Characterization of the power and efficiency of Stirling engine subsystems

García, David; González, Miguel A.; Prieto, Jesús-Ignacio; Herrero, Saioa; López, Susana; Mesonero, Iván; Villasante, Cristobal

doi:10.1016/j.apenergy.2014.01.067

Cited by 36 publications

(10 citation statements)

References 10 publications

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“…Lastly, the incidence of mechanical losses within the wobble yoke and the bearings as well as the electrical losses due to the non-ideal generator and auxiliary power drain are evaluated from the work of Garcìa et al [20] and of the authors [21].…”

Section: Numerical Modelmentioning

confidence: 99%

“…That engine is the preceding version of the one used in this work and is fed by a liquid fuel instead of natural gas. Lastly, García et al test the performances of two alpha engines under several working pressures and carry out a comparison among different numerical models [20]. They report a mechanical and an alternator efficiencies falling respectively in the range of 62-80% and 68-90% and depending mainly on the mechanical power output, which in its turn depends upon the mean pressure of the working gas.…”

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confidence: 99%

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Experimental and numerical study of a micro-cogeneration Stirling unit under diverse conditions of the working fluid

et al. 2015

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In the scenario of micro-cogeneration (or micro Combined Heat and Power, micro-CHP), Stirling units are a promising technology for residential applications because of high total efficiencies, favorable ratios of thermal to electrical powers and lower emissions compared to reciprocating engines and micro gas turbines. 1 The present work covers the experimental and numerical analyses of a natural gas-fired commercial unit capable of generating 8 kW of hot water (up to 15 kW with an auxiliary burner) and 1 kW of electricity. Although featuring in general a low electrical efficiency, these micro-cogeneration units are able to recover heat with a high thermal efficiency, thus qualifying positively in terms of primary energy savings. Moreover, the thermal-to-electrical power ratios of 8-to-1 (and 15-to-1 with the additional burner) are well suited for covering simultaneously the thermal and electrical loads of typical residences in continental climates. ☆This article is based on a short proceedings paper in Energy Procedia Volume 161 (2014). It has been substantially modified and extended, and has been subject to the normal peer review and revision process of the journal. This paper is included in the Special Issue of ICAE2014 edited by Prof. J Yan, Prof. DJ Lee, Prof. SK Chou, and Prof. U Desideri. AbstractMicro-cogeneration Stirling units are promising for residential applications because of high total efficiencies, favorable ratios of thermal to electrical powers and low CO as well as NO x emissions. This work focuses on the experimental and the numerical analysis of a commercial unit generating 8 kW of hot water (up to 15 kW with an auxiliary burner) and 1 kW of electricity burning natural gas. In the experimental campaign, the initial pressure of the working fluid is changed in a range from 9 to 24 bar g -20 bar g being the nominal value -while the inlet temperature of the water loop and its mass flow rate are kept at the nominal conditions of, respectively, 50 °C and 0.194 kg/s.The experimental results indicate clearly that the initial pressure of the working fluid -Nitrogen -affects strongly the net electrical power output and efficiency. The best performance for the output and efficiency of 943 W and 9.6%(based on the higher heating value of the burnt natural gas) are achieved at 22 bar g . On the other hand, the thermal power trend indicates a maximum value of 8420 W at the working pressure of 24 bar g , which corresponds to a thermal efficiency of 84.7% (again based on higher heating value). Measurements are coupled to a detailed model based on a modification of the work by Urieli and Berchowitz. Thanks to the tuning with the experimental results, the numerical model allows investigating the profiles of the main thermodynamic parameters and heat losses during the cycle, as well as estimating those physical properties that are not directly measurable. The major losses turn to be the wall parasitic heat conduction from heater to cooler and the non-unitary effectiveness of the regenerator.

