With the need to reduce CO2 emissions in the energy sector, ensure electric grid stability and reduce future cost uncertainties for process cooling, solar cooling can be an interesting solution. This report describes the comparison of solar cooling with either a photovoltaics system or a solar thermal system using a thermally driven chiller. The application investigated was industrial process cooling, for three load profiles and three locations in Europe. The method of comparing was by simulations in TRNSYS and calculation of the global levelized cost of cooling, taking into account the total cost of covering the whole cooling demand. The results for the global levelized cost of cooling showed that solar thermal cooling was not economically competitive compared to the reference system or the photovoltaic cooling system for any of the investigated boundary conditions. The general trend was that the global LCOC for the solar thermal cooling increased with the solar cooling fraction. The photovoltaic solar cooling system global LCOC was in parity with the reference system for low SCF of 20 % to 30 %, and even up to 60 % for some boundary conditions.

Atualmente, o processamento de dados é uma operação vital para os negócios de qualquer companhia, indústria ou prestador de serviços. Entretanto, os servidores em operação, dissipam energia térmica, aquecendo o ambiente, podendo ocasionar problemas operacionais, como funcionamento inadequado, paradas operacionais e até incêndios. Por isso, é necessário um sistema de condicionamento de ar para controlar de temperatura e umidade ambiental, entretanto o consumo de energia elétrica deste sistema aumenta o custo operacional da instalação, sendo necessário minimizá-lo. Baseado neste fato, esta tese avalia a aplicação de 2 tipos de sistemas de resfriamento solar, absorção térmica solar e fotovoltaico, para reduzir o consumo do tradicional sistema elétrico com unidades de resfriamento elétricas operadas por compressão de vapor, apresentando economias, disponibilidade diária e vantagens em uma sala de missão crítica localiza genericamente, em São Paulo, Abu Dhabi, Los Angeles e Nova York. Além disto, analisa a contribuição de sistemas de resfriamento natural e seus efeitos sobre carga e consumo. As densidades de carga propostas foram de 0,5 kW?m-², 1,0 kW?m-², 2,0 kW?m-², 4,0 kW?m-² e 8,0 kW/m. Os índices locais de irradiação e temperaturas anuais baseiam-se nos dados apresentados no banco de dados da ASHRAE para as localidades. Os resultados, válidos para um ano típico e são comparados com (1) Sala de missão crítica acionada por um sistema convencional, (2) combinação de métodos de resfriamento solar, (3) combinação de técnicas solares e resfriamento natural. Por meio de estimativas anuais, calculando as contribuições dos métodos de resfriamento solar e natural, concluiu- maioria dos casos o método de absorção solar apresenta maiores vantagens de economia de energia e retorno de investimento que o método fotovoltaico, especialmente quando associado ao resfriamento natural indireto. Ao final, conclui-se que a utilização de resfriamento solar, pode atingir a 50% de economia na conta de energia e um TIR de 25%. Quando associado a sistemas de resfriamento natural, a economia pode atingir valores de 68% de economia e um TIR de 134%. Para tal deverá ser observado a carga aplicada, o valor de investimento e a curva característica da unidade de resfriamento que irá complementar a carga. / Nowadays, data processing is a fundamental operation for modern business such as banks, technology companies, and factories, among others. However, computers dissipate non-negligible amounts of heat and as the operating temperature increases, these machines cannot operate properly or, under extreme conditions, can come to a stop by overheating. Consequently, it is necessary air conditioning systems to keep the proper operating temperature as well as the room temperature itself. On the other hand, a data center air conditioning system drains a large amount of electrical energy in the installation. Based on this, this thesis evaluates two types of solar cooling system, an absorption thermal system, and a photovoltaic system, to support the traditional electric chiller system showing the energy saving, advantage over conventional cooling and day availability for this system. In addition, it analyzed free cooling system contribution and his effects on consumption. A case study is analyzed in a generic data center located in the city of São Paulo, Abu Dhabi, Los Angeles, and New York. At first, the electrical power density simulated by the computers is 0.5 kW/m², 1.0 kW/m² 2.0 kW/m², 4.0 kW/m² and 8 kW/m², that would occur in half loads or in high loads computer installations. Local solar irradiation and temperature indexes are based on the ASHRAE database. The results are valid for a typical year and are compared to (1) a conventional data center; (2) the event combination of solar cooling; (3) the event combination of solar cooling and free cooling. In conclusion, the energy savings, payback and internal rate of return for 10 years are presented. In the main cases, the solar absorption takes advantage than photovoltaic cooling, However, It must be observed the load replicated and the influence on the work curve of the chiller and the beginning investment. In conclusion, the solar cooling, especially solar absorption can achieve great advantage to installation, resulting in 50% on savings in the electric bill a return internal rate for 10 years of 25%. When it is associated with free cooling this savings can achieve 68% and return rate of 134%.

