|
|
Analysis of Heat Transfer in the Air Gap of Electrical Machines Using Empirical Equations and Computational Fluid Dynamics
Súkeník, Jakub ; Toman, Marek
This paper deals with the thermal analysis of the air gap using empirical equations and computational fluid dynamics (CFD). First, empirical equations are introduced to calculate the air gap heat transfer coefficients. The thermal air gap model is shown. Next, numerical modelling is discussed, namely the shear stress transport k-omega model. Afterwards, parametric air gap models are presented. The air gap heat transfer coefficients calculated from empirical equations are compared with the air gap heat transfer coefficients from CFD. Next, a comparison between the thermal resistances calculated using the empirical equations and between thermal resistances of CFD is shown. Finally, velocity air gap profiles with air gap temperature contours are presented.
|
|
|
Thermal Model of a Permanent Magnet Synchronous Motor
Staněk, Jan Filip ; Súkeník, Jakub (referee) ; Toman, Marek (advisor)
This work deals with research on the topic of thermal calculations of synchronous machines with permanent magnets. In the first part, the basic mechanisms of heat transfer are described, the connection between thermal and electrical quantities is shown, and the procedure for calculating temperatures using a thermal network is shown. In the second part, a survey of used thermal networks for thermal modeling of synchronous motors is carried out. In the third part, the thermal resistances of some geometric bodies of which the machine is composed are derived and the heat transfer coefficients are described. In the next part, the geometric parameters of the machine are presented. In the fifth part, thermal models of the rotors are created and their verification is carried out. In the last part, the complete thermal network of the engine is shown and the resulting mean temperatures are listed.
|
|
|
Short time overload of cables in UPS applications
Toman, Dominik ; Pravda, Luděk (referee) ; Šimek, David (advisor)
This bachelor’s thesis is about dimensioning power cables in electrical instalation which is described in the third chapter. If is used cable with small cross-section, relatively high direct current which is flowing through these cables could cause too high warming. Function of this electrical instalation and comparison of batteries which should be possibly used, are described in the first chapter. Second chapter shows risk of using cable with small cross-section, which could be overheated due to current overloading. Cables are designing in accordance with IEC 60364-5-52, IEC 60364-5-54 and duty cycle. Cross section values calculated according to all methods are very different. Cross section calculated in accordance to IEC 60364-5-54 and duty cycle are smaller then cross-section values calculated in accordance to IEC 60364-5-52. Cable with smaller cross section is cheaper, but it is possible that smaller cross section could cause bigger warming. This thesis also contains thermal model and warming measurement, both methods are for verification that cable with smaller cross-section could be used. Third chapter also contains calculations of voltage drops on all calculated cross-sections. Values from thermal model and warming measurement are different but they are both confirming that the cable with smaller cross section could be used.
|
|
|
Thermal management for mission CIMER
Borovička, Matej ; Lazar, Václav (referee) ; Götthans, Tomáš (advisor)
Táto práca sa zaoberá tepelnou analýzou CubeSatu, pričom vyhodnotenie a následná implementácia výsledkov do samotnej konštrukcie družice je veľmi dôležitá na zabezpečenie správneho fungovania všetkých jej komponentov. V prvej časti je opísaná problematika tepelnej analýzy a návrhy pre vesmírne aplikácie. Druhá časť je venovaná tepelnému návrhu nanosatelitu CIMER, ktorého úlohou je kultivácia cyanobaktérií na nízkej obežnej dráhe Zeme. Sinice majú veľmi špecifické požiadavky, pokiaľ ide o teplotný rozsah, v ktorom môžu prežiť. Táto analýza je preto veľmi dôležitá pre fungovanie celej misie. Práca opisuje vytvorenie tepelného návrhu v softvéri Systema Thermica, jeho následnú analýzu a vyhodnotenie. Nakoniec je model upravený na podmienky potrebné na prežitie siníc vo vesmíre.
