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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.
1

Solar cooling of buildings in a Swedish climate : Analysis and design of solar cooling in Building 45 at Högskolan i Gävle.

Moreno Fernandez, Marcos January 2014 (has links)
Nowadays Solar Energy is one of the engineering fields most exploited, due to the ongoing need to developing new technologies based on renewable energy or improving the existing ones. One particular application of this kind of energy is Solar Cooling, which consist in generating cold from the heat received from the Sun. A common installation of solar cooling requires solar collectors, an absorption/adsorption chiller, fan coils, piping, valves and pumps. It calls for a minimal preventive maintenance which should allow keeping operating conditions within certain limits.The aim of this work is to analyze the viability of the installation of a solar cooling system in a roof. It has been chosen the Building 45 of the University of Gävle (Hus 45) as a pattern design. It was built in 2008, thirteen years after Högskolan i Gävle was inaugurated. This building uses electric compression coolers for its cooling demand. According to their heating demand, this is solved by using District Heating.This work is focused on the determination of the cooling demand of this particular building and the proposal of a solar cooling system that could supply it. Calculating the cooling demand means applying most of the concepts learnt during the whole speciality of the degree, like thermal loads in buildings. This calculation has been possible by using IDA ICE, which is a software that allows the user to develop a new construction through defining all structure parameters. After having defined all the contour conditions, the simulation shows all kinds of parameters in detail, in particular, the cooling demand of the respective building. Moreover, creating a new solar cooling system for this building means reviewing all the concepts related to refrigeration cycles and solar energy that have been learnt during the intensification. To do it, it has been necessary to use POLYSUN, another program that let the user to create solar thermal systems, photovoltaic systems or any other installation for getting heating, cooling or hot water.In addition, another important point to discuss is the usage of a solar cooling system based on absorption/adsorption technology instead of using photovoltaic as a way of providing to the current cooling units.The simulation about the cooling demand of the building shows that for covering the 95,22% of the operation hours (within the study), it is required to solve a cooling peak demand of 100 kW, which is in terms of energy a value of 68437,6 kWh. Regarding the designs of the solar cooling systems, two variants have been analyzed. While the first one is based on using the absorption technology, the second one has two subdivided proposals: a stand-alone photovoltaic system and a net metering installation. The absorption system could cover the cooling demand with the exception of July. The viability of this installation is questioned because of the low operation hours of the absorption machine, which is not working as it was expected since it is the cooling tower who really carries out the cooling function. On the other hand, the stand-alone system allows the building to cover all of its cooling demand, but the system is oversized and no profitable within a period of 30 years although it supposes a reduction of 100% in CO2 emissions, which is obvious since this option considers an electrical consumption from the grid of 0 kWh. Finally, the net metering system is probably the best option for covering the cooling demand of this building, as it has the shorter pay-back (18 years), the less visual impact when the solar modules are installed on the roof and requires less maintenance.Since there are no advantages in using an absorption machine for a cooling system in a Swedish climate, the next step would be analysing a system like the one proposed into another climate, where the solar radiation has more influence, thus, the absorption machine could work because of the inlet water (coming from the solar loop) is hot enough.
2

Modelización de sistemas de refrigeración por absorción con captadores solares de concentración

Montero Izquierdo, Iván Andrés 04 September 2012 (has links)
En esta tesis se analiza de manera detallada los sistemas de refrigeración solar con equipos de absorción de doble efecto con captadores solares de concentración en términos de energía primaria consumida. El análisis de estos sistemas permite compararlos con sistemas de refrigeración por absorción de simple efecto accionados con energía solar térmica de baja temperatura y con sistemas convencionales de compresión. Estos tres tipos de sistemas han sido modelizados mediante el software de simulación TRNSYS para cubrir la demanda frigorífica de un edificio genérico de oficinas localizado en Sevilla (España). Un aspecto importante en esta tesis es la modelización de las enfriadoras de absorción de simple y doble efecto mediante el método de la ecuación característica. Este método permite modelizar las prestaciones térmicas del equipo de absorción de manera sencilla y robusta, además que debido a su estructura puede ser aplicado a cualquier sistema de refrigeración por absorción. / This thesis presents a detailed analysis of solar cooling systems, with double-effect absorption chillers activated by concentrating solar collectors, in terms of primary energy savings. This analysis allows comparing this type of systems with solar assisted air-conditioning installations composed by single-effect absorption chillers and flat plate solar collectors, and conventional compression systems. These three types of systems have been modeled in a TRNSYS simulation environment and applied to a generic building located in the city of Seville (Spain) to cover its cooling demand. An important aspect of this thesis is the modeling of single and double-effect absorption chillers by means of the characteristic equation method (ChEM). This method permits modeling of thermal performance of the absorption machine in a simple and robust manner, and due to its structure, the method can be applied to any absorption refrigeration system.
3