Atualmente, o processamento de dados é uma operação vital para os negócios de qualquer companhia, indústria ou prestador de serviços. Entretanto, os servidores em operação, dissipam energia térmica, aquecendo o ambiente, podendo ocasionar problemas operacionais, como funcionamento inadequado, paradas operacionais e até incêndios. Por isso, é necessário um sistema de condicionamento de ar para controlar de temperatura e umidade ambiental, entretanto o consumo de energia elétrica deste sistema aumenta o custo operacional da instalação, sendo necessário minimizá-lo. Baseado neste fato, esta tese avalia a aplicação de 2 tipos de sistemas de resfriamento solar, absorção térmica solar e fotovoltaico, para reduzir o consumo do tradicional sistema elétrico com unidades de resfriamento elétricas operadas por compressão de vapor, apresentando economias, disponibilidade diária e vantagens em uma sala de missão crítica localiza genericamente, em São Paulo, Abu Dhabi, Los Angeles e Nova York. Além disto, analisa a contribuição de sistemas de resfriamento natural e seus efeitos sobre carga e consumo. As densidades de carga propostas foram de 0,5 kW?m-², 1,0 kW?m-², 2,0 kW?m-², 4,0 kW?m-² e 8,0 kW/m. Os índices locais de irradiação e temperaturas anuais baseiam-se nos dados apresentados no banco de dados da ASHRAE para as localidades. Os resultados, válidos para um ano típico e são comparados com (1) Sala de missão crítica acionada por um sistema convencional, (2) combinação de métodos de resfriamento solar, (3) combinação de técnicas solares e resfriamento natural. Por meio de estimativas anuais, calculando as contribuições dos métodos de resfriamento solar e natural, concluiu- maioria dos casos o método de absorção solar apresenta maiores vantagens de economia de energia e retorno de investimento que o método fotovoltaico, especialmente quando associado ao resfriamento natural indireto. Ao final, conclui-se que a utilização de resfriamento solar, pode atingir a 50% de economia na conta de energia e um TIR de 25%. Quando associado a sistemas de resfriamento natural, a economia pode atingir valores de 68% de economia e um TIR de 134%. Para tal deverá ser observado a carga aplicada, o valor de investimento e a curva característica da unidade de resfriamento que irá complementar a carga. / Nowadays, data processing is a fundamental operation for modern business such as banks, technology companies, and factories, among others. However, computers dissipate non-negligible amounts of heat and as the operating temperature increases, these machines cannot operate properly or, under extreme conditions, can come to a stop by overheating. Consequently, it is necessary air conditioning systems to keep the proper operating temperature as well as the room temperature itself. On the other hand, a data center air conditioning system drains a large amount of electrical energy in the installation. Based on this, this thesis evaluates two types of solar cooling system, an absorption thermal system, and a photovoltaic system, to support the traditional electric chiller system showing the energy saving, advantage over conventional cooling and day availability for this system. In addition, it analyzed free cooling system contribution and his effects on consumption. A case study is analyzed in a generic data center located in the city of São Paulo, Abu Dhabi, Los Angeles, and New York. At first, the electrical power density simulated by the computers is 0.5 kW/m², 1.0 kW/m² 2.0 kW/m², 4.0 kW/m² and 8 kW/m², that would occur in half loads or in high loads computer installations. Local solar irradiation and temperature indexes are based on the ASHRAE database. The results are valid for a typical year and are compared to (1) a conventional data center; (2) the event combination of solar cooling; (3) the event combination of solar cooling and free cooling. In conclusion, the energy savings, payback and internal rate of return for 10 years are presented. In the main cases, the solar absorption takes advantage than photovoltaic cooling, However, It must be observed the load replicated and the influence on the work curve of the chiller and the beginning investment. In conclusion, the solar cooling, especially solar absorption can achieve great advantage to installation, resulting in 50% on savings in the electric bill a return internal rate for 10 years of 25%. When it is associated with free cooling this savings can achieve 68% and return rate of 134%.

