8 resultados para Cooling-Degree Days
em Dalarna University College Electronic Archive
Resumo:
This research was carried out by studying possible renovation of a two-storey detached multifamily building by using passive solar design options in a cold climate in Borlänge, Sweden where the heating Degree Days are 4451 (base 20°C). Borlänge`s housing company, Tunabyggen, plans to renovate the project house located inthe multicultural district, Jakobsgårdarna. The goal of the thesis was to suggest a redesign of the current building, decrease the heating energy use, by applying passive solar design and control strategies, in a most reasonable way. In addition ensure a better thermal comfort for the tenants in the dwellings. Literatures have been studied, from which can be inferred that passive design should be abasic design consideration for all housing constructions, because it has advantages to ensure thermal comfort, and reduce the energy use. In addition further savings can be achieved applying different types of control strategies, from which the house will be more personalized, and better adapted to the user’s needs.The proposed method is based on simulations by using TRNSYS software. First a proper building model was set up, which represents the current state of the project building. Then the thermal insulation and the windows were upgraded, based on today's building regulations. The developments of the passive solar options were accomplished in two steps. First of all the relevant basic passive design elements were considered, then those advantages were compared to the advantages of applying new conventional thermostat, and shading control strategies.The results show that there is significant potential with the different types of passive solar design; their usage depends primarily on the location of the site as well as the orientation of the project building. Applying the control strategies, such as thermostat, and shading control, along the thermal insulation upgrade, may lead to significant energy savings (around 40 %), by comparison to the reference building without any upgrade.
Resumo:
A series of measurements on the performance of solar cell string modules with low-concentrating CPC reflectors with a concentration factor C ˜ 4X have been carried out. To minimise the reduction in efficiency due to high cell temperatures, the modules were cooled. Four different way of cooling were tested:1) The thermal mass of the module was increased, 2) passive air cooling was used by introducing a small air gap between the module and the reflector, 3) the PV cells were cooled by a large cooling fin, 4) the module was actively cooled by circulating cold water on the back. The best performance was given with the actively cooled PV module which gave 2,2 times the output from a reference module while for the output from the module with a cooling fin the value was 1,8.Active cooling is also interesting due to the possibility of co-generation of thermal and electrical energy which is discussed in the paper. Simulations, based on climate data from Stockholm, latitude 59.4°N, show that there are good prospects for producing useful temperatures of the cooling fluid with only a slightly reduced performance of the electrical fraction of the PV thermal hybrid system.
Resumo:
PANA V Evaluation of a Literacy ProjectSUMMARY AND CONCLUSIONSThis evaluation set out to explore the impact of the literacy work carried out through PANA V. It focussed on clarifying effects such as empowerment and poverty reduction in relation to the civil society. Two specific objectives were to evaluate the methodological approach and the didactic materials and to evaluate the sustainability of the project.Although the focus of the evaluation has been PANA V, the project has been evaluated in its context, as one in a series of five projects located in Rwanda ten years after the war and genocide. The conclusion will consider future plans in this field.The evaluator has striven to create a holistic picture of the effects of the project, although the given time for the evaluation was short. Only three weeks were spent in the field study and only ten days in the actual field. Although there were some organisational and logistic problems, as is common when carrying out a study like this in a poor country, many literacy sites were visited and quite many participators were interviewed. The overall impression from the study is overwhelmingly positive. So many people commit themselves in this task of teaching Rwandans reading, writing and numeracy. Despite harsh conditions learners strive to learn and group leaders devote themselves to the task. Many leaders on different levels try their very best to manage their difficult and demanding task. The main objective was to explore the impact of the project on poverty reduction, particularly on empowerment and strategies for everyday life. Women were to be regarded particularly. From the results it is clear that the project has a strong, positive impact both on poverty reduction and empowerment of marginalised groups. Among those who have benefited from the alphabetisation are mainly women. Unfortunately, when it comes to leaders in PANA, who may also be said to have benefited from the project, only a small minority is women. This is something that is recommended that it be reconsidered inside the organisation. As a majority of the targeted learners are women, and as the economic and social situation of women in Rwanda is generally weak, this is a question that I recommend the Pentesostal church and ADEPR to look particularly into. With many women being single breadwinners of their households, it is important that also