Chamber Relative Humidity Research Articles

Heat transport model for the deliquescence kinetics of crystalline ingredients and mixtures

Deliquescent crystalline solids undergo the first order dissolution process of deliquescence when the environmental relative humidity (RH) exceeds the deliquescence point (RH0). The rate at which deliquescence occurs increases as the RH increases above the RH0 in compressed disks of select deliquescent ingredients; however, a kinetic model for the deliquescence of powdered crystalline food ingredients and blends thereof has not been published. The water vapor sorption rates of commonly used powder food ingredients (citric acid, sodium chloride, sucrose, fructose, sorbitol, and xylitol) and blends were determined using a multi-sample gravimetric moisture sorption analyzer. The water vapor sorption rate was dependent on sample radius, temperature, and sample composition. The heat transport model for the deliquescence of compressed disks was successfully extended to the powder ingredients and blends. Such results enable further understanding of fundamental theories of deliquescence and provide a useful tool in the prediction of water vapor uptake rate during deliquescence in controlled RH chambers.

Water balance profiles, humidity preference and survival of two sympatric cockroach egg parasitoids Evania appendigaster and Aprostocetus hagenowii (Hymenoptera: Evaniidae; Eulophidae)

The impact of desiccation on habitat selection, foraging and survival has been characterized for many insects. However, limited information is available for parasitic wasps. In this study, water balance, relative humidity (RH) preference, and effect of humidity on survival of solitary Evania appendigaster (L.) (Hymenoptera: Evaniidae) and gregarious Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae) were examined. These species are both oothecal parasitoids of the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae). E. appendigaster had significantly higher cuticular permeability (CP) and a lower surface area to volume ratio but a similar percentage of total body water content compared to A. hagenowii. No differences in these attributes were found between sexes of each parasitoid species. The percentage of total body water loss rates among E. appendigaster males and females and A. hagenowii females were similar but significantly lower than that of A. hagenowii males. All parasitoids except E. appendigaster males exhibited reduced survival times as the RH of their enclosure decreased from 87% to 38%, but this phenomenon did not occur when parasitoids were given a sugar solution. In environmental chambers with a 44–87% RH gradient, both sexes of E. appendigaster resided significantly more often in the 87% RH chamber than in the 44% RH chamber. For A. hagenowii, females preferred both the driest and the wettest chambers and males preferred the driest ones. These results demonstrate the water balance profile and its relationship to life history traits and differential responses to RH in these competing parasitoid wasps, suggesting the role of physiological and behavioral adaptations in shaping their ecological niche.

P87 Klebsiella Pneumoniae Survival On Plastic Valved Holding Chamber Bodies

Introduction and objectives Klebsiella pneumoniae (KPN) is an opportunistic pathogen for patients with chronic pulmonary disease. In-use single time-point sampling of valved holding chamber spacer (VHC) bodies has shown evidence (Cohen and Cohen, JAMA 2003, 290:195–196) of bacterial contamination particularly with Pseudomonas species and Klebsiella. We are not aware of multi time-point bacterial survival research and, accordingly, have assessed in vitro two plastic VHC body materials which are in common use in the UK. Methods Test pieces, in n = 5 sub-group samples (Samples), of polystyrene (sterile Control) and of VHC bodies of AeroChamber Plus, Trudell Medical International (ACP) and A2A Spacer, Clement Clarke International Ltd. (A2A) were equilibrated for 24 h at 20°C/65% relative humidity (RH). Samples were inoculated with 100 muL distilled-water aliquots of KPN 3.6 × 106 cells.mL-1 and incubated at 20°C in 65% RH chambers. KPN surface survival was measured at 0, 24, 48 and 72 h time-points using a method based on ISO Standard 22196:2007 (Askew, Efficacy Assessment of Treated Articles: A Guidance, February 2014 http://dx.doi.org/10.6027/NA2014–904) and total viable count enumerated. 72 h data (Log10 Colony Forming Units (CFU).cm-2) were analysed using one-way analysis of variance. Results Geometric mean CFU.cm-2 data are given in the table. Control and ACP KPN populations declined to the 48 h time-point, thereafter increasing (Control) and remaining constant (ACP). A2A KPN population showed a constant decline, with no re-growth. At 72 h, Log10 CFU KPN data for A2A were significantly smaller (p Conclusions We interpret the 72 h increase in Control KPN as the outcome of the initial decline creating dead cell matter that acted as a nutrient source. The stability (ACP) and significant decline (A2A) in KPN is therefore an interesting finding. We subscribe the latter to the presence of an antimicrobial additive in the body polymer material. The clinical implications of these findings are relevant to VHC hygiene and patient health, and require further investigation.

