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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

KAN SOLEN KYLA LÖKAR? : En studie av soldrivet kylsystem i Nashik, Indien

Osta, Diana January 2015 (has links)
Sammanfattning Mer än en fjärdedel av Indiens befolkning motsvarande 311 miljoner människor saknar elanslutning. Det allra flesta av dem bor i fattigar landsbygden. Indien är även en av dem största producenterna av lök i världen där staten Maharashtra står för 30 % och distriktet Nashik för 60 %. Gällande förvaringen av lök på landsbygden i Nashik, i området Sinnar, är det ett problem. Under perioder med hög temperatur och hög luftfuktighet i distriktet ruttnar lökarna som förvaras som resultat kan inte bönderna sälja sina lökar på marknaden och allt slängs. Med hjälp av den icke-statliga organisationen Yuva Mitra i Indien och Mälardalens Högskola har detta arbete kunnat utföras till följd att hjälpa bönderna. Syftet med detta arbete har varit att komma med ett förbättringsförslag av nuvarande förvaringslager till lökarna. Främst att bönderna ska kunna bevara sina lökar i gott skick och öka deras livslängd så att dem kan användas och säljas till marknaden framöver. Fältstudier gjordes i Sinnar under två månader där det ingick intervjuer med bönder, producentföretag, chefer på ” National bank for agriculture and rural development” (NABARD) och kyl företag i både Sverige och Indien. Observationer gjordes också på tre olika förvaringslagrar och andra jordbruksfält i både byn Vadangali och Wadgaon. Beräkningar på en kyleffekt gjordes i Sverige med hjälp av en beräkningsmall, för kylbehovsberäkning av kyllager, och med hjälp av litteraturstudier. Programmet PVsyst användes för att beräkna hur stort ett solcellssystem krävs för att driva en kompressorkylmaskin. Revit användes för ritning av en exempel modell på ett kyllager med bestämt material och mått. Ekonomisk utvärdering utfördes för att se investeringskostnaden och återbetalningstiden. Ett förvaringslager i byn Vadangali valdes för detta arbete som utpunkt för förbättring. Lagret har en area på 105 m2, volym på 420 m3 och rymmer maximalt 50 ton lök. Förvaringstiden är på 8 månader mellan mars och oktober månad. Materialet som används idag är av lokalnivå, trä längder, plåt och stålgaller, lagret är sponsrat av regeringen och kostade cirka 35 500 kr. Arbetet inkluderade utformandet av ett kyllager med en kompressorkylmaskin driven av ett fristående solcellssystem. Det föreslagna kyllagret har samma area som det nuvarande, dock en annan volym på 525 m3, och är dessutom utformat för att klara av en inomhustemperatur på 0°C. Detta kräver en kyleffekt av 20 kW samt en soleffekt av 18,48 kW med arean 153 m2 på solpanelen som skall placeras på marken med hjälp av en ställning. Solpanelens ska även placeras med en riktning mod syd och ha en vinkel på 20 grader för att uppnå maximal effekt. Två resultat åstadkoms av detta arbete varav ena är ett självbyggt kyllager med ett solcellssystem, och den andra en prefabricerad kyllager med ett kylaggregat med samma solcellssystem. Som slutsats av detta arbete är bästa lösningen med lägst investeringskostnad och återbetalningstid en prefabricerad kyllager med kylaggregat och ett solcellssystem som ska driva kompressorn med elenergi. Den totala investeringskostnaden med bidrag och lån från NABARD för ett sådant system kommer att kosta 240 633 kr vilket motsvarar en återbetalningstid på 4 år. Nyckelord: Kyllager, solcellssystem, solenergi, kompressorkylmaskin, Yuva Mitra, lök, producentföretag, landsbygdsutveckling, jordbruk, förvaringslager / Abstract India is one of the largest producers of onion in the world, which means that there is a great demand of storage facilities for the harvested onions. Indian onion farmers usually don’t use cold storage for their onions because of lack of electricity in the rural areas. During periods of high temperature and high humidity large quantities of stored onions rot. This results in much of the produce being wasted as the rotten onions cannot be sold to the market. This is a serious problem to the farmers in Nashik, situated in a block called Sinnar. The non-government organization Yuva Mitra in Nashik is supporting farmers to improve their storage of onions. Malardalens University has been asked to assist the NGO with this, therefore this work has been carried out to investigate how to improve the cooling of harvested onions, in order to improve the situation for the onion farmers. The aim of the study was to investigate cost- and energy effective solutions to provide electricity to the farmers, using solar power, allowing the farmers to build a cold storage. The purpose of this work has been to present a suggestion for improvement of an existing warehouse that currently is used by the onion farmers in Nashik. The main purpose is to provide a solution to the farmers that allows them to preserve their onions in good condition and increase the onions lifetime so that more onions can be sold to the market. Field studies were made in Sinnar, including interviews with farmers, the producer companies, managers at "National Bank for Agriculture and Rural Development" (NABARD) and cooling companies in both Sweden and India. Calculations of cooling effect were made in Sweden using a calculation template, for cooling calculations of cold storage, and with the help of literature. The solar program, PVsyst, was used to calculate how big a PV system has to be to operate a compressor chiller. The Revit program was used to draw a model example of a cold storage with selected materials and dimensions. An economic evaluation was conducted to determine the investment cost and payback period. The suggested cold storage has the same area as the current storage facility of ​​105 m2, but a larger volume of 525 m3. The suggested storage can accommodate a maximum of 50 tons of onions. It is designed to hold an indoor temperature of 0°C, which requires a cooling capacity of 20 kW and solar power of 18,48 kW with a solar panel area of ​​153 m2 to be placed with a position on the ground facing south at an angel of 20 degrees. The results show that the total investment with grants and loans from NABARD for such a system will be 240 633 SEK, which corresponds to a payback period of 4 years. The best solution with the lowest investment cost and with the lowest payback period is a prefabricated warehouses, which has chillers and a solar system to drive the compressor with electrical energy. Keywords:    cooling storage, PV-system, solar energy, compressor chiller, Yuva Mitra, onion, Producer Company, rural development, agriculture, warehouse
62

