People for long term exposed to an air-conditioned but highly humid environment are vulnerable to hyper-sensitivity or asthma triggered by fungi or dust mites. This thesis aims to develop a high-linearity and low-hysteresis capacitive relative humidity (RH) microsensor to more precisely accommodate the humidity of living spaces. To reduce the hysteresis and enhance the linearity, this research uses not only one polyimide (PI) thin film as a humidity sensing layer but also utilizes another PI thin film as a protecting layer of the top electrodes. To improve further the RH sensitivity and responding speed, interlacing out-of-plane electrodes are designed in the RH microsensor. The main processing steps of the RH sensor developed in this study involve at least five photolithographic and four thin film deposition processes. The influences of sensing area, number of electrode pairs and testing temperature on the sensitivity and sensing linearity of humidity microsensors were investigated. Based on the measurement results, the sensitivity apparently increase as well as the sensing area (2 mm ¡Ñ 2 mm: 0.12 pF/%RH, 3 mm ¡Ñ 3 mm: 0.48 pF/%RH, 5 mm ¡Ñ 5 mm: 1.09 pF/%RH), and decrease with the number of electrode pairs (40 pairs: 0.51 pF/%RH, 20 pairs: 0.4 pF/%RH) and increase with the testing temperature. The thesis has demonstrated that the capacitance of the RH sensor vary from the relative humidity with a very linear relationship (linearity: 98.8%~99.99%) over the range of 30~70%RH. Finally, to increase effectively the surface area and to reduce further the hysteresis, three-dimensional (3D) moisture entrances and exits were designed and a very low hysteresis value (0.5%RH) can be achieved.

Polyimide thin films have been widely used in microelectronic and Micro-Electro-Mechanical System applications due to their many excellent characteristics including low dielectric constant, easy processing, good step coverage ability, high heat resistance and chemical resistance. This paper presents the design, fabrication and complete characterization of an innovative capacitive relative humidity (RH) microsensor. The double polyimide thin films adopted in this study function as a capacitance sensing layer and a protecting layer of top electrodes respectively. To improve the humidity sensitivity and responding speed, interlacing out-of-plane electrodes are designed in the RH microsensor. The higher sensitivity ( 1.25 pF/¢HRH ), optimized sensing linearity ( 99.968¢H ) , very low hysteresis ( 0.24 ¢HRH ), excellent stability ( 1.36 ¢HRH ) , high accuracy ( ¡Ó 1.12 ¢HRH ) and fast response ( within 1 seconds ) characteristics of the RH microsensor have been demonstrated in this thesis.

Cycling of the relative humidity (RH) levels in the reactant streams of polymer electrolyte membrane (PEM) fuel cells has been reported to decay fuel cell performance. This study focuses on the accelerated durability testing to examine different modes of membrane failure via RH cycling. A single PEM fuel cell with an active area of 42.25 cm2 was tested. A Greenlight G50 test station was used to establish baseline cell (Run 1) performance with 840 hours of degradation under high-humidity idle conditions at a constant current density of 10 mA cm-2. Under the same conditions, two other experiments were conducted by varying the RH. For the H2-air RH cycling test (Run 2), anode and cathode inlet gases were provided as dry and humidified gases. Another RH cycling experiment was the H2 RH cycling test (Run 3): the anode inlet gas was cycled whereas keeping the other side constantly at full humidification. These two RH cycling experiments were alternated in dry and 100% humidified conditions every 10 and 40 minutes, respectively. In the experiments, the fuel cells contained a GoreTM 57 catalyst coated membrane (CCM) and 35 BC SGL gas diffusion layers (GDLs). The fuel cell test station had been performed under idle conditions at a constant current density of 10 mA cm-2. Under the idle conditions, operating at very low current density, a low chemical degradation rate and minimal electrical load stress were anticipated. However, the membrane was expected to degrade due to additional stress from the membrane swelling/contraction cycle controlled by the RH. In this work the performance of the 100% RH humidified cell (Run 1) was compared with that of RH cycling cells (Run 2 and Run 3). Chemical and mechanical degradation of the membrane were investigated using in-situ and ex-situ diagnostic methods. The results of each measurement during and after fuel cell operation are consistent. They clearly show that changing in RH lead to an overall PEM fuel cell degradation due to the increase in membrane degradation rate from membrane resistance, fluoride ion release concentration, hydrogen crossover current, membrane thinning, and hot-spot/pin-hole formation.

Cycling of the relative humidity (RH) levels in the reactant streams of polymer electrolyte membrane (PEM) fuel cells has been reported to decay fuel cell performance. This study focuses on the accelerated durability testing to examine different modes of membrane failure via RH cycling. A single PEM fuel cell with an active area of 42.25 cm2 was tested. A Greenlight G50 test station was used to establish baseline cell (Run 1) performance with 840 hours of degradation under high-humidity idle conditions at a constant current density of 10 mA cm-2. Under the same conditions, two other experiments were conducted by varying the RH. For the H2-air RH cycling test (Run 2), anode and cathode inlet gases were provided as dry and humidified gases. Another RH cycling experiment was the H2 RH cycling test (Run 3): the anode inlet gas was cycled whereas keeping the other side constantly at full humidification. These two RH cycling experiments were alternated in dry and 100% humidified conditions every 10 and 40 minutes, respectively. In the experiments, the fuel cells contained a GoreTM 57 catalyst coated membrane (CCM) and 35 BC SGL gas diffusion layers (GDLs). The fuel cell test station had been performed under idle conditions at a constant current density of 10 mA cm-2. Under the idle conditions, operating at very low current density, a low chemical degradation rate and minimal electrical load stress were anticipated. However, the membrane was expected to degrade due to additional stress from the membrane swelling/contraction cycle controlled by the RH. In this work the performance of the 100% RH humidified cell (Run 1) was compared with that of RH cycling cells (Run 2 and Run 3). Chemical and mechanical degradation of the membrane were investigated using in-situ and ex-situ diagnostic methods. The results of each measurement during and after fuel cell operation are consistent. They clearly show that changing in RH lead to an overall PEM fuel cell degradation due to the increase in membrane degradation rate from membrane resistance, fluoride ion release concentration, hydrogen crossover current, membrane thinning, and hot-spot/pin-hole formation.