The photochemical production of organic nitrates from α-pinene and loss via acid-dependent particle phase hydrolysis

The hydroxyl radical oxidation of α-pinene under high NOx conditions was studied in a photochemical reaction chamber to investigate organic nitrate (RONO2) production and fate between the gas and particle phases. We report an organic nitrate yield of 26 ± 7% from the oxidation of this monoterpene in the presence of nitric oxide (NO). However, the apparent organic nitrate yield was found to be highly dependent on both chamber relative humidity (RH) and seed aerosol acidity, likely as a result of particle phase hydrolysis. The particle phase loss of organic nitrates is believed to increase the gas to particle partitioning within the system, leading to decreased RONO2 yields in both the gas and particle phases at elevated RH and an apparent non-equilibrium partitioning mechanism. The hydrolysis of particle phase organic nitrates in this study, starting at low chamber relative humidity, implies that aerosol partitioning of organic nitrates may be an important sink for atmospheric NOx and may have a significant impact on regional air quality.

Hydrothermal effect and mechanical stress properties of carboxymethylcellulose based hydrogel food packaging.

The PVP-CMC hydrogel film is biodegradable, transparent, flexible, hygroscopic and breathable material which can be used as a food packaging material. The hygroscopic character of CMC and PVP plays a big role in the changing of their mechanical properties where load carrying capacity is one of important criteria for packaging materials. This paper reports about the hydrothermal effect on the mechanical and viscoelastic properties of neat CMC, and PVP-CMC (20:80) hydrogel films under the conditions of combined multiple stress factors such as temperature, time, load, frequency and humidity. The dry films were studied by transient and dynamic oscillatory experiments using dynamic mechanical analyser combined with relative humidity chamber (DMA-RH). The mechanical properties of PVP-CMC hydrogel film at room temperature (25 °C), in the range of 0-30%RH remain steady. The 20 wt% of PVP in PVP-CMC hydrogel increases the stiffness of CMC from 2940 to 3260 MPa at 25 °C and 10%RH.

Suction effects on the residual shear strength of clays

The paper presents an experimental study on the residual shear strength of different clayey soils at varying total suctions. In a first part of the paper some insight into the behaviour of residual shear strength of a filled rock discontinuity is presented to bring into light the sensitivity to hydraulic states of a clayey gouge material subjected to shearing along large displacements. An adapted Bromhead ring shear apparatus, in which the sample is enclosed in a controlled relative humidity chamber, has been used to control total suction during shearing. Afterwards, results on different types of clayey materials are presented to discuss the importance of the plasticity of the clay on the residual friction angle changes. These changes show an important increase in the residual friction angle with imposed total suction that may reach 15° for medium plastic clay and without cohesion component. The reasons for this increase have been explained by the more granular character of the dry clay as a result of aggregate densification and desaturation during strong drying. The changes have been interpreted using a simple model inspired in both macroscopic and microstructural observations, which is based on the stiffness of the soil (or aggregates) and depends on the product of the total suction applied and the degree of saturation. A microstructural model, already developed to take into account microstructural aspects on water retention and following an equivalent behavioural response to the macroscopic shrinkage curve, has been used to estimate the degree of saturation at the microstructural level (inside aggregates). To highlight its applicability in geotechnical practice, the different parameters used in the water retention and residual shear strength models have been shown to depend on the plasticity index of the different clayey soils studied.

