A novel Franchot engine design based on the balanced compounding method

Daoud, Jafar M.; Friedrich, Daniel

doi:10.1016/j.enconman.2018.05.059

Cited by 4 publications

(9 citation statements)

References 29 publications

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“…The effect of piston weight on the thermodynamic forces is ignored due to the horizontal installation of the proposed machine. By applying Newton's second law of motion to each reciprocator, the force balance equation is given by

([], \begin{matrix} F_{1} \\ F_{2} \\ \begin{matrix} ⋮ \\ F_{n} \end{matrix} \end{matrix}) = ([], \begin{matrix} m_{1} \\ m_{2} \\ \begin{matrix} ⋮ \\ m_{n} \end{matrix} \end{matrix}) ([], {\ddot{x}}_{1} {\ddot{x}}_{2} \begin{matrix} \dots & {\overset{x}{true}}_{n} \end{matrix}) + ([], \begin{matrix} F_{l 1} \\ F_{l 2} \\ \begin{matrix} ⋮ \\ F_{italicln} \end{matrix} \end{matrix}),

where F i is the thermal driving force, m i is the total mass of reciprocating elements, F li is the load force, and x i is the reciprocator displacement. Unless otherwise stated, the parameter i goes from 1 to the number of reciprocators.…”

Section: Methodsmentioning

confidence: 99%

“…There are two mechanical friction sources in this configuration: friction due to the weight of the reciprocating masses and friction due to the side forces created by the cylinder offset. The side load due to piston friction can be calculated as

F = \frac{y}{L} ∆ F,

where y is the crank length and L is the distance between engine and cooler.…”

Section: Methodsmentioning

confidence: 99%

“…The multicylinder Franchot engine is a multiple engine configuration for which each engine has a distinct regenerator (see Figure ). Further details about the working principle of the multicylinder Franchot engine can be found in Daoud and Friedrich . These engines are either kinematically coupled to a common crankshaft or use the balanced compounding method to drive a free‐piston Stirling cooler.…”

Section: Direct Thermal Coupling Of the Franchot Engine With Cpcmentioning

confidence: 99%

“…For solar refrigeration, the Stirling refrigerator is mechanically coupled to the engine using the balanced compounding mechanism . The compression cylinder in the cooling machine can reject heat to the ambient similarly to the cold cylinder of the engine.…”

Section: Direct Thermal Coupling Of the Franchot Engine With Cpcmentioning

confidence: 99%

“…By increasing the number of cylinders, the mechanical vibrations are reduced and the Franchot engine becomes self‐starting . A new cranking mechanism based on the balanced compounding method for the multicylinder engine removes the need for rotational cranks and reduces the engine size . This mechanism is suitable for driving linear alternators, fluid pumps, and heat pumps.…”

Section: Introductionmentioning

confidence: 99%

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A new duplex Stirling engine concept for solar‐powered cooling

Daoud

Friedrich

2020

Int J Energy Res

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The global cooling demand is one of the fastest growing energy demands and is putting a strain on the electricity infrastructure. Solar-powered cooling could provide most of the cooling demand due to the coincidence of the cooling demand and the solar irradiance. In particular, the solar-powered Stirling-cycle cooler has low maintenance requirement, high theoretical efficiency, and use of environmentally friendly gases. However, Stirling-cycle coolers are expensive due to high driving temperatures, complex heat exchangers, and expensive solar tracking so that they have so far only been successful at high-temperature difference applications. This study introduces a novel directly coupled solar Stirling cooler for which the hot engine cylinders are deployed inside evacuated tube collectors. The machine uses air as working fluid, and its driving mechanism is based on the free-piston, balanced compound technology that was patented by Finkelstein. A second-order mathematical model is used to investigate the performance of the machine for different cylinder arrangements, gas leakage rates, chilling temperatures, and solar irradiance. In addition, the regenerators are optimised to maximise the cold production. It is shown that mechanical frictions can be reduced to 20% by selecting an appropriate cylinder arrangement. The solar cooler achieves a maximum cold production rate of 367.5 W/m 2 without using external heat exchangers at load temperature of 7 C, which is comparable with photovoltaic powered coolers.In addition, the machine is relatively simple, has safe and quiet operation, uses ambient air as working gas, and is able to produce a wide range of chilling including sub-zero temperatures without changing the working gas. The direct thermal coupling of the Stirling cooler to evacuated tube collectors significantly reduces the complexity of the machine and removes intermediate heat transfer steps which reduce the performance. Thus, the suggested cooling technology has great potential for solar refrigeration, especially for low power and near ambient cooling.

