature of 1123 K and 968 K for hot and cold cylinders, respectively. This developed prototype can be commissioned with the solar parabolic concentrator in the future based on the smooth operation while delivering power.

Experimental and Analytical Study of Sub-Watt Scale Tesla Turbine Performance

2012 ◽  
Author(s):  
Vince D. Romanin ◽  
Vedavalli G. Krishnan ◽  
Van P. Carey ◽  
Michel M. Maharbiz
Keyword(s):  
Analytical Study ◽  
High Efficiency ◽  
Analytical Models ◽  
Working Fluid ◽  
Test Results ◽  
Turbine Performance ◽  
Model Match ◽  
Performance Trends ◽  
Computational Fluid Dynamics Cfd ◽  
Scaling Down

Viscous turbines, like the Tesla turbine, can be manufactured inexpensively at small scales, are robust, and are low maintenance, making them ideal for micro to watt scale energy harvesting applications. However, high efficiency turbines have not yet been demonstrated at small (sub-watt) scales. Previous studies have developed analytical models of turbine performance and analyzed parametric trends in performance for larger turbines and for air as a working fluid. In this study, the same parametric trends in performance are compared to test data for a micro-scale Tesla turbine with water as a working fluid. A Computational Fluid Dynamics (CFD) model is then compared to both the analytical and experimental turbine efficiencies. Tesla turbines were tested with 8 different nozzle configurations, 3 different rotor configurations, and several different flow rates. The test results show that several of the performance trends predicted by the analytical model match experimental results. The CFD solutions of the flow field are then used to help reconcile areas where the analytical predictions do not match experimental data. Certain trends in turbine performance are discussed, and the feasibility of further scaling down Tesla turbines (< 1 cm) is discussed.

3D CFD Analysis of a Twin Screw Expander With Different Real Gas Models for R245fa

2015 ◽  
Author(s):  
Iva Papes ◽  
Lazhar Abdelli ◽  
Joris Degroote ◽  
Jan Vierendeels
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Ideal Gas ◽  
Production Costs ◽  
Working Fluid ◽  
Real Gas ◽  
Twin Screw ◽  
The Ideal

With the increasing importance of minimizing primary energy usage and complying with emission restrictions, a significant interest has been developed towards waste heat recovery from industrial processes. A large portion of this energy is available at low temperatures (350K–400K) but it can be relatively efficiently converted into mechanical power using an Organic Rankine Cycle (ORC). Twin screw expanders can be used as an alternative to turbines with their cheap production costs and well proven efficiencies. In this paper, 3D CFD simulations of a twin screw expander using R245fa as the working fluid are performed. Since the fluid properties show big deviations when using the ideal gas equation of state (EoS), the flow problem has been evaluated using different real gas models. Thermodynamic parameters for the ideal gas EoS, the cubic Aungier Redlich-Kwong EoS and the CoolProp fluid database (open source) were compared in a preliminary study. After that, the models have been included through user-defined functions (UDFs) in ANSYS Fluent and were tested on 3D CFD calculations of a twin screw expander and a simplified expansion model. Several performance indicators such as mass flow rates, pressure-volume diagrams and power output are used to compare different fluid models for R245fa. From the results of this study, it can be concluded that the ideal gas EoS shows big deviations going closer to the saturation vapor line and the deviation in power comparing to the Aungier Redlich-Kwong EoS is around 8%. Conversely, the Aungier Redlich-Kwong EoS and the CoolProp database present very similar results for this case.

scholarly journals Validation of a Radial Compressor CFD Analysis

2020 ◽  
Vol 3 (1) ◽  
pp. 85-90
Author(s):  
Süleyman Emre Ak ◽  
Sertaç Çadırcı
Keyword(s):  
High Speed ◽  
Pressure Ratio ◽  
Ideal Gas ◽  
Cfd Analysis ◽  
Test Results ◽  
Radial Compressor ◽  
Computational Fluid Dynamics Cfd ◽  
Relative Errors ◽  
Mesh Convergence ◽  
The Ideal

In this study, a radial compressor flow at a high speed is investigated by Computational Fluid Dynamics (CFD) methods. The radial compressor of interest consists of a rotor, diffuser, and exit guide vanes and has an operational rotational speed of 21789 rpm. The geometry of the compressor and its test results such as compression ratio and adiabatic efficiency are available in literature. After extensive mesh convergence tests, steady-state CFD analysis has been performed for compressible and turbulent flow using the ideal gas approach. The main motivation of the study is the determine the appropriate CFD approach and boundary conditions of the problem that will fit best to the measurements. The CFD analysis revealed that the maximum relative errors for the adiabatic efficiency and the pressure ratio were 3.6 % and 1.3 %, respectively.

