Chamber Relative Humidity Research Articles

ONE-DIMENSIONAL TRANSIENT MODEL OF FOOD PRODUCT TEMPERATURE AND WEIGHT LOSS EVOLUTION IN A VACUUM COOLER WITH MEMBRANE HUMIDIFICATION

A one-dimensional, transient model was developed to predict the temperature and weight loss evolution of a food product cooled using a vacuum cooling system with membrane humidification. The model included the following: (1) a sub-model based on the mass conservation of air and vapor inside the vacuum chamber; (2) a sub-model based on the coupled mass and heat transfer with inner vapor and heat generation; and (3) a sub-model based on the mass conservation of water vapor along the flow channels inside the humidifier. The vacuum chamber pressure was reduced from 1 atm to 2200 Pa using a vacuum pump with deflating speed of 500 m3/hr and condenser and membrane humidifier operating temperatures of 13°C and 60°C, respectively. A meat joint with a weight of 5.30 kg was cooled from an initial core temperature of 74°C to below 10°C. The conventional and modified models both cooled the food product to 10°C in 25 minutes. It was found out that increasing the chamber relative humidity reduced the surface water evaporation while the internal evaporation rate remained the same. Thus, the meat's moisture content, which was initially at 73.51%, was reduced to only 65.44%-an improvement from the conventional vacuum cooling system's 64.31%. This translated to product weight loss of only 10.98%, which represented significant progress compared to the conventional system's 12.51%. The simulation results indicated that employing humidification in a vacuum cooling system reduces the product total moisture loss while maintaining the rapid cooling rate.

Revisiting integrating nephelometer measurements

Integrating nephelometers are designed to measure the scattering coefficient, bsp, of an aerosol introduced into its sampling chamber. They have been and are used extensively in laboratory studies and short-term intensive aerosol characterization studies to validate and improve optical aerosol models. They are used to measure long-term temporal and spatial trends of the particle scattering coefficient, and to measure trends in the scattering enhancement factor, f(RH). The National Park Service (NPS) has operated Optec NGN nephelometers with an open sampling chamber, referred to as NGNambient, designed to measure total (coarse plus fine) particle scattering at near ambient relative humidity (RH). However, the NGN is no longer manufactured and will be replaced with Ambilabs 2WIN nephelometers. An intercomparison study was initiated to compare the NGNambient, an enclosed heated NGN, two 2WIN nephelometers, one held at RH ≤ 40% and another modified to sample at near ambient RH, and a TSI (Shoreview, MN, USA).The objective of the study was to evaluate the suitability of the 2WIN to replace the NGNambient and more generally to assess the suitability of the 2WIN instrument to be used to track long term trends in bsp and f(RH) values. The two 2WIN's, TSI and the heated NGN have enclosed sampling chambers with PM2.5 inlets. Measurements of particle physical and chemical properties and sampling chamber RH allowed for an assessment of the inter-comparability of relationships between optical models and nephelometer measurements. Heating of the sampling chamber to reduce RH to less than 40% did not significantly volatilize particle nitrate but heating to reduce the RH to near 20% did. It was also determined that measurement of the scattering enhancement function, f(RH), was underestimated in this study, by about 20% for RH levels of 70% or greater, when the reference RH nephelometer was held at RH ≤ 40% compared to when the RH ≤ 10%. The study highlighted the importance of careful calibration of the instrument and careful documentation of the sampling chamber environment in which the measurement is made. Knowing precisely the RH in the sensor volume is critical to the interpretation of measured bsp levels. Monitoring of long-term temporal and spatial trends should be done either with the sampling chamber at or near ambient RH to track changes in ambient bsp or at RH ≤ 10% to understand changes in particulate mass concentrations contributing to bsp. Understanding changes in f(RH) over time and space should be done with the reference bsp at RH ≤ 10%. The lower RH levels should be achieved by some method other than heating the chamber to avoid volatilization of the aerosol species such as ammonium nitrate.

