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Optimum indoor humidity is often associated with comfort and overall well-being. Occupant comfort is often evaluated with a focus on “thermal comfort” using the PMV (predicted mean vote), PDD (predicted percentage of dissatisfied), and adaptive thermal comfort models. Humidity-determined comfort parameters, like skin and respiratory comfort, are well acknowledged in the scientific community, but strangely not considered for indoor comfort computations. This study proposes a new computational approach for describing and evaluating humidity-related skin comfort in buildings using skin temperature, evaporative loss, and skin wettedness as critical parameters. The Development and validation of the computational model was demonstrated through a case study in a rural Indian context. The case study involves real-time monitoring of indoor environmental parameters and humidity-determined occupant comfort votes recorded through a novel aggregated humidity comfort vote method. The simulation results were compared with the community comfort/health survey. It was observed that, even at neutral skin temperatures, an increase in skin wettedness increases the thermal sensation vote. Clothing varies according to gender, community, and personal preferences, influencing physiological parameters which determine comfort. The acceptable humidity ratio was found to be in the range of 17.4 to 22.6 g-wv/kg-da for Indian participants. Including humidity-related comfort parameters in building simulation tools would aid in selecting building materials for improved indoor comfort.

This article contributes to the assessment of the hygrothermal conditions of residential buildings in the Azores archipelago and defines strategies that may contribute to the improvement in indoor air quality. These objectives were fulfilled by in situ monitoring of the hygrothermal conditions of a typical building on Terceira Island. Complementary tests to determine the thermal conductivity of exterior walls and ventilation rates were also conducted. The results were used to validate a simulation model, and different ventilation strategies were simulated using the combined heat, air, and moisture transfer model in EnergyPlus. The model took into account the typical construction methods and materials of the archipelago, as well as the reference weather data sets available for the region. The monitoring campaign showed that the percentage of time in which thermal comfort conditions were achieved was very low, varying from 5% to 32%, being the main cause for discomfort in the humidity level in the indoor environment. The simulation results pointed out the sensitivity of the problem, showing that ventilation may not always be, by itself, beneficial to thermal comfort. In particular, ventilation strategies should be established taking into account additional criteria other than the air change rate, namely the periods of the day and year in which ventilation should be performed, as well as the duration of these periods.

Gas boilers exhibit thermal inefficiency and unsatisfying pollutant emissions. In this study, numerical simulations were conducted to examine the effect of humidified oxygen-enriched air on methane combustion in a furnace and the effects of different premixed ratios of air on the temperature field inside the furnace, intermediate product OH groups, component concentration distribution, and pollutants. Although humidification of ambient air effectively reduced the flame center temperature and mass concentration of the NOx generated during combustion in the furnace, the highest growth rate of CO concentration at the furnace outlet was 18.6%. Humidification of oxygen-enriched air increased the center temperature and outlet NO concentration of the furnace compared with those during no oxygen enrichment, but the outlet CO concentration showed a decreasing trend, with the highest decrease rate of 34.6%. This study determined an optimal CO–air premix ratio with a moisture concentration of 50 g/kg dry air and an oxygen concentration of 23%. The air humidification and oxygen enrichment technology proposed in this article provides a technical reference for low nitrogen transformation of existing gas boilers.

The increase in global air temperature is well documented, as during the last several years each decade has been consecutively warmer than the preceding. As climatic conditions affect the energy performance of buildings, the changes in outdoor air temperature and humidity will inevitably lead to significant alterations in energy consumption and costs for the heating, ventilating and air conditioning (HVAC) of buildings. The availability and quality of climatic data play an important role in the accuracy of energy analysis results. In this study, the hourly temperature and relative humidity of outdoor air measurements, for a period of three decades (1983–2012), recorded at the climatic station of the National Observatory of Athens were processed, and an up-to-date set of specific data for the application of bin methods was produced and presented. The data were then used to calculate changes in the energy demands in a typical office building throughout the specified period. Results showed a progressive reduction in the low and increase in the high temperature intervals, leading to an increase in the building’s annual energy requirements for air conditioning of up to 14.5% from the first to the third decade, with decrease in the energy demands for heating and increase in the energy demands for cooling.

