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Efficient engine technologies to convert low-grade heat to electricity are urgently desired. In this work, a conceptual structure of engine for a novel cycle or one-way oscillating flow cycle (OOFC), which consists of two isochoric and two adiabatic processes, is described for low-grade heat utilization. Characteristics of OOFC allows for the working fluid temperature glide to be matched to the decrease in temperature of low-grade heat. Then, thermodynamic model is developed for evaluating the performance. Theoretical simulation results show that maximum specific output works are in the range of 12.2 kJ kg−1 – 79.7 kJ kg−1. Compared to Stirling cycle system, maximum specific output work in OOFC system could be improved by 16.2 %–24.8 %. Compared to ideal Carnot cycle engine system, maximum specific output works in OOFC system is nearly the same and 1.8 %–2.6 % lower. As Carnot cycle engine is ideal while thermodynamic cycle loss and heat transfer loss in cold heat exchangers are considered in OOFC engine, the ratios of maximum specific output work demonstrate that OOFC system could be very promising for low-grade heat utilization as a result of well-matched temperature profile in hot heat exchanger. • Structure of OOFC engine with temperature glide heat addition is described. • Large temperature glide heat rejection is achieved in OOFC engine. • Maximum specific output work of OOFC system is 116 %–125 % of Stirling cycle system. • Maximum specific output work in OOFC system are equivalent to ideal Carnot cycle system. • OOFC engine has well-matched temperature profile for low-grade heat utilization. [ABSTRACT FROM AUTHOR]

Highlights • Detailed study of piston-cylinder pair in Stirling machines. • Comparative sealing designs of Stirling refrigerators piston-cylinder pairs. • Minimization of cooling capacity losses thanks to a high-tolerance seal design. • Experimental study of a 10-micron high-tolerance seal without piston rings. • Discussion of advantages and necessary improvements for a high-tolerance seal. Abstract Optimal design of the sealing mechanism in the piston-cylinder pair of Stirling refrigerators is beneficial in terms of system's cost, reliability, efficiency and cooling capacity; yet this is often overlooked in the literature. We report on our experimental study of a high-tolerance lubricated piston-cylinder pair with cast iron-steel materials as an integral part of the Ross-yoke alpha-type Stirling refrigerator. We measured: the gas leakage rate through the sealing gap; the friction force in the piston-cylinder pair; and the refrigerator temperature during operation. Our results show that owing to careful design, the loss of the ideal cooling capacity due to gas leakages amounted to 2.2%, and that the friction loss to the ideal cycle power input was 8.1%. We also discuss which type of lubricants demonstrates a higher resistance to operational loading and what engineering problems must be solved for reliable operation of the sealing mechanism. [ABSTRACT FROM AUTHOR]

Highlights • A novel thermocapacitive cycle harvesting low-grade heat is proposed. • Optimal performance characteristics at the maximum power output are investigated. • Optimum criteria of important parameters are determined and provided. • A larger efficiency of the cycle can be obtained under finite power output. Abstract A novel Stirling-like irreversible electrochemical thermo-capacitive regenerative cycle operating between a heat reservoir and a heat sink for harvesting low-grade heat is proposed, in which the main irreversible losses are considered. Expressions for the efficiency and power output of the cycle are derived. The inherent regenerative heat loss of the cycle is revealed. The influences of several important parameters, such as the capacitance of the supercapacitor, charge ratio, endpoint voltage of the charging process on the power output of the cycle are discussed. The maximum power output and corresponding efficiency are calculated. The results show that when the charging endpoint voltage of the electrochemical thermo-capacitive regenerative cycle is 10 V, the maximum power output is 31.9 W and the efficiency at the maximum power output can reach 12.8%, which is 51.2% of the Carnot efficiency. The optimal values for several parameters at the maximum power output are determined. The parametric optimum selection criteria of the cycle are provided. The results obtained can ensure the cycle to operate in the optimum states. [ABSTRACT FROM AUTHOR]

Highlights • A novel method to cool superconducting magnet by using Stirling cooler is proposed. • The Stirling cryocooler is capable of providing 1048 W cooling power at 77 K. • Cooling processes of superconducting magnet by different cryocoolers are compared. • STL2 needs 23 days to cool a 30-ton superconducting magnet from 300 K to 40 K. Abstract Superconducting magnets have been widely applied in medical, transportation, scientific research, power storage and transmission systems, etc. The mass of superconducting magnets is often large in applications, so the cooling process is frequently quite slow. A novel method to speed up the cooling process by applying a large cooling capacity Stirling cryocooler is studied. The present cooling system consists of a Stirling cryocooler, a cryofan, and accessories, using helium gas as the circulating cryogen. A single-stage Stirling cryocooler is developed and it can provide 1048 W cooling power at 77 K with a relative Carnot efficiency of 26.1%. Under ideal conditions, the cryocooler is able to cool a 30-ton superconducting magnet from 77 K to 40 K in 59.7 h, which is faster than GM cryocooler. Considering the heat transfer temperature difference and heat leakage, the Stirling cryocooler needs 23 days to cool a 30-ton superconducting magnet from 300 K to 40 K. Furthermore, compared with the cooling process with liquid nitrogen and helium, this method makes the operation cleaner, simpler and more controllable. [ABSTRACT FROM AUTHOR]

Abstract This study concerns with the thermodynamic and dynamic analysis of an alpha type Stirling engine with Scotch-yoke piston driving mechanism. The thermodynamic aspect of the analysis is treated with a polytrophic nodal approximation. The pressure of nodal volumes is calculated with modified Schmidt formula which takes into account the pressure differences between nodal volumes caused by flow friction. The flow friction is calculated with adapted Darcy formula. The variation of the gas temperature in nodal volumes are calculated via the first law of thermodynamics given for unsteady open systems. The dynamic behavior of the engine is modeled via the motion equations of pistons and crankshaft. For a 2 kW nominal shaft power and 1400 rpm nominal speed, dimensions and working conditions of the engine were investigated by using realistic inputs. It was estimated that an engine having about 1.44 L swept volume, 1000 K hot source temperature, 400 K cold source temperature, 9050 cm2 total inner heat transfer area, 6 bar charge pressure, 2000 W/m2K inner heat transfer coefficient may produce more than 2 kW shaft power. For 142 rad/s average crankshaft speed the optimum thermal efficiency and torque of the engine were determined as 31% and 15.63 Nm respectively. Highlights • Dynamic and thermodynamic analysis of a Scotch yoke Stirling engine. • Nodal analysis. • Mathematical model including flow and mechanical frictions. • Performance examination at constant speed and charge pressure. • Speed fluctuation characteristics. [ABSTRACT FROM AUTHOR]

