Exposure to excess manganese via drinking water raises concerns due to potential for adverse neurological impacts, particularly in children. Manganese is ubiquitous in US groundwaters above the SMCL = 0.05 mg/L. Manganese is an essential nutrient, but exposures to elevated manganese have neurotoxic effects. Chapter 2 focuses on human senses\' ability to detect manganese in drinking water. Findings indicate human senses cannot be relied upon to detect excess Mn(II) in drinking water. Mn(IV) is easily visually detected, but cannot be tasted at 10 times the SMCL. Chapter 3 is an assessment the ability of an ultrasonic humidifier to expel drinking water impurities in aerosols. The quality of the water used to charge the humidifier reservoir affects the composition of elements in the aerosols and condensate. Findings indicate condensed humidifier aerosols contain 85% of elements present in the reservoir water for a variety of water types if there is no precipitation. Waters with high concentration of hardness or iron formed precipitates that decreased the concentrations of these metals in the aerosols causing variable results for other elements that were initially present at < 1mg/L in the charge water. This indicates that humidifiers could be a source of inhalation exposure for source water contaminants. / Master of Science

In its present form, polymer electrolyte membrane fuel cell (PEMFC) technology requires some method of humidification to ensure that high performance and long life of the fuel cell membrane is maintained. External humidification utilizing ‘gas to gas’ membrane based planar humidifiers is one method of humidifying fuel cell reactant gases. This type of humidification offers the benefit of recycling heat and moisture from the fuel cell exhaust, and returning it to the reactants entering the fuel cell. In designing a planar membrane based fuel cell humidifier the two important areas to be considered are: - humidifier channel and plate design; and - humidifier membrane selection. In this work a humidifier design procedure was developed based on prototype humidifier testing. This design procedure involves selection of design parameters based on a dimensionless parameter which describes the ratio of gas residence time, and water diffusion time from the membrane surface. Humidifiers of different flow channel geometries were created with a rapid prototyping technique. These humidifier units were tested at different operating conditions in an attempt to validate the design equations involving a design parameter which is the ratio between the residence times of gas in the humidifier over the diffusion time of water from the surface of the membrane into the channel. This parameter offers a good starting point for humidifier design, the target value of this parameter was found to be between 2.0 and 4.0, with a desired value of 3.0. A fuel cell stack humidifier design procedure and suggestions are presented based this parameter. The design also considers designing a humidifier on limited volume constraints in which the humidifier would have to fit into the fuel cell system. A membrane selection procedure was developed based on design criteria requirements developed during this work for the fuel cell humidifier. This criterion includes high water permeation, low air permeation, good mechanical strength, robust handling, and long lifetime under various operating conditions. . Specific values for membrane selection included a water flux of greater than 14 kg m-2 h-1 in a water permeation test, less than 3 cm3 min-1 cm-2 kPa-1 air permeation when the membrane was dry, and a lifetime of at least 1500 hours of operation without performance degradation. Sixty membranes from various sources were screened for candidacy for use in the humidifier application. Membranes which passed the initial screenings were tested for durability at high and moderate temperature conditions. These membranes were operated until failure, at which time analysis was completed to determine the failure modes of the membrane. Mitigation strategies were proposed when applicable. Recommendations were made for membrane materials for the proposed operating requirements. Suggested membranes materials included those based on UHMWPE and inorganic additives, as well as homogenous membranes based on Nylon 6,6, PEEK, and PFSA.