A laboratory-scale thermoelectric (TE) dehumidification system used to dehumidify air in a test chamber (volume of 1 m3) is described herein. The system consists of TE cooling modules, heat sinks, and a water cooling unit. Two rectangular-fin heat sinks were bonded with the hot and cold sides of the TE modules. The air from the test chamber circulated through the cold-side heat sink to remove moisture from the air in the test chamber. The water cooling unit was used to release heat from the hot side of the TE modules. A theoretical model was developed to simulate the air dehumidification process using the TE cooling system. Experiments were performed to validate the results of the developed model, indicating that the model showed good predictive ability. The TE dehumidification system reduced the humidity ratio by about 31.7% from the ambient value. The coefficient of performance of the system ranged from 0.44 to 0.94 under different operating electric currents supplied to the TE modules. The different electric current settings simulated weather conditions in Thailand. The main attraction of this approach is its compact, noiseless, reliable, and Freon-free operation.

Since composite materials are light and corrosion-resistant, they have replaced many traditional materials in the aviation and marine industries. Composite materials have the advantages of a much higher strength–weight ratio, lower maintenance requirements, and the ability to form complex shapes, such as bodies, compared to carbon steel. In this study, the mechanical properties of glass fiber reinforced (GFRP) and carbon fiber reinforced (CFRP) composite materials were investigated in marine applications in which composite materials had been used. In this study, 0/90 oriented twill weave eight-ply GFRP and eight-ply CFRP composite materials were used, incorporating the hand lay-up method and hot-pressing method. Seawater was taken from the Aegean Sea, Izmir Province (Balçova/İnciraltı), and had an average temperature of 22.43 °C. This seawater was kept in different containers for 30 days and 60 days (a total of 1440 h of keeping in seawater) with the intent to test the GFRP and CFRP composite samples separately. The produced CFRP and GFRP sheets were then cut with a wet (circular) saw in accordance with the standard procedure in the Composite Research and Testing Laboratory of the Dokuz Eylul University Department of Mechanical Engineering. Moisture retention percentages and Charpy impact tests were carried out. Then, three-point bending tests were carried out according to TS EN ISO 14125. The damage in the material was examined using a ZEISS Stereo Discovery.V12 imaging microscope (Oberkochen, Germany). The mechanical properties of CFRP- and GFRP-reinforced composite samples before and after aging were investigated using the Charpy impact test and three-point bending test. Then, the effects of the seawater environment on the mechanical properties of the CFRP and GFRP composite materials were evaluated by comparing the results. The aim was to better understand what kind of damage would occur in GFRP and CFRP composite materials given the effects of seawater and at what stages changes would occur in the mechanical properties of these materials. Moisture retention rates (%) in the tested samples after the Charpy impact test were 2.56% in GFRP and 0.47% in CFRP after 30 days. In the tested samples after the three-point bending test, these values were 1.41% in GFRP and 0.31% in CFRP after 30 days. Subsequent to the Charpy impact tests, the fracture toughness values of the CFRP samples tested at the 30 J impact energy level before aging in seawater conditions for 30 days or 60 days were found to be increased by 15.79% and 21.08%, respectively. The fracture toughness values of the GFRP tested at the 30 J impact energy level in dry conditions and kept in seawater for 30 days or 60 days were found to be 27.69% and 29.23%, respectively. The energy absorbed during the impact tests by the GFRP samples was higher than in the CFRP samples. This showed that the GFRP samples were more brittle. Subsequent to the three-point bending tests, the CFRP composite samples kept in seawater for periods of 30 days and 60 days showed changes in the modulus of elasticity of 7.48% and 7.46%, respectively, compared to the dry samples. The GFRP composite samples kept in seawater for periods of 30 days and 60 days showed changes in the modulus of elasticity of 7.015% and 11.53%, respectively, compared to the dry samples. The change in the modulus of elasticity was less in the CFRP samples than in GFRP. All of these results showed that the mechanical properties of CFRP were better than those of GFRP.

