Analysis of a high performance model Stirling engine with compact porous-sheets heat exchangers

Abstract

A high performance model Stirling engine, in which the heater, regenerator and cooler as a whole is formed by hundreds of porous metal sheets, is identified for theoretical analysis to facilitate the future scale-up design. The reciprocating flow and heat transfer both in the heat exhcanger and in the full engine is simulated by a dynamic mesh Co mputational Fluid Dynamics (CFD) method, and is validated by analytical solutions and experimental data.An optimization method is also developed to incorporate the entropy generation caused by flow friction and irreversible heat transfer. The results show that relatively high indicated power of 33.4 W is obtained, corresponding to a specific power of 1.88 W/cm 3 and a thermal efficiency of 43.9%, which are attributable to the extremely small flow friction loss and excellent heat transfer characteristics in the regular shaped microchannels, as well as to the compact heat exchanger design that significantly reduces the dead volume. Given the same operating conditions, the optimized porous-sheets regenerator has a significantly lower total loss of available work wh ile maintaining even higher thermal effectiveness in comparison with the optimized conventional wire mesh regenerator.

Analysis on the heat transfer characteristics of a micro-channel type porous-sheets Stirling regenerator

“…A series of engine tests were done by Matsuguchi et al [8] to optimize the geometrical parameters of the porous-sheets regenerator. The recent work of the present authors, via dynamic mesh Computational Fluid Dynamics (CFD) method and experimental validation, indicates that the regular-shaped micro-channel type porous-sheets regenerator has extremely low flow friction while maintaining high thermal effectiveness, thus achieving significantly lower total entropy generation rate and leading to higher comprehensive performance [9]. 192 Analytical method possess some recognized advantages both in theory and application, such as clear physical concepts, logical reasoning, rigorous mathematical base, able to reveal various influencing factors and convenient for use, so as to substantially improve the efficiency of design optimization process.…”

“…Furthermore, for both cases, Nux approaches a constant value along the flow direction corresponding to that of the fully developed reciprocating laminar flow. In our recent work [9], via a dynamic mesh CFD method, it is shown that for a micro-channel flow passage with a hexagonal shaped cross section in a porous-sheets Stirling regenerator, the spatialcycle averaged Nusselt number has an almost constant value. In order for comparison, a series of dynamic mesh CFD simulation is performed in this work for a micro-channel flow passage with circular cross section in a porous-sheets Stirling regenerator.…”

Numerical configuration design and investigation of heat transfer enhancement in pipes filled with gradient porous materials

“…The enhancement of heat transfer has been extensively studied because it plays a critical role in the design of many devices applied in the power and energy fields [1][2][3][4][5][6][7][8]. Among many techniques available, porous material filling has become one of the most effective methods to enhance the heat transfer in many applications, including but being not limited to heat exchangers [1,2], combustion equipment [3], microchannel heat sinks [4], solar thermochemical reactors [5] and heat pipes [6].…”

“…Among many techniques available, porous material filling has become one of the most effective methods to enhance the heat transfer in many applications, including but being not limited to heat exchangers [1,2], combustion equipment [3], microchannel heat sinks [4], solar thermochemical reactors [5] and heat pipes [6]. Using porous materials to enhance the heat transfer in energy systems has many advantages.…”

An investigation of thermo-fluid dynamic performance of a Stirling engine regenerator by means of OpenFOAM

“…[6], they carried out a study of the same configuration as porous media. In [7][8][9] the complete engine working process is simulated together with the regenerator performance and both friction coefficient and thermal heat have been evaluated. In all these works, Ansys Fluent has been employed for such simulations.…”