Synchronization of coupled Stirling engines

Abstract

Abstract:Because of an increasing demand on electric power and limited resources for conventional fuels, highly efficient engine that is capable of converting energy resource to electric power with a small loss is awaited. In this respect, Stirling engine provides a strong potential because of its efficient thermodynamic cycle, which is ideally close to the theoretical limit of the Carnot cycle. Practical use of the Stirling engine, however, has been limited because of its low output power. Towards its wider applicability, simultaneous operation of many individual Stirling engines is indispensable to increase the output power. This paper presents an experimental study of synchronized dynamics of two coupled Stirling engines. It is shown that the synchronized operation of the population of engines provides a key technology to extend the system size so as to produce a large-scale electric energy.

Experimental study on entrainment of Stirling engines to an external pacemaker

“…Compared to the power of P total = 161 W generated by the independent engines with their natural frequencies, the output energy was significantly increased to P total = 358 W in the synchronized state, indicating the increase of 186 %. Compared to the increase of 60 % achieved by the directly coupled Stirling engines in our previous study [2], the present result has been highly improved. This clearly demonstrates the significance of realizing the synchronized oscillations of the Stirling engines for the use of their population sum as the output energy.…”

“…In the previous study [2], two Stirling engines were directly coupled to each other to realize their synchronization. It has been shown that the synchronized engines produced much higher electric power than that of the nonsynchronized engines.…”

“…In our previous study, two Stirling engines were directly coupled to each other so as to realize the synchrony. It has been shown that the synchronized engines produced much higher energy than that of nonsynchronized engines [2]. The disadvantage of the coupled systems was that oscillation frequencies of the coupled engines were lowered from their natural frequencies.…”

“…According to the theory of phase reduction [3], a weak interaction is sufficient to entrain a limit cycle oscillator, if n times of its natural frequency is very close to m times of the pacemaker's frequency (n, m: integers). Because of its simplicity, the theory of weakly coupled phase oscillators has been applied to a variety of systems in science and engineering [4][5][6] including mutually coupled Stirling engines [2]. Here, the idea of phase oscillators is applied to the entrainment of Stirling engine to an external pacemaker, whose natural frequency is set to be close to n/m of the natural frequency of the Stirling engine.…”

Synchronization of Two Coupled Crystal Oscillators

“…Theoretical studies of synchronization of the limit cycle and chaotic oscillators have been carried out for many years [1]. From the experimental side, synchronization phenomena are observed in various oscillators, e.g., Stirling engines [2], metronomes [3] and candles [4]. Synchronization phenomena rely on the assumption that the oscillators are coupled with each other.…”