Recovering cold energy generated in the regasification process of liquefied natural gas (LNG) can help to improve the energy efficiency of LNG power generation systems, meanwhile, abundant low-grade waste heat can also be exploited from the exhaust gas of gas turbines. This study proposes to apply the thermoacoustic Stirling electric generator to recover LNG cold energy and waste heat simultaneously. A pair of linear alternators is directly coupled with the thermoacoustic loop by replacing the long and bulky resonator completely. Numerical simulation is conducted on the basis of the thermoacoustic theory to characterize and optimize the operations of the system. The effects of the back volumes of linear alternators, feedback tube length and regenerator length on the output performances are investigated. The distributions of key parameters, including pressure, volume flow rate, phase difference, acoustic power and exergy flow, are further studied. One design of the thermoacoustic Stirling electric generator operated with 4áMPa helium gas is capable of generating 2.3ákW electric power with the highest exergy efficiency of 0.253 when the cold and hot ends are maintained at 110áK and 500áK. Performances can be further improved if the conversion efficiency of the linear alternators is further increased.
» Author: Kai Wang, Swapnil Dubey, Fook Hoong Choo, Fei Duan
» Reference: Energy, Volume 127
» Publication Date: 15/05/2017
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