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Optimization of air transport in the fan chamber with a free impeller
Cakl, Dominik ; Bašta, Jiří (referee) ; Cifrinec, Ivan (referee) ; Rubina, Aleš (advisor)
The work deals with the improvement of the hydraulic properties of air transport in fan chambers with free impeller wheels, which are equipped in every larger central air handling system. Every larger central air handling system is equipped with a fresh air intake that transports the air into a fan chamber, which contains a free-wheel fan that provides air transport and provides kinetic energy to the air stream. From the fan chamber, the air is further transported by the air handling system to the individual distribution elements. Similiary, the extraction of polluted air is solved through the fan chamber. The turbulent flow of air at the outlet of the impeller causes a pressure loss in the discharge chamber of the air handling unit, as the air is transported in pulses according to the slip of the blades. In practice, fans with smaller performance parameters measured in laboratories under ideal boundary conditions are installed in air handling units, which do not solve the problem of the difference in real traffic pressure between the supply and exhaust air ducts, with the result that the installed fans in the real fan box do not reach the parameters specified by the manufacturer. Reduction the pressure losses in fan chambers is correlated with the reduction of energy consumption of equipment ensuring air transport in the context of sustainable construction. Based on the development of aerodynamic efficiency of fans and European legislation, the current trend of a significant reduction in energy consumption was described, among other things, for equipment providing air transport, through repairs, reuse, repurposing and recycling of used materials, and through extending the life of products and buildings. Furthermore, three research principles and methods of improving the efficiency of equipment in order to reduce the energy demand of equipment ensuring air transport are presented, the authors of which approach the research numerically and experimentally. The goal of the original technical solutions presented in this work is to present a development that optimizes the pressure losses of a fan chamber with a free impeller. The first solution describes the principle of lead-in plates, where the goal is to help the air stream eliminate the negative effects of swirling and facilitate the outflow of air from the fan chamber by means of a smooth slide along an inclined surface, which reduces the specific power of the fan, under the given marginal conditions, by up to 5.9 %. The essence of the second innovative technical solution is to present a free impeller, which is based on the connection of two rows of curved blades of concave and convex shape, which serves to optimize the pressure loss of the fan chamber with a free impeller, which produces smaller, more uniform, mutually interacting currents that help the flow of air to more smoothly change the direction of swirling in the fan chamber and which found practically no value for the specific measured boundary conditions. The essence of the third innovative technical solution is the introduction of modern production of products from "sustainable" materials with the help of 3D printing, in the form of a free impeller for fans with a free impeller. The results of geometric copies of free impellers made of lighter material reflect that there was a reduction in the average specific power of the fan by up to 4.4 %, while at the same time there was a reduction in the total sound level.
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Acoustics of small fans
Hájková, Lenka ; Rubina, Aleš (referee) ; Cifrinec, Ivan (referee) ; Hirš, Jiří (advisor)
Dissertation thesis falls within area of indoor climate and deals with investigation of acoustic microclimate in sanitary rooms of residential buildings during a mechanical ventilation. Sources of a noise in these areas are small fans. The thesis contains the evaluation of the existing situation concerning the referred issue, physical laws of acoustics and theoretical basics of acoustics of air conditioning. The part of the thesis is experimental measurement which aims to evaluate the situation in real applications and the possibility of influencing the acoustic microclimate by affixing of small fans on the building structure. The work contains a model for the verification of certain anticipated dependencies and theoretical investigation of the distribution of sound pressure levels in the sanitary room, depending on the location of the noise source. The last part of the work offers possible measures to improve the acoustic microclimate and elimination of the noise in sanitary rooms and in protected areas of residential buildings.
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Acoustics of small fans
Hájková, Lenka ; Rubina, Aleš (referee) ; Cifrinec, Ivan (referee) ; Hirš, Jiří (advisor)
Dissertation thesis falls within area of indoor climate and deals with investigation of acoustic microclimate in sanitary rooms of residential buildings during a mechanical ventilation. Sources of a noise in these areas are small fans. The thesis contains the evaluation of the existing situation concerning the referred issue, physical laws of acoustics and theoretical basics of acoustics of air conditioning. The part of the thesis is experimental measurement which aims to evaluate the situation in real applications and the possibility of influencing the acoustic microclimate by affixing of small fans on the building structure. The work contains a model for the verification of certain anticipated dependencies and theoretical investigation of the distribution of sound pressure levels in the sanitary room, depending on the location of the noise source. The last part of the work offers possible measures to improve the acoustic microclimate and elimination of the noise in sanitary rooms and in protected areas of residential buildings.
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