Highlights • Stirling cycle is suitable for waste heat recovery from internal combustion engines. • Specific power of three Stirling engine types are compared with parametric study. • With a novel non-dimensionalization method, more realistic results are reported. • Beta-type is the most suitable type due to its maximum specific power. • Sizing of a Stirling engine is given for measured exhaust gas temperatures. Abstract The requirements for cleaner engines and less fuel consumption force vehicle manufacturers to investigate new technologies on recovering from losses. As the main contributor to losses is the waste heat, studies are carried out to convert the waste heat to mechanical work. In this paper, an evaluation of Stirling engines is presented for waste heat recovery (WHR) from exhaust gases of a heavy-duty truck diesel engine. Maximum theoretical dimensionless shaft work for three types of Stirling engines are calculated and compared by optimizing selected parameters with a new dimensionless method. Results are used to size a WHR system that utilizes the thermal power of a commercial truck exhaust gas. Calculations done with exhaust gas temperatures measured during road tests show that, the WHR system with Beta-type Stirling engine is more effective than Alpha and Gamma types due to its higher power density. The WHR system presented provides more than 1.3% of ICE power output and about 1% reduction in fuel consumption, which offers Stirling engine as a reasonable option for WHR on heavy-duty truck engine. [ABSTRACT FROM AUTHOR]

Abstract A miniature integrated nuclear reactor design with gravity independent autonomous circulation (ACMIR) was newly proposed. The reactor core, energy transfer system of Stirling and linear electric motors are integrated in the reactor pressure vessel to achieve high power density and autonomous circulation capability. The coolant circulation is autonomously driven by gas expansion at heat end and compression at cool end thus is independent on gravity. Twelve sets of rotary drum controller and reflector are used to regulate reactivity outside the reactor pressure vessel. The physics and thermodynamic properties, as well as the safety performances are analyzed. According to these analysis, inherent safety characteristics are obtained, and the reactor is capable to shut down and remove residual heat passively without any external intervention, in accident conditions such as loss of external power supply, overtemperature/overpressure of the reactor, impact when rocket launching or landing, stagnation of the displacer or piston, et al. The integration, less pipes design, gravity independent autonomous circulation features make it a good candidate for space flight propulsion, the Moon and Mars base power supply, the deep-sea or other tilt and swing situation applications. [ABSTRACT FROM AUTHOR]

Abstract This study aims to develop a novel integrated geothermal based system by the application of different thermodynamic cycles such as Kalina, liquefied natural gas (LNG), Stirling and proton exchange membrane electrolyzer (PEME) to produce cooling, hydrogen, and electricity. Energy and exergy analyses of the system are performed to evaluate the performance of the system. Additionally, the effects of five different input variables are investigated to determine their impacts on the corresponding values of net power and cooling, exergy efficiency, hydrogen production, and sustainability index. In a defined condition, the exergy efficiency of the suggested system is computed around 43%. The cycle net generated power is 10.69 MW, which is the generated power by the Stirling, LNG, and Kalina turbines each by 8.07 MW, 1.13 MW, and 1.49 MW, respectively. The produced cooling load by the cooling unit of the LNG stream is also 6.09 MW, while the rate of hydrogen production in the electrolyzer is 204.77 kg/h by consuming all the generated power. Additionally, a sensitivity analysis is performed to study the effects of each design parameters on the system performance. Highlights • Thermodynamic analysis of a novel geothermal system by the application of Kalina, Stirling, LNG, and PEME cycles. • Evaluating the performance of the system by obtaining the exergy and energy efficiencies. • Parametric study of the hydrogen production by the variation of the five design parameters. • Sensitivity analysis to determine the dominant design parameter affecting on the system performance. [ABSTRACT FROM AUTHOR]

Highlights • A novel Stirling thermocompressor (STCP) is proposed. • A progressive three order non-equilibrium thermal model of STCP is established. • The performances of STCP in no-load and RC-load operation are studied. • Helium, nitrogen and hydrogen are compared as the working fluids of STCP. Abstract The Stirling thermocompressor (STCP), usually working at low frequency (<5 Hz), is a novel Stirling-type external-combustion machine. It utilizes the temperature difference between the heating temperature and ambient temperature to generate the thermoacoustic power and pressure wave for refrigerators. In order to explore the characteristics of STCP, a detailed thermal analysis based on the third order 1-D finite volume model considering the real gas effect and variable physical properties was proceeded. Three natural fluids, helium, nitrogen and hydrogen are chosen as the working fluids and compared with each other. The parameter effects of pressure fluctuation under no-load operation were studied. To understand the output capacities for refrigerator with using different working fluids, the RC load method is adopt to analysis the STCP's capacity and efficiency of the conversion from heat energy to acoustic energy, also the loss characteristics under different working gas. When the working pressure, frequency and heating temperature are 4 MPa, 4 Hz and 800 K respectively, the STCP using helium as the working fluid could output about 380 W acoustic power for the RC load and relative Carnot efficiency is about 33%. [ABSTRACT FROM AUTHOR]