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([], \begin{matrix} F_{1} \\ F_{2} \\ \begin{matrix} ⋮ \\ F_{n} \end{matrix} \end{matrix}) = ([], \begin{matrix} m_{1} \\ m_{2} \\ \begin{matrix} ⋮ \\ m_{n} \end{matrix} \end{matrix}) ([], {\ddot{x}}_{1} {\ddot{x}}_{2} \begin{matrix} \dots & {\overset{x}{true}}_{n} \end{matrix}) + ([], \begin{matrix} F_{l 1} \\ F_{l 2} \\ \begin{matrix} ⋮ \\ F_{italicln} \end{matrix} \end{matrix}),

Section: Methodsmentioning

confidence: 99%

F = \frac{y}{L} ∆ F,

where y is the crank length and L is the distance between engine and cooler.…”

Section: Methodsmentioning

confidence: 99%

Section: Direct Thermal Coupling Of the Franchot Engine With Cpcmentioning

confidence: 99%

Section: Direct Thermal Coupling Of the Franchot Engine With Cpcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new duplex Stirling engine concept for solar‐powered cooling

Daoud

Friedrich

2020

Int J Energy Res

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Modeling of the dynamic characteristics and performance of a four‐cylinder double‐acting Stirling engine

et al. 2020

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Summary In this article, a theoretical model that combines thermodynamic and dynamic models is proposed for predicting the performance and transient behavior of a double‐acting Stirling engine with four cylinders. A thermodynamic model is used for predicting the variation of thermal properties of working fluid. The temperature of a regenerator matrix is also solved. The volume variations of working chamber in the thermodynamic model are obtained by solving the dynamic model simultaneously. In this study, wobble yoke mechanism is adopted. The dynamic properties of the linking mechanism, such as displacement, velocity, and acceleration are solved by the dynamic model. The shaft power and total efficiency of the engine under different operating conditions and with different design parameters can be simulated. The simulation results show that the present engine can reach the maximum power of 1099 W at 1312 rpm with the total efficiency 19%. The model can be further applied to double‐acting Stirling engine design and modification.

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Design of the multi-cylinder Stirling engine arrangement with self-start capability and reduced vibrations

Daoud

Friedrich

2019

Applied Thermal Engineering

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The Franchot engine is a double acting Stirling engine that has a freely controllable phase angle and no shuttle and axial conduction losses but is inferior to the Siemens and free piston Stirling engines in terms of its ability to self-start. In addition, the Franchot engine is not widely used with the reliable slider crank mechanism due to vibrations. Here, the multi-cylinder Franchot engine is thermodynamically and mechanically studied with the simple slider crank mechanism with the aim of improving the self-start capability and to reduce the vibrations. Both instantaneous power and engine arrangements are used to judge the mechanical performance for different engine parameters and configurations. The optimal phase shifts and phase angles are derived and it is shown that both are governed by the number of cylinders. The theoretical analysis shows that by increasing the number of cylinders, different engine vibrations are reduced and the engine becomes self-starting. Hence, the Franchot engine can be superior to the Siemens engine, particularly due to the ability to remove the rocking couples for engines with more than two phases. Thus, the engine operation is stabilised and the simple slider crank mechanism can be used with the multi-cylinder Franchot engine.

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A novel Franchot engine design based on the balanced compounding method

Cited by 4 publications

References 29 publications

A new duplex Stirling engine concept for solar‐powered cooling

A new duplex Stirling engine concept for solar‐powered cooling

Modeling of the dynamic characteristics and performance of a four‐cylinder double‐acting Stirling engine

Design of the multi-cylinder Stirling engine arrangement with self-start capability and reduced vibrations

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