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Witanowski, Łukasz
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Witanowski
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Łukasz
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Łukasz Witanowski
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COMPREHENSIVE ANALYSIS OF ORC-VCC SYSTEM FOR AIR CONDITIONING FROM LOW-TEMPERATURE WASTE HEATWitanowski, ŁukaszDue to the need to reduce electricity consumption, methods of increasing the efficiency of energy use are being sought. One of the possibilities is the use of low-temperature waste heat for the production of electricity or cooling. Systems that convert heat into cold seem particularly attractive. This approach allows, above all, the removal of the generator. It eliminates the electrical part of the expander and, as a consequence, increases the efficiency of waste heat utilization, simplifies the construction of the ORC turbogenerator, and removes certain restrictions. The paper presents an analysis of the ORC-VCC cycle using waste heat at a temperature of 95℃ and heat up to 130kW. Various novel working fluids (e.g. R1224yd(Z), R1233zd(E), R1336mzz(Z)) are considered. Selected fluids are characterized by low global warming potentials. An in-house code was developed and used to calculate cycle parameters. Single and multi-objective optimization was performed, aiming at the maximization of the ORC efficiency, Net Present Value (NPV) and the Internal Rate of Return (IRR). Pareto frontiers were obtained, and a decision-making method was used to select an optimum solution. The obtained ORC efficiency was 5.25%, COPVCC 0.47 and the cycle efficiency was above 27.1%.- Evaluation of the performance of an axial one-stage 10kW turbogenerator through experimental testingKlimaszewski, Piotr; Klonowicz, Piotr; Witanowski, Łukasz; Suchocki, Tomasz; Lampart, Piotr; Ihnatowicz, Eugeniusz; Antczak, Łukasz; Zaniewski, Dawid; Jedrzejewski, ŁukaszThe paper describes the results of experimental research on a prototype one-stage turbo-generator with a nominal power of 10 kW and a rotational speed of 24 000 rpm. The expander at the Institute of Fluid- Flow Machinery, Polish Academy of Sciences was developed as part of the R&D project with Marani company. The unit construction consists of an overhanging rotor and shaft mounted on rolling bearings. The turbo-generator was tested on a specially constructed laboratory test stand in the first stage. Compressed air instead of refrigerant gas (R1233zd) was used. The test results converged with the parameters obtained using the RANS simulation. The convergence for the turbine mass flow was 97% of the value obtained in the CFD model, which is satisfactory. The power generated by the turbogenerator, which was compared at this stage, also achieved satisfactory convergence (95% to 97%) with the calculation model. These tests allowed determine the compliance of the adopted design assumptions and confirmed the correctness of the calculation tools used. The next stage of work was to examine the ORC unit in operating conditions. That stage was aimed at checking the correct work of the machine with the ORC system. The turbine achieved internal efficiency calculated from temperatures at a level slightly lower than that obtained from numerical calculations (total-to-static efficiency). The efficiency was equal to about 73%, and the difference between calculated and measured values do not exceed 0.25 pp. (percentage point). The electric efficiency was about 65% and a maximum electric power output of 6.8 kW was measured.
