4 research outputs found
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Study of Multiphase Flow at the Suction of Screw Compressor
Screw compressors are commonly used for industrial and commercial gas processing and refrigeration. These machines are known to be able to admit mixtures of gasses and liquids to a certain concentration. In oil injected compressors, oil is mostly injected in the working domain to seal, cool and lubricate. But would the injection of atomized oil or other liquid in the suction of the compressor be useful for better control of the discharge temperature and reduction in energy consumption, is still to be determined. Similarly, liquid neutral to the process may be injected in an oil free compressor suction to help controlling discharge temperature. It can be erosive and corrosive to the compressor rotors. Therefore mapping a two phase suction flow of a screw compressor may help in understanding the means to improve compressors efficiency and reliability. This paper is the initial phase of PhD program to determine the multiphase flow characteristic at suction of twin screw compressors by means of experimental techniques. Review of most common and up to date measurement techniques in field of multiphase flow was carried out to determine their suitability and feasibility. Also Modelling of single and multiphase flow at the suction domain of a twin screw compressor were performed in order to have a better understanding of flow distribution. The research is performed on an oil free screw compressor with βNβ rotor profiles of 128 mm and configuration of 3/5 lobes with L/D of 1.6 and 93 mm centre distance. A simplified CFD model of only suction domain which reduces computational time was compared with the CFD model of the entire compressor and it was found that it predicts most of flow features with same accuracy. The experimental study which will be used to validate the CFD model has been presented
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Numerical and Experimental Investigation of Pressure Losses at Suction of a Twin Screw Compressor
Rotary twin screw machines are used in the wide range of industrial applications and are capable of handling single and multiphase fluids as compressors, expanders and pumps. Concentration of liquid in the inlet flow can influence the performance of the machine significantly. Characteristics of the multiphase flow at the suction of a screw compressor depend on the local flow velocities and concentration. Local flow velocity measurements inside the screw compressors are difficult to obtain. However other flow properties such as local pressures are easier to attain. It is therefore useful to carry out experiments with local pressure variations in the suction which can be used to validate the 3D numerical Computational Fluid Dynamic (CFD) models that could help in studying the single and multiphase flow behaviour in screw compressors.
This paper presents experimental efforts to measure the local pressure losses inside the suction plenum of the screw compressor. Pressure variations are measured at 23 locations in the suction port at various operating conditions and compared with 3D CFD model. The grid generator SCORGTM was used for generating numerical mesh of rotors. The flow calculations were carried out using commercial 3D solver ANSYS CFX. It was found that the local pressure changes predicted by the CFD model are in the good agreement with measured pressures. This validated the use of CFD for modelling of the single phase flows in suction of screw machines
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Experimental study of radial low specific speed turbocompressor running in reverse as turboexpander
This paper includes small market research in the field of turboexpanders. The market research includes list of applications as well as list of some of major manufacturers of turboexpander. During the course of this research numbers of experiments were carried out to assess the performance of a small turboexpander with 65mm diameter rotor operating at relatively low speeds in comparison to standard radial turbines. The output power of the turboexpander was calculated based on the electrical output of the loading generator. The turbine rotor comprised of a TurboClaw compressor operating in reverse with two set of experiments for the following nozzles; as expander with single nozzle and a set of six nozzles. It was found that even for a non optimised geometry (rotor is a compressor not a turbine) the system efficiency for micro turboexpander is excellent