Submitted by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-11-11T15:24:04Z No. of bitstreams: 1 arquivototal.pdf: 2659414 bytes, checksum: daffe4d3b79a46f98678d09a7952e81b (MD5) / Made available in DSpace on 2015-11-11T15:24:04Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2659414 bytes, checksum: daffe4d3b79a46f98678d09a7952e81b (MD5) Previous issue date: 2015-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work, will be characterized two types of adsorptive wheels, an active effect and the other passive effect, known respectively as desiccant wheel and enthalpy wheel. These devices are used to compose the climatization adsorption systems as a means of promoting the dehumidification of air using the adsorption phenomenon that occurs in their adsorptive matrices. This phenomenon involves both the mass transfer and the heat, its cycles are defined by two processes taking place simultaneously, the adsorption and desorption. In the study, the characterization will boil down to assess the equipment in different working conditions with the main objective to achieve better dehumidification of air using the least amount of energy possible. Procedures were used for low air flow rates set in three categories: the process flow, which is the airflow to be treated, or dehumidified, a regeneration flow, which is the air stream in countercurrent flow desiccant rotor with process flow will serve as a means of maintaining the adsorptive cycle always performing heat exchange and mass, and the return flow, which flow against the enthalpy rotor will also serve as a means of promoting the dehumidification of process air. In the regeneration flow rates will be assessed the effects of low temperature heating and in both wheels will be evaluated the effects of different rotational speeds. Will also take place, procedures in order to verify the possibility of the wheel enthalpy work as a wheel desiccant . The findings contributed significantly to the climate control by adsorption systems is taken increasingly as a viable alternative to replacing conventional cooling. / No presente trabalho foram caracterizados dois tipos de rotores adsortivos, um de efeito ativo e outro de efeito passivo, conhecidos respectivamente como rotor dessecante e rotor entálpico. Esses equipamentos são usados para compor os sistemas de climatização por adsorção como meio de promover a desumidificação do ar usando o fenômeno da adsorção que ocorre em suas matrizes adsortivas. Esse fenômeno envolve tanto a transferência de massa quanto a de calor, seus ciclos são definidos por dois processos que ocorrem simultaneamente, a adsorção e a dessorção. No estudo, a caracterização se resume em avaliar os equipamentos em diferentes condições de trabalho tendo como principal objetivo alcançar a melhor desumidificação do ar usando a menor quantidade de energia possível. Durante os procedimentos foram usadas baixas vazões de ar definidas em três categorias: a vazão de processo, que é a corrente de ar a ser tratada, ou seja, desumidificada, a vazão de regeneração, que é a corrente de ar que em contra fluxo no rotor dessecante com a vazão de processo servirá como meio de manter o ciclo adsortivo sempre realizando as trocas de calor e massa, e a vazão de retorno, que em contra fluxo no rotor entálpico servirá também como meio de promover a desumidificação do ar de processo. Nas vazões de regeneração foram avaliados os efeitos de baixas temperaturas de aquecimento e em ambos os rotores foram avaliados os efeitos de diferentes rotações. Foram realizados também, procedimentos com o intuito de verificar a possibilidade de o rotor entálpico trabalhar como rotor dessecante. Os resultados desse trabalho contribuíram significativamente para que os sistemas de climatização por adsorção seja tido cada vez como uma alternativa viável à substituição da refrigeração convencional.

