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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Termodynamické tepelné čerpadlo / Thermodynamic Heat pump

Knebl, Viktor January 2020 (has links)
This diploma thesis deals with the design of thermodynamic heat pump, used to utilize thermal energy of flue gases arised from the combustion of natural gas in a heat exchanger. The flow rates of the compader compressor, bypass compressor and turbine are calculated. Part of this thesis is simplified design of gearbox and economical evaluation of heat pump installation. The appendix of the thesis contains technical documentation.
2

Termodynamické tepelné čerpadlo / Thermodynamic heat pump

Kadlec, Stanislav January 2017 (has links)
The aim of the Diploma Thesis is to discuss the design and construction solution for circulation of the thermodynamic heat pump especially used in the heating industry with stoichiometric combustion of chosen natural gas. The basic components of the proposed heat pump are turbine, compressor and gearbox. To solve the presented aims, the thermodynamic calculation of the individual components, the determination of the efficiency of the whole equipment and the analysis of the physical properties of the natural gas with regard to the specified input and output parameters were considered. In addition, an analysis of the individual components design of the proposed equipment was carried out, on the basis the technically most acceptable variant was chosen and the equipment construction was carried out incl. connecting elements. Drawing documentation is part of the attachments. On the basis of the analysis, it can be stated that the proposed plant leads to energy savings, is ecologically sufficient and has been shown to have approximately twice the amount of heat dissipated than without its use.
3

Morphology, Crystallization and Melting Behavior of Propylene-Ethylene Statistical Copolymers

Uan-Zo-li, Julie Tammy 25 October 2005 (has links)
In this work the morphology, crystallization and melting behavior of novel Dow Chemical propylene-ethylene copolymers were investigated. The incorporation of ethylene units into a polypropylene chain resulted in the decrease in crystallization, melting and glass transition temperatures and overall crystallinity. Based on the shape of heat capacity curves and the dependence of the melting temperature offset on ethylene content, it was concluded that copolymers prepared using different catalyst systems exhibited different ethylene sequence length distributions. The behavior of Dow Chemical propylene-ethylene copolymers was compared to that of copolymers prepared using traditional metallocene and Ziegler-Natta catalysts. The catalyst system used in the preparation of these new copolymers is similar to a metallocene catalyst system. It was demonstrated that ethylene defects are partially included in the polypropylene crystal. The thermodynamic heat of fusion at the equilibrium melting temperature decreased by 44% with an increase in ethylene concentration from 0 mol% to 21.2 mol%. On the basis of calorimetric and density data, the inclusion model based on the Sanchez-Eby crystallization theory was shown to be applicable for the evaluation of the degree of crystallinity. At the same time, inadequacies were found in application of the rigid amorphous fraction model to these copolymers. The formation of gamma-phase crystals was shown to be favored by both an increase in the ethylene content and a decrease in the crystallization rate. Increase in the ethylene content was shown to lead to a decrease in the density, length and thickness of alpha-phase crystals. It was also demonstrated that the cross-hatching morphology is present in all propylene-ethylene copolymers. / Ph. D.

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