Η ηλιακή ενέργεια αποτελεί μια από τις κύριες Ανανεώσιμες Πηγές Ενέργειας (ΑΠΕ). Μπορεί να αξιοποιηθεί είτε μετατρεπόμενη σε ηλεκτρισμό είτε σε θερμότητα. Για τη μετατροπή της σε ηλεκτρισμό η κύρια τεχνολογία που χρησιμοποιείται είναι η τεχνολογία των φωτοβολταϊκών. Αντίστοιχα, για την μετατροπή της σε θερμότητα χρησιμοποιούνται ευρέως οι τεχνολογίες των επίπεδων θερμικών ηλιακών συλλεκτών και των θερμικών συλλεκτών σωλήνων κενού. Βασικό ζητούμενο και στις δύο περιπτώσεις αποτελεί η μεγιστοποίηση της αποδοτικότητας τους. Μια από τις μεθόδους που μπορεί να χρησιμοποιηθεί για την αύξηση της αποδοτικότητας μιας ηλιακής συσκευής είναι η χρήση ενισχυτικών ανακλαστήρων. Επίσης, στις συνήθεις τεχνολογίες φωτοβολταϊκών που εφαρμόζονται σήμερα, η μείωση της θερμοκρασίας λειτουργίας τους βελτιώνει την απόδοση τους. Η διπλωματική ερευνητική εργασία που ακολουθεί περιλαμβάνει τη συγκριτική μελέτη φωτοβολταϊκών διατάξεων, επίπεδων θερμικών συλλεκτών και συλλεκτών σωλήνων κενού. Μελετήθηκαν συστήματα φωτοβολταϊκών με τη χρήση διαφόρων μεθόδων ψύξης, ενεργητικών και παθητικών. Επίσης μελετήθηκε η αύξηση της αποδιδόμενης ηλεκτρικής ενέργειας των φωτοβολταϊκών με χρήση ενισχυτικών ανακλαστήρων (ημικατοπτρικός ανακλαστήρας, ανακλαστήρας αλουμινίου (ματ), λευκός ανακλαστήρας). Υλοποιήθηκαν συνδυαστικά συστήματα με ταυτόχρονη ψύξη και χρήση ενισχυτικού ανακλαστήρα και μελετήθηκε η συμπεριφορά τους. Ακόμα, μελετήθηκε η αύξηση της αποδιδόμενης θερμικής ενέργειας επίπεδου ηλιακού θερμικού συλλέκτη με προσθήκη ενισχυτικών ανακλαστήρων (καθρέπτης, ανακλαστήρας αλουμινίου και λευκός ανακλαστήρας). Τέλος, κατασκευάστηκε διάταξη θερμικού συλλέκτη σωλήνα κενού με επίπεδη ανακλαστική επιφάνεια. Πραγματοποιήθηκαν πειράματα με την προσθήκη ενισχυτικών ανακλαστήρων (ημικατοπτρικός ανακλαστήρας, ανακλαστήρας αλουμινίου και λευκός ανακλαστήρας) και μελετήθηκε η αύξηση της θερμικής απόδοσης του συλλέκτη. Με βάση τα αποτελέσματα των πειραμάτων, εξάγονται αντίστοιχα συμπεράσματα και παρατίθενται προτάσεις σχετικά με τις διατάξεις αυτές. / Solar energy is one of the main Renewable Energy Sources (RES). It can be utilized by being transformed into electricity or heat. The main technology used to transform solar energy into electricity is photovoltaics. Respectively, flat plate solar thermal collectors and evacuated tube solar thermal collectors are the technologies mostly used to transform solar energy into usable heat. One of the main concerns on both cases, is the maximization of their performance. The use of booster reflectors is one of the methods that can be implemented in order to increase the performance of a solar device. Also, a method to increase the performance of the main photovoltaic technologies used at the moment, is to cool them. The following diploma – research thesis includes the comparative study of photovoltaic systems, flat plate solar thermal collectors and evacuated tube solar thermal collectors. Photovoltaic systems with the use of various cooling methods, active and passive, were studied. The increase of the photovoltaic electrical output using booster reflectors (semi specular, aluminum reflector and white reflector) was also studied. Combined systems were implemented, with simultaneous cooling and usage of booster reflector, and their behavior was observed. In addition, the increase of the thermal output of a flat plate collector by using booster reflectors (mirror, aluminum reflector and white reflector) was studied. Finally, an evacuated tube solar thermal collector system with an embedded reflective surface was implemented. Experiments were carried out with the addition of booster reflectors (semi specular, aluminum reflector and white reflector) and the increase of the collector’s thermal output was measured. Based on the experimental results, conclusions and suggestions are made about these systems.