Tyrime sulygintos senos kartos sniego valymo sistemos su nauja skaitmeninio valdymo šildymo sistema. Atsižvelgus į gautus rezultatus, pateiktiami pasiūlymai sniego valymo sistemoms efektyvumo didinimui. Tyrimas skirtas sistemų optimizavimui ir elektros energijos vartojimo mažinimui. / Point heating systems, used by SC „Lietuvos gelezinkeliai“, have to warrant safe and reliable train traffic. It is designed to melt ice which is between point’s spike and frame rail and accomplish heating elements’ and other system parts monitoring and control according the stated parameters. At present the snow blowing system use a lot of electrical energy, the research is dedicated to optimize the systems and to reeducated use of electrical energy.

Recently is topicality making wherewith more electrical energy from “clean” stockholding. Detractive hothouse gas exhaustion to the atmosphere. One “clean” energy is – wind power. Wind plans working in the commensurable electrical energy supply system, must “nuisance��. For this purpose essential wind electricity work forecast and respectively react to the situation. Wind power – station made electrical energy forecasting analysis I done sustaining by California experience. Forecasting is executable by wind forecast ground. Wind forecasts possible get from meteorological dimensional station or other institutions which doing wind range. Wind power – stations work essential to forecast at one hour 48 hours to the future. Such period is needful to other power – stations reaction. Wind power – stations worst worth to be built in the seaside zone or in the local pelagic there are not high flora or buildings. Wind power – stations can be built and in the others regions, but then increase the period of dividend.

Aim of the work 1. To analyze the methods used for the quality and resource assessment of complex insulation; 2. To develop the models for the assessment and analysis of polarization features, dielectric parameters and moisture content in oil- paper insulation; 3. To develop the method for the assessment of moisture quantity by measuring the polarization characteristics; 4. To analyze the impact of water quantity on dielectric parameters of transformer insulation; 5. To classify the quality criteria of oil-paper insulation; 6. To identify the tendencies in variation of insulation’s dielectric parameters and moisture quantity; 7. To implement the developed models and methods in the electricity industry of Lithuania for the assessment of the transformers’ insulation quality and resource.

A major challenge in the development of next generation electric and hybrid vehicle technology is the control and management of heat generation and operating temperatures. Vehicle performance, reliability and ultimately consumer market adoption are integrally dependent on successful battery thermal management designs. It will be shown that in the absence of active cooling, surface temperatures of operating lithium-ion batteries can reach as high as 50 °C, within 5 °C of the maximum safe operating temperature. Even in the presence of active cooling, surface temperatures greater than 45 °C are attainable. It is thus of paramount importance to electric vehicle and battery thermal management designers to quantify the effect of temperature and discharge rate on heat generation, energy output, and temperature response of operating lithium-ion batteries. This work presents a purely experimental thermal characterization of thermo-physical properties and operating behavior of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. Crucial to thermal modeling is accurate thermo-physical property input. Thermal resistance measurements were made using specially constructed battery samples. The thru-plane thermal conductivity of LiFePO4 positive electrode and negative electrode materials was found to be 1.79 ± 0.18 W/m°C and 1.17 ± 0.12 W/m°C respectively. The emissivity of the outer pouch was evaluated to enable accurate IR temperature detection and found to be 0.86. Charge-discharge testing was performed to enable thermal management design solutions. Heat generated by the battery along with surface temperature and heat flux at distributed locations was measured using a purpose built apparatus containing cold plates supplied by a controlled cooling system. Heat flux measurements were consistently recorded at values approximately 400% higher at locations near the external tabs compared to measurements taken a relatively short distance down the battery surface. The highest heat flux recorded was 3112 W/m2 near the negative electrode during a 4C discharge at 5 °C operating temperature. Total heat generated during a 4C discharge nearly doubled when operating temperature was decreased from 35 °C to 5 °C, illustrating a strong dependence of heat generation mechanisms on temperature. Peak heat generation rates followed the same trend and the maximum rate of 90.7 W occurred near the end of 5 °C, 4C discharge rate operation. As a result, the maximum value of total heat generated was 41.34 kJ during the same discharge conditions. The effect of increasing discharge rate from 1C to 4C caused heat generation to double for all operating temperatures due to the increased ohmic heating. Heat generation was highest where the thermal gradient was largest. The largest gradient, near negative electrode current collector to external tab connection and was evaluated using IR thermography to be 0.632 °C/mm during 4C discharge with passive room temperature natural convection air cooling. Battery designs should utilize a greater connection thickness to minimize both electrical resistance and current density which both drive the dominant mode of heat generation, ohmic heating. Otherwise cooling solutions should be concentrated on this region to minimize the temperature gradient on the battery.

