This article presents the current state of the art regarding the use resonators in straight pipes. There is considerable need to control and reduce pressure pulsation in pipelines supplied with pulsating flows. The use of a Helmholz resonator introduces an additional degree of freedom to the analysed dynamic system. Building on previous experimental investigations by the authors, which identified the nonlinear properties of straight pipes supplied with pulsating flows, this study describes an experimental test rig, measurement methods and mechanical analogies for one (1DOF) and two (2DOF) degrees of freedom. The results are presented in the form of a 3D map of amplitude-frequency characteristics, as a function of the resonator volume determined by piston height. The dynamic properties of the described system are presented as amplitude-phase characteristics, based on a comparison of the numerical and experimental results.

The evidence gathered during works on two prototype heat recovery systems is summarised. The first installation is a low-temperature vapour recompression system, whereas the second is a high-temperature (from an industrial viewpoint) installation. Vapour-contaminated air is the working medium. The authors focused their attention on machine issues mainly. All compressors described below were designed at the Lodz University of Technology.

In this paper modernization of a three-stage chlorine centrifugal compressor, in which chlorine is pressurized has been described. Machine nominal mass flow has been increased by 20% and the pressure rise has remained almost unchanged. New construction concept has been chosen basing on analysis of different design variants. Calculations were conducted with one-dimensional method with usage of in-house developed code. Algorithms implemented to this program are based on empirical studies and wide experience in compressor modernization and design. Moreover, results of modified machine acceptance test results, which satisfies VDI norm 2045/ISO 5389 has been presented.