This work focuses on humidity effects of turbofan engines, in order to identify the magnitude of the error in operational conditions and the implications on maintenance decision support. More specifically, this paper employs a set of different methods, including semi-empirical corrections used in engine test beds, performance simulation models and analysis of historical data, in order to investigate the effects of humidity. We show that varying humidity can have a noticeable influence on the performance of the engine. These discrepancies cannot be currently quantified by health monitoring systems. Simulation and test bed correlations indicate a decrease of EGT of 0.35% per 1wt% of absolute humidity, which varies worldwide between 0 and 3wt%. Consequently, deviations in EGTM can be up to 1%, a figure which can be up to 12K for a modern civil turbofan. In practice, variations in ambient humidity have the potential to conceal possible deterioration in engine components. Following, the flight historical data were corresponded to historical humidity data. The two methods were identified to provide comparable results, indicating a higher EGTM for increasing ambient humidity. Overall, it was concluded that EGTM corrections for ambient humidity is an area of significant interest, especially for newer engine types where accurate diagnostics are of increasing importance.
Humidification is not a common procedure in many buildings in the Netherlands. An exception are buildings used for healthcare, especially hospitals. There, e.g. in operating theatres, relative humidity (RH) generally is controlled stringently at levels around 50%. From an energy point-of-view humidification is an energy-intensive activity. Currently, more than 10% of the total energy used in healthcare buildings is spent on humidification. The basis for an RH of around 50%, however, is not clear. Therefore, we pursued a scoping review to find evidence for specific RH thresholds in such facilities. In addition, an inventory was made of the current practice in the Netherlands. After analyzing the title and abstracts, the remaining references were read by two persons and scored on several topics. Guidelines and current practice were analyzed by referring to existing (inter)national guidelines and standards, and by contacting experts from Dutch hospitals through a survey and semi-structured interviews. Outcomes from the literature review were grouped into four different topics: 1) micro-organisms and viruses, 2) medical devices, 3) human physiology and 4) perception. No scientific evidence was found for the currently generally applied RH set-point of ~50%. Some studies suggest a minimum RH of 30% but the evidence is weak, with exception of medical devices if specifications require it. A lack of research that addresses more long-term exposure (a couple of days) and includes frail subjects, is noted. It was found that RH requirements are strictly followed in all hospitals consulted, some only focusing on the hot zones, but in many cases extended to the whole hospital. Steam humidification is mostly applied for hygienic reasons. but is quite energy-intensive. The conclusion t is that there is no solid evidence to support the RH-setpoints as currently applied in the Netherlands. It merely appears a code of practice. Therefore, there appears room for quick and significant energy savings, and CO2 emission reductions, when considering control at lower RH values or refraining from humidification at all, while still fulfilling the indoor environment requirements and not negatively influencing the health risk. This outcome can be applied directly in current practice with the available techniques.
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Older people are often over-represented in morbidity and mortality statistics associated with hot and cold weather, despite remaining mostly indoors. The study “Improving thermal environment of housing for older Australians” focused on assessing the relationships between the indoor environment, building characteristics, thermal comfort and perceived health/wellbeing of older South Australians over a study period that included the warmest summer on record. Our findings showed that indoor temperatures in some of the houses reached above 35 °C. With concerns about energy costs, occupants often use adaptive behaviours to achieve thermal comfort instead of using cooling (or heating), although feeling less satisfied with the thermal environment and perceiving health/wellbeing to worsen at above 28 °C (and below 15 °C). Symptoms experienced during hot weather included tiredness, shortness of breath, sleeplessness and dizziness, with coughs and colds, painful joints, shortness of breath and influenza experienced during cold weather. To express the influence of temperature and humidity on perceived health/wellbeing, a Temperature Humidity Health Index (THHI) was developed for this cohort. A health/wellbeing perception of “very good” is achieved between an 18.4 °C and 24.3 °C indoor operative temperature and a 55% relative humidity. The evidence from this research is used to inform guidelines about maintaining home environments to be conducive to the health/wellbeing of older people. Original publication at MDPI: https://doi.org/10.3390/atmos13010096 © 2022 by the authors. Licensee MDPI.
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Air-to-Water (A2W) systems are innovative technologies which make possible to supply drinking water to regions without any nearby surface or ground water source. Such systems use green energy (solar, wind) to condense air humidity and provide fresh water in rather remote locations. As water production is area dependent, they operate at relatively small fluxes (few cubic meters per day, per unit), which makes them especially suitable for small isolated communities that are not supplied by municipal water supply services. Even though they have reached quite high technology redness level (TRL), in-situ, real scale, tests are still required to optimize energy performance and evaluate production at very specific meteorological conditions. In this project we propose an in-situ evaluation of the performance of a real scale A2W system produced by a Dutch company (Dutch Rain Maker, model AW-25) in the semi-arid region of Northeast Brazil. The cooperation with a HBO institute (Water Technology lectoraat, NHL Stenden) will provide the necessary analytical and technical support as well as extra expertise to conduct the tests. The project uses the opportunity given by the state government of Ceará State which built an infra-structure to provide space for in-situ tests for experts and companies who would like to test water technology solutions for arid regions. Finally, it is also intended to help establishing partnerships between European SME and Brazilian end users, i.e. municipalities of the Ceará state and small agriculture companies in the region.