Highlights • An active displacer allows cryocooler performance to be optimised during operation. • Both cooling power and relative Carnot efficiency have optimum displacer phase values. • Varying displacer phase angle boosts performance by increasing mass flow at cold end. • An active displacer cryocooler operates more efficiently than an inertance tube one. Abstract An in-line pulse tube cryocooler with an active displacer has been built and its performance has been examined in detail by experimental measurements and numerical modelling. An active displacer allows the mass flow at the cold end to be easily adjusted for optimum performance. It is demonstrated that both cooling power and relative Carnot efficiency have optimum phase values that are different. It is also shown that the phase optimisations are not critical – good performance is achieved over a significant range. The pulse tube cryocooler can deliver up to 3.8 W of cooling at 80 K with an input power of 88 W (shaft power of 69 W) when operating at optimal phase. Moreover, a numerical Sage model is used to enhance our understanding behind the trends observed by examining the mass flow and pressure pulse at the cold end. It is shown that the variation in phase of the active displacer helps boost the cryocooler performance by increasing the amplitude of the mass flow at the cold end and not by adjusting the phase of the mass flow. The Sage model is also used to demonstrate that using a displacer in place of an inertance tube can result in a more efficient cryocooler. [ABSTRACT FROM AUTHOR]

Highlights • Operational frequency deduced both analytically and computationally. • Previously untested cooling configuration found to be the optimal. • Development of validated computer model of physical system. • Liquid piston instability linked to Rayleigh-Taylor phenomenon. • Liquid piston maximum acceleration limit identified. Abstract The objective of this research project is to develop a solar-powered refrigerator in the lower capacity range of up to 5 kW of cooling power. With the use of liquid pistons and one of the most efficient thermodynamic cycles known, the Stirling cycle, this product has the potential to outperform rival solar cooling technologies while providing inexpensive, reliable, quiet, environmentally-friendly, and efficient solar cooling for residential use, due to its straightforward manufacturing, simple design and inert working gas. Presented in this paper are the newest results of the theoretical and experimental investigation into deducing the key design parameters and system configuration of the so-called Liquid Piston Stirling Cooler (LPSC), which will help lead to optimal performance. Computer models of the complex unconstrained system have been constructed and validated using the modelling software Sage and shown to replicate system behavior with reasonable accuracy in experiments. The models have been used to predict system improvements and identify limitations imposed by the use of liquid pistons. The results to date provide a unique insight into a relatively little studied area in Stirling cycle research. [ABSTRACT FROM AUTHOR]

Abstract The longest duration mission on the Venus surface was Venera 13 at just over 2 h. This time constraint was due to limited battery power life and craft thermal management challenges. A lithium combustion based power system has been proposed to increase landed mission durations for Venus and other extreme environment targets. This paper presents a new detailed thermodynamic and heat transfer model of a conceptual lithium combustion power system. Findings are applied to specify engineering requirements for potential missions. Results indicate that a lithium combustion power system using the in-situ carbon dioxide atmosphere as an oxidizer could power a Venus lander for up five days (24 h, Earth day) with 185 kg of fuel, delivering 14 kW th thermal energy continuously. Even greater durations are possible if lower power missions are considered. The potential performances of a Li-CO 2 powered Stirling engine and sulfur-sodium batteries were compared. It was found that sulfur-sodium batteries would require about 1.75–2.5 times more mass to provide 1 kW of power output for mission durations of five to ten days, respectively. A lithium combustion power system with a sulfur-hexafluoride oxidizer could power a Europa lander at 94W with a Stirling engine for up to twenty days with 43 kg of reactants mass. Lithium-combustion activated Stirling engines and TEG arrays were compared with batteries to meet this power and mission duration requirement. It was found that batteries would require less mass than either lithium-fueled system. However, for mission durations longer than twenty-six days the Stirling engine power system may require less total mass than batteries. Future work will include laboratory-based experimental studies to validate results and improve heat transfer closure models. Highlights • Li-CO 2 and Li-SF 6 combustion power are analyzed for Venus and Europa landers. • Greater specific energies are found for both landers than with batteries. • Power systems for a 5 Earth-day Venus and 20-day Europa landers are described. • 185 kg of Li fuel can power an in-situ Venus lander with 14 kW th for 5 days. • An 80 kg, Li-SF 6 combustion system can power a Europa lander for 20 days. [ABSTRACT FROM AUTHOR]

In this study, multi-objective optimization of a Gamma type Stirling refrigerator is carried out based on the experimental and analytical results. The cooling capacity and the coefficient of performance (COP) are experimentally investigated for helium and air. Beside to helium and air, carbon dioxide is also considered as the working fluid in the simulation. A non-ideal adiabatic analysis is developed for the simulation. The experimental and simulation results showed that the cooling capacity increases continuously with the rotational speed where the COP has a maximum value. The optimum COP value for helium occurs at higher rotational speed than that of the air. The Design of Experiment (DOE) method is used for multi-objective optimization. Three parameters namely COP, cooling capacity and pressure drop are investigated in this optimization study. Only helium and carbon dioxide are considered for optimization because of their higher specific heat capacity and enthalpy with respect to air. The optimum working pressure for the carbon dioxide takes place at lower pressure than that of helium. When the importance and weight factors equal one, the optimum point for helium is obtained at working pressure and rotational speed of 9 bar and 451.1 rpm, respectively. Where, the optimum point for carbon dioxide is found at working pressure and rotational speed of 3.3 bar and 798.5 rpm, respectively. [ABSTRACT FROM AUTHOR]

A generalized irreversible quantum Stirling refrigeration cycle (GIQSRC) is proposed. The working substance of the GIQSRC is a particle confined in a general 1D potential which energy spectrum can be expressed as ε n = ℏ ω n σ . Heat leakage and non-ideal regeneration loss are taken into account. The expressions of coefficient of performance (COP) and dimensionless cooling load are obtained. The different practical cases of the energy spectrum are analyzed. The results of this paper are meaningful to understand the quantum thermodynamics cycles with a particle confined in different potential as working substance. [ABSTRACT FROM AUTHOR]

