Parametric Analysis of the Thermal Components of an Alpha-Stirling Engine for Cogeneration Applications

2017 ◽  
Author(s):  
Ana C. Ferreira ◽  
Senhorinha F. C. F. Teixeira ◽  
José C. Teixeira ◽  
Luís A. Barreiros Martins
Keyword(s):  
Heat Exchanger ◽  
Parametric Analysis ◽  
Thermodynamic Cycle ◽  
Power Production ◽  
Stirling Engine ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Energy Needs ◽  
Temperature Heat ◽  
In Series

Stirling engines efficiency, the increased maintenance interval periods, the variety of energy sources and the relatively low gas emissions makes Stirling technology an interesting choice as prime mover for cogeneration applications. These are some of the reasons that justify the attention received from researchers in the last years, focused in its modelling, optimization and its application in the suppression of buildings energy needs. In this study, an alpha-Stirling engine was numerically modelled. At this configuration, the working fluid flows between expansion and compression spaces by alternate crossing of, a high temperature heat exchanger (heater), a regenerator and a low temperature heat exchanger (cooler). Thus, the engine is considered as a set of five components connected in series. MatLab® environment was used to implement a software-code to model the thermodynamic cycle of the Stirling engine. The modular code allows investigating the influence of different geometrical and thermal parameters of all the engine components that affects its power production and the efficiency, the effectiveness of heat exchangers and the design itself of the power plant. This parametric analysis helps finding some restriction values for geometrical parameters that cannot be solved through the optimization procedures. For instance, at some point, there is a geometrical limit for which the increase in heat transfer is overlapped by the void volume or pumping losses increase. The parametric analysis led to an enhanced configuration of the numerical model, which resulted in the increase of engine thermal efficiency (about 13.4%), with a power production close to 5 kW.

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.

Performance of Novel High Temperature Heat Exchanger for 1 kW Class Stirling Engine Considering Heat Recovery

2016 ◽  
Vol 24 (01) ◽  
pp. 1650007 ◽  
Author(s):  
Joon Ahn ◽  
Seok Yeon Kim
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Thermodynamic Cycle ◽  
Stirling Engine ◽  
Head Part ◽  
Fixed Temperature ◽  
Fuel Gas ◽  
Temperature Heat ◽  
Cogeneration System ◽  
Heat Quantity

This research proposed a novel shape design by integrating the geometry that showed the best performance including fin length, pitch and angle on the high temperature heat exchanger of Stirling engine designed for the prime mover of 1kW cogeneration system for home. First, the numerical simulation was conducted on the new design and existing shape, and the performance improvement according to the shape optimization was checked. Next, the validity of its performance was verified by additionally considering the heat loss from the recuperation and low-temperature heat exchanger. As a result, when the high temperature heat exchanger is optimized, a great amount of heat quantity is absorbed from the fuel gas from the upstream part where negative heat flux occurred in the cylinder head part. This was judged to be because of the fixed temperature of the high-temperature part in the thermodynamic cycle. Thus, when researching the shape of the high-temperature heat exchanger, an optimized geometry can be obtained when combining cycle interpretation of system rather than interpreting independently.

Preliminary Investigation of an Up-Scaled Gamma-Type Stirling Engine for Power Production

2015 ◽  
Vol 786 ◽  
pp. 220-225 ◽  
Author(s):  
M.F. Hamid ◽  
Mohamad Yusof ◽  
M.K. Abdullah ◽  
Z.A. Zainal ◽  
M.A. Miskam
Keyword(s):  
Stainless Steel ◽  
Heat Source ◽  
Material Selection ◽  
Power Production ◽  
Stirling Engine ◽  
Load Test ◽  
Working Fluid ◽  
Temperature Differential ◽  
Stainless Steel Mesh ◽  
Steel Mesh

