Geothermal district heating networks: modelling novel operational strategies incorporating heat storage

The value of integrating a heat storage into a geothermal district heating system has been investigated. The behaviour of the system under a novel operational strategy has been simulated focusing on the energetic, economic and environmental effects of the new strategy of incorporation of the heat storage within the system. A typical geothermal district heating system consists of several production wells, a system of pipelines for the transportation of the hot water to end-users, one or more re-injection wells and peak-up devices (usually fossil-fuel boilers). Traditionally in these systems, the production wells change their production rate throughout the day according to heat demand, and if their maximum capacity is exceeded the peak-up devices are used to meet the balance of the heat demand. In this study, it is proposed to maintain a constant geothermal production and add heat storage into the network. Subsequently, hot water will be stored when heat demand is lower than the production and the stored hot water will be released into the system to cover the peak demands (or part of these). It is not intended to totally phase-out the peak-up devices, but to decrease their use, as these will often be installed anyway for back-up purposes. Both the integration of a heat storage in such a system as well as the novel operational strategy are the main novelties of this thesis. A robust algorithm for the sizing of these systems has been developed. The main inputs are the geothermal production data, the heat demand data throughout one year or more and the topology of the installation. The outputs are the sizing of the whole system, including the necessary number of production wells, the size of the heat storage and the dimensions of the pipelines amongst others. The results provide several useful insights into the initial design considerations for these systems, emphasizing particularly the importance of heat losses. Simulations are carried out for three different cases of sizing of the installation (small, medium and large) to examine the influence of system scale. In the second phase of work, two algorithms are developed which study in detail the operation of the installation throughout a random day and a whole year, respectively. The first algorithm can be a potentially powerful tool for the operators of the installation, who can know a priori how to operate the installation on a random day given the heat demand. The second algorithm is used to obtain the amount of electricity used by the pumps as well as the amount of fuel used by the peak-up boilers over a whole year. These comprise the main operational costs of the installation and are among the main inputs of the third part of the study. In the third part of the study, an integrated energetic, economic and environmental analysis of the studied installation is carried out together with a comparison with the traditional case. The results show that by implementing heat storage under the novel operational strategy, heat is generated more cheaply as all the financial indices improve, more geothermal energy is utilised and less fuel is used in the peak-up boilers, with subsequent environmental benefits, when compared to the traditional case. Furthermore, it is shown that the most attractive case of sizing is the large one, although the addition of the heat storage most greatly impacts the medium case of sizing. In other words, the geothermal component of the installation should be sized as large as possible. This analysis indicates that the proposed solution is beneficial from energetic, economic, and environmental perspectives. Therefore, it can be stated that the aim of this study is achieved in its full potential. Furthermore, the new models for the sizing, operation and economic/energetic/environmental analyses of these kind of systems can be used with few adaptations for real cases, making the practical applicability of this study evident. Having this study as a starting point, further work could include the integration of these systems with end-user demands, further analysis of component parts of the installation (such as the heat exchangers) and the integration of a heat pump to maximise utilisation of geothermal energy.

A cidade sem barreiras é para todos?: avaliação das condições de deslocamento no bairro da Cidade Alta, Natal/RN

In this present work, the conditions of displacements and the behaviors of the users are evaluated, face to the physical adequacies in accessibility in the inserted area in the central quadrilateral of the Quarter of Cidade Alta, in the City of Natal/RN, space clipping established by its great meaning historical and cultural. For this reason such area was a target of an integrated actions plan during the years of 1993 and 1998, with the implantation of part of the Project CIDADE SEM BARREIRAS (City without Barriers) and, later, the implementation of the Project CIDADE PARA TODOS's proposals (City for All), having as supports the constant Brazilian norms inserted into the NB9050/1994 and in the Municipal law number 4.090/92, effective ones in the period of the interventions. Considering that the carried through actions at the time were directed to the elimination of the architectural barriers to guarantee the right to go and to come, the research received a human universe formed by all the people in situation of displacement in the central area of the interventions in the quarter of the Cidade Alta, independently of their locomotive or sensorial conditions, emphasizing the aspects most excellent how much to the accessibility of the sidewalk, as promotional of mobility, integration and urban organization, as well as of the public squares of that one quadrilateral, conceived, originally, as spaces of aggregation and social inclusion. The work appealed to the direct comment and the gotten results had been collated with the ex port facto law and technique norms, of the year of 2004, and with the legal devices contained in the Federal Decree number 5.296/2004, as way to certify the levels of efficiency of these adaptations in that it says respect to the current conditions of demanded accessibility and urban mobility