In this study, the effects of heat transfer enhancement on engine performance by introducing slot grooves on walls of the displacer cylinder of a γ -type medium-temperature-differential Stirling engine have been investigated using computational fluid dynamics. Cases include smooth displacer-cylinder wall with heat source and heat sink extension on displacer cylinder circumferential wall and slot-grooved displacer-cylinder walls with grooves at different locations and numbers. The grooves are at displacer cylinder circumferential wall or at top and bottom walls. The slot grooves are classified into three types according to their locations. It is found that the circumferential wall is very important on engine's heat transfer behavior. Extending heat source and heat sink on this wall can improve indicated power but losing efficiency. Type-1 grooves enhance both positive and inadequate heat transfer, hence its effects on enhancing engine performance is mixed. In contrast, Type-3 grooves mainly enhance positive heat transfer thus yield improvement on indicated power and efficiency as the number of grooves increases. However, Type-2 grooves, which enhance heat transfer on regenerative wall, have been shown to yield the best performance. Compared with the engine without any heat-transfer-enhancement measure, a case with 96 Type-2 grooves improves indicated power up to 49%. [ABSTRACT FROM AUTHOR]

Thermoacoustic engines (TAE) are special devices that convert thermal energy into mechanical energy in the form of a high decibel acoustic wave. These devices have a huge potential to revolutionize fields like refrigeration, if efficiently designed. They are simple in construction, having two main parts, i.e. the stack and the resonator tube, and work on a process similar to the Stirling cycle. Although, this technology exists for several years, there is still no strong design available that can be used for actual practical purposes. They have been tested through experiments and analytical techniques and recently through CFD based numerical simulations. In this work, a TAE has been analyzed through CFD simulations using a commercial package. Taking a step further from the existing research related to TAEs, a sensitivity study has been carried out. The study aims to analyze the pressure wave development in a TAE, and its dependency on the temperature gradient at the stack and the length of the resonator. It is seen that higher temperature gradient causes a higher pressure amplitude and early pressure wave development. The critical temperature gradient is found in the range 200 – 300 K. With resonator length, it is noticed that, very small resonator length results in failure, while very long resonator length causes delay in pressure wave initiation although it provides high amplitude. Medium lengths are better since they provide high pressure amplitude and faster wave initiation. Analysis of frequency showed that temperature gradient has minor effect whereas length has major effects. [ABSTRACT FROM AUTHOR]

The objective of this research project is to develop a solar-powered refrigerator in the lower capacity range of up to 5 kW of cooling power. With the use of liquid pistons and one of the most efficient thermodynamic cycles known, the Stirling cycle, this product has the potential to outperform rival solar cooling technologies while providing inexpensive, reliable, quiet, environmentally-friendly, and efficient solar cooling for residential use, due to its straightforward manufacturing, simple design and inert working gas. Presented in this paper are the newest results of the theoretical and experimental investigation into deducing the key design parameters and system configuration of the so called Liquid Piston Stirling Cooler (LPSC), which will lead to optimal performance. Computer models of the complex unconstrained system have been constructed and validated using the modelling software Sage and shown to replicate system behaviour with reasonable accuracy in experiments. The models have been used to predict system improvements and identify limitations imposed by the use of liquid pistons. The results to date provide a unique insight into a relatively little studied area in Stirling research. [ABSTRACT FROM AUTHOR]

An external heat source and a Stirling cycle are proposed for performance improvement of a direct carbon solid oxide fuel cell (DC-SOFC) system. The amount of the heat released in the DC-SOFC is determined based on a previously validated 2D tubular DC-SOFC model, in which the electrochemical reaction, chemical reactions, ion/electronic charge transport, mass transport and momentum transport are fully considered. Numerical calculations show that the overall heat released in the cell may be smaller than, equal to or larger than the heat required by the internal Boudouard reaction, and accordingly, three different operating modes of the system are given. The analytical expressions for the equivalent power output and efficiency for the DC-SOFC, Stirling cycle and the hybrid system are specified under different operating conditions. The results show that the power density and efficiency of the proposed system allow 4000 W m −2 and 30% larger than that of the stand-alone DC-SOFC at 30000 A m −2 , respectively. Parametric studies also show that a higher operating temperature and a smaller distance between carbon layer and anode will increase the overall power density and efficiency of the proposed system. [ABSTRACT FROM AUTHOR]

This article presents a performance study of using different working fluids (gases) to power on Concentrated Solar Gas Engine (CSGE-Stirling and/or Brayton). Different working gases such as Monatomic (five types), Diatomic (three types) and Polyatomic (four types) are used in this investigation. The survey purported to increase the solar gas engine efficiency hence; decreasing the price of the output power. The effect of using different working gases is noticed on the engine volume, dish area, total plant area, efficiency, compression and pressure ratios thence; the Total Plant Cost (TPC, $). The results reveal that the top cycle temperature effect is reflected on the cycle by increasing the total plant efficiency (2–10%) for Brayton operational case and 5–25% for Stirling operational case. Moreover; Brayton engine resulted higher design limits against the Stirling related to total plant area, m 2 and TPC, $ while generating 1–100 MW e as an economic case study plant. C 2 H 2 achieved remarkable results however, CO 2 is considered for both cycles operation putting in consideration the gas flammability and safety issues. [ABSTRACT FROM AUTHOR]

Introducing nanotechnology made a revolution in various industries such as upstream, downstream and energy industries. As a result, developing new types of nanoscale thermal cycles can develop the future of energy systems. The present work investigated a nanoscale irreversible Stirling refrigeration cycle thermodynamically in order to optimize the performance of the aforesaid cycle. In the above-mentioned cycle, an Ideal Maxwell–Boltzmann gas plays a role of a working fluid. Ideal Maxwell–Boltzmann gas was employed for working fluid in the cycle. Owing to the quantum limit influence on the gas particles restricted in the finite area, the cycle no longer retains the circumstance of perfect regeneration. He 4 is chosen as working fluid. This paper demonstrates two different plans in the process of multi-objective optimization; though, the results of each plan are assessed individually. The first scenario constructed with the purpose of maximizing the ecological coefficient of performance (ECOP) , the coefficient of performance ( C O P ) and the dimensionless Ecological function ( e c f ). Furthermore, the second scenario planned with the purpose of maximizing the exergy efficiency ( η e x ) , the coefficient of performance ( C O P ) and the dimensionless Ecological function ( e c f ). All the scenarios in this paper are performed through the multi-objective evolutionary algorithms (MOEA) joined with NSGA II approach. Moreover, to determine the final solution in each scenario three effective decision makers are employed. Deviation of the results obtained in each scenario and each decision maker are calculated individually. Finally, the results of the suggested scenarios were compared to each other, and it reveals that when the exergy efficiency achieved the maximum value, the values of COP, ECOP, and ecf also maximized. [ABSTRACT FROM AUTHOR]

