scholarly journals A Novel Passive Method for Regulating Both Air Temperature and Relative Humidity of the Microenvironment in Museum Display Cases

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3768 ◽  
Author(s):  
Meng Yu ◽  
Xuejun Zhang ◽  
Yang Zhao ◽  
Xiaobin Zhang
Keyword(s):  
Relative Humidity ◽  
Phase Change ◽  
Silica Gel ◽  
Air Temperature ◽  
Water Vapor Permeability ◽  
Moisture Diffusivity ◽  
Vapor Permeability ◽  
Transfer Model ◽  
Passive Method ◽  
Museum Display

Display cases are widely utilized in museums to build an appropriate microenvironment for artifacts. In this study, a novel passive method is utilized to regulate both the temperature and relative humidity simultaneously of the microenvironment in museum display cases by proposing the concept of composite temperature and humidity control materials (CTHCM), which can be fabricated by combining both phase change material (PCM) and silica gel. The PCM is helpful to reduce the range of air temperature changes caused by melting or solidification processes, while the silica gel is helpful to reduce the range of relative humidity changes caused by adsorption or desorption processes. In this study, a coupled heat and mass transfer model is established to analyze the temperature-regulating and humidity-regulating performance of CTHCM using the software COMSOL Multiphysics. The influences of thermodynamic parameters of materials on temperature-regulating and humidity-regulating performance are also analyzed numerically. Results show that CTHCM is able to regulate the air temperature and relative humidity of the microenvironment in museum display cases effectively. It performs well in temperature-regulating as the phase change latent heat increases, and performs well in humidity-regulating as the water vapor permeability or moisture diffusivity increases.

scholarly journals The effect of relative humidity on tensile strength and water vapor permeability in chitosan, fish gelatin and transglutaminase edible films

2015 ◽  
Vol 35 (4) ◽  
pp. 690-695 ◽  
Author(s):  
Sofia ALVARADO ◽  
Glória SANDOVAL ◽  
Isidro PALOS ◽  
Simón TELLEZ ◽  
Yaneli AGUIRRE-LOREDO ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Water Vapor ◽  
Relative Humidity ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Vapor Permeability ◽  
Fish Gelatin

Moisture Transport Mechanism and Drying Kinetic of Fresh Harvested Red Onion Bulbs under Dehumidified Air

2017 ◽  
Vol 13 (9) ◽  
Author(s):  
Nurul Asiah ◽  
Mohamad Djaeni ◽  
Ching Lik Hii
Keyword(s):  
Relative Humidity ◽  
Storage Time ◽  
Moisture Diffusion ◽  
Moisture Diffusivity ◽  
Transfer Model ◽  
Unsteady State ◽  
Mass Transfer Model ◽  
Drying Time ◽  
Onion Bulbs ◽  
Drying Kinetic

AbstractDrying plays an important role in post-harvest handling of onion for prolonging storage time. This research focuses on the drying studies of red onion bulbs using dehumidified air. The works were carried out by observing the microscopic structure of red onion bulbs layer and followed by developing mass transfer model for moisture diffusion during drying. Moisture diffusivity was estimated from drying experiments conducted at various temperatures (40, 50 and 60 °C) using the unsteady state solutions of Fick’s second law model. The diffusivity values were used to predict the drying kinetics as well as effective drying time for different air relative humidity. Results showed that combination of low relative humidity and low drying temperature significantly improved drying rate and reduced drying time.

scholarly journals Detrended Multiple Cross-Correlation Coefficient applied to solar radiation, air temperature and relative humidity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea de Almeida Brito ◽  
Heráclio Alves de Araújo ◽  
Gilney Figueira Zebende
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Solar Energy ◽  
Correlation Coefficient ◽  
Air Temperature ◽  
Cross Correlation ◽  
Global Solar Radiation ◽  
Meteorological Variables ◽  
Hourly Data ◽  
Cross Correlations