In its present form, polymer electrolyte membrane fuel cell (PEMFC) technology requires some method of humidification to ensure that high performance and long life of the fuel cell membrane is maintained. External humidification utilizing ‘gas to gas’ membrane based planar humidifiers is one method of humidifying fuel cell reactant gases. This type of humidification offers the benefit of recycling heat and moisture from the fuel cell exhaust, and returning it to the reactants entering the fuel cell. In designing a planar membrane based fuel cell humidifier the two important areas to be considered are: - humidifier channel and plate design; and - humidifier membrane selection. In this work a humidifier design procedure was developed based on prototype humidifier testing. This design procedure involves selection of design parameters based on a dimensionless parameter which describes the ratio of gas residence time, and water diffusion time from the membrane surface. Humidifiers of different flow channel geometries were created with a rapid prototyping technique. These humidifier units were tested at different operating conditions in an attempt to validate the design equations involving a design parameter which is the ratio between the residence times of gas in the humidifier over the diffusion time of water from the surface of the membrane into the channel. This parameter offers a good starting point for humidifier design, the target value of this parameter was found to be between 2.0 and 4.0, with a desired value of 3.0. A fuel cell stack humidifier design procedure and suggestions are presented based this parameter. The design also considers designing a humidifier on limited volume constraints in which the humidifier would have to fit into the fuel cell system. A membrane selection procedure was developed based on design criteria requirements developed during this work for the fuel cell humidifier. This criterion includes high water permeation, low air permeation, good mechanical strength, robust handling, and long lifetime under various operating conditions. . Specific values for membrane selection included a water flux of greater than 14 kg m-2 h-1 in a water permeation test, less than 3 cm3 min-1 cm-2 kPa-1 air permeation when the membrane was dry, and a lifetime of at least 1500 hours of operation without performance degradation. Sixty membranes from various sources were screened for candidacy for use in the humidifier application. Membranes which passed the initial screenings were tested for durability at high and moderate temperature conditions. These membranes were operated until failure, at which time analysis was completed to determine the failure modes of the membrane. Mitigation strategies were proposed when applicable. Recommendations were made for membrane materials for the proposed operating requirements. Suggested membranes materials included those based on UHMWPE and inorganic additives, as well as homogenous membranes based on Nylon 6,6, PEEK, and PFSA.

The durability and performance of commercially available polymer electrolyte membrane fuel cell (PEMFC) technology depends heavily on adequate humidification of the membrane electrode assembly (MEA). Early generation automotive fuel cell stacks will likely rely on an external humidification process based on gas-to-gas membrane planar humidifiers to humidify the inlet cathode stream. The membrane-based humidifier systems allow the reactants to receive recycled heat and moisture from the cathode outlet stream. The objective of this thesis is to develop a flexible, computer-based simulation tool that can be used to aid in the design of these planar humidifier systems. The simulation is based on fundamental mass transfer concepts and experimental membrane behaviour based on literature results. It was determined that the mass transfer resistance through the membrane is several orders of magnitude higher than the resistance contributed by the gas diffusion media (GDM) and thus the mass transfer resistance through the GDM are not considered. An important point to note is that the Schroeder’s Paradox observed in perfluorosulfonic acid (PFSA) membranes implies that membranes in contact with liquid water will exhibit higher mass transfer than membranes in contact with saturated water vapour despite the fact that the water activity in both situations are unity. Initial simulations for which no liquid water was present resulted in a humidifier water transfer rate less than half the rate observed experimentally. Thus it was hypothesized that condensed liquid water was present on the wet-side of the humidifier membrane and as such this work assumes a fraction of the membrane surface is covered by liquid water while the rest of the membrane is exposed to gaseous water concentrations comparable to the bulk channel stream above the GDM. For typical operating conditions the outlet wet-side stream retains 92% of the inlet water content and as such it was hypothesized that constant fractional liquid water coverage across the membrane could be assumed. Later simulations confirmed the validity of this hypothesis. Six models of water coverage estimation were derived using least squares and factorial design methods. The models were compared however no single method was determined to be superior for all situations as the methods exhibit similar sums of squared error.