We introduce a new statistic based on permutation descents which has a distribution given by the Stirling numbers of the first kind, i.e. , with the same distribution as for the number of cycles in permutations. We study this statistic on the sets of permutations avoiding one pattern of length three by giving bivariate generating functions. As a consequence, new classes of permutations enumerated by the Motzkin numbers are obtained. Finally, we deduce results about the popularity of the pure descents in all these restricted sets. [ABSTRACT FROM AUTHOR]

The low temperature differential Stirling engine with channel-shaped heat exchangers and regenerators achieved approximately 5 times the indicated power per a stroke volume of displacer of the cases using flat-shaped heat exchangers. The ratio of the maximum fluctuation of ensemble averaged working fluid temperatures, which is the ratio of the internal energy fluctuation to the heat capacity of the working fluid, to the temperature difference between the two heat exchangers in cases using flat-shaped heat exchangers was 0.08–0.09, that in cases using channel-shaped heat exchangers was 0.10–0.17, and that in case using channel-shaped heat exchangers and regenerators was 0.21. The improvement in the experiments is lower than the estimation by the CFD. In terms of the polytropic index, low temperature differential Stirling engines with channel-shaped heat exchangers and regenerators obtained a higher value than low temperature differential Stirling engines with flat-shaped heat exchangers before the displacer reached the dead center. [ABSTRACT FROM AUTHOR]

Duplex Stirling coolers are external heat-driven regenerative machines that obtain cooling power with high efficiency and reliability. Although the technology is promising, little progress has been reported since they were invented. This paper examines the influence of system parameters on the cooling performance of a duplex Stirling cooler. The study showed that the system was sensitive to a number of parameters, as slight changes in these parameters resulted in the cooling performance deviating significantly from the design. In practice, deviation of system parameters from the design is inevitable. Therefore, actual systems often produce unexpected performance, and this is likely the main obstacle to utilizing such a system in practical applications. To overcome this disadvantage, two methods were proposed to allow the power piston to move with a constant displacement, which may allow for duplex Stirling coolers to become a more widely used cooling system. A new configuration for duplex Stirling coolers was also considered, and it showed similar characteristics as the typical configuration. [ABSTRACT FROM AUTHOR]

The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of solar-heat driven Brayton, Rankine and Stirling cycles operating in space with different working fluids. Generation of power in space for terrestrial use can represent a great future opportunity: the low-temperature of space (∼3 K), allows the attainment of very high efficiency even with low-temperature heat inputs, and the solar energy input is higher in space than on earth. This paper shows a comparative analysis of advanced Brayton, Rankine and Stirling cycles to improve the understanding of the optimal trade-off between high efficiency and the smallest needed heat rejection area. The effect of the main cycles' operational parameters and plant layouts on efficiency and power to radiator area ratio have been analyzed. The thermal efficiency of regenerative-reheated-intercooled Brayton cycle was found to be the best among the investigated configurations. The power to radiator area ratio was found to increase with the introduction of reheating for both the Rankine and Brayton cycles. Stirling cycles efficiencies are lower than those obtained by the Brayton and Rankine cycles but with values of power to radiator area ratio equal to about half of those obtained by Brayton cycles but much higher than those obtained by the Rankine cycles. [ABSTRACT FROM AUTHOR]

• Obtained characteristic of cooling cycle with two isentropic and isochoric processes. • A concept of one-way heat exchange in oscillating flow's heat exchanger is proposed. • Conceptual design of one-way heat exchange regenerative cooler is described. • Proposed cooler has much better performance compared to Stirling cooler. • Proposed cooler has comparable or improved performance to vapor compression system. Distinctive characteristics of thermodynamic cycle consisting of two isochoric and two adiabatic processes have not been clarified and no specialized coolers have been developed for such cycle. In this work, the distinctive characteristics of such cycle were analyzed and obtained. Based on proposed concept of one-way heat exchange in oscillating flow's heat exchangers, conceptual design of such cycle cooler was introduced. Then, both analytical and second-order models without considering losses of heat transfer and flow were developed to obtain the practical coefficient of performance (COP) for such cycle cooler at room temperature conditions. Also, COP of Stirling cooler and vapor compression refrigeration systems were investigated and obtained for comparisons. Degrees of thermodynamic perfection defined as the ratio of practical COP over ideal COP were employed for compatible performance comparisons between different coolers at various conditions. The results showed that the values for such cycle cooler were 54.1%∼84.6% for cooling and 60.8%∼89.7% for heating respectively. The values for Stirling cooler were 14.7%∼73.9% for cooling and 16.7%∼79.3% for heating respectively. And the values for R32 systems were 69.1%∼89% for cooling and 63.5%∼89.5% for heating respectively, while the values for R1234yf systems were 73.1% ∼85.9% for cooling and 66.4%∼86.2% for heating respectively. As there was temperature glide heat exchange in such cycle cooler, the values based on lowest cold temperature or highest hot temperature could be up to 90.3%∼99.4% and 91.9%∼99.4% for cooling and heating respectively. Thus, degrees of thermodynamic perfection show that the irreversibility in such cycle cooler over Stirling cooler is largely reduced. And it also indicates that such cycle coolers have huge potential as an alternative for vapor compression refrigeration systems. [ABSTRACT FROM AUTHOR]

This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated. [ABSTRACT FROM AUTHOR]

A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype. [ABSTRACT FROM AUTHOR]