Integration of waste heat recovery in process sites

Oluleye, Oluwagbemisola Olarinde January 2016 (has links)
Exploitation of waste heat could achieve economic and environmental benefits, while at the same time increase energy efficiency in process sites. Diverse commercialised technologies exist to recover useful energy from waste heat. In addition, there are multiple on-site and offsite end-uses of recovered energy. The challenge is to find the optimal mix of technologies and end-uses of recovered energy taking into account the quantity and quality of waste heat sources, interactions with interconnected systems and constraints on capital investment. Explicit models for waste heat recovery technologies that are easily embedded within appropriate process synthesis frameworks are proposed in this work. A novel screening tool is also proposed to guide selection of technology options. The screening tool considers the deviation of the actual performance from the ideal performance of technologies, where the actual performance takes into account irreversibilities due to finite temperature heat transfer. Results from applying the screening tool show that better temperature matching between heat sources and technologies reduces the energy quality degradation during the conversion process. A ranking criterion is also proposed to evaluate end-uses of recovered energy. Applying the ranking criterion shows the use to which energy recovered from waste heat is put determines the economics and potential to reduce CO2 emissions when waste heat recovery is integrated in process sites. This thesis also proposes a novel methodological framework based on graphical and optimization techniques to integrate waste heat recovery into existing process sites. The graphical techniques are shown to provide useful insights into the features of a good solution and assess the potential in industrial waste heat prior to detailed design. The optimization model allows systematic selection and combination of waste heat source streams, selection of technology options, technology working fluids, and exploitation of interactions with interconnected systems. The optimization problem is formulated as a Mixed Integer Linear Program, solved using the branch-and-bound algorithm. The objective is to maximize the economic potential considering capital investment, maintenance costs and operating costs of the selected waste heat recovery technologies. The methodology is applied to industrial case studies. Results indicate that combining waste heat recovery options yield additional increases in efficiency, reductions in CO2 emissions and costs. The case study also demonstrates that significant benefits from waste heat utilization can be achieved when interactions with interconnected systems are considered simultaneously. The thesis shows that the methodology has potential to identify, screen, select and combine waste heat recovery options for process sites. Results suggest that recovery of waste heat can improve the energy security of process sites and global energy security through the conservation of fuel and reduction in CO2 emissions and costs. The methodological framework can inform integration of waste heat recovery in the process industries and formulation of public policies on industrial waste heat utilization.
63

Estudo de viabilidade técnico-econômica de pequenas centrais de cogeração a gás natural no setor terciário do Estado de São Paulo / Study of technical and economic feasibility of small cogeneration plants powered by natural gas in the tertiary sector of the state of São Paulo