Effect of Using Different Equations of State in the Analysis of Rotary Displacer Stirling Engine

2018 ◽  
Author(s):  
AmirHossein Bagheri ◽  
Pavlina J. I. Williams ◽  
Phillip R. Foster ◽  
Huseyin Bostanci
Keyword(s):  
Equations Of State ◽  
Compressibility Factor ◽  
Ideal Gas ◽  
Stirling Engine ◽  
Operating Conditions ◽  
Distributed Power Generation ◽  
Realistic Representation ◽  
Isothermal Analysis ◽  
Ideal Gas Model ◽  
The Ideal

The ideal gas equation of state is defined for a theoretical gas composed of molecules that have perfect elastic collisions and no intermolecular interchange forces. However, it has been widely reported that such an ideal model may not be a realistic representation under certain circumstances, in particular when the compressibility factor (Z) is not close to unity, and the consideration of other equations of state (real models) is imperative. This study investigates the effect of using different equations of state, namely, the van der Waals, Redlich-Kwong, and Peng-Robinson equations, in the ideal isothermal analysis of a rotary displacer Stirling engine with the most commonly used gases, helium and air. The results are obtained numerically considering two major SE applications (cryocooling and distributed power generation) and two sets of operating conditions, and plotted in the form of Pressure-Volume diagrams. The amount of work per cycle based on the ideal gas model is taken as reference to compare the results from other models. The data show that at low pressure or high temperature conditions (corresponding to low density), the ideal gas equation is suitable for both gases, and using different models has no significant impact in the overall analysis. Additionally, while the use of ideal gas model is rather practical and fast, implementation of other models necessitate intensive computational processes.

scholarly journals ANALYTICAL ASSESSMENT AND COMPARISON OF FACILITIES MANAGEMENT SERVICES FOR RESIDENTIAL ESTATES

2012 ◽  
Vol 16 (3) ◽  
pp. 236-253 ◽  
Author(s):  
Joseph H. K. Lai
Keyword(s):  
Cost Effectiveness ◽  
Residential Buildings ◽  
Evaluation Model ◽  
Facilities Management ◽  
Public And Private ◽  
Performance Levels ◽  
High Rise ◽  
Significant Difference ◽  
And Performance ◽  
The Cost

Populous places are particularly in need of high-rise residential buildings, which are increasingly built as estates. The facilities in these estates entail proper management in order to serve the numerous residents there. Aimed at evaluating the facilities management (FM) services for three major kinds of residential estates (‘public’, ‘semi-public’ and ‘private’), a study was conducted based on a performance-importance-cost (PIC) evaluation model. The end-users’ perceived importance and performance levels and the cost data of the FM services for a public estate, a semi-public estate and a private estate were analyzed using the analytical hierarchy process (AHP), analysis of variance (ANOVA) and Fisher's least significant difference (LSD) procedure. The importance and performance levels of the services and their differences between the estates were revealed. The highest service performance and cost levels were found with the private estate, followed by the semi-public estate and the public estate, while the orders of their cost-effectiveness reversed. Rather than assessing merely the cost or performance of services, using the approach of this study to examine their cost-effectiveness can enable more holistic evaluations towards strategic property management.

scholarly journals Quantum Lenoir Engine with a Single Particle System in a One Dimensional Infinite Potential Well

POSITRON ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 81
Author(s):  
Yohanes Dwi Saputra
Keyword(s):  
Quantum System ◽  
Single Particle ◽  
Thermal Efficiency ◽  
Particle System ◽  
Ideal Gas ◽  
Working Fluid ◽  
Potential Well ◽  
One Dimensional ◽  
Infinite Potential Well ◽  
The Ideal

Lenoir engine based on the quantum system has been studied theoretically to increase the thermal efficiency of the ideal gas. The quantum system used is a single particle (as a working fluid instead of gas in a piston tube) in a one-dimensional infinite potential well with a wall that is free to move. The analogy of the appropriate variables between classical and quantum systems makes the three processes for the classical Lenoir engine applicable to the quantum system. The thermal efficiency of the quantum Lenoir engine is found to have the same formulation as the classical one. The higher heat capacity ratio in the quantum system increases the thermal efficiency of the quantum Lenoir engine by 56.29% over the classical version at the same compression ratio of 4.41.

