This thesis studies the use of night ventilation as a passive cooling strategy for a traditional courtyard house in a hot dry climate. This was done by CFD simulation of the house and its surroundings, using weather data for Baghdad. The simulation was done for a large number of scenarios in which each represented a change in one of the house elements, such as courtyard and room dimensions, and in some cases included modern technologies such as a ceiling fan. The thesis suggests that performance should be calculated with the aid of a "Night Time Effectiveness Ratio" (NTER) and time constants. The findings show that building elements can change the performance to various degrees, that the airflow patterns inside the rooms change from day to night, and that the thermal conditions during the day depend more on the intensity of solar radiation than other factors. The results show that a courtyard house can ensure the thermal comfort for its residents. However, it needs some assistance from new techniques such as fans to keep the air quality inside the house within acceptable limits. The values for NTER from initial simulations are around ten, which indicate that night ventilation is not enough for cooling the building. However, the values drop to less than one by using a small and narrow courtyard with a two-level house and a gallery around the courtyard. Also, it is necessary to have a connection between the courtyard and alleyway at ground level in the night only and to cover the courtyard during the day. The windows have the largest role in deciding the performance of night ventilation. Ideally they should be small and tall, or preferably a pair of windows separated by a vertical distance and kept closed during the day. The effects of room dimension are clearer in affecting the thermal comfort more than improving the performance of night ventilation. The research also examines the indoor air quality and suggests ways to improve it. Some of the ways are traditional like the use of a wind catcher in ventilating the courtyard and the basement, and others are more modern like using an exhaust fan. Furthermore, it suggests an algorithm to control these ways and to introduce only a limited quantity of fresh air to avoid excessive warming. Suggestions for future work are given, including tests for more elements in the courtyard house and for longer duration runs. It would also be helpful to study the use of latent heat storage (e.g. phase change material) as an additional effective thermal mass.

Submitted by ALESSANDRO LUCINDO DA LUZ null (aledaluz@hotmail.com) on 2018-01-10T01:24:32Z No. of bitstreams: 1 Operacao flexivel conversores_ALuz.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-01-10T11:41:48Z (GMT) No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Made available in DSpace on 2018-01-10T11:41:48Z (GMT). No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) Previous issue date: 2017-11-13 / Este trabalho de mestrado descreve uma estratégia de operação multifuncional e flexível aplicado a conversores trifásicos CC-CA (inversores) conectados à rede de distribuição de energia elétrica. A estratégia proposta é capaz de injetar potência ativa na rede e compensar correntes de distúrbios (reativos, desbalanço e harmônicos) simultaneamente. O maior objetivo desta operação flexível é de melhorar a Qualidade de Energia Elétrica em um ponto de acoplamento comum (PAC) permitindo a compensação total ou parcial destes distúrbios ou fatores que degradam a Qualidade de Energia Elétrica. O fator de potência é o principal fator de qualidade a ser observado e ele é calculado através da Teoria da Potência Conservativa – CPT. Entretanto, com base no fator de potência medido pelo lado da rede de distribuição e o fator de potência desejado, um coeficiente de compensação – k é calculado para o ajuste das correntes de compensação dos distúrbios que geram a potência não ativa. / This paper depicts a multifunctional and flexible control strategy applied in three-phase inverters, which are connected to the distribution network. The proposed strategy is able to inject active power into the electrical grid and compensate current disturbances (reactive, harmonics and unbalance) simultaneously. The main goal of this flexible strategy is to improve the Power Quality at the point of common coupling (PCC) allowing full or partial compensation of disturbances. Power factor is the main quality index observed and it is calculated according to Conservative Power Theory - CPT. Therefore, based on the power factor measured in the grid side and the desired value for the power factor, a compensation coefficient - k is calculated continuously adjusting the amplitude of the compensation current.