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Section: Numerical Modelmentioning

confidence: 99%

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confidence: 99%

Experimental and numerical study of a micro-cogeneration Stirling unit under diverse conditions of the working fluid

et al. 2015

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“…The value of the exergetic efficiency takes into account the irreversibilities of the engine [20] and is found between , S ex = 0.55-0.88 [12], [18]. More generally, it is also necessary to consider that the performance of these kinds of systems depends on many factors [52], among which is the effect of the partialisation of the input thermal power due to fluctuations in solar radiation [30]. For solar dish-Stirling engines, it is often assumed , S ex = 0.5 [13], [18], though there are relatively few experimental works on the performance of these engines.…”

Section: Energy Balance Of the Dish-stirling Systemmentioning

confidence: 99%

A validated energy model of a solar dish-Stirling system considering the cleanliness of mirrors

Buscemi¹,

Brano²,

Chiaruzzi³

et al. 2020

Applied Energy

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Solar systems based on the coupling of parabolic concentrating collectors and thermal engines (i.e. dish-Stirling systems) are among the most efficient generators of solar power currently available. This study focuses on the modelling of functioning data from a 32 kWe dish-Stirling solar plant installed at a facility test site on the University of Palermo campus, in Southern Italy. The proposed model, based on real monitored data, the energy balance of the collector and the partial load efficiency of the Stirling engine, can be used easily to simulate the annual energy production of such systems, making use of the solar radiation database, with the aim of encouraging a greater commercialisation of this technology. Introducing further simplifying assumptions based on our experimental data, the model can be linearised providing a new analytical expression of the parameters that characterise the widely used Stine empirical model. The model was calibrated against datacorresponding to the collector with clean mirrors and used to predict the net electric production of the dish-Stirling accurately. A numerical method for assessing the daily level of mirror soiling without the use of direct reflectivity measures was also defined. The proposed methodology was used to evaluate the history of mirror soiling for the observation period, which shows a strong correlation with the recorded sequence of rains and dust depositions. The results of this study emphasise how desert dust transport events, frequent occurrences in parts of the Mediterranean, can have a dramatic impact on the electric power generation of dish-Stirling plants.

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“…In addition to this parametric estimate, the heat transfer coefficients are also calculated using non-dimensional characteristics of the V161 Stirling engine obtained from the work by Garcia et al (2014) 29 . This model assumes the following relationship between wetted area and swept volume :…”

Section: Heat Exchangers Modelmentioning

confidence: 99%

Stirling Engine Systems Tradespace Exploration Framework

Smirnov

Golkar

2015

Procedia Computer Science

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The purpose of this work is to propose a tradespace exploration framework for the design and system analysis of Stirling engines. The framework can be used to execute trade studies for different objectives. The framework obtains Pareto frontiers of optimal designs by evaluating performance (power, efficiency) and cost metrics for 750 Stirling engine design alternatives. The proposed system design framework integrates four domain models. An engine cycle thermodynamic model is to calculate engine cycle and performance parameters. A heat exchanger model is to estimate areas of heat exchangers. An economic model to predict the capital cost of the engine system. And a tradespace model based on five design parameters identified as drivers of the design: Stirling engine type (alpha, beta, or gamma), engine bore, stroke, hot space temperature, and cold space temperature. The results of the model shed insights on the design of Stirling engines and develop guidelines to identify the most suitable combinations of engine architectures and design parameters to address specific applications. The paper shows how the proposed framework can be applied to the design of Stirling engines for two different applications, namely waste heat recovery and combined heat and power generation for residential real estate units. Considering the identified customer needs for these two applications, the results of the study indicate that alpha-type Stirling engines are more appropriate for industrial waste heat recovery, e.g. heat treating furnaces and cement kilns, having a power output 50% higher for a given efficiency then other engine types. Beta-type engines result more beneficial for residential combined heat and power generation. Gamma-type engines result advantageous for low power applications such as toy models and tool kit engines.

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Characterization of the power and efficiency of Stirling engine subsystems

Cited by 36 publications

References 10 publications

Experimental and numerical study of a micro-cogeneration Stirling unit under diverse conditions of the working fluid

Experimental and numerical study of a micro-cogeneration Stirling unit under diverse conditions of the working fluid

A validated energy model of a solar dish-Stirling system considering the cleanliness of mirrors

Stirling Engine Systems Tradespace Exploration Framework

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