Development and assessment of a score™ demo2.1 thermo-acoustic engine

The early low-cost,wood burning thermo-acoustic engine (tae) known as demo2.0-build-1 was developed by score™ at the uk centre and was capable of achieving 22.7 watts of electricity. this prototype was limited to an operating temperature of about 300°c and due to excessive leaks could not operate continuously above ambient pressure. to absorb a thermal heat input of 4.4 kw from the burning wood so as to fulfil the required acoustic power,the hot heat exchanger (hhx) requires heating to the highest possible temperature. therefore,a corrugated stainless steel plate hhx design that maximises heating surface area was adopted to the current demo2 tae design. in addition,the system is often pressurised to achieve higher acoustic intensity. rigorous sealing of the system at high temperature is also required. a demo2.1 tae design based on the demo2 tae design and its prototype which is developed recently by the score™ centre in malaysia was successfully constructed and well integrated with the stove. during the early construction and assembly process,fabrication difficulties and serious leak problems around the hhx's edges were found when the apparatus operated at high temperatures. this is because the uneven geometrical hhx (convolution profile) makes it difficult and relatively costly to be sealed. the demo2.1 tae is focused on the sealing efficiency and effective manufacturing cost by meantime to allow further modification variation. the design was made to adopt the local manufacturing technologies and materials available or easy to access in malaysia. it also aims to minimise the parasitic heat losses to lower the system onset temperature. by removing the linear alternator and tuning volume from the system,preliminary measurements shown that the apparatus was oscillating at the frequency of 70 hz. a much lower onset temperature was observed at around 144°c for the new configuration when the apparatus was oscillating at approximately 200 pa. this paper describes the main design features of the demo2.1 tae including easy fabrication and assembly methodology,together with apparatus construction and rig test assessment. © school of engineering,taylor's university.