This paper presents the development of Gamma-type Stirling engine for High Temperature Differential (HTD) and self-pressurized mode of operation. The engine is the up-scaled version from the Low Temperature Differential (LTD) miniaturized gamma-type Stirling engine. The test engine is featured with 85cc power piston and 4357cc displacer piston swept volumes, respectively. The characterization of few critical engine parameters and components that includes heater head section, cooler section, displacer and power pistons material selection and heat source system had been conducted. Air is used as a working fluid and Liquefied Petroleum Gas (LPG) is utilized as the heat source in order to cater for the heater temperature up to 1000°C. The workability test of the engine revealed that the lightweight in mass of the displacer piston and the auxiliary cooling effect at the cooler section had contributed to a significant improvement on the engine rotational motion. The static load test determined that the engine is capable of producing the friction power of 1.2W for stainless steel mesh wire displacer and 0.3W for polystyrene displacer. Based on Beale formula, the estimated power of 4W can be produced by the engine using stainless steel mesh wire displacer and 2.4W of power using polystyrene displacer. Good agreement has been shown, where the potential net power production of 3.8W and 2.1 W for stainless mesh wire displacer and polystyrene displacer, respectively. Further investigation is needed to improve the heat regeneration in between hot and cold sections of the engine to realize the sustainable performance of the engine at higher range of temperature difference and output power.

scholarly journals Utilization Waste Brine Water Separator for Binary Electric Energy Conversion in Geothermal Wells

2021 ◽  
Vol 16 (4) ◽  
pp. 411-420
Author(s):  
Herianto
Keyword(s):  
Heat Exchanger ◽  
Electric Energy ◽  
Thermodynamic Cycle ◽  
Geothermal Field ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Binary Cycle ◽  
Water Separator ◽  
Geothermal Wells

Nowadays, geothermal is one of the most environmentally friendly energy that can replace the role of fossils energy by converting steam to electricity. Brine is one of the by-products of the production of geothermal wells that are generally not used or simply re-injected. In fact, brine can be converted into electricity using the binary cycle process. In binary cycle, brine from separator is used as a heater of working fluid and transform it into a vapor phase. The vapor will be used to turn turbines and generators to produce electricity. The working fluid selection in accordance with the heating fluid temperature becomes important because it results in optimization of the thermodynamic cycle. The temperature of the wellhead in the geothermal field will decrease 3% per year and reducing the heating fluid temperature in heat exchanger. So, in this paper intends to utilizes brine to heat the heat exchanger by using iso-butane, n-pentane, and iso-pentane because its critical temperature can be stable at 193℃ wellhead temperatures. From the results of predictions from brain 2 production well for 17 years with iso-butane in this binary cycle planning, can utilize waste brine water separator to converse electric energy to produce 4 MWh electricity.

Theoretical Studies on the Application of Pulsating Heat Pipe in Vapour Compression Refrigeration System

2014 ◽  
Vol 592-594 ◽  
pp. 1801-1806 ◽  
Author(s):  
Rudra Naik ◽  
Linford Pinto ◽  
K. Rama Narasimha ◽  
G. Pundarika
Keyword(s):  
Heat Exchanger ◽  
Theoretical Model ◽  
Heat Pipe ◽  
Parametric Analysis ◽  
Working Fluid ◽  
Theoretical Studies ◽  
Refrigeration System ◽  
Pulsating Heat Pipe ◽  
System A ◽  
Vapour Compression

This paper proposes a simplified theoretical model of Pulsating Heat Pipe (PHP) employed in a vapour compression refrigeration system. The model developed is mainly based on well known physical equations and partially based on empirical correlation. The present theoretical investigation of PHP is focused to explore its suitability as a heat exchanger in the condenser of vapour compression refrigeration system. A parametric analysis is carried out to design the vapour compression refrigeration system with PHP as the condenser. The performance of the system is evaluated for different PHP diameters, working fluids, evaporator and condenser temperatures and evaporator and condenser lengths. The effect of super heating and sub cooling the refrigerant are also studied. The results showed an increase in performance of the system at higher evaporator and lower condenser temperatures. The best results are obtained with R-12 as the working fluid. Also there is an increase in the COP of the system due to decrease in pressure drop in the condenser.

scholarly journals Supercritical CO2 Heat Exchanger Fouling and its Impact on RCBC Efficiency