Study of a new humidifier configuration designed for climatic chambers

Climate chambers are crucial for testing and developing different products under specific atmospheric conditions. To ensure the accuracy and reliability of the results, it is essential to maintain precise control over the chamber's relative humidity and temperature levels. However, designing a humidifier that meets the stringent requirements of a climate chamber remains a challenge. This paper presents a modular piezoelectric ultrasonic humidifier designed to fulfill the high reliability and homogeneity standards demanded in industrial and pharmaceutical applications. The experimental design and testing of the prototype are discussed, and the simulations performed to evaluate the humidifier's homogeneity and airflow orientation are presented. The prototype was tested by coupling it to an 85 m3 climate chamber dedicated to storage and validated under a temperature condition of 25 °C ± 2 °C and relative humidity of 60% ± 5%. Compared to commercial humidifiers, the specific design of the prototype allowed for better insulation while ensuring the required homogeneity in the climate chamber. During the tests, the relative humidity was 60% ± 3% with temperatures of 25 °C ± 0.5 °C. The results also show that the prototype enabled quick and efficient rebalancing of the relative humidity level while keeping the chamber within the permitted relative humidity limits. Overall, this work contributes to the advancement of climate chamber technology, which is critical in product development and research applications.

Effect of white tea extract incorporated calcium silicate cements on flexural strength and collagen degradation of dentin

ABSTRACT Aim: The aim of the study was to comparatively evaluate the effect of white tea extract-incorporated mineral trioxide aggregate (MTA) and Biodentine (BD) on collagen degradation and flexural strength of coronal dentin. Methods: Two hundred and fifty dentin beams (10 mm × 2 mm × 2 mm) were obtained from the mid-coronal portion of caries-free human 3rd molars. They were randomly assigned to five experimental groups (n = 50). Group 1-control group (No experimental materials placed); Group 2-MTA; Group 3-MTA with 10% white tea extract (WMTA); Group 4-BD; and Group 5-BD with 10% white tea extract (WBD). All experimental materials were mixed and then spread onto the prepared dentin beams. Each group was further divided into five subgroups with each 10 samples according to aging periods of 24 h, 1, 3, 6 months, and 1 year as A, B, C, D, and E, respectively. The dentin beams were placed in contact with a set calcium silicate cement block in silicone molds, with only one side of each beam exposed to the cement at 37°C in a 100% relative humidity chamber. At each designated time period, the beams were copiously rinsed with deionized water and tested for flexural strength and collagen degradation using a universal testing machine and Fourier Transform-Raman spectrometer, respectively. Flexural strength results were statistically analyzed using one-way ANOVA, followed by post hoc adjustment with Tukey’s test for pair-wise comparisons with P < 0.05. Results: Collagen degradation was more in Group 2, followed by 4, 3, and 5. All the groups showed a gradual reduction in flexural strength over 1 year. Group 2 showed the highest reduction in flexural strength over 1 year. Group 5 showed the least reduction in flexural strength. Conclusion: BD and white tea-incorporated BD showed less collagen degradation and better flexural strength than MTA and white tea-incorporated MTA, respectively.

Design of mechanically advantaged glasses with hydration‐induced stress profiles

AbstractThe glass composition design work leading to the discovery of highly crack resistant glasses exhibiting hydration‐induced stress profiles is described. Initial hydration studies on ternary aluminosilicate glasses show the importance of potassium for facilitating hydration. Further modification of the glass composition through the incorporation of P2O5 increased the hydration rate such that a specimen with a 29‐µm hydration depth was prepared by holding in an 85°C 85% relative humidity chamber for 65 days. Not only did this glass have a high Vickers indentation crack resistance of >20 kgf, but the sample also displayed considerable stored energy at failure. This indication of a stress profile was subsequently measured and a compressive stress (CS) of 400 MPa with a compressive depth of layer of 29 µm was found. The initially long process times were shortened using pressurized steam vessels. When held at 250°C and .3 MPa, samples can be prepared with surface CSs >300 MPa and compressive depths >30 µm in less than 8 h.

