59688 - Evaluation of Thermoacoustic Applications Using Waste Heat to Reduce Carbon Footprint 

Evaluation of thermoacoustic applications using waste heat to reduce carbon footprint

^aPhilip Spoor,

^aIndependent consultant, formerly Chart Industries, Ball Ground, USA

^bDeoras Prabhudharwadkar*, ^bSrinath Somu, ^bSaumitra Saxena, ^bDeanna Lacoste, ^bWilliam Roberts

^bClean Combustion Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia

*Corresponding author:

E-mail: deoras.prabhudharwadkar@kaust.edu.sa; Tel: +966128084697; Address: Clean Combustion Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia

Abstract

Thermoacoustics (T.A.) engines and refrigerators typically run on the Stirling cycle with acoustic networks and resonators replacing the physical pistons. Without moving parts, these T.A. machines achieve a reasonable fraction of the Carnot’s efficiency. They are also scalable, from fractions of a Watt up to kW of cooling. Despite their apparent promise, T.A. devices are not in widespread use, because outside of a few niche applications, their advantages are not quite compelling enough to dislodge established technology.

In the present study, the authors have evaluated of a selected group of applications that appeared suitable for utilization of industrial waste heat using T.A. devices, and arrived at a ranked order. The principal thought is to appraise if thermoacoustics can be a viable path from both economic and energy standpoint aiming at carbon mitigation for those applications. The applications considered include, cryogenic carbon capture for power plant exhaust gases, waste-heat powered air conditioning/water chilling for factories and office buildings, cryogenic energy storage, natural gas sweetening, hydrogen liquefaction, and zero-boiloff liquid hydrogen (LH2) storage. Although the criteria used for evaluation of the applications are somewhat subjective, but the overall approach has been consistent with same set of criteria applied to each of them. Thermo-economical analysis is performed to evaluate the system viability, together with an overall consideration of a thermoacoustic device’s general nature, advantages, and limitations.

From our study, we convincingly demonstrate that the most promising application is the zero-boiloff liquid hydrogen storage, which is physically well-suited to thermoacoustic refrigeration and requires cooling at a temperature and magnitude not ideal for standard refrigeration methods. Waste-heat powered air conditioning ranks next in its potential to be a viable commercial application. The rest of the applications have been found to have relatively lower potentials to enter the existing commercial space.