Blocos solo-cal utilizando resíduo da construção civil

Novas técnicas vêm sendo desenvolvidas com o objetivo de incentivar o desenvolvimento sustentável e tentar minimizar a degradação ambiental causada pela extração indiscriminada de recursos naturais além da constante geração de resíduos de construção e demolição. Esta pesquisa objetiva avaliar a utilização de resíduos da construção civil, oriundos de demolição, como agente pozolânico na fabricação de blocos solo-cal. As matérias primas convencionais e alternativas (resíduos) foram caracterizados por meio dos seguintes ensaios: massa especifica real, área específica, análise granulométrica por peneiramento e por difração á laser,limites de liquidez e plasticidade, análise química e difração de raios X. Para os ensaios tecnológicos foram confeccionados corpos de prova solo-cal no traço 1:10 em peso, com substituição da cal por resíduos nas seguintes proporções: 0, 10, 20, 25, 30, 40, 50 e 75%. Os corpos de prova foram curados por períodos de 28, 60 e 90 dias, em câmara úmida com 100% de umidade relativa, em seguida determinada sua resistência à compressão simples e absorção de água. Com os melhores resultados de resistência a compressão simples, foram moldados blocos solo-cal e solo-cal-resíduo. Os resultados obtidos com os blocos solo-cal incorporados com resíduo evidenciaram valores dentro das especificações das normas da ABNT, apontando que existe viabilidade técnica no aproveitamento de resíduos de demolição para uso na fabricação de blocos solo-cal sem função estrutural.

Effect of Sorbed Water on Disintegrant Performance of Four Brands of Polacrilin Potassium NF

Polacrilin Potassium NF is a commonly used weak cation exchange resin disintegrant in pharmaceutical tablets. The objective of this research was to evaluate the effects of sorbed moisture on physical characteristics and disintegrant performance of four brands of Polacrilin Potassium NF. The disintegrants were stored in five different relative humidity chambers and their dynamic vapor adsorption-desorption analysis, effect of moisture on their compressibility, compactability, particle size, morphology, water uptake rate, and disintegration ability were studied. Moisture seemed to plasticize the disintegrants, reducing their yield pressures. However, certain optimum amount of moisture was found to be useful in increasing the compactablity of the tablets containing disintegrants. The tablets, however, lost their tensile strengths beyond this optimum moisture content. Moisture caused two brands of the disintegrants to swell; however, two other brands aggregated upon exposure to moisture. Swelling without aggregation increased the water uptake, and in turn the disintegrant performance. However, aggregation probably reduced the porosities of the disintegrants, reducing their water uptake rate and disintegrant performance. Different brands of Polacrilin Potassium NF differed in the abilities to withstand the effects of moisture on their functionality. Effect of moisture on disintegrant performance of Polacrilin Potassium NF needs to be considered before its use in tablets made by wet granulation.

Water Sorption Isotherm Characteristics of Seeds of Six Indigenous Forest Tree Species in Ghana

The relationship between storage temperature, relative humidity and seed water content was investigated for six indigenous forest tree seed species, namely Garcinia kola, Terminalia superba, Terminalia ivorensis, Mansonia altissima, Entandrophragma angolense and Khaya anthotheca in Ghana. Seeds were equilibrated over a series of lithium chloride solutions with relative humidities ranging from 12 to 93% and silica gel with relative humidity of 3% at 20 ºC. Seeds reached equilibrium with different days depending on seed size and structure, ranging from 13 days for E. angolense to 91 days for G. kola. When seeds equilibrated, moisture contents were determined gravimetrically, and values of moisture contents were then plotted against relative humidity to construct moisture sorption isotherms for the species. Seeds of T. superba, T. ivorensis, M. altissima, E. angolense and K. anthotheca, exhibited a sigmoidal relationship between seed water content and relative humidity indicative of three regions of water binding. Contrarily to other reports, the shape of the isotherm curve for G. kola – a desiccation sensitive species – also showed the reversed sigmoid pattern similar to isotherm curves of orthodox species rather than the monotonic shape. The isotherms showed that seed moisture content increased with increasing relative humidity. Seed samples of G. kola, placed at all relative humidities chambers, lost water(desorption) as the initial water content of 58% was very high and, therefore, possessed a higher water potential than the environments. Seeds of the other species either lost water (desorption) to the relative humidity chambers, or absorbed water from the chambers depending on the relative humidity of the environment they were placed.

Relative Humidity Preference and Survival of Starved Formosan Subterranean Termites (Isoptera: Rhinotermitidae) at Various Temperature and Relative Humidity Conditions