Fiber-welded polyionic biocomposites using 1-alkyl-3-vinylimidazolium alkylphosphonate ionic liquids

In this study, imidazolium-based polymerizable ionic liquids (Poly-ILs) were used to prepare novel polyionic biocomposites through Natural Fiber Welding. Two new Poly-ILs containing a 1-alkyl-3-vinylimidazolium cation and an alkylphosphonate anion were synthesized and evaluated for their ability to (i) solubilize a biopolymer (cellulose) matrix and (ii) polymerize with and without dissolved cellulose. Raman spectroscopy and scanning electron microscopy (SEM) were used to characterize the fiber-welded composites. Optimized fiber-welding parameters yielded polyionic biocomposite materials whose physicochemical properties were evaluated using SEM, energy dispersive X-ray spectroscopy (EDS) and water sorption testing in a controlled relative humidity chamber. SEM/EDS revealed polymerized Poly-IL integrated throughout a fiber-welded, polyionic biocomposite matrix; the materials absorbed ca. 38-40 % of their mass in water when exposed to a controlled (70%) relative humidity environment. To reduce the hygroscopic nature of the fiber-welded composites, the methylphosphonate anion was partially exchanged for a more hydrophobic anion (bis-trifluorosufonylimide, TFSI) through a single-pass anion exchange. SEM/EDS of sample cross sections before and after treatment show that this simple anion exchange and rinse procedure delivers up to ca. 5% exchange from methylphosphonate to TFSI. In spite of this low exchange, the water sorption properties of the exchanged polyionic biocomposites were successfully reduced by 14% and could be easily returned to their original dry state at low temperature under vacuum.

Utilizing an electrical low-pressure impactor to indirectly probe water uptake via particle bounce measurements

Abstract. Secondary organic aerosol (SOA), formed through oxidation of volatile organic compounds (VOCs), displays complex viscosity and phase behaviors influenced by temperature, relative humidity (RH), and chemical composition. Here, the efficacy of a multi-stage electrical low-pressure impactor (ELPI) for indirect water uptake measurements was studied for ammonium sulfate (AS) aerosol, sucrose aerosol, and α-pinene-derived SOA. All three aerosol systems were subjected to greater than 90 % chamber relative humidity, with subsequent analysis indicating persistence of particle bounce for sucrose aerosol of 70 nm (initial dry diameter) and α-pinene-derived SOA of number geometric mean diameters between 39 and 136 nm (initial dry diameter). On the other hand, sucrose aerosol of 190 nm (initial dry diameter) and AS aerosol down to 70 nm (initial dry diameter) exhibited no particle bounce at elevated RH. Partial drying of aerosol within the lower diameter ELPI impaction stages, where inherent and significant RH reductions occur, is proposed as one explanation for particle bounce persistence.

Design, construction and implementation of relative humidity and temperature climatic chamber for metrology laboratory

For the calibration of thermohygrometers it is necessary to have a means of generating temperature and relative humidity for this reason in this development we will build a climatic chamber which will generate and control these two magnitudes. For the generation of temperature a thermoresistance was used and the decrease of relative humidity was done through a silica gel trap through which the air inside the chamber is recirculated with the use of a vacuum pump. On the other hand, an ultrasonic humidity generator also known as fogger was used to increase the relative humidity. For the construction of the chamber, acrylic was used as the main material, since it is translucent and facilitates the visualization of the thermohygrometers’ indications. For the control of the process variables such as temperature and relative humidity, an Arduino card was used, which through PWM pulse width modulation, the control was performed achieving a variation of 0.3 °C and 2 %RH, which will be evaluated by an accredited laboratory in the characterization of isothermal media certified by ONAC, since it is in this way that the inhomogeneity, stability and thermal load of the medium, components that affect the uncertainty of the instruments under calibration, are evaluated. It should be remembered that this development was carried out in order to create an air medium with which temperature and relative humidity measuring instruments can be calibrated in the metrology laboratory VALIDACIONES Y METROLOGIA LM S.A.S., since it is in the process of growth and one of its main objectives is to be accredited in the magnitudes of temperature and relative humidity before the accreditation body in Colombia (ONAC), which is the entity that will finally give the technical approval to release the chamber and put it into operation.

