Experimental research of thermoacoustic engines with two-phase working body

Abstract

A distinguishing feature of these days is the general tendency to decrease the temperature level of the waste heat of engines for power plants in industry, transport, and energy. These circumstances complicate the usage of traditional energy-saving technologies designed to transform this heat into mechanical work. Given the lack of effective technologies, large volumes of such heat emissions are lost. As an example, we can consider ship power engineering. On ships that are equipped with dual-fuel medium and low-speed engines, the thermal emissions of the cooling systems have a temperature of 355…365 K. Given the small exegetical potential, the use of such low-temperature waste energy sources by any heat engines is a difficult problem. Therefore, the task of improving existing energy-saving technologies or developing new ones remains relevant. Thermoacoustic technologies can be useful in solving this problem. A significant advantage of thermoacoustic heat machines is the ability to use any external heat source, in this case low-temperature sources, and produce mechanical work. There are known cases of thermoacoustic oscillations at small temperature differences between heat sources under conditions of high humidity of the working environment. This phenomenon can be used to create low-temperature energy-saving systems based on thermoacoustic engines (TAE) with a wet two-phase working environment. The practical use of thermoacoustic systems as part of ship power plants requires additional research to solve low-level issues, in particular, increasing the specific power of the TAE. This work provides a description of the experimental equipment, design of experimental TAE with a wet working body and research methods. The results of the experiments showed that in experimental TAEs with a two-component (moist) working environment, the temperature of spontaneous thermoacoustic oscillations was 355…359 K, while the longitudinal temperature gradient in the matrix was 1.19…1.30 K/m. The specific power of TAE with a moist environment increased by 1.7…7 times, and the acoustic pressure increased by 2…4.7 times compared to the operation in dry air. It is shown that in the existing TAEs, the condensation of water vapor in the ceramic matrix and on the surfaces of the heat exchangers can lead to a loss of power, roughly up to 25 %, while maintaining the operational capacity.