Mustard aphid, Lipaphis erysimi (Kaltenbach), is the most serious pest of Rapeseed-Mustard which is known to be responsible for a tremendous loss in yield and oil content, under various agro-climatic conditions of India. Information support on aphid occurrence and intensity is necessary for effective management by the farmers in the mustard-growing belt. In this study, an effort is made to develop forewarning model using the field data on aphid for 12 consecutive rabi seasons from 2003–2004 to 2014–2015 under different agro-climatic locations in India. Three main components of aphid-related stages were identified for which necessary forewarnings were needed to be issued: (1) severity, (2) the time of reaching the economic threshold level (ETL) for decision-making on pesticide application, and (3) time of occurrence of peak population. To address these, three different models were developed/used and validated using incident field dataset. Those field observations when the infestation level were below severe category (< 60) during rising phase of the aphid population were found to indicate highest R sqr. (0.82) for the model-I during validation. When model-II was used, 11 out of 14 locations (78.57%) stood validated. The assumptions made in model-III also got validated when humidity thermal ratio (HTR) of the week of peak population ranged between 1.5 and 4 (lowest among the weeks considered), and population reached severe category. The models showed better results during real-time validation in seasons 2016–2017 and 2017–2018, thus suggesting that these three models can be used to ascertain the severity, week of ETL, and week of peak aphid population for Brassica juncea varieties all over the mustard belt in India and can be operationalized spatially to forewarn against the aphid pest population in future under Gramin Krishi Mausam Sewa (GKMS) scheme.

O tucuma é um fruto amazónico, possui alto poder nutricional e é utilizado em diversos segmentos económicos. Portanto, estudos para a reduçao de umidade devem ser realizados para o aumento do tempo de prateleira deste fruto. Este trabalho tem como objetivo realizar o estudo de secagem do epicarpo (casca), mesocarpo (polpa) e endocarpo (amendoa) do tucuma nas temperaturas de 60 °C, 70 °C e 80 °C. Foi observado que o aumento da temperatura reduziu o tempo de queda da razao de umidade do epicarpo, mesocarpo e endocarpo. Modelos matemáticos foram utilizados para estimar dados experimentais e foram calculadas propriedades termodinámicas do processo. Baseado no maior R2 e o menor SE e DQM, o modelo Logistico apresentou melhor ajuste para cinética de secagem dentre os avaliados, estimando energia de ativaçao de 39,50 kJ mol-1, 46,62 kJ mol-1 e 17,76 kJ mol-1 para o epicarpo, mesocarpo e endocarpo, respectivamente. Os resultados das propriedades termodinámicas mostraram que a entalpia (ДИ) caracteriza a secagem como um processo endotérmico. A entropia (AS) diminui com o aumento da temperatura. Os valores da energia de Gibbs sao positivos, ou seja, o processo é nao espontáneo e necessita de energia externa para difusividade da água no ar.

The dryness of the membrane of a polymer electrolyte fuel cell (PEFC) decreases the ionic conductivity, resulting in performance reduction. In this study, the effects of external humidification to the membrane were investigated by varying the humidification side such as anode humidification, cathode humidification, and both anode and cathode humidification (called as both-side humidification). The amount of required water vapor into the gas was increased rapidly to maintain the relative humidity constant with the increase of cell temperature. The best performance of the cell was achieved by both-side humidification. However, as the humidity condition approached saturation state, anode humidification yielded comparable performance to both-side humidification. In anode humidification, the increase of the cell temperature degraded the performance, even though the amount of water supply to the membrane remained constant. At constant relative humidity conditions with anode humidification, the polarization curves of the PEFC were almost the same, regardless of the cell temperature when the relative humidity was higher than 60%.[PUBLICATION ABSTRACT]

For the purpose of realizing non-dewfall condition of the radiant panels, low energy consumption and nice comfort of the freezing dehumidification-based radiant air-conditioning system, the design temperature and humidity of the room were figured out according to the mean comfort index of human body during the design. And in order to lower the energy consumption, the necessity of the reasonable load allocation between the dehumidification unit and the radiant unit was discussed by means of the calculation with the quasi heat-humidity-ratio line. As a result, much more precise design parameters were acquired through the approximation calculation. And it was proven to be a good design method by applying these parameters to the design of the reading rooms of the library. In the design example of the reading room, the load ratio between the dehumidification unit and the radiant unit was 48 to 52, and the recirculation air flow rate of the dehumidification unit was not less than 36.8% of the total air rate of the room.