Thermoacoustic heat transfer for energy conversion

• Main Author: Shantidass Yat-Ming Shum-Nader
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/141747
• Institution: Nanyang Technological University

With the increasing need of finding newer means to generate clean energy to reduce the effect of global warming, thermoacoustic systems are gaining attention with the possibility of utilising waste heat for renewable energy generation. These devices work on thermoacoustic effect that is an interaction between solid/stack surface and an inert working fluid in a thermal and hydrodynamic way by inputting heat from an external source to stack for temperature gradient is formed. These devices do not need chemical reactions, like combustion of fuel, for power generation. The key component of this system is the stack, which is responsible for facilitating thermoacoustic effect by generating temperature difference from pressure oscillation or vice versa. Hence, simplifying manufacturing of this device as it won’t require moving mechanisms to operate. Thermoacoustic systems are limited by their low efficiency & research into this system is needed to commercialise them. This paper pursues cost reduction in stack production and research on innovative material by using cheap and accessible materials for stack production & improved efficiency. These materials have experimented in a thermoacoustic heat pump prototype under various acoustic frequency, power, and stack positioning to determine the performance of the stack based on temperature difference and drive ratio. From the results, low-density steel wool and stainless steel mesh stack were discovered being the best performing material due to their relatively high-temperature difference of 6.85˚C and 7.917˚C. A novel stack design made of alternating fibre-glass and stainless steel mesh stack in hopes of achieving greater performance, however, preformed moderately with a temperature difference of 4.74˚C and lower drive ratio of 1.97. There are still diverse combinations of types of stack designs and materials with the potential of achieving greater thermoacoustic performance. Further studies can be conducted into different stack material & design, examples are an alternating stack of metal and plastic mesh sheets or porous material like metallic wool, for the thermoacoustic system.