Spray Drying é um processo de secagem por atomização em uma câmara fechada, que visa retirar a umidade de um produto por transferência de calor e massa de água contida no produto para o ar que é previamente aquecido neste processo. Este trabalho apresenta um estudo de caso para uma indústria que produz aditivos alimentícios. O ar de entrada pode chegar à câmara com alta umidade proveniente da atmosfera, neste caso, haverá mais consumo de energia de acordo com as estações do ano. Esta pesquisa promove um estudo do processo atual, através da instalação de um equipamento de pré-desumidificação no ar de entrada do processo e mostra diferentes sistemas de desumidificação: por refrigeração e por adsorção, comparando os desempenhos sob o ponto de vista energético, ambiental e econômico com sistema original. Os objetivos deste estudo são analisar a capacidade de remoção de umidade de cada dispositivo de desumidificação, a influência de cada dispositivo e a variação da umidade do ar de entrada no processo, bem como o impacto econômico e ambiental de cada equipamento no sistema global. Além disso, promove o aumento do gradiente de umidade entre o ar de entrada e do produto otimizando o processo de secagem, aumentando a eficiência energética global do sistema e reduzindo o impacto ambiental. / Spray drying is a dehumidification process by atomization in a closed chamber that aims to remove moisture of a product by heat and mass transfer from the contained water in the product to the air which is previously heated in this process. This paper presents a case study for an industry that produces food ingredients. The inlet air can reach the chamber with high moisture from the atmosphere condition requesting, in this case, more energy consumption according to the seasons of the year. This paper promotes a study of the current process through the installation of a pre-dehumidification device of the inlet air and shows different dehumidification systems: The refrigeration and the adsorption and comparing their performance in an energetic, environmental and economic point of view. The goals of this study are to analyze the capacity of moisture removing of each dehumidification device, the influence of moisture variation of the inlet air in the process as well as the economic impact of each device in the global system. Moreover, it promotes the increasing of moisture gradient between the inlet air and the product optimizing the drying process, increasing the global energy efficiency in the global system and reducing environmental impact.

Parameters that characterizes quality internal building environment come forth these days. One of the main reasons for the choice of the topic of this thesis is to ensure the quality of the internal environment and well-being during the usage of the buildings. Prevention of the excessive wall dampness is one of the basic conditions of a healthy and quality building environment. The thesis verifies reliability and compares the efficiency of the selected damp-proof materials and its joints. The first part deals with the influences that are reasons for the dampness of the buildings, earmark of an interest area, introducing of the valid legislation focused on the building redevelopment, consideration and evaluation of the building constructions in light of the dampness. The next part of the thesis sets main and partial targets and consecutive steps leading to fulfilment of the targets. Selection of the appropriate redevelopment procedures, materials and joints of the selected materials selected for the experiment realization follows. As this area is relatively large, we selected mechanical redevelopment methods reaching the walls and three most commonly used materials and its joints within the framework of the selected methods. There are three main steps set in the thesis: preparation of the methodology and experiment realization, measurement optimization and measurement within the laboratory and on the real buildings, comparison and evaluation of the measured values. Experimental part of the thesis took place between the years 2008 - 2011. Experiment realization comprises of material acquisition, building of the test samples and application of the single redevelopment measures. The next step includes measurement on the individual samples on the fixed measuring points. Measurements are evaluated through the mathematical statistical methods. Efficiency of the particular materials are compared and evaluated.

Master of Science / Department of Mechanical and Nuclear Engineering / Steven J. Eckels / Membrane dehumidification and evaporative cooling applications have the potential to significantly improve the energy efficiency of air conditioning equipment. The use of wire mesh media in such membrane applications is feasible but has not been studied extensively. Therefore, the aim of this work is to investigate the heat and mass transfer performance of several different wire mesh media in membrane based dehumidification and evaporative cooling. There were six wire mesh membranes tested in an experimental facility. The wire mesh membranes vary with respect to percent open area, wire diameter, pore size and material. Two non-permeable, solid membranes were also tested in the facility and compared with the wire mesh membranes. The test section of the experimental facility consists of a narrow air duct and a plate apparatus. The membrane samples were fashioned into rectangular plates and installed into the test section. The plate membranes separate liquid water and air flow streams. The inlet air temperature and humidity are altered to produce condensation or evaporation at the membrane surface. The average convective heat and mass transfer coefficient of the air boundary layer is measured for each of the experimental plates. Membrane based dehumidification and evaporative cooling were accomplished using the wire mesh media. However, the wire mesh membranes did not exhibit any significant differences in their performance. The mesh plates were compared with the solid plate membranes and it was discovered that the solid plates exhibited significantly higher heat transfer coefficients during condensation conditions. This result most likely is due to the formation of large water droplets on the solid plates during condensation. The experimental data is then compared to analytical predictions of the heat and mass transfer coefficients developed from several heat transfer correlations and by invoking the heat and mass transfer analogy. The experimental data is also compared directly with the heat and mass transfer analogy. It was found that the data did not compare well with the heat and mass transfer analogy. This result is attributed to the fact that the membrane surface limits the amount of direct exposure to the gas-liquid interface.