Orientador: Luiz Fernando Milanez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-21T01:50:40Z (GMT). No. of bitstreams: 1 Santiago_Fabio_M.pdf: 8778625 bytes, checksum: 682efcdc5efb8549b7c4dbd3564ef87e (MD5) Previous issue date: 2012 / Resumo: O objetivo deste trabalho é utilizar o método da integral dupla na obtenção de soluções analíticas aproximadas para problemas de condução térmica unidimensional em regime transitório. Sendo o método da integral dupla um refinamento do amplamente utilizado método da integral simples, também conhecido Karman-Pohlhausen para a camada limite ou método de Goodman para mudança de fase, inicialmente foi proposto um minucioso estudo do capítulo Application of Integral Methods to Transient Nonlinear Heat transfer, cujo objetivo era compreender o funcionamento deste método, assim como selecionar os problemas apresentados neste trabalho. Posteriormente realizou-se o estudo do artigo primordial de aplicação do método da integral dupla publicado por Volkov, bem como dos principais trabalhos envolvendo o método da integral dupla. Ao todo foram selecionados seis casos do trabalho original de Goodman, os quais foram resolvidos com o uso do método da integral dupla para perfis quadrático e cúbico. A escolha de perfis polinomiais se justifica uma vez que estes são de fácil manipulação diante das operações de diferenciação e integração comum os métodos integrais, além disso, o uso de perfis de grau distinto tem como objetivo mostrar a influência da variação deste na obtenção de melhores aproximações. De modo a convalidar os resultados apresentados pelo método da integral dupla, estes foram comparados com as soluções analíticas exatas presente na literatura assim como, com as soluções aproximadas apresentadas por Goodman e com a solução numérica obtida pelo método de volumes de controles. Os resultados obtidos neste trabalho revelam o melhor desempenho do método da integral dupla quando comparado com os resultados obtidos por Goodman em seu trabalho anteriormente citado / Abstract: The objective of this work is to use the method of the double integral to obtain approximate analytical solutions for one-dimensional heat conduction problems in the transitional regime. As the method of a double integral refinement of the widely used simple integral method, also known Karman-Pohlhausen for the boundary layer or the Goodman method for phase change, was initially proposed a thorough study of Chapter Application of Integral Methods to Transient Nonlinear Heat transfer, the objective of which was to understand the functioning of this method as well as selecting the problems presented in this paper. Subsequently we carried out the study of the primary article of the method of the double integral posted by Volkov as well as major works involving the method of double integral. In all six cases were selected from the original work of Goodman, which were solved using the method of the double integral for quadratic and cubic profiles. The choice of polynomial profiles is justified as they are easy to handle before the operations of common differentiation and integration methods, moreover, the use of profiles of different degree is intended to show the influence of the variation in obtaining better approximations. In order to validate the results presented by the method of the double integral, they were compared with the exact analytical solutions in the literature as well as with the approximate solutions presented by Goodman and the numerical solution obtained from a volume control. The present results show the improved performance of the method of the double integral compared with the results obtained by Goodman in their work cited above / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Baigiamajame magistro darbe buvo išanalizuota didelių įstiklintų atitvarų plotų įtaka šildymo ir vėsinimo energijos sąnaudoms. Atlikta stiklo paketų, jų terminių savybių bei pasyvių energijos taupymo priemonių taikymo apžvalga. Konkretiems objektams pasirinkti penki energijos poreikių analizės variantai. Nustatyta, kaip energijos poreikius įtakoja didžiausio įstiklinto pastato fasado orientacija pasaulio šalių atžvilgiu, skirtingos stiklo paketų optinės ir šiluminės savybės bei pasyvių energiją taupančių priemonių naudojimas. Išnagrinėta apie septyniasdešimt skaičiavimo variantų. Palyginti skirtingų vėsinimo poreikių skaičiavimo metodikų rezultatai. Atlikta 2009 – 2010 m. šildymo sezono vidutinių išorės oro temperatūrų analizė. Natūrinėmis sąlygomis nustatytas patalpų oro temperatūros ir santykinio drėgnumo kitimas ir palyginta su reglamentuojamomis vertėmis. Nagrinėjamajame objekte atlikta skaičiuojamųjų ir faktinių šilumos suvartojimų, perskaičiuotų į norminius dydžius, palyginamoji analizė. / The Master's degree paper analyses the influence of large glazed areas of heating and cooling energy costs. Carried out the review of glazing, their thermal properties and the passive energy saving measures. The analysis of five options for energy needs of certain objects has been done. Established the affect to energy needs of the largest glazed façade orientation of the world's countries, different glazing optical and thermal properties and passive energy-saving tools. Examined about seventy calculation options. The results of different methods of calculating the cooling needs have been compared. Carried out the average outside air temperature analysis in 2009 - 2010 heating season. At subsistence conditions the indoor air temperature and relative humidity has been identified, and compared with the governing values. The comparative analysis in considered object of estimated and actual consumption of heat, expressed in the normative values, has been done.

