Studies concluded that more that 10% of all energy consumed in the world is expended by building air-conditioning systems. Energy efficiency in building and HVAC (Heating, Ventilating and Air-conditioning) design is therefore exceptionally important. A cost¬-effective way to improve the energy efficiency of a HV AC system, without compromising indoor comfort, is by implementing better control. System energy cost savings of up to 50% can be realised by optimising the system operating control strategies with direct payback periods of less than a year. However, when changing the operating strategy of a system it is often difficult to predict the resulting changes in system energy consumption and indoor comfort. To achieve these predictions, a dynamic simulation tool, which can efficiently and accurately simulate the building with the HV AC and control system in an integrated fashion, is required. Extensions to the integrated tool QUICKcontrol is therefore proposed to suite the needs of the energy service contractor. QUICKcontrol still has many shortcomings in the availability of component models for certain equipment commonly used in building systems today. New dynamic component models were therefore derived in this study. The accuracy and applicability of integrated building and natural ventilation modelling is illustrated in animal housing facilities. The predicted results obtained during this study were satisfactory to use these models with confidence in this type of building applications. The applicability of building, HV AC system and control simulations was illustrated in conference facilities. The results obtained show the value of integrated building and system simulation in the evaluation of energy cost saving inventions in commercial buildings. The mining and industrial sectors in South Africa consume about 40% of ESKOM's total electrical energy production. Mines alone use nearly 20% of the electricity provided by ESKOM. Ventilation and cooling (VC) systems are responsible for approximately 25% or R750 million of this energy. It will therefore be beneficial if the mines can be more energy clever in order to reduce their VC operating costs. The use of an extended integrated building and system simulation tool was therefore realised to investigate the potential for energy cost savings in mine VC applications. To extend QUICKcontrol for the simulation of other large thermal systems found in mining and industrial applications, new component models and simulations procedures were developed. Two case studies were performed with the extended tool to illustrate its applicability in thermal systems other than building systems. The potential for Demand Side Management (DSM) on a surface cooling plant and an underground clear water-pumping system was investigated. Satisfactory results were obtained during the two investigations to utilise this extended tool with confidence in practice. With more extensions to the tool it should be possible to investigate the potential for energy cost saving on any other thermal industrial applications. / Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

[pt] A determinação dos coeficientes convectivos de troca de massa em regeneração (retirada de água) de desumidificante líquido (trietileno glicol), para posterior utilização em condicionamento de ar,utilizando-se coletores solares planos é feita neste trabalho. A partir de balanços de massa e calor, é desenvolvido um modelo para o cálculo de um trocador de massa do tipo placas paralelas analogamente ao cálculo de torres de resfriamento, levando-se, entretanto, em consideração o abaixamento da pressão de vapor d água em equilíbrio com a solução aquosa de trietileno glicol. Das experiências realizadas com esta geometria, é possível estimar um valor médio para o número de Lewis, e correlação de vazões líquido-ar. Utilizando-se a analogia existente entre as transferências de calor e de massa, obtém-se uma correlação válida para a variação das características geométricas do coletores solares planos utilizados na regeneração do líquido desumidificante, bem como vazões e temperaturas de operação. É realizada finalmente uma análise das incertezas das medidas associadas aos valores de Merkel, Le e Lep obtidos, objetivando-se o estudo da confiabilidade das correlações desenvolvidas e do modelo de cálculo do regenerador. / [en] This experimental research deals with the determination of the mass transfer coefficient in the regeneration processo of a liquid dehumidifier (triethylene glycol), used in a solar air condittioning system. It is also developed, from na overall energy and massabalance, a model for calculating a parelal plate type regenerator using the same methodology as already accepted for designing colling towers. The model includes the lowering of the water vapor pressure in equilibrium with the aqueous glycol solution The heat and mass transfer analogy hás been used for obtaining na expression for the mass transfer coefficient from heat tranfer data, which is useful for designing solar regenerators from geometry, flow rates and temperature conditions. Finally, an uncertainty analysis of the Merkel, Le and Lep parameters has been carried on to validate the correlation developed from experimental data.

[pt] Como parte de um sistema solar de condicionamento de ar por resfriamento evaporativo, foi projetado e construindo um desumidificador de ar utilizando tri-etileno glicol como agente higroscópio líquido. O modelo teórico desenvolvido, baseado no procedimento adotado para cálculo de torres de resfriamento. Levou em consideração o abaixamento de pressão de vapor na superfície líquido-gás assim como o calor de mistura de tri-etileno glicol e água. Os dados experimentais obtidos concordam satisfatoriamente com os resultados previstos pelo modelo teórico proposto, dentro das faixas de vazão pesquisadas. Uma correlação semi-empírica foi desenvolvida para cálculo dos coeficientes de difusão de desumidificadores de ar como função das vazões das fases líquida e gasosa. Finalmente é sugerido um procedimento para projeto de desumidificadores de ar de características semelhantes ao modelo proposto. / [en] As part of solar evaporative cooling air conditioning system, using tri-ethylene glicol as a liquid dehumidifier, an absortion tower was designed and built for drying air. The theory of heat and mass transfer between liquid and gas was developped following the same procedure as usually adopted for cooling tower calculations.The lowering of vapor pressure and the heat of solution were taken into account. Experimental data agree reasonably with theory within a wide range of flow rates. A correlation was developped relating mass transfer coefficients to liquid and gás flow rates. A procedure is finally suggested for designing and estimating the performance of na absortion tower.