Due to the increasing generation capacity of intermittent renewable electricity sources and an electrical grid ill-equipped to handle the mismatch between electricity generation and use, the need for advanced energy storage technologies will continue to grow. Currently, pumped-storage hydroelectricity and compressed air energy storage are used for grid-scale energy storage, and batteries are used at smaller scales. However, prospects for expansion of these technologies suffer from geographic limitations (pumped-storage hydroelectricity and compressed air energy storage), low roundtrip efficiency (compressed air energy storage), and high cost (batteries). Furthermore, pumped-storage hydroelectricity and compressed air energy storage are challenging to scale-down, while batteries are challenging to scale-up. In 2015, a novel compressed gas energy storage prototype system was developed at Oak Ridge National Laboratory. In this paper, a near-isothermal modification to the system is proposed. In common with compressed air energy storage, the novel storage technology described in this paper is based on air compression/expansion. However, several novel features lead to near-isothermal processes, higher efficiency, greater system scalability, and the ability to site a system anywhere. The enabling features are utilization of hydraulic machines for expansion/compression, above-ground pressure vessels as the storage medium, spray cooling/heating, and waste-heat utilization. The base configuration of the novel storage system was introduced in a previous paper. This paper describes the results obtained from a transient, analytical, physics-based thermodynamic system model used for the system design and evaluation of three design configurations (including base configuration). The system model captures real gas effects and all loss mechanisms. The model demonstrates an energy storage roundtrip efficiency of 82% and energy density of 3.59 MJ/m 3 . Experimental evaluation of system performance and detailed cost-analysis will be presented in future publications. [ABSTRACT FROM AUTHOR]

This work presents the development and validation of computational fluid dynamics (CFD) model of 500 W gamma-type Stirling engine prototype to highlight the effects posed by phase angle and dead volume variations on engine performance. The model is based on a realistic Local Thermal Non-Equilibrium (LTNE) approach for porous domains in the engine (cooler and regenerator). The simulation results showed an acceptable degree of accuracy of 9% and 5%, respectively when comparing with experimental results in predicting the indicated and cooling powers at different heating temperatures. It is found that the maximum indicated power is achieved at a phase angle of 105° rather than at the common phase angle of 90°. The dead volume (connecting pipe) is observed to pose negative effects on engine indicated power and therefore, an optimum value of pipe diameter exists. [ABSTRACT FROM AUTHOR]

A review is presented for the research development of Stirling cycle engines for recovering low and moderate temperature heat. The Stirling cycle engines are categorized into four types, including kinetic, thermoacoustic, free-piston, and liquid piston types. The working characteristics, features, technological details, and performances of the related Stirling cycle engines are summarized. Upon comparing the available experimental results and the technology potentials, the research directions and the possible applications of different Stirling cycle engines are further discussed and identified. It is concluded that kinetic Stirling engines and thermoacoustic engines have the greatest application prospect in low and moderate temperature heat recoveries in terms of output power scale, conversion efficiency, and costs. In particular, kinetic Stirling engines should be oriented toward two directions for practical applications, including providing low-cost solutions for low temperatures, and moderate efficient solutions with moderate costs for medium temperatures. Thermoacoustic engines for low temperature applications are especially attractive due to their low costs, high efficiencies, superior reliabilities, and simplicities over the other mechanical Stirling engines. This work indicates that a cost effective Stirling cycle engine is practical for recovering small-scale distributed low-grade thermal energy from various sources. [ABSTRACT FROM AUTHOR]

Throughout the recent years, several efforts have been conducted in studying Stirling engine which have yielded various models for analysis of Stirling engine thermal efficiency and output power. In the present study, the applicability of a combined Stirling and Otto cycle power plant where a Stirling cycle engine would serve as a bottoming cycle for a stationary Otto cycle engine is investigated. Output power of Stirling engine and Stirling engine thermal efficiency are optimized and total pressure losses of Stirling engine is optimized executing NSGA approach and finite speed thermodynamic analysis. The outcomes gained are satisfactory verified versus actual recorded data of Stirling engine. Decision making was performed via three well-known methods. Finally, error analysis was performed on the outputs obtained from this optimization. [ABSTRACT FROM AUTHOR]

A high pressure hybrid refrigerator that combines the active magnetic refrigeration effect with the Stirling cycle refrigeration effect at room temperature is studied here. In the apparatus, a helium-gas-filled alfa-type Stirling refrigerator uses Gd sheets as the regenerator and the regenerator is put in a magnetic field varying from 0 to 1.4 T, which is provided by a Halbach-type rotary permanent magnet assembly. With an operating pressure of 5.5 MPa and a frequency of 2.5 Hz, a no-load temperature of 273.8 K was reached in 9 minutes, which is lower than that of 277.6 K for pure Stirling cycle. For the hybrid operation, cooling powers of 40.3 W and 56.4 W were achieved over temperature spans of 15 K and 12 K, respectively. For the latter case, the cooling power improves by 28.5% if compared with that exploiting only the Stirling cycle refrigeration effect. [ABSTRACT FROM AUTHOR]

Linear compressors with clearance seals are well established for cryocoolers using either a Stirling cycle or pulse tube. However, both piston stroke and piston offset require detection and control in valved compressors. In order to manufacture linear compressor in large scale, then a simple, robust, and cheap control system is required with a minimum of sensors and actuators. This work introduces an approach to sensing the position of the piston using a search coil. The piston stroke is detected by calculating the peak-to-peak flux linkage in relation to the measured drive voltage and current. The piston offset is proportional to an integrated modulus of the back electromotive force (emf) of the search coil. Two PID (proportional-integral-derivative) controllers were developed to control the piston stroke by adjusting the drive voltage and a solenoid valve and bleed flow to control the piston offset. Experimental results validate the proposed compressor control technique. [ABSTRACT FROM AUTHOR]

Sustainable energy supply is a major challenge for the lunar base because of the lengthy night of the Moon. In-situ resource utilization based on lunar regolith heat storage is a promising solution to this challenge. Herein, a dish solar thermal power system with lunar regolith heat storage is proposed to supply energy to a lunar base. A theoretical model is established using finite-time thermodynamics to investigate system performance in a lunar circadian cycle. A case study shows that the output power and efficiency of the system gradually decrease whether in lunar day or lunar night. The average output power during the lunar day and night is 10.8 kW and 7.0 kW, respectively. The system can achieve a high energy efficiency of 48.0%, which is mainly owing to the full utilization of lunar resources. In addition, the effects of several key parameters on the system performance are discussed and the results show that the energy supply of the system requires a tradeoff between lunar day and night. This work reveals that the proposed system has the potential to supply energy to the lunar base continuously and efficiently, providing a scheme for the energy supply system of the future lunar base. • A dish solar thermal power system is proposed for energy supply of lunar base. • A theoretical model using finite-time thermodynamics analysis is established. • The effects of several key parameters on the system performance are discussed. • The system can achieve a high efficiency of 48.0% for circadian energy supply. [ABSTRACT FROM AUTHOR]