Anti-thermal quenching of Eu3+ luminescence in negative thermal expansion Zr(WO4)2

Thermal quenching of luminescence is the most critical problem for rare earth doped phosphors used in light-emitting diodes (LEDs). Herein, we demonstrate that thermal quenching can be considerably suppressed via the negative thermal expansion effect in Zr(WO4)2 that serves as host for Eu3+ red emission. The photoluminescence (PL) intensity is surprisingly enhanced by 130% when the temperature is raised from room temperature to 100 °C. As temperature further increases to 160 °C, the PL intensity turns to reduce, which is still 1.4 times of that at room-temperature. Moreover, Zr(WO4)2:15%Eu phosphor has good durability, which still exhibits strong red luminescence (only 13% loss) after being kept in 85 °C/85% relative humidity chamber for 240 h. The anti-thermal quenching of Eu3+ luminescence can be ascribed mainly to the following two factors: first one is the thermal-enhanced energy transfer between Eu3+ ions induced by the contraction of Zr(WO4)2 unit-cell volume that leads to the strong structural rigidity of host lattice; second one would be electron traps in the host that favors the increase of electrons on the excited energy levels. This important anti-thermal quenching effect induced from the negative thermal expansion of the host matrix may stimulates a novel and efficient approach to design highly thermal stable phosphors for next-generation LEDs.

Efficient Model Selection for Moisture Ratio Removal of Seaweed Using Hybrid Of Sparse And Robust Regression Analysis

The Internet of things ((IoT) consisted of physical devices networks such as sensors, home appliances, electronics, and software’s. It enables us to collect and exchange data in several fields. After data collection from IoT, variable selection is considered a major problem because many variables are involved in real life datasets. The current study focused on large data analysis of the problem of model selection, including interaction terms. The dataset used in this study is taken from solar drier with moisture ratio removal (%) as dependent variable while ambient temperature, chamber temperature, collector temperature, chamber relative humidity, ambient relative humidity, and solar radiation as independent variables. LASSO with Huber M, LASSO with Hampel M and LASSO with Bisquare M are proposed in this study. Comparison of proposed techniques are made with ridge regression and OLS (ordinary least square) after multicollinearity test and coefficient test. MAPE (mean absolute percentage error) is calculated for the efficient selected model to forecast. As a result, the model using LASSO with Bisquare-M provides a minimum MAPE value for the best efficient model. Thus, the resulting model with the selected variables can be used to predict Moisture Ratio Removal (%) to determine seaweed drying behavior.

Design and fabrication of humidity sensor

Design and fabrication of the humidity sensor is done by using the different Degree of Sulfonation (DS) (15%, 29% and 42%) of the polymer Sulfonated-Poly ether ether ketone (sPEEK) which was derived by the sulfonation reaction using concentrated H2SO4 with poly ether ether ketone (PEEK) and the reaction temperature was carried out in the microwave reactor. For different degree of sulfonation 2.0 wt% of nano powder of SiO2 (particle size 7 nm particle size 7 nm i.e. 0.007 µm purchased directly from Aldrich Chemistry Product Number: S5130) were added while dissolving the sPEEK beads of weight 1 g in DMSO solvent. Interdegitized copper electrode was etched on the conventional printed circuit board and the sensing area of 4.68 cm2. The polymer sPEEK is used as a sensing layer which shows the change in impedance as the relative humidity (%) increase as the impedance (ohm) value decreases vice versa and the impedance values was calculated by frequency response analyzer, auto lab potentiostat/galvanostat. The sensing nature of the sensing layer was measured at different thickness and at the different degree of sulfonation of the sPEEK. The sensor data was collected at different relative humidity chamber at 7%, 32%, 53%, 75% and 97% and all the data at different thickness of the sensing layer was linearized and important characteristics such as response time, recovery time, sensitivity and linearity were calculated.