A simulation study for single and double effect absorption solar cooling systems operated under Taiwan climate

Shen, Jyun-long 09 September 2010 (has links)
Abstract There is much rich solar energy in Taiwan situated at the subtropics;Therefore it¡¦s suitable for solar energy is utilized as the driving energy for absorption cooling system. Simultaneously the use of solar energyreduces our dependence on fossil fuel ,and reaches the goal of energy conservation and reduction of carbon footprint deeply.After establishing absorption cooling system in TRNSYS.16 platform, climate data TMY2 form for several cities of Taiwan are input to the simulation program. As a result of Taiwan climate variation, summer is getting more and more longer ; winter is getting shorter gradually .Hence we simulated program from March to October .Then system operating the parameters of solar collector area and the volume of the storage tank are varied to research those effects on the system performance. The research focuses on the simulation data for monthly solar fraction(f),seasonal solar fraction(F) as well as how much solar energy saved could transform carbon dioxide content for single effect and double effect absorption cooling system operated under the climate of the major cities in Taiwan .Those data could provide the design needs.
4

Solární chladící systém / Solar cooling system

Mikyska, Lukáš January 2008 (has links)
Diploma work is bent on technology production cold with usage absorbing circulations powered heat energy. Work it is possible divide by to the of several part. First volume of work is introduction tenet absorbing circulations, their elements, division, applicable working couple, basic operation parameters and possibilities realized solar refrigerating systems. Alternative part smoothing - out practical page. Elaboration project proposal wiring solar refrigerating system with absorbing period, about refrigerating achievement 6 kW and processing constructional proposal personal refrigerating troop. In fine will basic technical economic juxtaposition solar refrigerating troop with compressor refrigerating period
5

Solar Powered Air Conditioning System

Ibrahim, Munzer January 2019 (has links)
No description available.
6

Simulation study for an absorption solar cooling system operated under Taiwan climate

Chiu, Yi-ying 22 August 2008 (has links)
In this thesis, solar energy is utilized as the driving energy for an absorption cooling system, and a TRNSYS computer code is employed to simulate the operation of the system under Taiwan climate. Climate data in TMY2 form for several major cities of Taiwan are input to the simulation program. Also system operating parameters of solar collector area and the size of the system storage are varied to study there effects on the system performance. This research provides computer simulation data for the monthly solar fraction (f) as well as the seasonal solar fraction (F) for the absorption solar cooling system operated under the climate of the major cities in Taiwan. The data can provide the design needs.
7

Modelling a Solar Driven Absorption Heat Pump

Gigos, Pierre-Antoine January 2016 (has links)
Absorption Heat Pumps (AHP) have been developed since the late 19th century. They enable to produce cooling and heating directly from a heat source, unlike Compression Heat Pumps that require mechanical work. In the context of scarcity of resources and global warming, the company Helioclim develops solar air conditioning using an Absorption Heat Pump. The heat is gathered at rooftop solar concentrators and powers an ammonia-water AHP. The present study proposes an EES model of Helioclim’s AHP allowing assessing its performances under various operating conditions. Another aspect developed is the Modelling of the whole system (from solar energy to the economic assessment) in order to find the best parameters to propose to a potential client. Regarding EES model, three existing EES examples of AHP have been used. Those models, ranging from the simple single-stage ammonia AHP to a more complex GAX-cycle, did not correspond exactly to the features of Helioclim’s cycle. Therefore, a new model has been built: the position of the GAX and its connections to the other heat exchangers have been adapted and a recirculation in the generator has been proposed in order to correspond to Helioclim’s design. The model obtained is then used to assess the improvement of the performances with the GAX. It is also compared to the available experimental data. In the present study, a software program representing the whole solar air conditioning system is also developed, integrating the previous EES model. The software program considers the solar energy gathered by the collectors and deduces the energy transmitted to the heat pump. The EES model is then used to assess the performances of the heat pump in the operating conditions, allowing determining the produced cooling and heating. An economic and energy synthesis is produced, summarizing effectively the parameters and economic advantages of the installation. This software program allows sizing an installation for a client much more quickly than before.
8