The durability and performance of commercially available polymer electrolyte membrane fuel cell (PEMFC) technology depends heavily on adequate humidification of the membrane electrode assembly (MEA). Early generation automotive fuel cell stacks will likely rely on an external humidification process based on gas-to-gas membrane planar humidifiers to humidify the inlet cathode stream. The membrane-based humidifier systems allow the reactants to receive recycled heat and moisture from the cathode outlet stream. The objective of this thesis is to develop a flexible, computer-based simulation tool that can be used to aid in the design of these planar humidifier systems. The simulation is based on fundamental mass transfer concepts and experimental membrane behaviour based on literature results. It was determined that the mass transfer resistance through the membrane is several orders of magnitude higher than the resistance contributed by the gas diffusion media (GDM) and thus the mass transfer resistance through the GDM are not considered. An important point to note is that the Schroeder’s Paradox observed in perfluorosulfonic acid (PFSA) membranes implies that membranes in contact with liquid water will exhibit higher mass transfer than membranes in contact with saturated water vapour despite the fact that the water activity in both situations are unity. Initial simulations for which no liquid water was present resulted in a humidifier water transfer rate less than half the rate observed experimentally. Thus it was hypothesized that condensed liquid water was present on the wet-side of the humidifier membrane and as such this work assumes a fraction of the membrane surface is covered by liquid water while the rest of the membrane is exposed to gaseous water concentrations comparable to the bulk channel stream above the GDM. For typical operating conditions the outlet wet-side stream retains 92% of the inlet water content and as such it was hypothesized that constant fractional liquid water coverage across the membrane could be assumed. Later simulations confirmed the validity of this hypothesis. Six models of water coverage estimation were derived using least squares and factorial design methods. The models were compared however no single method was determined to be superior for all situations as the methods exhibit similar sums of squared error.

Ultrasonic humidifiers use sound vibrations at frequencies higher than can be heard by humans (> 20,000 Hz) to generate aerosolized water also have potential for inducing sonochemical reactions for chemicals present in water. This research focuses on examining oxidants formed within ultrasonic humidifiers, as well as the oxidants effects of contaminants in water used in the systems. Hydroxyl radicals were found using DMPO as a spin trap. Caffeine and 17β-estradiol, as pharmaceutical contaminants of drinking water, were both emitted from the humidifier when present in the water reservoir and would enter breathing air. Emitted 17β-estradiol was found at 60% of the initial concentration filled in the ultrasonic humidifier after 480 minutes. Caffeine exhibited less degradation than 17β-estradiol. Degradation of both pharmaceuticals was attributed to ultrasonic processes, most likely oxidation with hydroxyl radicals produced. Bromide as a contaminant of the fill water was found to remain constant over time. / MS / Ultrasonic humidifiers carry health benefits from humidified air, but also have potential for chemical reactions within the systems that can impact human health. This research focuses on examining oxidants formed in ultrasonic humidifiers, as well as the degradation of contaminants in water used in the ultrasonic humidifiers. Hydroxyl radicals were found to be generated within the humidifier system. Caffeine and 17β-estradiol, a common estrogen, are possible contaminants in drinking water, which may be used to fill a humidifier. Both were introduced and emitted from the ultrasonic humidifier. Emitted 17β-estradiol was found at 60% of the initial concentration filled in the ultrasonic humidifier at the start of 8 hours. Degradation of both pharmaceuticals was attributed to ultrasonic processes, most likely oxidation with hydroxyl radicals produced.