Foraging groups of Formosan subterranean termites, Coptotermes formosanus Shiraki were tested for their relative humidity (RH) preference in a humidity gradient arena in the laboratory at a constant temperature of 26°C. Five RH levels (9%, 33%, 53%, 75%, and 98%) were maintained in the test arena comprising of a series of closed containers by using dry silica gel, saturated salt solutions, or distilled water alone. Termites gradually aggregated to the highest RH chamber in the arena. After 1 h, a significantly greater percentage of termites (≈46%) aggregated to the highest RH chamber (98%) than to the lower RH chambers (≤75%). After 12 h, > 97% of the termites aggregated to the 98% RH chamber. In survival tests, where termites were exposed to 15 combinatorial treatments of five RH levels (9%, 33%, 53%, 75%, and 98%) and three temperatures (20°C, 28°C, and 36°C) for a week, the survival was significantly influenced by RH, temperature, and their interaction. A significantly higher mortality was observed on termites exposed to ≤75% RH chambers than to 98% RH chamber at the three temperatures and significantly lower survival was found at 36°C than at 28°C or 20°C. The combination of temperature and RH plays an important role in the survival of C. formosanus.

Comparative Study of Phenolic-Based and Amine-Based Underfill Materials in Flip Chip Plastic Ball Grid Array Package

Phenolic and amine epoxy systems are widely used as hardeners in underfill materials for flip chip packaging. A comparison was made between these two systems in order to evaluate the reliability performance of a flip chip plastic ball grid array (FC-PBGA). The coefficient of thermal expansion, glass transition temperature (Tg), Young’s modulus (E), and fracture toughness were revealed by using a thermal mechanical analyzer, a dynamic mechanical analyzer, and a single-edge notch three-point bending test, while moisture absorption study was performed using an 85°C/85% relative humidity chamber. The adhesion strength with different conditions of temperature and humidity was performed using a die shear test. The series of standard reliability tests such as accelerated temperature cycle test, pressure cooker test, thermal humidity storage test, and high temperature storage test were executed upon the FC-PBGA, which was filled by phenolic and amine epoxy systems of underfill materials. It was found that the adhesion strength of phenolic-based underfills is better than that of amine-based underfills in almost all test conditions. Phenolic-based underfills also demonstrated better reliability compared with amine-based underfills.

Effect of Gas Jet on Agglomeration of Inhalable Particles

The turbulent-induced agglomeration behaviors of inhalable particles were investigated in this paper. A turbulent gas jet was introduced into the particle agglomeration chamber to generate the local turbulent field. Inhalable particles were driven by turbulence to collided and yield agglomeration. The agglomeration efficiency of inhalable particles was determined by the measurement of the particles mass concentration from a cascade impactor and number concentration using a laser particle counter. Experimental findings indicated the mass and number removal efficiency increased with increasing Reynolds number at jet exit and velocity ratio of jet to cross flow. The gas jet at the angle of 90° achieves high removal efficiency. Increasing relative humidity in chamber may improve the aggregate efficiency of particles up to the maximum removal. Increasing initial concentration of fly ash causes decreasing removal efficiency of inhalable particles. The single-stage removal efficiency revealed that particle diameter had an influence on the agglomeration process. For inhalable particles, the small particles (<1>µm) were easy to be removed in turbulent-induced agglomeration, but mid-size particles (1-5µm) were difficult to remove.

Humidity influence on gas‐particle phase partitioning of α‐pinene + O3 secondary organic aerosol

Water vapor uptake to particles could potentially affect organic‐aerosol mass in three ways: first, water in the organic phase could reduce organic (equilibrium) partial pressures according to Raoult's law; second, an aqueous phase could attract water soluble organics according to Henry's law; finally, deliquescence of inorganic particle cores could mix the organic and inorganic particle phases, significantly diluting the organics and again reducing organic partial pressures according to Raoult's law. We present experiments using initially dry α‐pinene + ozone secondary organic aerosol (SOA) on ammonium sulfate (AS) seeds at atmospheric concentrations in a smog chamber. After SOA formation, the chamber relative humidity is increased steadily by addition of steam to near 100%. Little subsequent SOA mass growth is observed, suggesting that none of these potential effects play a strong role in this system.

Formation of Salt Crystal Whiskers on Porous Nanoparticle Coatings

Salt crystal whiskers were grown from aqueous solution on porous nanoparticle silica coatings. Coated substrates were partially immersed in an aqueous potassium chloride solution and then kept in a controlled relative humidity chamber for whisker growth. The salt solution was pulled into the porous coating, reaching a steady level about 1 h after immersion. Crystals with whisker morphologies, typically 2-50 microm in lateral dimension and up to approximately 1 cm in length, emerged from the coating surface at a position above the original liquid level. Crystallites pushed upward by attached whiskers indicated a base growth mechanism in which ions are added to the surface of a growing whisker that is in contact with the coating. Sheetlike crystals formed from the base growth of whiskers that had fallen flat onto the porous coating surface. The effects of solution concentration and relative humidity on growth were characterized and used to elaborate the transport phenomena and growth mechanisms. Salt whiskers were also grown on bare substrates immersed in salt solutions containing nanoparticles. In this case, growth occurred below the original contact line on coatings created by convective assembly.

