Thermoeconomics as a tool for the design and analysis of energy savings initiatives in buildings connected to district heating networks

District Heating (DH) is a rational way to supply heat to buildings in urban areas. This is expected to play an important role in future energy scenarios, mainly because of the possibility to recover waste heat and to integrate renewable energy sources. Even if DH is a well known technology, there are open problems to face. Some of these problems are related to tendencies to reduce design temperatures, the improvement of control strategies, connection of new users to existing networks, implementation of energy savings initiatives and the access of multiple heat producers to the same network. This paper aims to show that exergy is an appropriate quantity for the analysis of DH systems and thermoeconomics can be profitably used to improve their design and operation. Three possible applications of thermoeconomic theories are presented: variation of supply temperature along the heating season, opportunities to connect new users, effects of energy savings initiatives in buildings connected with the network

Thermoeconomic approach for the analysis of low temperature district heating systems

In this paper a thermoeconomic analysis of district heating systems is performed. The analysis aims at comparing possible options to supply heat to the users, using low temperature networks. Thermoeconomic analysis consists a powerful tool to perform such analysis as it allows one to evaluate the possible options in terms of primary energy cost or economic costs. In the first case, the use of exergy as the quantity that is transported along the network makes it possible to properly consider the various qualities of energy that are used to supply heat to the network and to distribute it to the users. In the case of economic cost, the various cost contributions are considered: investment cost, cost of heat supplied to the network, pumping cost. A different cost can be calculated for the various users depending on their position and characteristics of the heating devices. This is a useful information in order to compare possible options for supply them hea

Effective Online Safety Awareness for Young People in Less Developed Countries

In less developed countries (LDCs) there is a research deficit on the positive and negative aspects of their respective emerging digital cultures. Education programmes that seek to raise awareness of online safety, needs to be based on evidence and not simply transposed from other countries as the issues involved may be very different. Thailand, in particular, has very little data that can be used to create meaningful educational material. This was determined after a thorough literature review which found that most of the research has been carried out in the advanced economies of North America, Europe and Australasia. By contrast in South East Asia very little research had been carried out. This research proposes an integrative security awareness education framework for emerging digital cultures. It was constructed from the ground up so that it would be evidence led. In the first phase, a survey of the online behaviour and attitudes of young people in Thai schools was undertaken. Between November 2016 and June 2018, 352 students aged between 12 and 18 completed a comprehensive online questionnaire. In addition, 25 students were interviewed and asked to describe their online experiences both good and bad. From the survey it was found that 69% of students had been upset by an online interaction with 55% experiencing some form of cyber-bullying. They were also exposed to potentially harmful content. At least a third or more had seen posts or discussions on; committing suicide, self harm, being very thin, sexual images and hate messages against individuals and groups. In terms of mediation the interviews revealed a slightly different picture than the one painted in the survey. In the latter, young people suggested that they did sometimes talk to their parents and teachers about upsetting experiences. In the interviews most said that they did not tell their parents or teachers about negative online interactions. This was backed up during the workshops with most reasoning that what they were going through was not important enough to tell a parent or teacher or that they might be the ones that get blamed. They would either stay silent or tell a close friend. A series of online safety workshops were carried out structured around the theme of cyber-bullying as that was the standout issue from the surveys and interviews. An action-research approach was taken to determine what kind of activities would be best to engage Thai students. Activities that were based around active learning strategies like gamification (i.e. using elements of game design) and involving cooperation or competition proved the most successful. Activities where students had to present something or be involved in classroom discussions did not fare too well. The resulting education framework from the field research consists of themes and topics that are relevant to LDCs as well as the type of activities that works best. A novel component, ‘Cultural Mask’ was added to the framework. This looks at the influence of a country’s culture and its impact on education. In Thailand this includes the Sufficiency Economy Philosophy (SEP). In the education sector, SEP schools should promote student centric learning with creativity, critical thinking and problem solving amongst other goals. Knowledge they learn should lead to the betterment of their school and community. Therefore, the education framework can be adapted to reflect the SEP goals. In other LDCs by working through the education framework, awareness programmes can be developed that will be effective and culturally relevant

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Circuitry for a remotely powered bio-implantable gastric electrical stimulation system

Power to bio-implantable devices is usually supplied through a battery implanted with the system or through wires extending to an outside power source. The latter case with wires protruding out of the body can be unaesthetic in appearance and can cause infection. In this research, we consider an alternative way to power a bio-implantable microsystem. It involves using rechargeable lithium batteries. Here, power is delivered remotely to charge implanted battery or batteries. This approach avoids periodic surgery necessary for battery replacement. It also does not tie a person to an external power source at all times. This improves patient’s quality of life. The present work involves design and fabrication of signal conditioning circuit for a remotely rechargeable, bio-implantable, Battery-powered Electrical Stimulation System (BESS). A rechargeable lithium ion battery with a voltage of 3.7 V powers the proposed circuit. The desired output, which goes directly to the electrodes, is a series of 10 V, 15 mA pulses with a duty cycle of 4.5 %. A second rechargeable lithium ion battery serves as back-up. A lithium ion charging chip is included which is connected to the designed IC through a logic interface. The two batteries work in tandem i.e. when one battery powers the IC the other gets recharged and vice versa thereby providing an uninterruptible output. The IC uses a series of charge pumps to get the required boost in voltage. The IC also includes voltage detector circuits to detect battery voltages, voltage regulator, pulse generator circuits, logic circuits and necessary switches. Individual subsystems of the IC were designed, simulated and fabricated using standard CMOS technology. Individual subsystem circuits were found to work satisfactorily except for the charge pump. A revised design is now under fabrication. The microsystem utilizes a hybrid approach. Experiments done with a bench-top circuit model to simulate the proposed IC showed that a 3 V battery with a capacity of 190 mAh could power the IC for 15 hrs and needed 4 hrs for recharging

