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In many dry desert climates such as in Kuwait, the summer season is long with a mean daily maximum temperature of 45°C. A round 80% of total electricity generation is consumed by air-conditioning systems in domestic buildings. A hybrid cooling technique to reduce the domestic cooling demand would have both environmental and economic benefits for Kuwait. A passive cooling technique, which assists the situation, is ground cooling. In this thesis a thermal model of an earth air heat exchanger (EAHE) has been developed to calculate the pre-cooling of ventilation air that can be achieved for a building through use of a buried pipe below ground surface.

WIND-CHIMNEY Integrating the principles of a wind-catcher and a solar chimney to provide natural ventilation Fereshteh Tavakolinia Abstract This paper suggests using a wind-catcher integrated with a solar-chimney in a single story building so that the resident might benefit from natural ventilation, a passive cooling system, and heating strategies; it would also help to decrease energy use, CO2 emissions, and pollution. This system is able to remove undesirable interior heat pollution from a building and provide thermal comfort for the occupant.The present study introduces the use of a solar-chimney with an underground air channel combined with a wind-catcher, all as part of one device. Both the wind-catcher and solar chimney concepts used for improving a room’s natural ventilation are individually and analytically studied. This paper shows that the solar-chimney can be completely used to control and improve the underground cooling system during the day without any electricity. With a proper design, the solar-chimney can provide a thermally comfortable indoor environment for many hours during hot summers. The end product of this thesis research is a natural ventilation system and techniques that improve air quality and thermal comfort levels in a single story building. The proposed wind-chimney could eventually be designed for use in commercial, retail, and multi-story buildings.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Increased awareness of environmental problems has awakened interest in renewable energy systems. Natural ventilation systems are especially of interest, as people spend most of their time indoors. Indoor air quality is an important consideration when human health and occupant comfort is to be maintained. This study focusses on determining the best inlet and outlet shape for a natural ventilation system from a chosen set of configurations. The inlet and outlet configurations were tested on a PDEC (Passive Downdraught Evaporative Cooling) shaft and solar chimney. The PDEC incorporated an evaporative cartridge made from cotton cloth. Independent models of the PDEC and solar chimney were built in a thermally controlled space where the configurations were tested at different wind speeds. The configurations were tested on a wet or dry PDEC shaft and on a hot or cold solar chimney. One-dimensional finite difference models, accounting for some two-dimensional effects in the evaporative cartridge, of the cartridge and solar chimney were developed. CFD (Computational Fluid Dynamics) models were further constructed in FLUENTr, simulating operating conditions for each inlet and outlet test. The CFD models were constructed to obtain numerical comparisons for the experimental data. The ability of the one-dimensional and CFD models to predict the performance of the PDEC and solar chimney were investigated. The results indicated that an inlet configuration called a TFI (Turbine Fan Inlet) performed the best at the tested wind speeds. The TFI was further able to significantly increase volumetric flow rate in the PDEC shaft for the dry evaporative cartridge tests. The outlet that performed best under the tests is a Windmaster Tornado Wind Turbine, or Whirlybird, which is a commercially available configuration. The one-dimensional models were not able to accurately predict conditions during start-up. The CFD models were highly accurate in predicting the experimental values. It is recommended that a two-dimensional theoretical model be developed to better predict start-up conditions. / AFRIKAANSE OPSOMMING: Verhoogde bewustheid van omgewings probleme het belangstelling in hernubare energie stelsels ontwaak. Natuurlike ventilasie stelsels is veral van belang, sedert mense die meeste van hul tyd binnenshuis spandeer. Binnenshuise lug kwaliteit is ’n belangrike oorweging wanneer menslike gesondheid en insittendes se gemak in stand gehou moet word. Hierdie studie fokus op die bepaling van die beste inlaat en uitlaat vorm van ’n gekose stel konfigurasies vir ’n natuurlike ventilasie-stelsel. Die inlaaten uitlaat-konfigurasies is op ’n PDEC (Passive Downdraught Evaporative Cooling) skag en sonkrag skoorsteen getoets. Die PDEC het ’n verdampings doek, gemaak van katoen, ingesluit. Onafhanklike modelle van die PDEC en sonkrag skoorsteen is in ’n termies-beheerde ruimte en die konfigurasies is by ’n onveranderende wind spoed getoets. Die konfigurasies is op ’n nat of droog PDEC skag en op ’n warm of koue son skoorsteen getoets. Een-dimensionele eindige verskil modelle, wat sommige twee-dimensionele effekte in ag neem in die verdampings doek, van die doek en sonkrag skoorsteen is ontwikkel. CFD (Computational Fluid Dynamics) modelle is verder gebou in FLUENTr, wat die werkstoestande vir elke inlaat en uitlaat toets simuleer. Die CFD modelle is ontwikkel om die eksperimentele data met numeriese waardes te vergelyk. Die vermoë van die een-dimensionele en CFD modelle om die verrigting van die PDEC en sonkrag skoorsteen te voorspel, is ondersoek. Die resultate dui daarop dat ’n inlaat opset genoem TFI (Turbine Fan Inlet) die beste vaar by die elke getoetsde wind spoed. Die TFI was verder in staat om die volumetriese vloeitempo in die PDEC skag aansienlik te verhoog vir die toetse met ’n droë verdamping doek. Die uitlaat wat die beste presteer het in die toetse is ’n Windmaster Tornado Wind Turbine, of Whirlybird, wat ’n kommersieel beskikbare konfigurasie is. Die een-dimensionele modelle was nie in staat om die toestande tydens die begin-fase akkuraat te voorspel nie. Die CFD modelle was hoogs akkuraat in die voorspelling van die eksperimentele waardes. Dit word aanbeveel dat ’n twee-dimensionele teoretiese model ontwikkel word om die toestande tydens begin-fase beter te voorspel.