Effects of Biomass in Polyethylene or Polylactic Acid Composites

There is need for bioplastics to replace some of the total petroleum plastics used in the world, and help alleviate environmental pollution. Compounding bioplastics with Polyethylene (PE) or Polylactic acid (PLA) containing a dairy-based bioplastic resulted in composites with good mechanical properties. In this study, mass ratios of a dairy-protein-based material (DBP) ranging from 0, 5, 10 and 20 wt% replaced equivalent masses of PE or PLA in the blends used for injection-molding of ASTM D4065 composite specimens. The PE/DBP composites were moldable up to 20 wt%, but PLA/DBP composites were moldable only up to 10 wt%. PE/DBP and PLA/DBP composites placed in 75% relative humidity chambers absorbed less than 1% moisture after 500 h. Peak melt for PE/DBP composites increased by 2.8 � C at 5 wt% DBP and by 4.2 � C at 20 wt% DBP; melt enthalpy decreased by 8.1 J/kg at 20 wt% DBP. Peak melt for PLA/DBP composites increased by 3.7 � Ca t 5 wt% DBP and 2.0 � C at 10 wt% DBP; melt enthalpy did not change. Cold crystallization of PLA was at 184.9 � C, but with 5 wt% DBP at 104.3 � C, and 10 wt% DBP at 99.1 � C. Storage modulus of PE/DBP decreased by 44 MPa at 5 wt% DBP, and increased by 117 MPa at 20 wt% DBP. Storage modulus of PLA/DBP increased by 210 MPa at 5 wt% DBP, but decreased by 190 MPa at 10 wt% DBP. Adding DBP to PE increased elongation at peak, tensile modulus and impact resistance and flexural modulus at 20 wt%, but decreased peak load at break, flexural modulus between 5 to 10 wt%, and impact resistance at 20 wt%. Impact failure was partial for PE/DBP. Adding DBP to PLA increased stiffness at 5 wt%, but caused complete failure at 10 wt%. The effect of DBP on PE or PLA depended on the quantity added; PE composite properties were generally less negatively affected.

Fabrication of microlens array diffuser films with controllable haze distribution by combination of breath figures and replica molding methods

This work demonstrates the fabrication of a simple, low-cost microlens array (MLA) diffuser film with controllable haze distribution (diffusion effect) by a combination of "breath figures" (BFs) and micro-replica molding methods. Polystyrene (PS) molds obtained by BFs method contain concave, hexagonal packed air holes formed by the condensation of water vapor on cooling surfaces in a chamber in which relevant influence factors can be controlled. The sizes of the air holes in the BFs PS molds can be controlled by varying such factors as chamber temperature, chamber relative humidity, substrate temperature and others. The temperature distribution on the substrate affects the distribution of diameters of the air holes formed in a BFs PS mold. Convex PDMS (poly-dimethylsiloxane) MLAs were obtained by molding from the BFs PS molds. The focal lengths of MLAs were measured and compared with theoretical values. The diffusion effect of the diffuser films with MLAs of diameters 6 microm and 3 microm were compared. The results indicate that an MLA with a smaller diameter has a larger diffusion effect.

Phosphoric acid-assisted constant relative humidity chambers utilized for controlled deterioration of rice seeds

Constant relative humidity (RH) chambers using phosphoric acid (PA) are useful for controlled desiccation of pollen and in vitro cultured materials for cool-dry storage or cryopreservation (Ishikawa et al., 2005, Ishikawa and Oda, 2008). Here we demonstrate that the chambers are also convenient for accelerated ageing of seeds. Rice seeds 3-11 years old (stored at 8-9°C) were artificially aged for 0-41 days in PA-assisted relative humidity (RH) chambers (RH 93%) placed in an incubator set at 37°C. At designated time periods during ageing, vigour and longevity of the seeds with different storage history were evaluated by monitoring germination timecourse and seedling shoot and root growth. Under these ageing conditions, seeds harvested in 2002 had half germinability (50% longevity) period of 33 days while older seeds (stored for longer periods) showed faster decline in germinability, longer lag time before germination, slower rates of germination and reduced shoot and root growth. Root growth was more sensitively affected by storage and accelerated ageing than shoot growth. PA-assisted system is simple, economical and safer than conventional RH chamber systems using saturated solutions or H2SO4 (Winston and Bates, 1960, Solomon, 1951). Various constant RH are available at desired temperatures using a single compound and convenient for realizing controlled deterioration of seeds at various RH and temperature regimes.