This diploma thesis deals with the design of the air-conditioning unit of the wellness center in Brno and includes experimental measurement of HEPA filters. The thesis is divided into three main parts: the theoretical part, the experimental part and the air-conditioning unit design. The theoretical part of the thesis contains basic introduction to air filters. The experimental part aims to evaluate the pressure loss and the effectiveness of HEPA filters. The last part of the diploma thesis is practically focused on the comparison of three air-conditioning unit of the wellness center.

<p>Evaporative cooling is a highly energy efficient alternative to conventional vapor compression cooling system. The sensible cooling effect of evaporative cooling systems is well documented in the literature. Direct evaporative cooling however increases the relative humidity of the air as it cools it. This has made it unsuitable for data centers and other applications where humidity control is important. Desiccant-based dehumidifiers (liquid, solid or composites) absorb moisture from the cooled air to control humidity and is regenerated using waste heat from the data center. This work is an experimental and theoretical investigation of the use of desiccant assisted evaporative cooling for data center cooling according to ASHRAE thermal guidelines, TC 9.9. The thickness (depth) of the cooling pad was varied to study its effect on sensible heat loss and latent heat gain. The velocity of air through the pad was measured to determine its effect on sensible cooling. The flow rate of water over the pad was also varied to find the optimal flow for rate for dry bulb depression. The configuration was such that the rotary desiccant wheel (impregnated with silica gel) comes after the direct evaporative cooler. The rotary desiccant wheel was split in a 1:1 ratio for cooling and reactivation at lower temperatures. The dehumidification effectiveness of a fixed bed desiccant dehumidifier was compared with that of a rotary desiccant wheel and a thermoelectric dehumidifier. A novel condensate recovery system using the Peltier effect was proposed to recover moisture from the return air stream, (by cooling the return air stream below its dew point temperature) thereby optimizing the water consumption of evaporative cooling technology and providing suitable air quality for data center cooling. The moisture recovery unit was found to reduce the mass of water lost through evaporation by an average of fifty percent irrespective of the pad depth.</p> <p> </p>

