Thermal Chamber Research Articles

Influence of new dimethylaminoethanol derivatives, butanoic and trans-butenedioic acids, on the tolerability of hypoxia, hyperthermia, and hypothermia

BACKGROUND: The need to increase the tolerance of various extreme effects is associated not only with the expansion of human professional activity regions but also with the need to assist victims of natural and man-made disasters. The use of pharmacological agents for individual adverse effects is a well-known method; however, considering the combined effects of several physical or chemical factors, only a few references are found in the literature.
 AIM: This preclinical study aimed to examine the effectiveness of a new derivative of aminoethanol and intermediates of the Krebs cycle in relation to the isolated and combined effects of hypoxia and temperature (hyperthermia and hypothermia).
 MATERIALS AND METHODS: The fumaric salt of the amber ether of diethylaminoethanol was synthesized at St. Petersburg State University of Chemistry and Pharmacy, Department of Organic Chemistry (Head Professor I.P. Yakovlev). The study was conducted on small laboratory animals. Resistance to hypoxia was assessed by the dynamics of the altitude threshold of animals, tolerance to hyperthermia by survival in a thermal chamber at 40°C, and tolerance to hypothermia by the time of maximum swimming in water at 10–12°C. Under combined exposure, the condition of the animals was assessed by the dynamics of physical performance, hypoxia was induced by preliminary administration of the methemoglobin former sodium nitrite at a dose of 50 mg/kg, and thermal exposure was induced by placing the animal in water at 40°C (hyperthermia) or 9–11°C (hypothermia).
 RESULTS: After a single intragastric administration in a wide range of doses, the test compound stimulated the physical performance of animals and exhibited a protective effect under the isolated effects of hypobaric hypoxia, hyperthermia, and hypothermia. With combined exposure to hemic hypoxia and hyperthermia, the compound was effective at a dose of 250 mg/kg. With combined exposure to hemic hypoxia and hypothermia, efficiency was also noted at lower doses (25 and 50 mg/kg).
 CONCLUSION: Fumaric salt of dimethylaminoethanol amber ether, a new derivative of dimethylaminoethanol, butenedioic, and trans-butenedioic acids, is promising for further study as a means of increasing the body’s resistance to extreme influences.

Bio‐inspired Thermal Diode with Anti‐Gravity Unidirectional Heat Transfer and Switchable Functionality for Intelligent Thermal Management

AbstractPhase‐change thermal diodes with asymmetric and adjustable heat transfer capacity exhibit great application prospects in spacecraft heat management and solar energy storage. Current heat modulation strategies mainly depend on the anisotropic assistance from gravity and the rectification ratio can hardly be adjusted due to the immobilized inner structures. Here, a novel bioinspired thermal diode vapor chamber has been carried out with magnetic microgroove cones array sealed between two copper plates, where the evaporating plate with porous copper foam can reserve water and the condensing plate with patterned wettability can coagulate vapor into droplets at designated spot. With microgroove cones rooting from the evaporating plate and their tips contacting the condensing plate, these cones can directionally and rapidly transport condensed liquid from the condensing plate to evaporating plate under the unbalanced strong capillarity while prohibiting water flowing backward. This eventually leads to unidirectional liquid‐vapor circulation and anti‐gravitational directional heat transferring with a rectification ratio as high as 7.4. Such flowing of liquid can also be regulated by magnetically controlling the bending of cones to realize switched ON–OFF of thermal diode and achieve further modulation of heat management. This bioinspired thermal diode vapor chamber provides new ideas for intelligent thermal management systems.

Experimental correlation of natural convection in low Rayleigh atmospheres for vertical plates and comparison between CFD and lumped parameter analysis

This paper offers a comprehensive exploration of thermal analysis for space systems operating in low Rayleigh atmospheres, with a primary focus on enhancing the accuracy and reliability of convective heat transfer modeling. The study centers around an analysis of a vertical heated plate experiment, where a lumped parameter model is employed to encompass conductive, radiative, and convective heat transfer mechanisms. To advance the accuracy of convective heat transfer coefficient calculations, this paper introduces a novel approach involving the utilization of Nusselt number correlations. These correlations are developed through an analytical solution derived from the Navier-Stokes equations, tailored specifically for the internal natural convection problem. This approach treats convection as a heat exchange process between the heated plate and the surrounding air, thereby improving the precision of modeling internal convection within a lumped parameter framework. A specific correlation (González-Bárcena et al.) is obtained for the proposed problem, derived from experimental tests conducted in a thermal vacuum chamber, under varying pressure conditions to control the Rayleigh number. Additionally, the findings are validated using Computational Fluid Dynamics (CFD) tools to calculate the velocity and temperature fields within the cavity. The González-Bárcena et al. correlation significantly enhances temperature predictions, demonstrating an improvement of up to 10∘C when compared to conventional literature correlations. The methodology presented in this paper holds promise for extension to more complex experiments in low Rayleigh atmospheres, including those conducted in the Earth's stratosphere or on the Martian surface, thereby contributing to the advancement of thermal analysis in challenging space environments.