[pt] A partir do funcionamento contínuo e em regime permanente do sistema de ar condicionado solar, projetado pelo Departamento de Engenharia Mecânica da PUC/RJ, são feitas experiências variando-se as vazões de ar, tri-etileno glicol e água, nas torres de secagem, regeneração e umidificação, que compõem o sistema. As condições destes fluidos são medidas na entrada e saída destas torres. Através dos dados experimentais levantados, obtiveram se para cada experimento os valores dos coeficientes de transferência de massa para as torres de absorção e determinaram-se correlações empíricas para o cálculo destes coeficientes como função de vazões e da seção das torres. Com estas equações, montou -se uma simulação numérica do sistema projetado, e através de parâmetros como .coeficiente de desempenho e capacidade frigorífica, avaliou-se o desempenho do sistema, variando-se a vazão de ar na secagem, vazão e concentração do tri-etileno glicol e a temperatura da água no regenerador. Com esta Simulação, foi determinada a operação ótima do sistema de ar condicionado solar em termos das condições de operação. / [en] Experimental data were obtained by operating a solar air conditioning system installed on the roof of PUC/RJ. As working fluids, air, triethylene glycol and water were used in the drying and regeneration towers, together with the air washer. Their flow rates were varied during the esperiments. Correlations for mass transfer coefficients were obtained from experimental data, as a function of flow rates and cross section area. Thus, by knowing the performance parametrs of each component, a numerical simulation scheme was developed to calculate the overall performance of the air conditioning under different operating conditions. Flow rates and concentration can be varied in this simulation. Based on this simulation, optimum Operating conditions of the solar air conditioning system were specified.

[pt] No Brasil, devido ao clima tropical, muita energia elétrica é utilizada em sistemas de ar condicionado. Devido à excelente irradiação solar que incide na maior parte do país, existem boas condições para atender esta grande demanda de refrigeração através da utilização de sistemas de ar condicionado assistido por energia solar térmica. Nesta dissertação, as mais importantes tecnologias que utilizam a energia solar para a climatização foram verificadas quanto a sua aplicabilidade técnica e econômica no Brasil, com foco em sistemas de médio porte. Os princípios básicos para o dimensionamento de um sistema de refrigeração solar são descritos e um estudo de caso é apresentado e discutido, comparando-se um sistema de ar condicionado assistido por energia solar (auditório em Guaratinguetá, São Paulo) com um sistema tipo split convencional. No estudo deste caso, a dinâmica de simulação térmica de edifícios foi modelada utilizando o programa Helios-PC. Também se analisa como a carga térmica de resfriamento pode ser diminuída considerando-se uma temperatura adequada no interior da edificação, de acordo com as normas brasileiras de conforto térmico, como também pelo emprego de isolamento adequado na construção do edifício. / [en] In Brazil a lot of electrical energy is used by building air-conditioning because of the tropical climate. In many cases there is a general congruence of solar irradiation and demand for building air-conditioning and solar thermal cooling has the potential to satisfy a part of the rapidly growing cooling demand. Due to excellent solar irradiance and a high cooling demand there exists in Brazil good conditions for the use of solar-assisted air-conditioning. In this work the most important solar cooling techniques and their suitability in Brazil are discussed. The objective of the present study is to analyze the technical and economic feasibility of medium sized solar-assisted air-conditioning in Brazil. The energy saving potential of solar-thermal air-conditioning in comparison to best practical solutions in Brazil using conventional split air-conditioning systems, is shown based on a case study (auditorium in Guaratinguetá - São Paulo). The economy of solar-assisted air-conditioning is thereby discussed. The basic principles for the dimensioning of a system for solar cooling are described. The auditorium in the case study is modelled by using the dynamic thermal building simulation program Helios-PC. In this context it is, as well, demonstrated how the cooling load could be decreased by adapting the indoor temperature according to the Brazilian standards of thermal comfort and by using building insulation.

The diploma thesis solves a project of air-conditioning with heat recovery in the gym and adjacent dressing rooms. Furthermore, experimental measurement of temperature and relative humidity is carried out in one year in an air-conditioning device with a heat recovery heat exchanger.

Diploma thesis is divided into two parts. The theoretical part deals with natural ventilation and the practical part focuses on the optimization of the ventilation in the original hall using CFD simulation. One of the solutions is proposed in the design part of the diploma thesis.

The aim of the diploma thesis is the simulation of different types of air conditioners using the CFD methods. The main goal of this thesis is to design the most suitable type of air conditioning in the consideration room, due to the air flow rate in the residental area. The conclusion of the work is to devote the design of air conditioning system with the application of selected type of air conditioning based on the results of CFD simulations.

The design of air conditioning unit is based on combination of the product itself and related architecture. The large-scale 3D printing is becoming more and more popular, that is why this thesis chose additive manufacturing robotic technology for designing the air conditioner. According to analysis the air distribution through perforations is the most convenient one for an indoor unit. An outdoor unit tends to be hidden because of inhomogeneity with the building. To obtain more variant studies for the design a generative process was applied. This method was applied also later on, because additive manufacturing is able to easily change dimension parameters and thus fulfil individual customer requests. Other advantages of robotic printing are the lattice structures that enable perforation manufacturing without waste and the possibility of using generative design methods.

This thesis presents and describes new global trends among build and operation of datacenters. Further it contains practical application of particular examples, and the theory is supplemented by new findings from given field.