Portable ultrasonic humidifiers add moisture into room air, but they simultaneously add exposure risks of aerosolized metals from drinking water used as fill water. The inhalation exposure from emitted metals can be overlooked, and thus, co-exposure of inhalation and ingestion and co-exposure to multiple inorganic metals is investigated. The objectives of this work are: 1) predict airborne metal concentrations and particle sizes in four realistic room scenarios (33 m3 small or 72 m3 large, with varying ventilation rates from 0.2/hr -1.5/hr), and the investigated metals are arsenic, cadmium, chromium, copper, lead, and manganese; 2) characterize exposure doses and consequent risks for adults and 0.25, 1, 2.5, and 6 yr old children, when using identical drinking water ingested and as fill water, including inhalation of fine, respirable particles generated at the frequency of 8 hrs/day (equals 121.67 days/yr) and daily ingestion, under four realistic room scenarios. The risk assessment includes non-cancer [calculation of average daily dose (ADD) and hazard quotient (HQ)] and cancer risk evaluation; 3) quantify deposition fraction and deposited doses of multiple metals in human adult's and children's respiratory tract, using multi-path particle dosimetry (MPPD) model. Results show airborne-particle-bound metal concentrations increase proportionally with water metals, and a poorly ventilated room causes greater exposure. Ingestion ADDs are 2 magnitudes higher than inhalation ADD, at identical water metal concentrations and daily exposure frequency. However, in the worse-case scenario of 33 m3 small room with low air exchange rate, the consequent inhalation HQs are all greater than 1 for children and adults, except for lead, indicating significant non-cancer risks when exposed to humidifier particles under the worse-case scenario. The cancer risks for arsenic, cadmium, chromium, and lead metals reveal are greater than acceptable one case in a million population (1E-6) produced from inhalation of the humidifier emitted metal-containing particles only. The MPPD model results indicate inhaled metal-containing airborne particles deposit primarily in head and pulmonary regions, and a greater dose (unit in µg/kg body weight/day) deposits in children than adults. Inhalation of ultrasonic humidifier aerosolized metals results in additional, and potentially greater risks (indicated by HQinhalation >1, and greater deposited dose) than ingestion at the same aqueous metal concentration, especially for children. Room conditions (i.e. volume and ventilation) influence risks. Both inhalation and ingestion exposures require consideration for eliminating multiple metal exposures and health-based environmental policy making. Consumers should be aware that they may be degrading their indoor air quality by using ultrasonic humidifiers even when filling with acceptable water quality for drinking. / Doctor of Philosophy / The purpose of this work is to investigate the exposure from use of ultrasonic humidifiers filled with drinking water containing inorganic metals. Typical exposure pathway of drinking water metals is ingestion. However, inhalation of aerosolized metals can cause undesirable health effects towards metal exposure, when fill water of ultrasonic humidifiers is the same drinking water, and the inhalation of aerosolized metals exposure pathway can be overlooked. Emitted airborne particles are composed of soluble metals in drinking water, and are respirable with diameters between 100-200 nm. PM2.5 (particulate matter with aerodynamic under 2.5 µm) concentrations increase from approximately 2 µg/m3 to hundreds of µg/m3 in a common-sized room, exceeding the USEPA's regulatory level of 15 µg/m3 for ambient air PM2.5. The resulting air metal concentrations increase with increasing metals in the fill water, and/or lower ventilation rates in a household room. In addition, children receive greater average daily exposure doses than adults (i.e. average daily dose and deposited dose, in unit of µg/kg body weight/day), when assuming daily inhalation exposure of 8 hr/day and daily ingestion exposure. The ingestion doses from various metals are greater than inhalation doses, however, the inhalation risks may be greater for certain metals than ingestion. Even when using acceptable drinking water quality that meets regulations for metals, the indoor air quality is still degraded and can pose adverse health effects. In conclusion, the dissertation work presents a framework to estimate risks developed from multi-media and single or multi-metals exposure. The addition from inhalation of aerosolized metals in drinking water should be considered in an overall risk assessment, especially for the susceptible population of young children. Consumers should be aware that they may be degrading their indoor air quality by using ultrasonic humidifiers even when filling with acceptable water quality for drinking.