För att ha en chans att ändra trenden med ökande utsläpp av växthusgaser är internationella samarbeten nödvändiga. Därför har EU genom miljökvalitetsmålet Begränsad Miljöpåverkan satt krav på högsta tillåtna utsläpp av växthusgaser. Att sänka energianvändningen för upp- värmning är ett steg i att även sänka utsläpp av koldioxid, som är en av växthusgaserna. Sänkning av energianvändning kan göras på flera sätt, bl.a. genom att öka tjockleken på isoleringen eller återvinna värmen i frånluften. Men dessa åtgärder ska inte helt okritiskt göras.  Att använda roterande värmeväxlare är ett sätt att återvinna värmen i frånluften. Luften passerar då en rotor med öppna kanaler som roterar kring sin egen axel över till tilluftssidan. Detta möjliggör fuktöverföring oberoende om rotorn är hygroskopisk eller ej. Dvs. möjligheten för kanalväggen att ta upp vattenmolekyler eller inte.  Mätningar av relativ fuktighet, temperatur och daggpunkt har gjorts på tre objekt. Därefter har ånghalter och verkningsgrader beräknats. Med objekt menas småhus där roterande värmeväxlare installerats i ventilationssystemet. Objekten är belägna i Linköping, Stockholm och Norge. Ett beräkningsexempel har ställts upp som visar hur fuktverkningsgraden påverkas av olika fukttillskott. I verkligheten råder dock inte stationära förhållanden för fukttillskottet som är en förutsättning för resultaten på dessa beräkningsexempel.  I denna rapport kommer den skrivande således fram till att fuktåterföring sker även för icke hygroskopiska värmeväxlare. Även att fuktverkningsgraden svarar med en viss tröghet vid återhämtning av ett tillfälligt förhöjt fukttillskott. Fuktverkningsgraden är dock betydande för fukttillskott över ca 1-2 g/m3. / To have a chance to change the trend of increased greenhouse gases are international collaborations necessary. Therefore, the EU through the environmental quality objective of Reduced Environmental Impact sat requirements for maximum allowable emissions of greenhouse gases. Reducing energy use for heating is a step that also reduces emissions of carbon dioxide; which is one of the greenhouse gases. Reducing energy use can be done in several ways, including by increasing the thickness of the insulation or heat recovery from exhaust air. However, these measures should not be uncritically made. The use of a rotating heat exchanger is a means to recover heat from exhaust air. The air then passes a rotor with open channels that rotates around its own axis over to the supply air side. This allows moisture transfer regardless of whether or not the rotor is hygroscopic. That is, the ability of the channel wall to take up water molecules or not.  Measurements of relative humidity, temperature and dew point has been made on three objects. Thereafter steam content and efficiencies was calculated. In other words, the objects are referred to single- ore two-family homes where a rotary heat exchanger is installed in the ventilation system. The objects are located in Linköping, Stockholm and Norway. An example calculation is set up that shows how moisture efficiency is affected by different moisture addition. In reality in which the conditions is not stationary the moisture supplement that is a prerequisite for the results of these calculation examples.  In this report, the writer thus concluded that moisture reversal will occur even for non- hygroscopic heat exchangers. Although the moisture efficiency corresponds with a certain slowness in the recovery of a temporarily elevated moisture addition. Moisture efficiency is significant for moisture supplement of about 1-2 g/m3.

In this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%. The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted. A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings. The outcome of this thesis could be summarised as follows; - - - -

<p>In this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%.</p><p>The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted.</p><p>A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings.</p><p>The outcome of this thesis could be summarised as follows;</p><p>-</p><p>-</p><p>-</p><p>-</p>

This paper deals with the determination of the capillary pore-size distribution (CPSD) and equilibrium moisture content (EMC) of untreated and thermally modified (TM) Norway spruce [Picea abies (L.) Karst.] by means of the pressure plate technique (PPT). Desorption experiments were conducted at very high values of relative humidity (RH) in the range between 99.2% and 100%. The thermal modification of spruce results in an alteration of the CPSD, owing to the formation of intercellular cracks in the middle lamella, as a result of cell-wall compression. The desorption curves for both untreated and TM spruce show an extremely upward bend at 99.97% RH. This step reflects an EMC of 38.1% for untreated spruce and 33.8% for TM spruce. None of the samples shrunk during the PPT measurements. Following desorption experiments at 97.4% RH, all samples shrunk. This step reflects an EMC of 27.9% for untreated spruce and 21.7% for TM spruce.