AbstractDue to the importance of generating energy sustainably, with the Sun being a large solar power plant for the Earth, we study the cross-correlations between the main meteorological variables (global solar radiation, air temperature, and relative air humidity) from a global cross-correlation perspective to efficiently capture solar energy. This is done initially between pairs of these variables, with the Detrended Cross-Correlation Coefficient, ρDCCA, and subsequently with the recently developed Multiple Detrended Cross-Correlation Coefficient, $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2. We use the hourly data from three meteorological stations of the Brazilian Institute of Meteorology located in the state of Bahia (Brazil). Initially, with the original data, we set up a color map for each variable to show the time dynamics. After, ρDCCA was calculated, thus obtaining a positive value between the global solar radiation and air temperature, and a negative value between the global solar radiation and air relative humidity, for all time scales. Finally, for the first time, was applied $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2 to analyze cross-correlations between three meteorological variables at the same time. On taking the global radiation as the dependent variable, and assuming that $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}={\bf{1}}$$DMCx2=1 (which varies from 0 to 1) is the ideal value for the capture of solar energy, our analysis finds some patterns (differences) involving these meteorological stations with a high intensity of annual solar radiation.

Ultraviolet blocking and antioxidant polyvinyl alcohol films incorporated with baicalin extraction from Scutellaria baicalensis Georgi

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jinshu Liu ◽  
Xiaoyan Ma ◽  
Wenzhao Shi ◽  
Jianwei Xing ◽  
Chaoqun Ma ◽  
...  
Keyword(s):  
Water Vapor ◽  
Polyvinyl Alcohol ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Water Vapor Permeability ◽  
Scutellaria Baicalensis ◽  
Vapor Permeability ◽  
Protective Film ◽  
Uv Blocking

Abstract Baicalin, an active flavonoid ingredient of Scutellaria baicalensis Georgi, was extracted by heat reflux extraction and showed the same significance UV absorption property with standard baicalin. Active films were prepared from polyvinyl alcohol (PVA) containing baicalin extract by casting method. The effect of baicalin extracts on the UV-blocking, optical, antioxidant property, water vapor permeability, swelling and mechanical properties of the films were studied. UV–vis transmittance spectra showed that PVA films incorporated with baicalin extract blocked ultraviolet light range from 280–400 nm even with low concentration of baicalin (0.5 wt%) and maintain the high transparency in visible spectrum. The outstanding UV-blocking properties of PVA films incorporated with baicalin extract were also confirmed by Rhodamine B degradation. Baicalin conferred antioxidant properties to PVA films as determined by DPPH radical scavenging activity. Due to the interaction between hydroxy groups of baicalin and PVA molecule, water vapor permeability, swelling and elongation at break of the films were decreased accompanied with the increasing in tensile strength and Young’s modulus. FTIR reveal that the interaction between PVA molecules was significant changed by the introduction of baicalin. These results suggest that PVA film incorporated with baicalin extract can be used for the development of functional protective film.

scholarly journals Effects of trees, gardens, and nature trails on heat index and child health: design and methods of the Green Schoolyards Project

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kevin Lanza ◽  
Melody Alcazar ◽  
Deanna M. Hoelscher ◽  
Harold W. Kohl
Keyword(s):  
Physical Activity ◽  
United States ◽  
Relative Humidity ◽  
Air Temperature ◽  
The United States ◽  
Heat Index ◽  
Activity Levels ◽  
Natural Setting ◽  
Physical Activity Levels ◽  
Nature Trails

Abstract Background Latinx children in the United States are at high risk for nature-deficit disorder, heat-related illness, and physical inactivity. We developed the Green Schoolyards Project to investigate how green features—trees, gardens, and nature trails—in school parks impact heat index (i.e., air temperature and relative humidity) within parks, and physical activity levels and socioemotional well-being of these children. Herein, we present novel methods for a) observing children’s interaction with green features and b) measuring heat index and children’s behaviors in a natural setting, and a selection of baseline results. Methods During two September weeks (high temperature) and one November week (moderate temperature) in 2019, we examined three joint-use elementary school parks in Central Texas, United States, serving predominantly low-income Latinx families. To develop thermal profiles for each park, we installed 10 air temperature/relative humidity sensors per park, selecting sites based on land cover, land use, and even spatial coverage. We measured green features within a geographic information system. In a cross-sectional study, we used an adapted version of System for Observing Play and Recreation in Communities (SOPARC) to assess children’s physical activity levels and interactions with green features. In a cohort study, we equipped 30 3rd and 30 4th grade students per school during recess with accelerometers and Global Positioning System devices, and surveyed these students regarding their connection to nature. Baseline analyses included inverse distance weighting for thermal profiles and summing observed counts of children interacting with trees. Results In September 2019, average daily heat index ranged 2.0 °F among park sites, and maximum daily heat index ranged from 103.4 °F (air temperature = 33.8 °C; relative humidity = 55.2%) under tree canopy to 114.1 °F (air temperature = 37.9 °C; relative humidity = 45.2%) on an unshaded playground. 10.8% more girls and 25.4% more boys interacted with trees in September than in November. Conclusions We found extreme heat conditions at select sites within parks, and children positioning themselves under trees during periods of high heat index. These methods can be used by public health researchers and practitioners to inform the redesign of greenspaces in the face of climate change and health inequities.