|
|
|
Coupled modeling of induction motor using finite element method
Gregor, Tomáš ; Huzlík, Rostislav (referee) ; Vlach, Radek (advisor)
This thesis describes complex modeling of asynchronous motor by finite element method. Complex modeling concerns to making models based on different physical principles and their connection. Models are made in Ansys program components and their connection is made in program Ansys Workbench. This thesis includes creating electromagnetic model, thermal model, mechanical model and coupled model which connect partial models.
|
|
|
Thermal analysis of servomotor
Přibyl, Daniel ; Duroň, Jiří (referee) ; Klíma, Petr (advisor)
This thesis deals with the design of the thermal model of servomotor in program Motor-CAD and using it for analyze of servomotor. In the beginning is a short familiarization about its parts, especially important for the thermal model. Further are described principles of heat exchange. There is a chapter, which is dedicated to the program support of the Motor-CAD. Thermal model and electromagnetic model inputs are tuned according to the measured data. Then a way of active cooling is designed and based of it the model in program is edited. Using the model is found the points of load of the motor for maximum allowable temperature with water cooling. In the conclusion is a valorization of benefit of water cooling for the servomotor.
|
|
|
Modeling and Control of Electric and Thermal Flows in Fully Electric Vehicles
Glos, Jan ; Horák, Bohumil (referee) ; Janeček, Eduard (referee) ; Václavek, Pavel (advisor)
Systematické řízení tepelných a elektrických toků v plně elektrických automobilech se stává velmi důležitým, protože v těchto typech automobilů není k dispozici dostatek odpadního tepla pro vytápění kabiny. Aby v zimním období nedocházelo ke snížení dojezdu, je nutné použití technologií, které umožní snížení spotřeby energie nutné k vytápění kabiny (např. tepelné čerpadlo, zásobník tepla). Je také zapotřebí vytvořit řídicí algoritmy pro tato zařízení, aby byl zajištěn jejich optimální provoz. V letním období je nezbytné řídit tepelné toky v rámci elektromobilu tak, aby nedocházelo k nadměrnému vybíjení baterie kvůli chlazení kabiny a dalších částí. Tato práce řeší jak návrh řídicích algoritmů, tak i vývoj rozhodovacího algoritmu, který zajistí směřování tepelných toků.
|
|
|
Modeling of the thermal effects on living tissue during electroporation process
Kafka, Roman ; Cipín, Radoslav (referee) ; Červinka, Dalibor (advisor)
The work deals with the current state of knowledge of heat transfer in living tissue. It is described here what the distribution of heat is affected with and the existing calculation options. For solving Pennes equation using finite element method COMSOL Multiphysics 5.4 is used. From the current state of the published studies, three are selected and described, each using a different approach. Based on the benefit of each of the studies described, a simple model of its own that simulates an ablation catheter attached to cardiac tissue is solved. A change in electrical conductivity as a function of the electric field intensity is taken into account, but there is also a comparison with anisotropic tissue that has electrical conductivity in different directions. The result of the calculation is voltage distribution, density of electric current and losses, temperature distribution in the model at several time points and graph of temperature development over time.
|
|
|
Milling spindle thermal model
Chlapek, Ondřej ; Musil, Filip (referee) ; Hadraba, Petr (advisor)
The aim of this thesis is to create two thermal models (black box and grey box), which would allow to predict the development of the milling spindle temperature, based on measured operating data. The accuracy of both created models was determined by statistical methods, and the models were compared with each other.
|
|
|
Thermal calculation of electric motor with permanent magnets and squirrel cage
Homolová, Romana ; Bárta, Jan (referee) ; Toman, Marek (advisor)
In the first part, this project deals with the elaboration of a Line Start Permanent Magnet Synchronous Motor. Possible designs of the motor, used magnets and also its function are listed there. The next part of the project summarizes the theory of heat transfer needed to calculate the heating of rotating electric machines. The following section deals with the calculation of the heating of the motor using the method of thermal networks and a specific network for asynchronous motor is presented there. A newly designed rotor network of the Line Start Permanent Magnet Synchronous Motor is based on this network. To verify the functionality of the network, a calculation of the rotor temperature distribution was done in Ansys Workbench program. The designed thermal network of the whole motor and a verification of its functionality with the calculation from Ansys are presented in the last part of the project.
|
guest ::