Ronaldo Andreos 28 February 2013 (has links)
Esta dissertação analisa a viabilidade técnico-econômica de pequenas centrais de cogeração a gás natural no setor terciário do estado de São Paulo, os estudos de cogeração foram baseados em casos reais de estabelecimentos comerciais dos principais segmentos do setor terciário com demanda elétrica e térmica compatível ao balanço energético para a configuração de cogeração. A análise dos resultados inclui o fator de utilização de energia (FUE), investimentos iniciais, economia operacional (fluxo de caixa), retorno dos investimentos (Payback), taxa interna de retorno (TIR) e valor presente líquido (VPL). As tecnologias empregadas nos estudos foram gerador do tipo Motor a Combustão Interna (MCI) e Microturbina (TG), resfriador de líquido por absorção (ABS) e resfriador de líquido elétrico convencional. Foi realizada análise do potencial de mercado para aplicação de cogeração através do mapeamento dos principais segmentos do setor terciário e realizado o levantamento do estado da arte. Foram estudadas as legislações brasileiras tanto no que se refere à cogeração qualificada como geração distribuída, realizado análise de emissões com destaque ao comparativo entre emissão de CO2 das centrais de cogeração e a emissão de CO2 das termelétricas a gás natural. Foi realizado estudo do cenário energético brasileiro do ponto de vista geração e distribuição de energia elétrica, cenário da oferta de gás natural no Brasil e a sua estrutura de distribuição no estado de São Paulo e, por fim, foram destacados os benefícios e barreiras da cogeração no Brasil. Os resultados alcançados apontam para um revés na viabilidade financeira da cogeração devido aos consecutivos aumentos no preço da tarifa de gás natural, apesar de bastante racional e com benefícios diretos ao meio ambiente e ao país, fazem-se necessários incentivos específicos relacionados à tarifa do gás natural para o crescimento da aplicação de cogeração no setor terciário do estado de São Paulo. / This dissertation examines the technical and economic feasibility of small cogeneration plants powered by natural gas in the tertiary sector of the state of São Paulo. Cogeneration studies were based on real cases of commercial facilities of the main segments of the tertiary sector with electrical and thermal demands compatible for energy usage in cogeneration configuration. The analysis results include energy utilization factor (EUF), initial investments, operational savings (cash flow), return on investment (payback), internal rate of return (IRR) and net present value (NPV). The technologies investigated in the study were Internal Combustion Engine (ICE) and Microturbine (TG) generator, absorption chiller (ABS) and conventional electrical chiller. It was carried out an analysis of the potential market for application of cogeneration by mapping the main segments of the tertiary sector and conducted a survey of the state of the art. Brazilian laws were studied both with regard to qualified cogeneration and distributed generation, performed emissions analysis with emphasis on the comparative between CO2 emission from cogeneration plant and CO2 emission from power plants by natural gas. It was made a study of Brazilian energy scenario from the viewpoint of generating and distributing of electricity, scenario of supply of natural gas in Brazil and its distribution structure in the São Paulo state and, finally, it was appointed the benefits and barriers of cogeneration in Brazil. The results indicate a setback on the financial viability of cogeneration due to consecutive increases in the price of natural gas, although quite rational and with direct benefits to the environment and the country, it\'s necessary specific incentives related to the natural gas price for the growth of the application of cogeneration in the tertiary sector of the state of São Paulo.
64

Miljövänlig kyla : En studie för framtagning av verktyg för att underlätta val av olika kylsystem / Environmentally friendly cooling : How to facilitating the choice of cooling systems

Fuentes, Cristopher, Peralta, Christopher January 2016 (has links)
The study compared four different cooling systems and analyzed the competitiveness in those systems regarding electricity consumption, environmental impact and life cycle cost analysis. The assignment was given from the consultant company Ramböll who believed in these systems design as a solution to minimize the energy consumption in cooling systems. The purpose of the study was to facilitate the selection of cooling system by finding a key ratio for profitability in terms of energy consumption. This makes it easier to select one of these systems in project planning. A representative building model was built in the energy simulation program IDA ICE. From these result an energy profile was achieved.   The energy profile was then used in another simulation program called Polysun were detailed system regulations could be made. By programing the controllers to regulate the distribution in an efficient way the energy consumption was minimized and matches the building cooling demand. The simulation was done for one full year and the obtained total energy consumption for each system, it was then used to calculate the operational cost. The life cycle cost analysis is a tool that compare each system costs during its lifetime. A depth analysis was also done regarding the sensitivity of changes in the profitability for the systems, by applying different electrical price and cost of capital.   The study shows that the systems with different borehole storage solutions proves to be effective systems for covering the building cooling demand with a significant lower electricity consumption, compared to the system with a chiller. The different borehole storage systems also contribute to cover some parts of the heat demand, since the stored heat needs to be used in order to make the borehole storage functional. By analyzing the cooling systems in a comparative perspective, the most effective solution is identified from an economic and environmental point of view. The cooling system that only contained a borehole storage was the solution that distinguished the most regarding total electricity consumption and environmental impact. This system resulted in being the most profitable cooling system between the compared systems. The combined system with a borehole storage system and a heat pump solution was also proven to be an effective cooling system, additionally with an advantage of providing parts of the hot water demand in the building.
65