The diploma thesis Strategic concept of company Bristec cz s.r.o. analyses and evaluates company's position in the market and searches opportunities for future development. The thesis is divided into theoretical and application part, which is then divided according to business activity of the company. Terms as mission, vision and goals and explained in the theoretical part. Principles of strategic management and conduction of strategic analysis are also described. Types of strategy from renowned authors and specifications of family companies are then introduced. The theoretical part furthermore consists of quotations from famous personalities, which emphasize on importance of strategy creation. The application part introduces Bristec cz, its business activities and main supplier. Then, strategic analysis is conducted on both ventilation systems and physiotherapy. After analysis follow creation of company's mission and vision and evaluation of business portfolio. The application part is concluded by strategic recommendations for the company.

As in-suite heat recovery ventilator (HRV) use increases, cases of cross-contamination and odour transmission in MURBs are beginning to appear. To mitigate these issues and maximize HRV benefits, a better design and construction methodology specific to MURBs is required. Previously conducted condition surveys suggest the possibility of the fresh air supply becoming contaminated by the exhaust air stream from adjacent units. It is suggested that the intake and exhaust configuration has a significant influence on the potential for cross contamination. The results show cross contamination is an issue in high-rise condominiums. With a low exhaust vent angle and the right wind direction and speed, contaminants can travel from an exhaust source to a fresh air supply in a significant quantity. The potential impact here is to protect the health and safety of all home owners living in high-rise condominiums that utilize in-suite ventilation systems.

As in-suite heat recovery ventilator (HRV) use increases, cases of cross-contamination and odour transmission in MURBs are beginning to appear. To mitigate these issues and maximize HRV benefits, a better design and construction methodology specific to MURBs is required. Previously conducted condition surveys suggest the possibility of the fresh air supply becoming contaminated by the exhaust air stream from adjacent units. It is suggested that the intake and exhaust configuration has a significant influence on the potential for cross contamination. The results show cross contamination is an issue in high-rise condominiums. With a low exhaust vent angle and the right wind direction and speed, contaminants can travel from an exhaust source to a fresh air supply in a significant quantity. The potential impact here is to protect the health and safety of all home owners living in high-rise condominiums that utilize in-suite ventilation systems.

Scandinavian countries have always been the first in investigation and development of new ventilation systems. In the last years, engineers from Finland and Sweden are studying a new ventilation system known “Confluent jet ventilation system” which is trying to improve displacement and mixing results. The aim of this thesis master is to study the behaviour of three different ventilation systems, mixing ventilation, displacement ventilation and confluent jet ventilation, in an office room by mean of three analysis, temperature gradient analysis, tracer gas analysis and thermal comfort analysis, and to compare them to know if the new one, confluent jet, increases the performance of mixing or displacement ventilation system. In case of confluent jet ventilation system, there were two different cases: one with the supply air device at 2.2m high, and the other with it at 1.7m high to compare which one was the correct position and gets the best results. For each studied system 3 different cases were analyzed, having the same parameters each one of them for the three ventilation systems.The measurements were taken in an office room located in the laboratory of the University of Gävle, Högskolan I Gävle, in collaboration with the Finnish company specialized in ventilation systems, Stravent. For temperature gradient analysis, ten sensors took temperatures from the low level, 0.1m high, to the top level of the room, 2.4m, during all the time that the other measurements were being taken. For tracer gas analysis, a data logger took measurements of the contaminant concentration, N2O, from when the contaminant was thrown into the room until it disappeared following a Decay curve. Lastly, in thermal comfort analysis 4 transducers took measurements each 12 minutes of air temperature, operative temperature, air velocity and air humidity are measured in 6 different points inside the office room and at 3 different heights, 0.1m, 1.1m and 1.7m. After analyzing the results of temperature gradient, tracer gas and thermal comfort the best results were obtained by confluent jet system with the supply air device at 2.2m in case of temperature gradient, since the difference of temperatures between the low and the top level were the minimum and contaminants and indoor air were not in a homogeneous mixing. In case of tracer gas, the results about air change efficiency were not the expected because they showed a well-mixed situation for every system and it should not have been like that. It was caused for the influence of a cooling system situated in the ceiling of the room and the temperature difference between inside and outside the room that affected more than expected. Finally, in thermal comfort analysis, the best results were obtained by confluent jet ventilation, therefore in case of the supply air device at 2.2m and in case of it at 1.7m. To sum up, taking account the results achieved, the confluent jet ventilation got the best results and showed that it is a new ventilation system that must be taken in consideration in the following buildings. Between supply air device at 2.2m and 1.7m the results were very similar, but a bit better in case of the highest height.

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The diploma thesis deals with smoke and heat ventilation systems in underground car parks. In the theoretical part of the thesis, legislative and standard background is described. The theoretical part also contains description of fire dynamics simulation methods and effect of carbon monoxide on human health. The practical part includes the design of service, smoke and heat ventilation systems in the selected building. Functionality of particular design is verified by FDS simulations.