2018 ◽  
Author(s):  
Darryn Fleming ◽  
Kirsten Norman ◽  
Salvador Rodriguez ◽  
James Pasch ◽  
Matthew Carlson ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Supercritical Co2 ◽  
Critical Factor ◽  
Power Production ◽  
Working Fluid ◽  
Power Cycles ◽  
Power Cycle ◽  
Printed Circuit ◽  
Overall Efficiency

As supercritical carbon dioxide (sCO2) is emerging as a potential working fluid in power production Brayton cycles, fluid purity within the power cycle loops has become an issue impacting commercialization. Sandia National Laboratories has been evaluating the longevity of sCO2 recompression closed Brayton power cycles to quantify the advantages of sCO2 over other fluids as utilizing sCO2 yields comparatively greater efficiencies. Hydrocarbon plugging has been observed in the small printed circuit heat exchanger channels of our high temperature recuperator, increasing pressure drop across the heat exchanger. As pressure drop is a critical factor in the overall efficiency of sCO2 recompression closed Brayton cycles, in this paper we report on our investigation into heat exchanger efficiency reduction from hydrocarbon plugging induced pressure drop.

Performance of Cogeneration Systems Using Waste Heat

2013 ◽  
Author(s):  
Mohammed Khennich ◽  
Nicolas Galanis ◽  
Mikhail Sorin
Keyword(s):  
Waste Heat ◽  
Thermal Conductance ◽  
Combined Heat And Power ◽  
Working Fluid ◽  
Temperature Heat ◽  
Two Systems ◽  
In Series ◽  
Heating Load ◽  
Net Power Output ◽  
The Impact

The performance of two systems using a low-temperature heat source (100 and 125 °C) and an ORC with R245fa as the working fluid for combined heat and power production has been modeled. The first system supplies the heating load with a heat exchanger in series with the ORC boiler. In the second one this function is fulfilled by the ORC condenser. The results show that the effects of the heating load on the performance of the two systems are very different. The net power output decreases monotonically with increasing heating load for the first system while it exhibits a maximum in the case of the second one. The impact of the heating load and the source temperature on the turbine size, on the total thermal conductance of the heat exchangers, on the total exergy destruction and on several other parameters is also presented and discussed.

Numerical and Analytical Analyses of a High Temperature Heat Exchanger

2006 ◽  
Author(s):  
Donato Aquaro ◽  
Franco Donatini ◽  
Maurizio Pieve
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Analytical Model ◽  
Electric Utility ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Test Loop ◽  
Temperature Heat

In this paper some analytical and numeric analyses of a high temperature heat exchanger are performed. This heat exchanger should be employed in a test loop of a EFCC (Externally Fired Combined Cycle), placed in a experimental facility owned by the Italian electric utility, ENEL. The heat exchanger is the crucial element in this cycle, as it undergoes temperatures above 1000°C and pressures of about 7 bars. The enthalpy of the combustion products of low cost fuels, such as coal, bottom tar, residuals from refineries, is used to heat a clean working fluid, in this case pressurized air. There are some outstanding benefits for the turbine, in regard to the manufacturing and maintenance costs, and also for its life. The heat transfer components are some bayonet tubes, assembled in 4 modules. A half of them is made of ceramic materials, the others of an advanced metallic material (ODS), due to the burdensome operating conditions. First of all, the heat exchanges are evaluated by means of a simplified analytical model. The radiant contribution also has been taken into account, due to the presence of non-transparent gases. Subsequently, the in-tube fluid temperature increase is calculated for all the heat exchanger modules, through an enthalpy balance and with some simplifying assumptions. Moreover, a comparison is made between the analytical solution and the results of a numerical model implemented in a CFD code. A good agreement is found, which indicates that the analytical model is reasonably valid. In fact, the whole heat exchanger temperature change is determined by means of the two methods with a difference of about 7% for both the streams. Finally, these results are to be compared with the experimental data which should be available in the near future, when the facility will begin working. Also, by this way, the developed calculation model would get a validation.

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