Průmyslové chladicí systémy / Industrial cooling systems

Doležal, Jan January 2017 (has links)
This thesis describes the design of cooling ice rink. Cooling system design is based on a physical nature, measured data and observations from practice. The result is a proposal cooling system with the highest possible cooling factor, which uses waste heat for technology needs snow pit and hot water, in order to achieve the lowest cost of operation ice rink.
66

Velkoplošné systémy vytápění a chlazení / Large-area heating and cooling systems

Kohlová, Vendula January 2022 (has links)
The aim of the diploma thesis is to design heating and cooling in the office building and the showroom. The theoretical part deals with large-scale heating and cooling systems. The types of these systems and their advantages and disadvantages are described here. The practical part is devoted to the design of heating and cooling in the assigned office building and the showroom. In this part, two variants of the design are considered. The first variant considers the use of a heat pump as a source of heat and cold. In the second variant of the solution, a gas condensing boiler is used as a heat source and a chiller as a cold source. The experimental part deals with measuring the properties of one ceiling panel. The main task was to determine the cooling capacity of the ceiling panel.
67

Generic design and investigation of solar cooling systems

Saulich, Sven January 2013 (has links)
This thesis presents work on a holistic approach for improving the overall design of solar cooling systems driven by solar thermal collectors. Newly developed methods for thermodynamic optimization of hydraulics and control were used to redesign an existing pilot plant. Measurements taken from the newly developed system show an 81% increase of the Solar Cooling Efficiency (SCEth) factor compared to the original pilot system. In addition to the improvements in system design, new efficiency factors for benchmarking solar cooling systems are presented. The Solar Supply Efficiency (SSEth) factor provides a means of quantifying the quality of solar thermal charging systems relative to the usable heat to drive the sorption process. The product of the SSEth with the already established COPth of the chiller, leads to the SCEth factor which, for the first time, provides a clear and concise benchmarking method for the overall design of solar cooling systems. Furthermore, the definition of a coefficient of performance, including irreversibilities from energy conversion (COPcon), enables a direct comparison of compression and sorption chiller technology. This new performance metric is applicable to all low-temperature heat-supply machines for direct comparison of different types or technologies. The achieved findings of this work led to an optimized generic design for solar cooling systems, which was successfully transferred to the market.
68

Trigenerace a její využití v praxi / Trigeneration and its use in practice

Čupera, Pavel January 2009 (has links)
e master's thesis clarifies the concept of trigeneration and the principle of absorbing cooling. Compare the advantages and disadvantages of this method of manufacture cool with compressor cooling. It presents an overview of the implementation of a developing cold absorption and performance. Acquainted with the types of absorption chillers of the two leading suppliers, their characteristics and existing applications of these refrigeration units in operation in the Czech Republic and abroad. It also assesses the possibility of using these units in conjunction with a cogeneration unit powered by internal combustion engine. It follows from the economic assessment of costs and income of the absorption chillers and compressor chillers and on concrete examples and an assessment of the effectiveness of the various options.
69

Vzduchotechnika hotelového komplexu / Air Conditioning of Hotel Komplex

Očkan, Tomáš January 2014 (has links)
The first part of the thesis is aimed on creating internal microclimate of the hotel complex by air conditioning systems. The choice of systems is based on theoretical knowledge’s and practical application in abroad. In the second part there is designed solution for hotel apartments and conference hall. The other areas are designed only conceptual. Technical solutions of chosen systems are the main outcome of the thesis. In the third part there are published my experimental measurements from laboratories of Oulu University of Applied Sciences. For the study field of Air Conditioning has been chosen Air Flow Measurement and Test Operation of HVAC unit. For the study field of Renewable Energy has been chosen the Heat Pump and for study field of Refrigeration has been chosen Water Cooling and Chiller Box.

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