Avaliação do potencial energético de cana (Arundo donax L.) no Algarve

Dissertação de Mestrado, Energias Renováveis e Gestão de Energia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016

Memory-enhancing effect of Rhodiola rosea L extract on aged mice

Purpose: The memory-enhancing effects of Rhodiola rosea L. extract (RRLE) on normal aged mice were assessed. Methods: In the open-field test, the effect of RRLE (150 and 300 mg/kg) on mouse locomotive activities was evaluated by investigating the extract’s influence on CAT and AchE activities in the brain tissue of mice. Results: Compared with aged group, high dose of RRLE reduced the total distance (3212.4 ± 123.1 cm, p < 0.05) significantly, increased catalase (CAT) activity (101.4 ± 12.2 U/mg pro, p < 0.05), and inhibited acetyl cholinesterase (AChE) activity (0.94 ± 0.12 U/mg pro, p < 0.05) in the brain tissue of aged mice. Conclusion: The results show that RRLE improves the memory functions of aged mice probably by increasing CAT activity while decreasing AChE activity.

Added value from biomass by broader utilization of fuels and CHP plants

The present work, where additional value-creating processes in existing combined heat and power (CHP) structures have been examined, is motivated by a political- and consumer-driven strive towards a bioeconomy and a stagnation for the existing business models in large parts of the CHP sector. The research is based on cases where the integration of flash pyrolysis for co-production of bio-oil, co-gasification for production of fuel gas and synthetic biofuels as well as leaching of extractable fuel components in existing CHP plants have been simulated. In particular, this work has focused on the CHP plants that utilize boilers of fluidized bed (FB) type, where the concept of coupling a separate FB reactor to the FB of the boiler forms an important basis for the analyses. In such dual fluidized bed (DFB) technology, heat is transferred from the boiler to the new rector that is operating with other fluidization media than air, thereby enabling other thermochemical processes than combustion to take place. The result of this work shows that broader operations at existing CHP plants have the potential to enable production of significant volumes of chemicals and/or fuels with high efficiency, while maintaining heat supply to external customers. Based on the insight that the technical preconditions for a broader operation are favourable, the motivation and ability among the incumbents in the Swedish CHP sector to participate in a transition of their operation towards a biorefinery was examined. The result of this assessment showed that the incumbents believe that a broader operation can create significant values for their own operations, the society and the environment, but that they lack both a strong motivation as well as important abilities to move into the new technological fields. If the concepts of broader production are widely implemented in the Swedish FB based CHP sector, this can substantially contribute in the transition towards a bioeconomy.

Characterization of Chimney Flue Gas Flows : Flow Rate Measurements with Averaging Pitot Probes

Performance testing methods of boilers in transient operating conditions (start, stop and combustion power modulation sequences) need the combustion rate quantified to allow for the emissions to be quantified. One way of quantifying the combustion rate of a boiler during transient operating conditions is by measuring the flue gas flow rate. The flow conditions in chimneys of single family house boilers pose a challenge however, mainly because of the low flow velocity. The main objectives of the work were to characterize the flow conditions in residential chimneys, to evaluate the use of the Pitot-static method and the averaging Pitot method, and to develop and test a calibration method for averaging Pitot probes for low