Kondensbildning är ett stort problem i ishallar vilket leder till stora konsekvenser ifall det inte åtgärdas. Installation av ett avfuktningssystem är ett måste i ishallar men det betyder högre energianvändning. Denna studie undersöker hur RH-styrning (relativ fukthalt) för en avfuktare i PF Arenan lokaliserat i byn Lindefallet i Hudiksvalls kommun kan energieffektiviseras och samtidigt se till att kondensbildning undviks i ishallen. Kondensbildning i ishallar framkommer framförallt på takytan och isplanen. Kondens på isplanen sker när luftens absoluta luftfuktighet är större än den absoluta fuktigheten för isens gränsskikt. Eftersom isen har en temperatur under 0 °C så kommer vattnet att frysas på planen vilket åtgärdas genom att slipa isen med en ismaskin. Forskning visar att avfuktningsstyrning för att undvika kondens på isplanen leder till att avfuktaren blir överdimensionerad för att undvika takkondens. Konsekvenser för takkondens anses som mer allvarliga än de för kondens på isplanen, vilket har lett till att framtagning av ny styrning har fokuserat på att undvika takkondens. Mätningar har utförts i PF Arenans roterande sorptionsavfuktare och lufttillstånden inuti ishallen samt utomhus. Resultatet från mätningar används för att avgöra om det sker kondensbildning i ishallen. Olika styrstrategier jämförs med befintlig RH‑styrning för att fastställa vilka förbättringar som kan tillämpas. Resultat visar att vid stora personlaster och användning av ismaskinen leder till att takkondens framkommer under korta perioder. Samtidigt så går inte regenereringsbatteriet på maxeffekt under dessa perioder vilket betyder att avfuktningskapaciteten kan höjas. RH-styrning leder till överdimensionering i förhållande till båda kondensfenomenen under stora perioder, speciellt under kalla inomhustemperaturer. Föreslagen styrning går ut på att processluftens daggpunkt ska hållas två grader Celsius under takets yttemperatur. Styrningen kan definieras som en varierande daggpunktsstyrning. Det rekommenderas också att regenereringstemperaturen ökar ju mer börvärdet avviker från målfunktionen. Dock så analyserades inte en sådan ökning av regenereringstemperaturen i detalj. Det approximerades att ungefär 1 100 kWh el per månad kan sparas för avfuktaren motsvarande en energiminskning av 22 % gentemot den befintliga styrningen. Approximering förmodar att ismaskin slipar isen lika mycket med båda styrningarna och tar inte hänsyn till den ökade energianvändningen ifall högre regenereringstemperaturer tillämpas i avfuktaren. / Condensation is a major problem in ice rink arenas and if it is not resolved, will lead to construction damages. Generally, ice arenas use dehumidifiers to dehumidify the indoor air which causes an increase in energy use in the facility. This study investigates how the control strategy of the dehumidifier in the PF Arena localized in Lindefallet in Hudiksvall municipality can be improved to save energy while preventing the occurrence of condensation in the ice rink arena. Condensation in ice arenas occur on the ice surface and roof surface. Ice surface condensation occur if the indoor air humidity is higher than the humidity of the ice surface boundary layer. The ice will freeze the moisture onto the surface which require an ice resurfacer to flatten the playing field. Studies has shown that control strategies for dehumidification to prevent condensation on the ice surface results in oversizing of the dehumidifier for preventing condensation on the roof surface. And as condensation on roof surface leads to more serious consequences than that of ice surface condensation, it is of more interest to prevent the former. Measurements has been carried out on PF Arenan’s desiccant wheel dehumidifier and indoor as well as outdoor air. Results from measurements are used to analyze if any condensation occurs in the ice rink arena. Other control strategies are compared to the one used in PF Arenan to determine what improvements can be applied to the dehumidifier. Results show that during events and use of ice resurfacers some condensation on the roof surface occurs for short periods. During these periods, the regeneration heater does not use full power which could be used to increase the moisture removal capacity. The RH-control strategy results in oversizing for most hours when controlled to both condensation phenomenon, especially during cold temperatures. The recommended control strategy is to keep the dewpoint of the inlet process air 2 °C below the roof surface temperature. This control strategy is a type of variable dewpoint control function. It is also recommended to increase the regeneration temperature proportionally to the difference between the setpoint and the objective function. However, the results of this measure were not analyzed in detail. The new control strategy would approximately save 1 100 kWh per month over the current control function which amounts to an energy use decrease of 22 % for the dehumidifier. Assumed that behavior of ice resurfacing is not changed with the new control function and the approximation does not consider the increase of energy use if the regeneration temperature is increased.

The diploma thesis deals with microclimate of a pool hall. This is divided into three parts. The first part describes the theoretical aspects of the environment in swimming pools in general. The second part of the diploma thesis deals with the calculation of the course of specific moisture concentration during the day in the pool hall. Different humidity concentration curves are assessed based on different electable input parameters. Subsequently, suitable setting options are evaluated in order to achieve acceptable environment in the hall in terms of humidity and optimal operating costs. The last part relates to the experimental part. This examines the measurement of evaporation under different boundary conditions and the subsequent comparison with some calculation methods for the calculation of evaporation.