The aim of this work is to optimize γ Stirling engine performances with a special care given to the heater. This latter consists of 20 tubes in order to increase the exchange area between the working gas and the hot source. Different parameters were chosen to evaluate numerically and experimentally the heater. The selected four independent parameters are: heating temperature (300–500 °C), initial filling pressure (3–8 bar), cooling water flow rate (0.2–3 l/min) and frequency (2–7 Hz). The amount of energy exchanged in the heater is significantly influenced by the frequency and heating temperature but it is slightly enhanced with the increase in the cooling water flow rate. The thermal and the exergy efficiencies of the heater are very sensible to the temperature and pressure variations. [ABSTRACT FROM AUTHOR]

This paper presents a novel solar-powered active Stirling converter with liquid power piston and solid controllable displacer. First, the working principle of the proposed converter is described. Then, finite time thermodynamic approach incorporating heat transfer equations are employed to determine gas temperatures in hot and cold spaces based on the assumption of imperfect regeneration. Accordingly, pressure variation of the gas due to reciprocating motion of the displacer piston is investigated using the obtained gas temperatures and Schmidt theory. Next, total work done by the converter and thermal efficiency are evaluated. Kinematic and dynamic equations governing the pump system are presented and the water flow characteristics in suction and discharge states are investigated. A simulation study is carried out through coupling and simultaneously solving the obtained equations. An optimization scheme is thus conducted to find an optimum frequency of the active converter so that a maximum power is generated. The influences of regenerator efficiency, dead volumes, and water head on the optimum operating frequency and the generated power are investigated. Finally, the proposed converter is constructed and primarily tested. The experimental outcomes clearly reveal the feasibility of pumping water at low temperature difference through the proposed active Stirling pump. [ABSTRACT FROM AUTHOR]

This paper analyses the recently-observed temperature–time dependence in a GM-cooler near its low-temperature limit. The paper mainly focusses on GM-coolers with 4 He as the working fluid, but some attention is also paid to pulse-tube refrigerators (PTR’s) using 3 He and many features of the treatment equally apply to Stirling coolers. Ample attention is paid to the thermodynamics of the cycle by considering the isentropes in the Tp -diagrams of 4 He and 3 He. The role of the line, where the thermal expansion coefficient is zero, is emphasized. Some fundamental thermodynamic relationships are derived. [ABSTRACT FROM AUTHOR]

He-3 is generally recognized for its ability to provide more excellent thermophysical performance than He-4, especially in the 4 K temperature range. However, this was not always the case in our preliminary experiments on a three-stage Stirling-type pulse tube cryocooler (SPTC). Our ongoing studies, as reported in this paper, demonstrate that the different working fluids also affect the performance through their phase shifting capability. This feature has been passed over in large part by researchers considering refrigerant substitution. Unlike previous theoretical analyses that focus primarily on regenerator losses, this report investigates the effects of the working fluid on the phase angle at the cold end in order to quantitatively reveal the relationship between the lowest attainable temperature and the cooling capacity. The analysis agrees well with our experimental results on a three-stage SPTC. While running with the operating parameters optimized for He-3, the lowest temperature of the SPTC decreased from 5.4 K down to 4.03 K. This is the lowest refrigeration temperature ever achieved with a three-stage SPTC. [ABSTRACT FROM AUTHOR]

A concept for a new type of pneumatically-driven split-Stirling-cycle cryocooler with clearance-phase-adjustor has recently been described, along with a theoretical model for simulating its operation and performance (Zhang, in preparation, 2003). This paper describes experiments that have been carried out to systematically validate the model, and to characterize the performance of the cryocooler in several key areas. These include: oscillatory flow within the cooler, correlation between the compression piston and the free displacer, the impact of the cold-tip temperature and phase-adjusting clearance gaps on cooler performance. The minimum cold-tip temperature is used as primary gauge of refrigeration performance. Real-time measurements of gas pressures in different chambers, displacements of the compression piston and the free displacer have been performed to reveal the internal physical processes. The experimental results are found to be in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

The concept of a new type of pneumatically-driven split-Stirling-cycle cryocooler with clearance-phase-adjustor is proposed. In this implementation, the gap between the phase-adjusting part and the cylinder of the spring chamber is used, instead of dry friction acting on the pneumatically-driven rod to control motion damping of the displacer and to adjust the phase difference between the compression piston and displacer. It has the advantages of easy damping adjustment, low cost, and simplified manufacturing and assembly. A theoretical model has been established to simulate its dynamic performance. The linear compressor is modeled under adiabatic conditions, and the displacement of the compression piston is experimentally rectified. The working characteristics of the compressor motor and the principal losses of cooling, including regenerator inefficiency loss, solid conduction loss, shuttle loss, pump loss and radiation loss, are taken into account. The displacer motion was modeled as a single-degree-of-freedom (SDOF) forced system. A set of governing equations can be solved numerically to simulate the cooler’s performance. The simulation is useful for understanding the physical processes occurring in the cooler and for predicting the cooler’s performance. [ABSTRACT FROM AUTHOR]

In this paper, a promising heat pump based on Stirling technology is examined. Based on the volume variation produced by the oscillating displacement of two pistons, the advantages of this particular system lie in the elimination of a transmission mechanism, as the driving machines are directly coupled to the working pistons, and in the use of environmentally friendly working gases. The system is analysed by coupling the dynamics to an isothermal model of the Stirling cycle. A methodology is proposed to preliminarily size this type of heat pump based on simulations performed on a mathematical model built in MATLAB. The stability of operation is analysed by considering possible changes in working conditions. Actions are proposed to minimize the effect of these changes on the performance of the system. [ABSTRACT FROM AUTHOR]