A High-throughput, Robotic System for Analysis of Aerosol Sampling Filters.

The determination of accumulated mass on filter-based aerosol samples is the basis for many forms of scientific research and regulatory monitoring of air quality. However, gravimetric analysis of air sampling filters is tedious, time-intensive, and prone to human error. This work describes the development of an Automated Air Analysis Facility (AIRLIFT) for high-throughput gravimetric mass and optical black carbon measurements of filter-based aerosol samples. The AIRLIFT consists of a sealed environmental enclosure, a 6-axis articulating robotic arm, a programmable control system, a filter weighing apparatus, and an optical system for the determination of aerosol black carbon via light attenuation. The system actively monitors microbalance stability and chamber relative humidity. Digital imaging and QR code scanning support sample tracking and data logging. Performance metrics for temperature and humidity control and weight stability were found to meet or exceed minimum requirements set forth by the US Environmental Protection Agency. The AIRLIFT is capable of analyzing approximately 260 filters per day while reducing the required personnel time by a factor of ~4.

Brown spot in table grape Redglobe controlled in study with sulfur dioxide and temperature treatments

Brown spot is a postharvest disease of grapes caused byCladosporiumspecies in the San Joaquin Valley of California. It spreads during cold storage and transport, resulting in severe economic losses to late table grape cultivars, which are grown mainly for export to countries such as China and Mexico. We examined the effect of temperature and sulfur dioxide (SO2) treatments on fungal growth and infection of Redglobe berries by threeCladosporiumspecies:Cladosporium ramotenellum, C. cladosporioidesandC. limoniforme.Redglobe is especially popular for export. Fungal colonies growing on potato dextrose agar in petri plates stored at −2°C grew slower than those stored at 2°C, and an 400 ppm-h SO2treatment significantly reduced fungal growth of all three species and at all temperatures tested. Redglobe berries inoculated with theCladosporiumspecies, treated with SO2concentrations of 100 ppm-h, 200 ppm-h and 400 ppm-h and incubated in high relative humidity chambers for 28 to 32 days at 2°C, showed little incidence of disease. The development of brown spot on berries was entirely prevented with the treatment of 200 ppm-h SO2for allCladosporiumspecies tested.

Surface tension measurement of normal human blood samples by pendant drop method

The surface tension of blood plays an important role not only in the birth and decompression sickness but also in other functionality of the organism. It also provides capillary action during blood flow process. In this article, a simple and low-cost device is designed and fabricated for measuring the surface tension of blood by pendant drop method. In this device, a droplet of blood is formed in a closed chamber on tip of an 18-gauge blunt needle and it is photographed by a camera in very humid conditions (RH = 99%) to minimise the evaporation. A wetted wick is provided at the bottom of the chamber for maintaining constant relative humidity in chamber. Surface tension of blood is inferred using drop shape factor method and image analysis technique at various experimental conditions. This device is validated and calibrated with surface tension measurements of water and silicone oil. Its measurements are in good agreement against data reported in literature. Post-validation, surface tensions of blood samples with and without anticoagulant of healthy persons at various temperatures (range from 20 to 40 °C) was measured. It was found that the surface tension of normal blood samples strongly correlates with blood temperature. The surface tension of female blood was remarkably different from same of male blood. However, the effect of age (21–60 year) on the surface tension was negligible for all practical purposes. Increased percentage of anticoagulant in blood increases its surface tension. This research specifies a baseline for surface tension of normal blood samples at various conditions which in turn provides new insights to pathologists in identifying various disease conditions.