scholarly journals Energy Saving and Charging Discharging Characteristics of Multiple PCMs Subjected to Internal Air Flow

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 275
Author(s):  
Ahmed J. Hamad
Keyword(s):  
Phase Change ◽  
Energy Saving ◽  
Air Temperature ◽  
Temperature Control ◽  
Phase Change Materials ◽  
Energy Savings ◽  
Heating System ◽  
Air Heating ◽  
Room Model ◽  
Model Temperature

One essential utilization of phase change materials as energy storage materials is energy saving and temperature control in air conditioning and indirect solar air drying systems. This study presents an experimental investigation evaluating the characteristics and energy savings of multiple phase change materials subjected to internal flow in an air heating system during charging and discharging cycles. The experimental tests were conducted using a test rig consisting of two main parts, an air supply duct and a room model equipped with phase change materials (PCMs) placed in rectangular aluminum panels. Analysis of the results was based on three test cases: PCM1 (Paraffin wax) placed in the air duct was used alone in the first case; PCM2 (RT–42) placed in the room model was used alone in the second case; and in the third case, the two PCMs (PCM1 and PCM2) were used at the same time. The results revealed a significant improvement in the energy savings and room model temperature control for the air heating system incorporated with multiple PCMs compared with that of a single PCM. Complete melting during the charging cycle occurred at temperatures in the range of 57–60 °C for PCM1 and 38–43 °C for PCM2, respectively, thereby validating the reported PCMs’ melting–solidification results. Multiple PCMs maintained the room air temperature at the desired range of 35–45.2 °C in the air heating applications by minimizing the air temperature fluctuations. The augmentation in discharging time and improvement in the room model temperature using multiple PCMs were about 28.4% higher than those without the use of PCMs. The total energy saving using two PCMs was higher by about 29.5% and 46.7% compared with the use of PCM1 and PCM2, respectively. It can be concluded that multiple PCMs have revealed higher energy savings and thermal stability for the air heating system considered in the current study.

scholarly journals The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 602
Author(s):  
Carmen Rodica Pop ◽  
Teodora Emilia Coldea ◽  
Liana Claudia Salanţă ◽  
Alina Lăcrămioara Nistor ◽  
Andrei Borşa ◽  
...  
Keyword(s):  
Water Vapor ◽  
Conformational Changes ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Film Structure ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Water Molecules ◽  
Compact Structure ◽  
Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

scholarly journals Protein-Based Films and Coatings for Food Industry Applications

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 769
Author(s):  
Vlad Mihalca ◽  
Andreea Diana Kerezsi ◽  
Achim Weber ◽  
Carmen Gruber-Traub ◽  
Jürgen Schmucker ◽  
...  
Keyword(s):  
Food Packaging ◽  
Meat Products ◽  
Water Vapor Permeability ◽  
Food Product ◽  
Edible Films ◽  
Vapor Permeability ◽  
Area Of Interest ◽  
Industry Applications ◽  
Economic Perspectives ◽  
Materials Used

Food packaging is an area of interest not just for food producers or food marketing, but also for consumers who are more and more aware about the fact that food packaging has a great impact on food product quality and on the environment. The most used materials for the packaging of food are plastic, glass, metal, and paper. Still, over time edible films have become widely used for a variety of different products and different food categories such as meat products, vegetables, or dairy products. For example, proteins are excellent materials used for obtaining edible or non-edible coatings and films. The scope of this review is to overview the literature on protein utilization in food packages and edible packages, their functionalization, antioxidant, antimicrobial and antifungal activities, and economic perspectives. Different vegetable (corn, soy, mung bean, pea, grass pea, wild and Pasankalla quinoa, bitter vetch) and animal (whey, casein, keratin, collagen, gelatin, surimi, egg white) protein sources are discussed. Mechanical properties, thickness, moisture content, water vapor permeability, sensorial properties, and suitability for the environment also have a significant impact on protein-based packages utilization.

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