Aeroacoustics and Performance Modeling of a Counter-Rotating Propfan

2010 ◽  
Author(s):  
Martin Olausson ◽  
Richard Avella´n ◽  
Niklas So¨rman ◽  
Filip Rudebeck ◽  
Lars-Erik Eriksson
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Performance Modeling ◽  
Design Method ◽  
Preliminary Design ◽  
Propeller Design ◽  
Noise Evaluation ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
The Ideal

This paper presents a method for design and analysis of counter-rotating propfans with respect to performance and aeroacoustics. The preliminary design method generates the ideal optimum propeller design corrected for losses in terms of profile and compressibility drag. The propeller design is further analyzed by computational fluid dynamics, CFD, to calculate the performance and the deterministic interaction noise. The unsteady flow around the propellers is calculated using URANS such that only one blade per propeller needs to be discretized. The unsteady pressure distribution around the blades is integrated, using a Ffowcs Williams-Hawkings method, to an observer for noise evaluation. The results of the performance analysis, the CFD computations and the aeroacoustic analysis are compared with experimental data available from the nonproprietary reports regarding the counter-rotating propellers developed in the 1980s.

scholarly journals Thermophysical Properties of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFE-356mmz) in the Vapor Phase Measured by Using an Acoustic-Microwave Resonance Technique

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5525
Author(s):  
Yuya Kano
Keyword(s):  
Heat Capacity ◽  
Dielectric Permittivity ◽  
Sound Velocity ◽  
Vapor Phase ◽  
Thermophysical Properties ◽  
Resonance Method ◽  
Ideal Gas ◽  
Working Fluid ◽  
Microwave Resonance ◽  
The Ideal

Thermophysical properties of HFE-356mmz in the vapor phase were measured by means of an acoustic-microwave resonance method. HFE-356mmz, which is 1,1,1,3,3,3-hexafluoro-2-methoxypropane in chemical name, is expected to be used as a working fluid with low global warming potential for the Organic Rankine cycle (ORC). The sound velocity and dielectric permittivity were simultaneously measured by using a cylindrical acoustic-microwave resonator. The sound velocity data were analyzed to obtain the ideal-gas heat capacity at constant pressure. The integral of the ideal-gas heat capacity as a function of temperature derives the ideal-gas enthalpy, which is a fundamental and important energy property to simulate the thermodynamic cycle. Similarly, the analysis of the dielectric permittivity data leads to information on the ideal-gas molar polarizability, dipole moment, and density. The acquired thermophysical properties of HFE-356mmz were compared to those of R-245fa and n-pentane, which are the existing working fluids for the ORC system, to prospect a feasibility of HFE-356mmz as their alternative.

Return on Invesment (ROI) of Software Product: A Systematic Literature Review

2015 ◽  
Vol 6 (1) ◽  
pp. 50-57
Author(s):  
Rizqa Raaiqa Bintana ◽  
Putri Aisyiyah Rakhma Devi ◽  
Umi Laili Yuhana
Keyword(s):  
Return On Investment ◽  
Assessment Criteria ◽  
Software Product ◽  
And Performance ◽  
Rational Consideration ◽  
Actual Return ◽  
The Cost ◽  
Investment Models ◽  
The Impact

The quality of the software can be measured by its return on investment. Factors which may affect the return on investment (ROI) is the tangible factors (such as the cost) dan intangible factors (such as the impact of software to the users or stakeholder). The factor of the software itself are assessed through reviewing, testing, process audit, and performance of software. This paper discusses the consideration of return on investment (ROI) assessment criteria derived from the software and its users. These criteria indicate that the approach may support a rational consideration of all relevant criteria when evaluating software, and shows examples of actual return on investment models. Conducted an analysis of the assessment criteria that affect the return on investment if these criteria have a disproportionate effort that resulted in a return on investment of a software decreased. Index Terms - Assessment criteria, Quality assurance, Return on Investment, Software product

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