No description available.

No description available.

The structure of old monumental churches differs a lot from contemporary buildings. The structural materials were wood, brick and stone. In order to construct high buildings with huge spans, thick massive walls and many massive columns were needed. Originally these buildings had no heating and for centuries the outdoor temperature determined the indoor climate. As churches are considered historical heritage buildings their renovation should be thoroughly studied.               In this thesis the transmission losses of Hamrånge church will be analysed. Hence, the transmission trough walls and windows as well as the heat buffering of materials will be examined. In addition, the effect of possible reformation measurements will be concluded.               Finally, this project belongs to a complete study of the church, were not only transmission losses are considered but also air infiltration losses and solar heat gain. That way, a comparison between them will be carried out in order to contribute to attain the objective of the project: possible restoration for church heating system with respect to preservation, energy requirements, thermal comfort and aesthetics. / Church project

Thesis (doctoral)--Helsinki University of Technology, 2007. / Includes bibliographical references. Also available on the World Wide Web.

Orientador: Antonio Padilha Feltrin / Banca: Jose Roberto Sanches Mantovani / Banca: Sergio Azevedo de Oliveira / Banca: Benemar Alencar de Souza / Banca: Jorge Coelho / Resumo: Nesta tese busca-se uma solução para o problema de cálculo de perdas elétricas para grande parte das empresas distribuidoras de energia elétrica. As perdas de energia em sistemas de distribuição vêm recebendo uma maior atenção por parte das empresas de energia elétrica de todo o mundo. Isto se deve principalmente aos elevados índices de perdas nãotécnicas (associadas a ligações ilegais, falhas na medição, etc.), em especial em países em desenvolvimento como o Brasil. Porém, para se chegar aos valores de perdas não-técnicas dos sistemas busca-se um método que calcule as perdas técnicas, e por subtração das perdas totais, obtê-las. O cálculo das perdas técnicas de forma precisa requer uma análise detalhada do sistema de distribuição, e consequentemente uma base de dados completa e atualizada, o que dificilmente as empresas possuem. Propõe-se, portanto, um método para o cálculo das perdas técnicas que identifique essas perdas de forma consistente, porém utilizando-se de uma base de dados de fácil obtenção em todas as empresas do setor. Dentre esses dados, têmse as curvas de carga medidas nas subestações (ou até mesmo nos alimentadores) através de medidores eletrônicos. Assim, com essas curvas é utilizado um método de alocação de carga que distribui o carregamento da subestação (ou alimentador) para os transformadores. Com a utilização do fator de perdas, também obtido pelas curvas de cargas medidas, têm-se as perdas técnicas de energia nas redes de distribuição. Os cálculos das perdas técnicas são realizados nos principais segmentos da rede: redes de média tensão, transformadores, circuitos de baixa tensão e outros (incorpora os demais segmentos e componentes em que as perdas ocorrem). Além da alocação de carga nos transformadores, outra característica importante do método proposto é a utilização... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work is aimed at solving the problem of calculating electrical losses for distribution networks. Electrical losses have been and continue to be a concern for distribution network operators (DNOs) around the world. In many developing countries, such as Brazil, this concern is mainly due to non-technical losses (related to illegal connections, measurement errors, etc.). Consequently, to evaluate the non-technical losses of a given distribution system it is required a methodology that computes the technical losses, and then by subtracting them from the total losses the non-technical ones can be also obtained. To accurately calculate technical losses it is needed a detailed analysis of the distribution network, and therefore a complete and updated database. However, such a data is hardly available at distribution companies. Thus, here it is proposed a method for the calculation of technical losses that indentifies those non-technical ones in a consistent fashion, using those databases already available at most distribution companies. The data includes load curves measured at the substations (or the feeders) by electronic meters. With this load curves a load allocation method is used to distribute the aggregated load from the substation (or the feeder) among the distribution transformers. By using a loss factor, also obtained from the measured load curves, it is possible to compute the technical energy losses of the distribution networks. These calculations of technical losses are carried out at the main segments of the network: medium voltage networks, transformers, low voltage circuits and 'others' (including the remaining segments and components where the losses occur). In addition to the load allocation at the transformers, another important characteristic of the proposed methodology is the usage of a power flow algorithm for... (Complete abstract click electronic access below) / Doutor

Doctor of Philosophy / Department of Civil Engineering / David Steward / Western Kansas has a semi-arid climate where the demand for water resources is greater than the natural supply. To meet the demand for irrigated agriculture, the groundwater has been extracted at a rate greater than the natural recharge rate, resulting in declining water table in the aquifer and reduced streamflow in the rivers and streams in the region. An assessment of the rivers in western Kansas was conducted to determine the fluxes between the river, groundwater, and the atmosphere. Riverbeds were instrumented to determine the conductivity of the riverbed sediments, the transmission losses of the Arkansas River were modeled to determine the interactions between the surface water and groundwater, and the evapotranspiration of the Arkansas River corridor was estimated using satellite remote sensing to quantify of water lost to the atmosphere. The Arkansas River and Cimarron River are shown to have a high hydraulic conductivity and a large infiltration capacity at the surface of the riverbed. However, the large surface infiltration capacity does not translate into large transmission losses, which are a fraction of the rate of the surface infiltration capacity of the riverbed. Thus, surface infiltration is only one factor of what controls the transmission losses. It is shown that transmission losses for a connected river-aquifer system are driven by induced infiltration by riparian vegetation. The interactions between the surface, groundwater and atmosphere were assessed over time, revealing that the flux to the atmosphere can be decoupled from the Arkansas River discharge and the groundwater recharge. While the declining discharge in the Arkansas River can be attributed to the extraction of groundwater resources and the management of surface water resource, the atmospheric fluxes are independent of the surface water and groundwater at an annual scale. When the river ecosystem is water stressed, the trees continue to draw water. This points to both the reliable store of water from the alluvial aquifer and the ability of the tree community to respond to water stress. While the water in the alluvial deposits are currently being lost from the system through evapotranspiration, this provides a potential store for consideration in future water management decisions.

The general food supply is usually the source of vitamin C for many people, and since squash is a common food in the popular diets of Texans and is so generally grown over the state, this study has a two-fold purpose: (1) to ascertain the amount of vitamin C in the two varieties of squash most commonly used as food in Texas, and (2) to determine the effect of various methods of cooking upon the vitamin C content of these two varieties of squash.

Digesters at a biogas plant have high temperatures and poor insulation. There is great potential to save energy by improving the construction. This study has two aims. One is to compare the difference between a simple steady-state calculation and a calculation that uses simulated values from Heat2. The second is to develop an improved insulation method at the concrete digester that can be used in future projects. Ten different insulation scenarios have been simulated to understand how to improve the insulation method to develop an idea of where the insulation has the most impact. Then a combined insulation method was created from the scenarios. That combined method was then simulated with 5 different insulation thickness to find the most profitable design. The conclusion was that there is great value in making more advanced calculations for the walls and floor because the energy losses are very excessive using the simplified calculation, especially on surfaces covered in soil. It was proved difficult to calculate the losses for the roof, this was because the assumption that was needed to perform the calculation does not mirror the reality. Due to this, the roof has been neglected in the suggested insulation method. The insulation method proposed provides an energy saving of 58 MW h/year and a discounted payback time of 4, 3 years if the saved energy can be delivered as 90◦C degree hot water into the district heating network.

No description available.

No description available.