women get access to positions that may bring benefits of different kind.It is also clear that the project has positive effects for the civil society. In the present situation in Rwanda, during the process of reconciliation and rapid progress, basic education for the poor majority is a democratic issue. In a country with a plethora of internet-cafés in the capital and a small minority that use cars and mobile-telephones to communicate nation-wide, it is of outmost importance that the majority acquires basic education, of which literacy is a central part. To strengthen the civil society in Rwanda literacy is important. One central issue is then that Rwanda develops toward becoming a country where literacy is used for the benefit of the citizens and it is a democratic issue that all citizens get an opportunity to participate. Crucial for this is that strong efforts are put into primary schools nation-wide. Literacy projects for adults, like PANA, may only complement these efforts, but they constitute important and necessary complements. Other relevant ways to promote literacy are campaigns in Radio and TV and through cultural events such as festivals, music and theatre. News papers, magazines and books are natural parts of such campaigns as well as adult education. As stated under the results not much can be said about the didactics in this evaluation. On the whole the methodology and the materials fill their function well and receive a high reputation. As people learn to read and write under very simple conditions, obviously the approach is appropriate. A few suggestions may be given from the study:•Focus groups leaders’ attention on clearness, that they show very clearly what is to be read. Good structuring is probably of great importance for many learners.•Make clear what is tested in the tests and consider the possibility to use a holistic test that would be more congruent with the methodology. The possibility to use only one grade, pass, would enable a more practical test, such as reading a short, relevant text, writing something relevant and solving practical mathematic problems. Avoid tests that demand school knowledge.•Avoid using methaphors such as “fight against illiteracy” and connections between illiteracy/literacy and darkness/light. It is not true that illiteracy causes bad things and that literacy only brings good. •Be prepared that it may be more difficult in the future to achieve the goals as it may be the case that the early learners where the ones who achieved easily. The goal of “literacy in six month” in PANA will probably hold only for some learners but also those who do not manage in six months need literacy skills.A third objective was to secure sustainability. As for sustainability of the project in itself, and of the literacy process, the main conclusion is that there is a good potential. The commitment and devotedness among many involved in PANA proves good. One weakness is individual leaders in ADEPR who do not see this as an important task for the Pentecostal church in Rwanda. Other weaknesses are the unwillingness to mention explicitly the wish, for example among group leaders, to get some kind of incentive and the fear of loosing believers by cooperation with other organisations. A higher degree of transparency in this issue would probably solve some irritations and tensions.As for the sustainability of the literacy skills much may be done to improve. The acquired skills seem to be comparably relevant. The level achieved, and the level tested, may be defined as basic literacy skills, consisting of basic reading, writing and numeracy skills. However, these skills are very restricted and there is a high risk that the skills will decline, which means that there is a high risk that people will forget how to read and write because of lack of exercising. From these conclusions a few suggestions for future development will be given.
Resumo:
This essay studies how dialectal speech is reflected in written literature and how this phenomenon functions in translation. With this purpose in mind, Styron's Sophie's Choice and Twain's The Adventures of Huckleberry Finn are analysed using samples of non-standard orthography which have been applied in order to reflect the dialect, or accent, of certain characters. In the same way, Lundgren's Swedish translation of Sophie's Choice and Ferres and Rolfe's Spanish version of The Adventures of Huckleberry Finn are analysed. The method consists of linguistically analysing a few text samples from each novel, establishing how dialect is represented through non-standard orthography, and thereafter, comparing the same samples with their translation into another language in order to establish whether dialectal features are visible also in the translated novels. It is concluded that non-standard orthography is applied in the novels in order to represent each possible linguistic level, including pronunciation, morphosyntax, and vocabulary. Furthermore, it is concluded that while Lundgren's translation intends to orthographically represent dialectal speech on most occasions where the original does so, Ferres and Rolfe's translation pays no attention to dialectology. The discussion following the data analysis establishes some possible reasons for the exclusion of dialectal features in the Spanish translation considered here. Finally, the reason for which this study contributes to the study of dialectology is declared.
Resumo:
The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high. This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices. The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume. The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.
