Porous Cores in Small Thermoacoustic Devices for Building Applications

Fabio Auriemma,Elio Di Giulio,Raffaele Dragonetti,Marialuisa Napolitano

doi:10.3390/en13112941

Fabio Auriemma, Elio Di Giulio + Show 2 more

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https://doi.org/10.3390/en13112941

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Abstract

The thermoacoustic behavior of different typologies of porous cores is studied in this paper with the goal of finding the most suitable solution for small thermoacoustic devices, including solar driven air coolers and generators, which can be used in future buildings. Cores provided with circular pores, with rectangular slits and with arrays of parallel cylindrical pins are investigated. For the type of applications in focus, the main design constraints are represented by the reduced amount of the input heat power and the size limitations of the device. In this paper, a numerical procedure has been implemented to assess the behavior of the different core typologies. For a fixed input heat power, the maximum acoustic power delivered by each core is computed and the corresponding engine configuration (length of the resonator and position of the core) is provided. It has been found that cores with parallel pins provide the largest amount of acoustic power with the smallest resonator length. This conclusion has been confirmed by experiments where additive manufactured cores have been tested in a small, light-driven, thermoacoustic prime mover.

Highlights

This paper addresses the main technical problems involved with the use of small thermoacoustic heat engines—prime movers and heat pumps—in building applications
The main goal is to to compare different solutions in order to find out the one which better fits building applications compare different solutions in order to find out the one which better fits building applications where where the available power is limited. Another important parameter which willbebeassessed assessedisis the the the available input input power is limited. Another important parameter which will ability of different cores to work with small resonator lengths, which is often a further constraint for ability of different cores to work with small resonator lengths, which is often a further constraint for building applications
The numerical procedure described in Section 2.2.2 is used to compare the performance of the porous cores listed in Table 2 in a thermoacoustic standing wave prime mover

Summary

Introduction

This paper addresses the main technical problems involved with the use of small thermoacoustic heat engines—prime movers and heat pumps—in building applications. A linear generator, a reversed loudspeaker or a piezoelectric device can be combined with the prime mover to perform the acoustic-to-electric power conversion [5,6] This kind of solutions can help reducing the total emissions of future buildings. Thermoacoustic heat engines (TAHE) exploit the thermal diffusion process occurring in internal porous cores in order to pump mechanical energy into the working fluid or to extract heat from it [7]. These cores act as thermal reservoirs, providing heat exchanges between the solid surface of the pores and the oscillating fluid. Large viscous losses take place in the fluid within the porous core

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