Allometry of evaporative water loss in marsupials: implications of the effect of ambient relative humidity on the physiology of brushtail possums(Trichosurus vulpecula)

To better understand the effects of ambient relative humidity (RH) on physiological variables and the implications of RH-correcting evaporative water loss (EWL) data for marsupials, we examined the effect of RH on EWL, body temperature (Tb), metabolic rate (MR) and thermal conductance (C) of the brushtail possum (Trichosurus vulpecula), a medium-sized marsupial. Correcting EWL data for 27 species of marsupial for water vapour pressure deficit (DeltaWVP) in the chamber during measurement significantly increased, rather than decreased, the variability of the allometric relationship for EWL. For the brushtail possum, both ambient temperature (Ta) and RH significantly affected EWL. At Ta=25 degrees C, EWL was independent of RH at "63% RH, but decreased linearly at higher RH values. At Ta=30 degrees C, EWL was significantly related to RH from 26% to 92% RH. There was a significant effect of Ta on Tb and dry thermal conductance (Cdry; higher at 30 degrees C), but no effect of RH. For MR and wet thermal conductance (Cwet) there was a significant effect of Ta (MR higher and Cwet lower at 25 degrees C), and RH at Ta=30 degrees C (MR higher and Cwet lower at the lowest RH) but not at 25 degrees C. Our results indicate that brushtail possums do not necessarily show the linear relationship between ambient RH and EWL expected for an endotherm, possibly because of behavioural modification of their immediate microclimate. This may account for the failure of WVP deficit correction to improve the allometric EWL relationship for marsupials. Chamber RH is an important environmental factor to be considered when measuring standard physiological variables such as MR and Cwet.

Reevaluation of constant relative humidity chambers using phosphoric acid for controlled desiccation of small biological samples

Relative humidity (RH) in constant RH chambers using various concentration of phosphoric acid (PA) was re-determined with a recently developed hygrometer (HygroLog NT2-D equipped with a sensor HygroClip S, ROTRONIC AG), which is superior in accuracy. Newly determined RH-PA concentration profiles were reverse semi-sigmoidal and very similar at 25 and 10°C. Differences in RH values between the present and previous determinations were larger at PA concentrations of 0-50% and 90-100%, primarily due to the property of the hygrometers employed. Accordingly, amendments were made to all the RH values in the previous paper (Ishikawa et al., 2005). This will make the PA-based constant RH system more accurate and reliable and ready to be used for various purposes.

Modeling of Camembert-Type Cheese Mass Loss in a Ripening Chamber: Main Biological and Physical Phenomena

A model of the mass loss of Camembert-type cheese was established with data obtained from 2 experimental ripening trials carried out in 2 pilot ripening chambers. During these experiments, a cheese was continuously weighed and the relative humidity, temperature, oxygen, and carbon dioxide concentrations in the ripening chamber were recorded online. The aim was to establish a simple but accurate model that would predict cheese mass changes according to available online measurements. The main hypotheses were that 1) the cheese water activity was constant during ripening, 2) the respiratory activity of the microflora played a major role by inducing heat production, combined with important water evaporation, 3) the temperature gradient existing inside the cheese was negligible, and the limiting phenomenon was the convective transfer. The water activity and the specific heat of the cheeses were assessed by offline measurements. The others parameters in the model were obtained from the literature. This dynamic model was built with 2 state variables: the cheese mass and the surface temperature of the cheese. In this way, only the heat transfer coefficient had to be fitted, and it was strongly determined by the airflow characteristics close to the cheeses. Model efficiency was illustrated by comparing the estimated and measured mass and the mass loss rate for the 2 studied runs; the relative errors were less than 1.9 and 3.2% for the mass loss and the mass loss rate, respectively. The dynamic effects of special events, such as room defrosting or changes in chamber relative humidity, were well described by the model, especially in terms of kinetics (mass loss rates).