Disertacijoje, taikant dinaminį pastatų energijos poreikių modeliavimą, nagrinėjamos viešosios paskirties pastatų energinio efektyvumo problemos. Pagrin-dinis tyrimo objektas yra viešosios paskirties pastato fasado įstiklinimo įtaka energijos poreikiams. Greta savo pagrindinės funkcijos – pakankamo natūralaus apšvietimo užtikrinimo, fasado įstiklinimas privalo būti energiškai efektyvus. Tai prieštaringi reikalavimai. Pagrindinis disertacijos tikslas – įvertinant natūralaus apšvietimo poreikį, kompleksiškai išanalizuoti viešosios paskirties pastato įstiklinimo charakteristi-kų įtaką pastato mikroklimato ir apšvietimo sistemų energijos poreikiams bei nustatyti, kokioms pastato įstiklinimo charakteristikoms esant, Lietuvoje bei panašaus klimato šalyse pastato energijos poreikius galima būtų sumažinti iki mažai energijos vartojančio pastato lygio. Darbe sprendžiami du pagrindiniai uždaviniai: pirmasis – atliekama įstiklinimo įtakos kondicionuojamo pastato energijos poreikiams analizė; antrasis – nustatomos efektyvios energiškai efektyvaus pastato įstiklinimo charakteristikos. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai, pristatomos... [toliau žr. visą tekstą] / Applying building energy simulations, the dissertation investigates the issu-es of energy efficiency of public buildings. The main object of research – influ-ence of the glazing of the public building on its energy demand. Next to its main function to ensure daylighting, glazing must to be energy efficient. So these requirements conflict. The aim of this dissertation is to perform the complex analysis of the influ-ence of glazing characteristics on the building‘s microclimate and lighting sys-tems energy demand, taking into account DL demand. Also define, what glazing characteristics in Lithuanian and similar climate countries, are able to decrease buildings energy demand to the level of the low energy building. The paper ap-proaches two major tasks. Task 1 is performance of the detailed analysis of inf-luence of glazing on energy demand of the public building. Task 2 is determina-tion of the efficient glazing characteristics of the energy efficient building. The dissertation consists of Introduction, 4 chapters, Conclusions, Referen-ces and list of published works of the author on the topic of dissertation. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, re-search methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presen-ting the author’s publications on the subject of the... [to full text]

Applying building energy simulations, the dissertation investigates the issu-es of energy efficiency of public buildings. The main object of research – influence of the glazing of the public building on its energy demand. Next to its main function to ensure daylighting, glazing must to be energy efficient. So these requirements conflict. The aim of this dissertation is to perform the complex analysis of the influence of glazing characteristics on the building‘s microclimate and lighting systems energy demand, taking into account DL demand. Also define, what glazing characteristics in Lithuanian and similar climate countries, are able to decrease buildings energy demand to the level of the low energy building. The paper approaches two major tasks. Task 1 is performance of the detailed analysis of influence of glazing on energy demand of the public building. Task 2 is determination of the efficient glazing characteristics of the energy efficient building. The dissertation consists of Introduction, 4 chapters, Conclusions, references and list of published works of the author on the topic of dissertation. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presenting the author’s publications on the subject of the defended... [to full text] / Disertacijoje, taikant dinaminį pastatų energijos poreikių modeliavimą, nag-rinėjamos viešosios paskirties pastatų energinio efektyvumo problemos. Pagrin-dinis tyrimo objektas yra viešosios paskirties pastato fasado įstiklinimo įtaka energijos poreikiams. Greta savo pagrindinės funkcijos – pakankamo natūralaus apšvietimo užtikrinimo, fasado įstiklinimas privalo būti energiškai efektyvus. Tai prieštaringi reikalavimai. Pagrindinis disertacijos tikslas – įvertinant natūralaus apšvietimo poreikį, kompleksiškai išanalizuoti viešosios paskirties pastato įstiklinimo charakteristi-kų įtaką pastato mikroklimato ir apšvietimo sistemų energijos poreikiams bei nustatyti, kokioms pastato įstiklinimo charakteristikoms esant, Lietuvoje bei pa-našaus klimato šalyse pastato energijos poreikius galima būtų sumažinti iki ma-žai energijos vartojančio pastato lygio. Darbe sprendžiami du pagrindiniai užda-viniai: pirmasis – atliekama įstiklinimo įtakos kondicionuojamo pastato energijos poreikiams analizė; antrasis – nustatomos efektyvios energiškai efek-tyvaus pastato įstiklinimo charakteristikos. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, apra-šomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai, pristatomos... [toliau žr. visą tekstą]

