Experimental and Numerical Study of a Micro-cogeneration Stirling Engine for Residential Applications

Valenti, Gianluca; Silva, Paolo; Fergnani, Nicola; Marcoberardino, Gioele Di; Campanari, Stefano; Macchi, Ennio

doi:10.1016/j.egypro.2014.01.129

Cited by 35 publications

(19 citation statements)

References 7 publications

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“…All data are taken constant for every simulation, exception made for the cooler water temperature, the heater wall temperature and the gas pressure that are varied according to the operating conditions and the experimental campaign. Table 4 Working gas initial pressure (bar g ) See Table 4 Heater wall temperature (°C) See Table 4 a Evaluated in previous works [21]. Table 3 shows the main results from the experimental campaign.…”

Section: Numerical Modelmentioning

confidence: 99%

“…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%

“…As part of an ongoing study [21], a second campaign on the above-mentioned natural gas-fueled commercial Stirling unit is carried out at the Laboratory of Micro-Cogeneration of Politecnico di Milano [22]. The objective is to collect experimental data under diverse initial pressures of the working fluid, taking measurements at the boundary of the engine as well as inside the engine itself.…”

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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%

Section: Numerical Modelmentioning

confidence: 99%

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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

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“…These installations are promising for industrial or residential applications thanks to their high efficiency, their simplicity to connect to existing installation, and their low emissions with respect to alternative technologies [2]. A cogeneration unit that is principally composed of a Stirling engine, an alternator and a heat exchanger used to produce electricity can save 30% of fuel and moreover, if the unit is adapted to work at higher pressures and temperatures, power over 1.5 kW can be obtained in the alternator [2].…”

Section: Introductionmentioning

confidence: 99%

“…Some installation techniques can be used to optimize the combustion of the coal. The thermal losses can be valorized by the use of cogeneration or combined heat and power (CHP) systems [2,3]. In this context the Stirling engines are presented as possible solution to convert thermal losses either into electricity or to produce hot water for domestic or industrial installations.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical investigation of Stirling engine heater: Parametrical optimization

Gheith

Hachem

Aloui

et al. 2015

Energy Conversion and Management

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Theoretical investigations of Stirling engine performances for different filling gas properties

Hachem

Gheith

Aloui

2022

Intl J of Energy Research

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Summary Stirling engine research has increased and opened new industrial opportunities. Stirling engines have the advantage of running on any sort of thermal energy. However, their biggest downside is their low experimental efficiency compared to Carnot's optimal efficiency. Thus, much research studies the optimal working parameters of this engine. Most existing models evaluate the Stirling engine's performance using the perfect gas assumption. However, this assumption is only valid for low pressures. At high pressure, real gas behaves differently from perfect gas. Hence the necessity and the interest of the conducted research work. The major goal of this numerical study was to analyze the influence of gas qualities on Stirling engine power and efficiency using a semi‐real gas assumption. The impact of operating and geometric parameters on the performance of a four‐cylinder Stirling engine (FCSE) were explored for three monatomic gases (Helium, Neon, and Argon) and one diatomic gas (Nitrogen). The dependence of volume ratio, regenerator form factor, load pressure, hot end temperature and rotation speed on gas properties were investigated. Major significant losses were accounted for at different conditions. To figure out parameters that maintain the highest performance, four different regenerator porosity (60%, 70%, 80%, 90%), three different cylinder diameters (3.5, 4, 4.5 cm) and three different phase shifts between the two pistons (2π5, π2, 3π5) were evaluated. As regards, the obtained results, not only the optimum parameters that provide higher output power were identified but also predicted correlations for each studied filling fluid as a function of the geometric and operating parameters. The outcomes of the study would be very helpful for a new more powerful engine design. The obtained results clearly demonstrated that: (a) The choice of the filling gas is determined by the regenerator form factor. (b) The optimum volume ratio for nitrogen is roughly 1.1, whereas for Helium it is around 0.7. (c) For Helium and Neon, the output power diminishes as the volume ratio rises. (d) The output power increases significantly when the regenerator form factor (length by diameter) <0.2 and then reaches an optimum of around 2.1 kW for the Helium case. (e) Among the four studied gases, the use of Helium allows obtaining the highest output power. On the other hand, it is observed that the lowest output power is obtained when using Argon. Inside Stirling engines, the use of lightweight monoatomic gases (with high thermal conductivity and heat capacity values) boosts the output power. There is a variation in power up to 50% depending on the properties of the filling gas.

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Experimental and Numerical Study of a Micro-cogeneration Stirling Engine for Residential Applications

Cited by 35 publications

References 7 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

Experimental and theoretical investigation of Stirling engine heater: Parametrical optimization

Theoretical investigations of Stirling engine performances for different filling gas properties

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