Degradation in photovoltaic encapsulant transmittance: Results of the first PVQAT TG5 artificial weathering study

AbstractReduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation is frequently identified as a cause of decreased performance through the service life of photovoltaic modules. However, the present module safety and qualification standards apply short UV doses, only capable of examining design robustness and “infant mortality” failures. Furthermore, essential information remains unknown that might be used to screen encapsulants through product lifetime. We conducted an interlaboratory study to provide the understanding that will be used toward developing a higher‐fidelity, more‐rigorous UV weathering test. Five representative known formulations of poly (ethylene‐co‐vinyl acetate) were studied, in addition to one thermoplastic polyurethane material. Replicate laminated silica/polymer/silica specimens were examined at seven institutions using a variety of indoor chambers (including xenon, UVA‐340, and metal‐halide light sources). Specimens were artificially weathered for 180 cumulative days at steady‐state accelerated test conditions, predesignated relative to the default irradiance of 1.0 W·m−2·nm−1 at 340 nm, chamber temperature of 60°C, and chamber relative humidity of 30%. The solar‐weighted transmittance, yellowness index, and the UV cut‐off wavelength—each determined from the measured hemispherical transmittance—are examined to provide understanding and guidance for the UV light source (type lamp and filters), temperature, and humidity used in accelerated UV aging tests. The relative efficacy of xenon‐arc and UVA‐340 fluorescent sources and the typical range of activation energy for degradation is quantified from the experiments.

Morphology of cementitious material during early hydration

Morphology of hydration products, mainly calcium-silicate-hydrate (C-S-H), has a strong influence on the mechanical and transport properties of hardened cementitious materials. This paper examines the effect of curing conditions and drying methods during specimen preparation on C-S-H morphology. It shows that an appropriate drying method, either supercritical drying (SCD) or isopropanol (IPA) replacement, is able to preserve the delicate microstructure on both macro and micro scales. On the surface of the specimen, the structure is fibrillar for specimens cured in high relative humidity (RH) chamber or reticular for specimens cured in pore solution/limewater. A thin layer with cluster-like structure was found for specimens cured in high RH. By observing the fracture surface, it is found that the interior morphology is complex and varies with depth and curing methods. Consequently, one must take into account the effect of ion transport during the curing and drying when preparing specimens for microstructure analysis. We proposed that the basic units of C-S-H are fine fibers and thin sheets.

Molecular formula composition of β-caryophyllene ozonolysis SOA formed in humid and dry conditions

We studied the molecular formula composition of six β-caryophyllene SOA samples using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry under various reaction conditions. The SOA samples were generated in dry or low relative humidity (RH) chamber conditions with or without cyclohexane. All of the studied SOA mass spectra have three distinct clusters of hundreds of negative ions referred to as Group I (100 < m/z < 400), Group II (400 < m/z < 700) and Group III (700 < m/z < 1 000) compounds. C14-16H22-28O2-11, C28-29H42-48O6-16 and C42-43H68-70O14-16 were observed as highly abundant organic compounds in the compound class of Group I, II and III, respectively. The relative intensities of most analytes were higher in humid conditions compared to those in dry conditions, indicating the importance of water-dependent reactions and the catalytic role of water both in the presence and absence of cyclohexane. In addition, molecular formulas with higher average carbon numbers were observed in humid SOA than in dry SOA in the absence of cyclohexane, suggesting a decrease of cleavage reactions in humid condition. This study characterizes β-caryophyllene ozonolysis SOA based on ultrahigh mass resolution and demonstrates the significance of humidity in terms of the molecular distributions and relative abundances of the analytes. We also discuss the possible mechanism for the formation of Group I-III compounds based on the current understanding of SOA formation in the atmosphere.

Decontamination of indoor air to reduce the risk of airborne infections: Studies on survival and inactivation of airborne pathogens using an aerobiology chamber.