The idea of a teacher: paradigms of change

The focus of the article is the ‘idea’ of a teacher; not just the proactive role teachers play in inculcating creative traits in students but the meaning of a teacher within an institution. Is the idea of a teacher a dated notion of a paternalistic figure playing the role of transmitter of values from a mainstream social order to students in classrooms who are relearning what has already been given to them within the confines of a home? Have teachers been made redundant in the era of Internet technologies where information along with critical interpretations have taken an impersonal character and students are less inclined to be influenced by one dominant way of thinking? Although information is democratized to include wider sections of people, there is no basis to subscribe to the notion that people are more open-minded than in earlier times. The argument applies to the idea of a teacher as well: while corporatization at a global level has reduced the role of a teacher to teaching what is useful in fulfilling the requirements of the free market, the resistance of students to tailored worldviews is greater than ever before. There are changing paradigms of the idea of a teacher while there are also paradigms of change that teachers could espouse to bring about social and political transformation. My paper deals with the dynamics of imagining such a transformation

EXERGETIC AND THERMOECONOMIC APPROACH FOR OPTIMAL PLANNING OF DISTRICT ENERGY SYSTEMS

A sustainable urban energy planning for achieving the EU 2020 and 2050 energy goals requires adopting a systemic approach based on reducing end-user energy requirements, recycling energy that otherwise would be wasted and replacing fossil fuels by renewable. District Heating and District Cooling play a key role in such a concept. From the sustainability viewpoint, district heating is an important option to supply heat to the users in urban areas. The energy convenience of such option depends on the annual energy request, the population density and the efficiency in heat production. Among the alternative technologies, geothermal heat pumps (both open loop and closed loop heat pumps) play a crucial role. In order for the DHN to remain an effective solution with respect to alternative technologies, the optimal configuration, design and operation must be investigated. This thesis aims to propose a methodology for the Multiobjective Optimizations of district heating networks, where the objective functions (the minimum specific primary energy consumption or the minimum economic cost) of a district heating network are investigated using a thermoeconomic based probabilistic procedure. A procedure, derived from Simulating Annealing optimization technique, to select which users in a urban area should be connected with a district heating network and which ones should be heated through an alternative technology is proposed. The goal of this procedure is to reach a globally optimal system from the energy and economic viewpoints. The procedure proposes district heating as the initial choice for all the users. The users are then progressively disconnected to the network, according with the primary energy required to supply them heat, and the alternative technology is considered for disconnected users. Here, ground water heat pump and condensing boilers are considered as the alternative technologies. The optimization technique developed in this PhD thesis develops the three levels of the optimization of energy systems: - Development of a Synthetic Method: The optimal synthesis is performed though a method which starts with a superstructure (where all the buildings (users) in the considered area for the expansion of DH network are supplied by district heating network) and then reduced to the optimal configuration (some of the users are disconnected from the DHN and supplied with an alternative technology such as geothermal heat pumps or condensing boilers). - Development of Optimal Design Method for the components and the properties at the nominal load selected in order to reach optimal performances: - as the users are disconnected from the district heating network, the mass flow rate flowing in the pipes is reduced resulting in different pipe diameters in comparison to the initial configuration. The optimal value velocity in the pipes is obtained as a function of the pipe diameters; - The cogeneration ratio (the ratio between the thermal power of the CHP appliances and the total thermal power installed in the power station ) has been considered as a parameter in the optimal design of the system. - Development of Optimal Operating properties: the operating properties under specific conditions has been changed, like the operating supply temperatures, but also the evolution of the network during its construction is considered. The application to an Italian town is considered as a test case. The main advantage of this procedure is that complex networks, like the DHN in Casale Monferrato characterized by 198 users, grouped in 21 macrozones, can be easily processed. The optimal configuration of the overall urban heating system is obtained. This configuration corresponds to the minimum primary energy request to supply heat to all the users (those connected to the network and those using an alternative heating system). After a brief introduction where the district heating technology is presented, the Thesis is divided in two parts: the first parts introduces the methodological approach proposed for the optimization of a District heating network, together with the description of the optimization model. The second part focuses on a specific application case, showing the preliminary operations required for the application of the model and the results obtained from the optimizations performed. The results have been interpreted trying to reach a more general conclusion which is not related only to the specific case stud