Thermoacoustic devices, such as refrigerators and heat pumps, present unique measurement challenges due to the simultaneous presence of rapidly fluctuating acoustic parameters and more stable thermal variables. Accurate and informative measurements during operation are crucial for developing effective control algorithms and optimizing performance under specific conditions. However, issues like inappropriate sampling frequencies and excessive data storage can lead to unintended averaging, compromising measurement quality. This study introduces a comprehensive experimental procedure aimed at enhancing the reliability of measurements in thermoacoustic systems. The approach encompasses meticulous experimental design, identification of measurement uncertainties and influencing factors during standard operation, and a statistical uncertainty analysis. Experimental findings reveal a significant reduction in temperature measurement uncertainty with increased thermoacoustic channel length and highlight the substantial impact of device structural features on performance. These insights are instrumental for refining measurement protocols and advancing the development of efficient thermoacoustic technologies.

Although the widespread introduction of numerical tools and the CFD models have improved the design methodology of thermoacoustic coolers and eased optimization of such units, high computational costs vitally limit their application in parametric analyses of thermoacoustic devices. Thus, experimental investigation remains essential field of research, considering design of such units. In the paper, the design and construction of an experimental setup, dedicated to perform an extensive multiparametric analyses on compact thermoacoustic devices with varying characteristic parameters, is discussed in detail. A complete design path, beginning with general consideration, with further detailed dimensioning and selection of market-available parts, ending with installation of control and data acquisition equipment, is described. Initial testing of the device, performed both computationally at the design stage and experimentally after the final setup assembling, is discussed as well. The results of the tests demonstrated ability to observe the variability in the operational parameters of the cooler following change in number of environmental and constructional parameters. The data acquired indicated vital importance of the stack porosity and frequency of the acoustic wave on performance of the thermoacoustic device, which corresponds to the data presented in the literature.

Due to escalating role of mitigation of climate change in power and energy sector, power units based on renewable energy sources (RES) became vital part of global power and heat market, including distributed heat generation as well. Significant number of such installations belong to individual users, commonly using solar collectors to prepare domestic hot water directly at their sites. However, the vitally variable solar irradiance makes the solar energy difficult in efficient harvesting considering long time period. Thus, maximization of power gain from single solar absorber, when the solar radiation flux is temporarily high, might lead to further rise in overall, year-averaged efficiency of such units. The paper concerns modelling of intensification of heat transfer, taking place within the absorber of a vacuum solar collector, due to insertion of vibrating element inside the thermal oil canal, compared to static turbulization method. Different geometries of vibrating elements and amplitudes of oscillatory motion, as well as heat carriers, are investigated using commercially available CFD software. Results indicate rise in solar power acquired within the absorber using vibrating elements, with essential difference between circulating media, and suggest vital benefits from utilization of static turbulizing devices.

Primary element of an oxy-combustion plants is ambient air separation unit. This paper presents the results of experimental research concerning the parameters of the separation of N2/O2 from ambient air, using capillary polymer membranes, potentially applicable in oxy-combustion technology, under variable operational conditions. Collected data were utilized to approximate continuous functions describing the variability of essential parameters of the air separation based on such membranes. The functions were introduced to develop a complete mathematical model of the separation unit, intended to be applied in oxy-Moderate or Intense Low Oxygen Dilution (oxy-MILD) zero-emission plants. Computational analyses were performed for three variants of the unit’s configuration: serial connection of membrane modules, unit with retentate recirculation and unit with permeate recirculation. The results of the research, in the form of sets of characteristic curves, depicting parameters of the separation process as a function of the variable operational conditions, show that crucial differences to the subsequent separation parameters (permeate purity, real selectivity coefficient, recovery coefficient) and with regard to the power consumed, were obtained. The highest parameters of the module were gained for serial connection, whereas the lowest – for permeate recirculation. The lowest energy consumption was acquired for the retentate recirculation variant.