Design of renewable energy powered solar cool research centre

Rathnasooriya, Prageeth January 2012 (has links)
Solar cooling research center is being developed on CSEM-UAE outdoor research facility in RAK/UAE.  The research center is capable to test system from 1 TR cooling capacity to 10 TR cooling capacity. The source of heat is solar radiation and heat pipe type evacuated tube solar collectors are used to collect the solar energy. Solar station controls and circulates water in solar collectors and helps charge the hot water stratified tank. While in operation of the solar cooling facility, circulation pumps for hot water, chilled water and rejection circuit have to be continuously operated along with fan coil units, solar station, chiller and cooling tower. These all components require continuous electrical power. Currently, the entire electrical power requirement is supplied by a diesel generator. Since the center is for research activities, most of the time solar cooling center is on no load condition. Thus solar collectors are subjected to saturation. To prevent heat collection during no load conditions solar collectors are covered. Research project carried out to design of the renewable energy powered system to ensure the electricity availability for all the components so that the facility can be operated continuously without fossil fuel. UAE climate is sunny throughout the year thus Photovoltaic will be most prominent as a renewable source in generating electrical power. The PV is subjected to UAE harsh hot and dust environment which affect the performance of the PV. Thus the performance variations of PV due to dust deposition and temperature have analyzed. A matlab simulink model has developed to analyze the energy generation in UAE environment with available weather data. Technical and economical analysis has done for different PV technologies and find out the optimum PV design for the solar cooling center. To prevent the saturation of the solar collectors, a heat rejection unit have designed and installed. The control system for the automatic operation also implemented.
9

Soldriven kylning i Sverige / Solar Cooling in Sweden

Nilsson, Jonas January 2013 (has links)
No description available.
10

Solar Cooling : -A study of two thermal systems

Åhlund, Anton January 2015 (has links)
Electricity-driven air-conditioning is energy-intensive and puts a strain to many grids during hot periods in warm climates. Solar thermal cooling could be an alternative to conventional cooling, using a renewable energy source and supplying the most energy during peak demand periods with insignificant effect to the electric grid. Office buildings in warm climates have high cooling loads, naturally peaking during daytime because of occupancy and ambient temperature. Thus, office buildings have a seemingly advantageous relationship between the possible supply of solar thermal energy and cooling demand. With this background, solar cooling systems for two office buildings with the same dimensions are investigated, placed in a tropical- and a sub-tropical location. There are great differences in the design conditions for solar cooling systems in the tropics and the sub-tropics, between the chosen locations Manila and Abu Dhabi more specifically. Manila has a quite evenly distributed cooling load while Abu Dhabi has a strongly pronounced summer season with very high maximum cooling loads, while the winter temperatures are relatively low. The prior described conditions creates a big difference between loads throughout the year, making a thermal chiller less effective in this aspect. However Abu Dhabi is expected to have an overall smoother- and ultimately a more high performance solar cooling system due to lower humidity, which facilitates the important cooling of the chiller. Evacuated tube collectors were used at both sites, where the collectors in Manila needs to be larger relative to the chiller cooling capacity, in order to compensate for the irregularity of direct solar radiation. The electricity price in Abu Dhabi is too low for the solar cooling system to be economically feasible compared to a conventional system, where the net values over 20 years are 163 000 € and 127 000 €, respectively. Manila has on its hand a very high price for electricity, making the 20-year net values for both the solar cooling- and the conventional system approximately 170 000 €.

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