Study on woody biomass Stirling cycle for cold region houses

Obara, Shin’ya; Kito, Shunsuke; Hoshi, Akira; Sasaki, Seizi

doi:10.1002/er.1431

Cited by 8 publications

(5 citation statements)

References 5 publications

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“…In this sense, different prototypes suitable for CHP applications have been recently developed. Some examples correspond to the prototypes developed by Sato [30], Nishiyama [42],Biederman [43], Zeiler [44], Li [33] and Obara [45]. In addition, some field tests were reported by Thomas [5] and Klemes [6].…”

Section: Technology Overviewmentioning

confidence: 72%

Numerical simulation for the design analysis of kinematic Stirling engines

et al. 2015

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The Stirling engine is a closed-cycle regenerative system that presents good theoretical properties. These include a high thermodynamic efficiency, low emissions levels thanks to a controlled external heat source, and multi-fuel capability among others.However, the performance of actual prototypes largely differs from the mentioned theoretical potential. Actual engine prototypes present low electrical power outputs and high energy losses. These are mainly attributed to the complex interaction between the different components of the engine, and the challenging heat transfer and fluid dynamics requirements. Furthermore, the integration of the engine into decentralized energy systems such as the Combined Heat and Power systems (CHP) entails additional complications. These has increased the need for engineering tools that could assess design improvements, considering a broader range of parameters that would influence the engine performance when integrated within overall systems. Following this trend, the current work aimed to implement an analysis that could integrate the thermodynamics, and the thermal and mechanical interactions that influence the performance of kinematic Stirling engines. In particular for their use in Combined Heat and Power systems. The mentioned analysis was applied for the study of an engine prototype that presented very low experimental performance. The numerical methodology was selected for the identification of possible causes that limited the performance. This analysis is based on a second order Stirling engine model that was previously developed and validated. The simulation allowed to evaluate the effect that different design and operational parameters have on the engine performance, and consequently different performance curves were obtained. These curves allowed to identify ranges for the charged pressure, temperature ratio, heat exchangers dimensions, crank phase angle and crank mechanical effectiveness, where the engine performance was improved. In addition, the curves also permitted to recognise ranges were the design parameters could drastically reduce the brake power and efficiency. The results also showed that the design of the engine is affected by the conditions imposed by the CHP interactions, and that the engine could reach a brake power closer to 832 W with a corresponding brake efficiency of 26% when the adequate design parameters were considered. On the other hand, the performance could also be very low; as the reported in experimental tests, with brake power measurements ranging 52-120 W.

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Section: Technology Overviewmentioning

confidence: 72%

Numerical simulation for the design analysis of kinematic Stirling engines

et al. 2015

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“…Regenerative cycles, such as the well‐known Stirling cycle, may utilize and transform virtually any heat flow, particularly including heat from various renewable sources, and may thus contribute to the global energy transformation. Therefore, they are increasingly under consideration for micro‐cogeneration applications 1‐4 and particularly for utilizing various forms of biomass 5‐11 as well as solar energy 12‐15 . However, the performance of the idealized, theoretically reversible cycles is in practice degraded by a variety of loss mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Performance improvements in Stirling cycle machines by a modified appendix gap geometry

Sauer

Kühl

2021

Intl J of Energy Research

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Summary In this contribution, the optimization potential of the seal geometry in Stirling machines is explored both numerically and analytically, leading to a significant reduction of the related losses which are often referred to as appendix gap losses. These are induced by the narrow gap between the displacer and the cylinder and have mostly been underestimated so far. A recent experimental investigation revealed large optimization potentials by reduction of the seal and cylinder wall diameter near the seal, resulting in reduced appendix gap losses and further indirect positive effects. In this work, these experimental findings could be reproduced by a one‐dimensional differential simulation model at a fully satisfyingaccuracy. Furthermore, these investigations reveal that the optimum geometry is largely machine‐dependent. To provide an easily applicable design rule for this optimum geometry, a refined analytical model for the mass flow at the top of the gap is derived, which is based on a phasor analysis and a linearized mass balance that also accounts for changes in the spatial mean gas temperature in the gap. The optimum design predicted by this model is very close to numerical optimization results and sufficiently accurate under practical aspects. Furthermore, this model contributes to a better theoretical understanding of the loss mechanisms in the gap.

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“…Various systems adopting SEs and running on biomasses have been proposed in the past, adopting different conversion technologies. Direct burning of solid biomass in a boiler [13][14][15][16] is the simplest option, and improved performances in terms of combustion efficiency, reduced pollutant emissions, and fuel flexibility can be obtained by adopting fluidized bed combustors, 11,17 at the cost of an increased start-up time. Offline production of gaseous fuels, for example, in anaerobic digesters, allows the use of fuel cells 18,19 or innovative gas-fired burners.…”

Section: Introductionmentioning

confidence: 99%

Development of an experimental test rig for cogeneration based on a Stirling engine and a biofuel burner

et al. 2020

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A system consisting of a last-generation Stirling engine (SE) and a fuel burner for distributed power generation has been developed and experimentally investigated. The heat generated by the combustion of two liquid fuels, a standard Diesel fuel and a rapeseed oil, is used as a heat source for the SE, that converts part of the thermal energy into mechanical and then electric energy. The hot head of the SE is kept in direct contact with the flame generated by the burner. The burner operating parameters, designed for Diesel fuel, were changed to make it possible to burn vegetable oils, not suitable for internal combustion engines. The possibility of adopting different configurations of the combustion chamber was taken into account to increase the system efficiency. The preliminary configurations adopted allowed to operate this integrated system, obtaining an electric power up to 4.4 kW el with a net efficiency of 11.6%.

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Study on woody biomass Stirling cycle for cold region houses

Cited by 8 publications

References 5 publications

Numerical simulation for the design analysis of kinematic Stirling engines

Numerical simulation for the design analysis of kinematic Stirling engines

Performance improvements in Stirling cycle machines by a modified appendix gap geometry

Development of an experimental test rig for cogeneration based on a Stirling engine and a biofuel burner

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