Although indoor air can spread many pathogens, information on the airborne survival and inactivation of such pathogens remains sparse. Staphylococcus aureus and Klebsiella pneumoniae were nebulized separately into an aerobiology chamber (24.0 m3). The chamber's relative humidity and air temperature were at 50% ± 5% and 20°C ± 2°C, respectively. The air was sampled with a slit-to-agar sampler. Between tests, filtered air purged the chamber of any residual airborne microbes. The challenge in the air varied between 4.2 log10 colony forming units (CFU)/m3 and 5.0 log10 CFU/m3, sufficient to show a ≥3 log10 (≥99.9%) reduction in microbial viability in air over a given contact time by the technologies tested. The rates of biologic decay of S aureus and K pneumoniae were 0.0064 ± 0.00015 and 0.0244 ± 0.009 log10 CFU/m3/min, respectively. Three commercial devices, with ultraviolet light and HEPA (high-efficiency particulate air) filtration, met the product efficacy criterion in 45-210 minutes; these rates were statistically significant compared with the corresponding rates of biologic decay of the bacteria. One device was also tested with repeated challenges with aerosolized S aureus to simulate ongoing fluctuations in indoor air quality; it could reduce each such recontamination to an undetectable level in approximately 40 minutes. The setup described is suitable for work with all major classes of pathogens and also complies with the U.S. Environmental Protection Agency's guidelines (2012) for testing air decontamination technologies.

Informing the improvement of forest products durability using small angle neutron scattering

A better understanding of how wood nanostructure swells with moisture is needed to accelerate the development of forest products with enhanced moisture durability. Despite its suitability to study nanostructures, small angle neutron scattering (SANS) remains an underutilized tool in forest products research. Nanoscale moisture-induced structural changes in intact and partially cut wood cell walls were investigated using SANS and a custom-built relative humidity (RH) chamber. SANS from intact wood sections cut from each primary wood orientation showed that although wood scattered anisotropically across 1.3–600 nm length scales, measurement of elementary fibril spacing and low-q surface scattering were independent of orientation. Water sorption caused spacing between elementary fibrils to increase with RH, and this swelling accounted for over half the transverse swelling in S2 secondary wood cell walls. Elementary fibril spacing in longitudinally cut wood cells, which were designed to mimic cells near wood-adhesive bondlines, was greater than the spacing in intact cells above 90 % RH. This suggested that some cell wall hoop constraint from the S1 and S3 cell wall layers on the S2 layer was released by cutting the cells. Furthermore, increased spacing between elementary fibrils may also create diffusion channels that are hypothesized to be responsible for the onset of fungal decay in wood. Protocols were established to use SANS in future research to study adhesives and protection treatments to improve moisture durability in forest products.

Design and Performance Evaluation of a Solar Assisted Heat Pump Dryer Integrated with Biomass Furnace for Red Chilli

The performance of a solar assisted heat pump dryer integrated with biomass furnace has been designed and evaluated for drying red chillies, and drying kinetics of red chillies were evaluated. The red chillies were dried from 22 kg with moisture content of 4.26 db to moisture content of 0.08 db which needed 11 hours, with the average drying chamber temperature, drying chamber relative humidity, and an air mass flow rate of 70.5°C, 10.1%, and 0.124 kg/s, respectively, while the open sun drying needed 62 hours. Compared to open sun drying, this dryer yielded 82% saving in drying time. The drying rate, the specific moisture extraction rate, and thermal efficiency of the dryer were estimated in average to be about 1.57 kg/h, 0.14 kg/kWh, and 9.03%, respectively. Three mathematical models, the Newton, Henderson-Pabis, and Page models, were fitted to the experimental data on red chillies dried by solar assisted heat pump dryer integrated with biomass furnace and open sun drying. The performance of these models was evaluated by comparing the coefficient of determination (R2), mean bias error (MBE), and root mean-square error (RMSE). The Page model gave the best results for representing drying kinetics of red chillies.