Darbo tikslas: Parengti lauko baseino vandens šildymo sistemą naudojant saulės kolektorius, siekiant prailginti jo naudojimo laiką. Nagrinėjama tema yra aktuali, kadangi bet koks saulės energijos panaudojimas žmonių tikslams energiją paverčiant šiluma yra aktyviai skatinamas, nes ši energija yra atsinaujinanti, nieko nekainuoja ir neteršia aplinkos, o panaudojimo galimybės - didelės. Atlikti įvairūs tyrimai ir skaičiavimai leidžia teigti, jog baseino panaudojimo negalima prailginti naudojant savos gamybos saulės kolektorių. Vandens temperatūrų pokyčiai esant skirtingiems gyliams yra nežymūs, kai apšvieta yra pakankama veikti saulės kolektoriui, o apšvietai esant mažai, skirtumai tarp skirtingų sluoksnių siekia net 3,7 oC, o tai yra pakankamai daug, kai baseino gylis yra 60 cm. Atlikus temperatūrų ir apšvietos tyrimus ir išanalizavus rezultatus matyti, jog daugeliu atvejų vandens temperaūros pokyčiai maketiniame baseine atitinka dienos apšvietos pokyčius. Šių tyrimų rezultatus galima pritaikyti, siekiant apskaičiuoti, kokių išmatavimų savadarbio kolektoriaus reikės, norint pašildyti pasirinktą lauko baseino vandenį. / Work purpuose: to prepare the open air swimming pool heating system by using sun collectors, to extend it’s working period. The relevance of investigating theme is really big, because of any sun energy using for people purpouse transferring sun energy into heat is active promoting, because this energy is renewable, costs nothing and it’s better for the environment and the usabilitys are big. Studies let’s state, that we can’t extend the use of open air swimming pool by using home made sun collector. The changes of water temperature, when the depth is different are not big when the lighting is enough to work sun collector, and when the lighting is small, the differences between water depth reaches even 3,7oC and it’s really big, when the depth of swimming pool is just 60 cm. When all the researches are done and results are analyzed, we see, that in many cases the temperature changes of pool water corresponds lighting changes. These research results may be adapted by calculating parameters of collector, by which we want to heat the open air swimming pool.

Šiame darbe pateikta gluosninių žilvičių auginimo, ruošimo bei naudojimo analitinė apžvalga, gluosnių auginimo technikos ir technologijų energetinis vertinimas, nesubrendusių gluosnių pjaustinio ilgio teoriniai tyrimai naudojant žolinių augalų smulkintuvą. Taip pat eksperimentiškai nustatytos gluosnių fizikinės – mechaninės savybės, poveikis aplinkai deginant skirtingo pjaustinio gluosnius. Tyrimai atlikti naudojant 10 kW biokuro katilą, skirtą kūrenti energetinių augalų skiedroms, briketams, paletėms. Nustatytos kenksmingų medžiagų (CO2 , CO, NO, NOx) emisijos į aplinką deginant skirtingo tipo smulkintuvais susmulkintus gluosnius. / In this work the willow cultivation, preparation and use of analytical review of willows growing energy technology and technology assessment in juvenile willow cuttings-length adaptation of the theoretical studies of herbaceous plants shredder. It is well established experimentally rushes physical - mechanical properties of the environmental impact of combustion of different willow cuttings. Investigations were carried out using a 10 kW biofuel boiler to burn energy crops for wood chips, briquettes, pallets. Down (CO2 , CO, NO, NOx) emissions into the environment by burning different types of chopped willow cutter.