<p>With increasing concerns about the global warming effects of HFC refrigerants, low-GWP refrigerants and non-vapor compression heat pumps are investigated as potential mid- and long-term replacements for current vapor compression heat pump systems that rely on high-GWP refrigerants. To address the need for more environmentally friendly space cooling and heating, and water heating solutions. the U.S. Department of Energy (DOE) Office of Energy Efficiency & Renewable Energy (EERE) is supporting the development of smarter, more efficient, and affordable heat pumping systems operating with low- or near-zero GWP refrigerants through different programs including the Energy, Emissions, and Equity (E3) Initiative. In addition, the Emerging Technologies (ET) Program within the Building Technologies Office (BTO) emphasized the research and development efforts needed to support new technologies that could reduce energy usage in residential and commercial buildings by 50\% over the next decades. In the literature, limited studies were found that systematically investigated different combinations of conventional and emerging space conditioning and water heating technologies while accounting for real building loads, different climate zones, utility structures, and current state-of-the-art equipment. Existing literature primarily focused on thermodynamic performance evaluations at fixed boundary conditions. In addition, separate sensible latent cooling (SSLC) and other novel cooling and dehumidification systems (e.g., membrane-based systems) can significantly reduce the electricity usage for space conditioning. To compare the performance of conventional and emerging technologies several figures-of-merit such as the second law efficiency, are often used. However, limitations exist in previous studies to define the thermodynamic reversible limits and second law efficiency for cooling and dehumidification systems.</p><p>This study developed a comprehensive modeling framework to evaluate both current state-of-the-art vapor compression systems and emerging HVAC\&R technologies in real-world scenarios. The platform will be used to assess potential energy savings, scalability issues, and the effectiveness of combined technologies for different buildings, climate conditions, and utility structures.</p><p>To compare HVAC technologies, a new physics-based definition for the reversible limit and the second law efficiencies for cooling and dehumidification systems with air recirculation has been developed. The new framework is then extended to define a novel performance metric, the seasonal second law efficiency, to form a universal benchmark for assessing various cooling and dehumidification systems. Five cooling and dehumidification systems including magnetocaloric cooling, solid desiccant dehumidification, and membrane dehumidification are evaluated using this benchmark. Steady-state thermodynamic models are constructed for each system. Second law efficiency for each system under various outdoor temperatures and indoor sensible heat ratios (SHR) are calculated. The annual electricity usage of the five systems is used to justify the seasonal second law efficiency definition. The results show that compared to conventional vapor compression systems with mechanical dehumidification, the membrane-based AMX-R cycle can reduce annual electricity use by 12.2%-22.2% and increase the seasonal second law efficiency by 36%.</p><p>The advancements of nine not-in-kind (defined as non-vapor compression systems, solid-state, and chemical-based systems) technologies, i.e. magnetocaloric, thermoelectric, elastocaloric, electrocaloric, membrane-based, Vuilleumier, sorption, chemical looping, and desiccant, were reviewed in detail and compared with the state-of-the-art vapor compression systems. Suitable figures-of-merit were defined to compare the different technologies from a thermodynamic standpoint as well as technology readiness level. As a result of the thorough literature review, a roadmap was created to track the development of emerging HVAC&R technologies and future developments. More importantly, the roadmap enabled the identification of several case studies to evaluate potential energy savings both for space conditioning and water heating. Techno-economic studies for eight HVAC configurations for space heating, cooling, and water heating were conducted for a realistic building scenario under various climate conditions. Different combinations of advanced equipment such as heat pump water heater (HPWH), ground-source heat pumps (GSHP), cold-climate heat pumps (CCHP), and membrane-heat pumps were compared with traditional vapor compression heat pumps and gas furnaces. A building model was developed in EnergyPlus and validated with historical data from the DC Nanogrid House at the Purdue University campus. A total of eleven climate zones were considered, and both local weather conditions and utility pricing were implemented in the simulations. Moreover, future SEER2/HSPF2 equipment ratings and E3 Initiative targets were also included in the analyses.</p><p>The initial simulation results provided climate-based equipment selection guidelines and quantitative techno-economic assessments. For instance, CCHPs with two-stage compression in heating mode save 10%-20% in annual heating cost compared with single-stage VCHPs in Climate Zone 4A, 4C, 5A, 5B, 6A, and 6B. Membrane evaporative air-conditioners could provide cooling cost savings in places where is a significant cooling load, such as Zone 1A, 2A, 2B, 3A, 3C, 4A, 5A, and 6A. Gas furnaces should only be used in cold places where the electricity price per kWh to gas price ratio is higher than 3. GSHP has the lowest HVAC annual energy cost in six out of eleven climate zones in the U.S. Dual fuel heat pumps are not always the most economical option but yield better average cost savings among the eleven locations. HPWHs should be recommended in areas where the electricity price to gas price ratio is below 3. </p><p>The developed simulation framework will be instrumental to continue in-depth investigations of current and next-generation heat pump technologies. The ultimate goal of this research is to provide future guidelines on the selection of building-specific and climate-specific equipment solutions that will enable energy savings and future decarbonization strategies (e.g., geospatially-resolved simulations).</p>

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