In this thesis, experimental and numerical studies have been carried out to investigate the performance of a solar desalination system working on humidification-dehumidification principle under the climatological conditions of Ankara, Turkey. The desalination unit was configured mainly by a double-pass flat plate solar air heater with two glass covers, pad humidifier, storage tank and dehumidifying exchanger. The system used in this work is based on the idea of closed water and open air cycles. A computer simulation program based on the mathematical model was developed by means of MATLAB software to study the effect of different environmental, design, and operational parameters on the desalination system productivity. In this simulation program, the fourth order Runge-Kutta method was used to solve the energy balance equations simultaneously and numerically. In order to compare the obtained theoretical results with experimental ones and validate of the developed mathematical model of the system, an experimental study has been carried out. For that, an experimental set-up was designed, constructed and tested at the solar house of the Mechanical Engineering Department of METU. In addition, the existing solar desalination system was integrated with an evacuated tubular solar water heater unit (closed water circulation) and performance of the system has been studied experimentally.

Introduktion: Befuktning vid mekanisk ventilation är nödvändigt för att inte skador skall uppstå i luftvägarna. Luften kan befuktas aktivt eller passivt och då tekniken ständigt utvecklas kan tidigare riktlinjer för vilken metod som är bäst behöva revideras. Syfte: Studiens syfte var att undersöka evidensen för användning av aktiv befuktning hos intuberade eller trakeostomerade patienter. Metod: I enlighet med Whittemore &amp; Knafls metod utfördes en integrerad litteraturstudie. Litteratursökning gjordes i databaserna PubMed, CINAHL och Cochrane. Även en manuell sökning i referenslistor utfördes och ledde till att totalt 14 artiklar valdes ut, varav 13 var kvantitativa och 1 kvalitativ. Resultat: Analysen av de 14 artiklarna resulterade i fyra huvudkategorier med efterföljande underrubriker: Aktiv befuktnings påverkan på nosokomiala infektioner: Infektionsincidens och Infektionstyp; Aktiv befuktnings påverkan på luftvägsproblem: Ocklusionsproblemoch Sekretviskositet/sekretmängd; Aktiv befuktnings påverkan på mekanisk ventilation: Vårdtid med mekanisk ventilation och Påverkan på andningsarbete;Upplevelse av aktiv befuktning: Upplevd påverkan på hälsa och Negativ påverkanpå vårdmiljön. Konklusion: Denna studie var att aktiv befuktning har en viktigfunktion att fylla hos vissa patienter, men borde inte användas slentrianmässigt.Sjuksköterskan har en viktig roll i att hitta de patienter som är mest hjälpta av det. / Introduction: Humidification during mechanical ventilation is necessary to avoid damage in the airways. The air can be humidified actively or passively and since thetechnique is constant developing the guidelines for which of the alternative that’sthe best may need to be revised. Aim: The aim of the study was to examine the evidence of using active humidification in intubated patients or in patients withtracheostomy. Method: An integrated literature review according to Whittemore &amp;Knafl was carried through. The literature search was done in the databases PubMed, CINAHL and Cochrane. A manual search in reference lists was also made and resulted in a total of 14 articles whereof 13 were quantitative and one was qualitative. Result: The analysis of the 14 articles led to four main categories with the following subcategories: Active humidifications influence on nosocomial infections: Infectionincidence and Infection type; Active humidifications influence on airway problems: Occlusion problems and Mucus viscosity/mucus volume; Active humidifications influence on mechanical ventilation: Time on mechanical ventilation and Influenceon respiratory work; Experience of active humidification: Experienced influence on health and Negative impact on hospital environment. Conclusion: The conclusion of this study was that active humidification is the better choice among certain patientgroups but should not be used routinely. The nurse plays an important role in finding the patients who can benefit the most of it.

This project deals with comparing types and properties of commercial produced incubators for exotic birds. It searches the best solution from these area. In this project are compars individual components and their choice for realization in this project. Then in this project is solution of regulation temperature and humidity in engineered mechanism and discovered parameters of specifically space. Then is developed solution of thermostat and hydrosatat for this prototype. Temperature is changed by Peltier module, who is involved in correct system. Humidity is regulated by resistor humidifier. Complex system is managed by microcontroler. System communicates with PC via USB interface and Ethernet. Solution of this project is maked functional prototyp.