A dynamic model for the simulation of gas micro combined heat and power devices (μCHP boilers) has been developed in order to assess their energy performances. From a literature review and experimental investigations, the new model is designed with the aim of limiting the number of parameters which need to be easily accessible in order to be suitable with annual building energy simulations. At first, this paper focuses on the description of the μCHP boiler which has been tested, on the development of the test bench and on the experimental results. Then, it focuses on the model description, on its parameterization and on its validation. The modelling approach is based on an energy balance on the device and on empirical expressions for the main inputs and outputs. The model characterizes the μCHP boiler behaviour for different inlet water flow rates and temperatures. The dynamic phases with the start-up and cooling phases are taken into account. Finally, the models for the Stirling engine and the additional boiler are limited respectively to 28 and 24. Further experimental investigations led to simplify the μCHP model from 28 to 17 parameters without reducing the accuracy. [ABSTRACT FROM AUTHOR]

Highlights: [•] A parametric investigation of irreversible Stirling cryogenic refrigerator cycles is presented. [•] Both internal and external irreversibilities are included in this study, moreover, heat capacities of external reservoirs are involved. [•] Multi-objective evolutionary algorithm based on NSGA-II approach is utilized. [•] Three robust decision making approaches are utilized to determine final optimum solution. [Copyright &y& Elsevier]

Highlights: [•] An investigation is made on thermodynamic evaluation of a Stirling heat pump. [•] The present analysis provides a good theoretical guidance for designing of such systems. [•] Optimum Pareto frontier has been determined by implementing NSGA-II method. [•] Optimum solutions have been chosen by executing LINMAP, Fuzzy and TOPSIS decision making approaches. [Copyright &y& Elsevier]

• A Stirling cycle thermodynamic IPD-MSM, based on Simple model, was proposed. • Stirling cycles with H2, He, and He-Xe mixture as working fluids were analyzed. • He-Xe mixture reaches the best thermodynamic properties when Xe is about 2%. • Mass leakage of H2, He, and He-Xe mixture as working fluids were analyzed. A Stirling cycle is a thermoelectric conversion method with high efficiency and reliability. The Stirling cycle applies to small- and medium-sized power space nuclear reactors or radioisotope heat sources. A high-precision and well-predicted Stirling cycle thermodynamic model is the key to optimizing and improving the Stirling engine for space. The present study modified the classical Simple model by incorporating the local pressure loss into the pressure loss. An improved second-order adiabatic model based on the Simple model, namely the Incorporated Pressure Drop-modified Simple Model (IPD-MSM), was proposed. The prediction of the IPD-MSM shows well with the changing tendency of the GPU-3 Stirling engine experimental data. Moreover, this model has better prediction accuracy at high-pressure and high-frequency conditions than other adiabatic models, such as CAFS and ISAM. The thermodynamic properties of He, H 2 , and Helium-Xenon mixtures in the Stirling cycle were also analyzed. Results show that the He-Xe mixture reaches the highest output power and thermal efficiency when the mole percentage of Xe is approximately 2%. The mechanism is as follows: the addition of Xe leading to the reduction in non-ideal heat transfer loss exceeds the increase in pressure loss. The addition of Xe leads the pressure loss to increase abruptly as the mole percentage of Xe exceeds 2%. The characteristics and application analysis of H 2 , He, and He-Xe mixture were discussed. The present study provided theoretical support for the Stirling cycle analysis for space missions and the selection of working fluids. [ABSTRACT FROM AUTHOR]

Abstract: Cryogenic generation is one of the most important ways to utilize cold energy during LNG (liquefied natural gas) regasification. This paper fundamentally investigates LNG cryogenic generation with the Stirling cycle method based on previous studies. A basic process of LNG cryogenic generation with the Stirling cycle was presented initially with seawater and LNG as heat source and heat sink. And its thermodynamic analysis was performed to verify the theoretical feasibility of the Stirling cycle method. The generating capacity, the exergy efficiency and the cold energy utilization efficiency of the basic process were also calculated. Subsequently, the influences of evaporation pressure on net work, equipment performance and comprehensive efficiency of cold energy utilization were discussed and the effect of LNG mass flow as well as the ambient temperature was also studied. Finally an improved process of LNG cryogenic generation with Stirling cycle method combined with an air liquefaction process is proposed as feasibility in improvements of the basic process. [Copyright &y& Elsevier]

Highlights: [•] The optimal power of an endoreversible Stirling cycle is investigated. [•] In the endoreversible cycle, external heat transfer processes are considered irreversible. [•] Optimal temperature of the heat source leading to a maximum power for the cycle is detained. [•] Effect of design parameters on the power and its corresponding thermal efficiency is studied. [ABSTRACT FROM AUTHOR]

Abstract: As the environmental problems caused by the use of conventional fuels have risen significantly and due to the increase in fossil fuel prices, the importance of reducing society dependence on non-renewable energy sources becomes more and more urgent. It is clear that this could only happen by switching to extensive use of clean energy sources such as renewable energy sources. In this paper a technical feasibility and economic viability study of a dish/Stirling solar power plant in Greece is presented. The proposed power plant uses Dish/Stirling technology and has nominal power 10 MW. The proposed solar concentrator system consists of a primary mirror, formed by elastic film, used to focus the sun's rays onto a secondary mirror which then deviates this radiation into the receiver (Stirling engine). TRNSYS program was developed to simulate Dish/Stirling power plant operation in order to investigate its performance in Greece. The simulation predicted that the proposed power plant could produce 11.19 GWh annually. Project investment cost is approximately 27,000,000 €, while payback is achieved after 16 years of operation. The total profit at the end of the analysis period of 25 years is estimated to be 25,500,000 €. [Copyright &y& Elsevier]

Abstract: In the recent years, numerous studies have been done on Stirling cycle and Stirling engine which have been resulted in different output power and engine thermal efficiency analyses. Finite speed thermodynamic analysis is one of the most prominent ways which considers external irreversibilities. In the present study, output power and engine thermal efficiency are optimized and total pressure losses are minimized using NSGA algorithm and finite speed thermodynamic analysis. The results are successfully verified against experimental data. [Copyright &y& Elsevier]