Demonstration of Solar Heating and Cooling System using Sorption Integrated Solar Thermal Collectors
Resumo:
Producing cost-competitive small and medium-sized solar cooling systems is currently a significant challenge. Due to system complexity, extensive engineering, design and equipment costs; the installation costs of solar thermal cooling systems are prohibitively high. In efforts to overcome these limitations, a novel sorption heat pump module has been developed and directly integrated into a solar thermal collector. The module comprises a fully encapsulated sorption tube containing hygroscopic salt sorbent and water as a refrigerant, sealed under vacuum with no moving parts. A 5.6m2 aperture area outdoor laboratory-scale system of sorption module integrated solar collectors was installed in Stockholm, Sweden and evaluated under constant re-cooling and chilled fluid return temperatures in order to assess collector performance. Measured average solar cooling COP was 0.19 with average cooling powers between 120 and 200 Wm-2 collector aperture area. It was observed that average collector cooling power is constant at daily insolation levels above 3.6 kWhm-2 with the cooling energy produced being proportional to solar insolation. For full evaluation of an integrated sorption collector solar heating and cooling system, under the umbrella of a European Union project for technological innovation, a 180 m2 large-scale demonstration system has been installed in Karlstad, Sweden. Results from the installation commissioned in summer 2014 with non-optimised control strategies showed average electrical COP of 10.6 and average cooling powers between 140 and 250 Wm-2 collector aperture area. Optimisation of control strategies, heat transfer fluid flows through the collectors and electrical COP will be carried out in autumn 2014.
Resumo:
Exploiting solar energy technology for both heating and cooling purposes has the potential of meeting an appreciable portion of the energy demand in buildings throughout the year. By developing an integrated, multi-purpose solar energy system, that can operate all twelve months of the year, a high utilisation factor can be achieved which translates to more economical systems. However, there are still some techno-economic barriers to the general commercialisation and market penetration of such technologies. These are associated with high system and installation costs, significant system complexity, and lack of knowledge of system implementation and expected performance. A sorption heat pump module that can be integrated directly into a solar thermal collector has thus been developed in order to tackle the aforementioned market barriers. This has been designed for the development of cost-effective pre-engineered solar energy system kits that can provide both heating and cooling. This thesis summarises the characterisation studies of the operation of individual sorption modules, sorption module integrated solar collectors and a full solar heating and cooling system employing sorption module integrated collectors. Key performance indicators for the individual sorption modules showed cooling delivery for 6 hours at an average power of 40 W and a temperature lift of 21°C. Upon integration of the sorption modules into a solar collector, measured solar radiation energy to cooling energy conversion efficiencies (solar cooling COP) were between 0.10 and 0.25 with average cooling powers between 90 and 200 W/m2 collector aperture area. Further investigations of the sorption module integrated collectors implementation in a full solar heating and cooling system yielded electrical cooling COP ranging from 1.7 to 12.6 with an average of 10.6 for the test period. Additionally, simulations were performed to determine system energy and cost saving potential for various system sizes over a full year of operation for a 140 m2 single-family dwelling located in Madrid, Spain. Simulations yielded an annual solar fraction of 42% and potential cost savings of €386 per annum for a solar heating and cooling installation employing 20m2 of sorption integrated collectors.
Resumo:
In 1977, when teacher education inSwedenwas incorporated into the university system, the main reason was to transform it into an academic tradition. Now, nearly 30 years later, there is still tension between the academic and the vocational tradition; they show up as different and separated elements in a program that is meant to prepare students for a career as a teacher and for a possible future career as a researcher in this field. This tension gives rise to a risk of allowing parallel “tracks” to develop and of isolating the degree thesis work from other courses. On the teacher-training program in which we are involved, close co-operation with partner-schools, where the practical part of the program takes place, has been established. Here, the students´ degree theses are an important factor in making this co-operation work on a concrete level. Accordingly, the purpose of the degree thesis is both to reflect problems in schools and contribute to better teaching in the individual school, but also to offer relevant educational subject matter to the students, which may be adapted as an element in the university’s research environments. From these points of view, the degree thesis is an important part of teacher education and rather more than just a single course. The degree thesis should be an element that gives the students an opportunity to show that they have reached central goals in the teacher education program. It should also be an integral part in the development of critical and scholarly thinking, deepening pedagogical and didactic knowledge and giving the students an opportunity to apply research methods. We will here use two minor case studies: one that compares teacher education programs in five Swedish universities and one minor study at one of those universities, in order to elaborate on the questions: - What purpose has a degree thesis and what role does it play in teacher education? - What criteria are relevant to assessing a degree thesis and what qualities do the degree theses have? - Is it possible to assess a degree thesis fairly and what happens to students who do not pass? - How could the degree thesis be used to improve the contact between the teacher education program and its partner schools in order to contribute to the development of the individual school?