Characterization of thermal expansion in additively manufactured continuous carbon fibre reinforced polymer composites using fibre Bragg grating sensors

This study investigates thermal strains in fibre reinforced polymeric samples manufactured using a modified Fused Deposition Modelling (FDM) method. The investigated material was a composition of polylactic acid (PLA) resin and continuous carbon fibres. Each test sample was equipped with two Bragg grating (FBG) sensors, one embedded inside and the other bonded to the surface. Both sensors monitored temperature-induced deformations during the conditioning of the specimens in a thermal chamber. Multiscale, analytical and finite element method based models were implemented to quantify the temperature deformations.Research has revealed that in investigated samples, bending occurs due to thermal loading. This can result in an inaccurate estimation of the coefficient of thermal expansion when relying on surface deformation measurements. A proposed solution involves the use of one FBG sensor embedded inside the specimen or two FBG sensors placed symmetrically, capable of measuring axial thermal deformation and averaging the effects associated with bending.

Correction of the sample temperature in the thermal analysis chamber for studying the kinetics of carbon oxidation

This paper proposes a method for correcting the sample temperature under experimental conditions in the STA449F1 thermal analysis chamber. Carbon samples are oxidized in air-argon mixture, calorimetric signal is recorded and then processed to study the nutual interactions of heat transfer and chemical reaction. The technique is based on selecting the coefficients of the kinetic model and assessing its correctness using the simplest statistical metric.

On-Site Calibration Procedure and Uncertainty Contributions on Air Temperature Sensors

Due to the increasing demand of climate change studies, traceability of measurements according to the International System of Units (SI) becomes fundamental to establish data quality and comparability in time. With the aim of guaranteeing the traceability, in October 2022, an on-site calibration of three thermometers operated by the Osservatorio meteorologico di Moncalieri was assessed. The calibration by comparison against traceable travelling standards was performed in a transportable thermal chamber manufactured by the Istituto Nazionale di Ricerca Metrologica (INRIM). Results showed that the main uncertainty contributions to the expanded uncertainty were the interpolation method, the chamber inhomogeneity and the repeatability of the sensors under calibration. This current calibration was compared with previous calibration in 2012 (on-site calibration) and in 2016 (laboratory calibration). The comparison analysis evidenced the drift effect on the thermometers and the importance of having an active calibration program to reduce this effect. Regarding the expanded uncertainty, both on-site calibrations presented the same order of magnitude and smaller than the correction values. This paper points out the advantage of performing an on-site calibration: since the calibration involves the same dataloggers and cables in the same environmental conditions, the calculated calibration curve represents more convincingly the real measurement conditions.

Battery Venting Caused By Fast Charging

Lithium-ion batteries (LIBs) experience high risks of failure during unreasonable fast charging. Various degradation mechanisms inside the LIBs such as lithium (Li) plating, solid electrolyte interphase growth and electrolyte dry-out can undermine the electrochemical performance and induce massive gas generation alongside the operation. As a typical failure behaviour, venting occurs when the internal pressure of battery cell exceeds the safety threshold, releasing the gaseous products as well as depressurizing the cell. Recent studies1–3 of thermal runaway (TR) tests after fast charging have found that accumulated plated Li can react with electrolyte at elevated external temperatures, decreasing both self-heating and onset temperatures of TR. Yet, how fast-charging degradation will affect battery venting behaviours remains unclear.To answer this question, in this study, a series of fast charging experiments under controlled cooling as well as adiabatic TR tests were conducted with 51 Ah LiNi0.6Mn0.2Co0.2O2/graphite prismatic LIBs. The results showed that the prismatic battery underwent severe Li plating with over 30% capacity fade after 10 cycles of 4C charging. In the adiabatic TR tests, the aged batteries after 4C charging exhibited lower self-heating temperature and venting temperature as compared to the fresh batteries, by 51 ℃ and 34.4 ℃ respectively. This can be explained by the additional gas generation from the reaction between plated Li and electrolyte in the fast-charged batteries. Gas analyses of 120 ℃ hot-box tests for the degraded anodes with the electrolyte showed that the vented gas at the early venting stage primarily consisted of carbon dioxide, carbon monoxide and ethylene. The same charging protocols were then conducted in a natural convection thermal chamber with poor heat dissipation, where the temperature rise was much higher than those under forced convection as expected. Excessive cycling operations with off-limit charge rates (5C and 5.6C) were observed to directly cause battery swelling and venting without TR, and the temperature decreasing rates during rest after each charging process tend to slow down and even remain stable during a certain period of time. This indicates that the exothermic reaction between plated Li and electrolyte can be directly triggered by fast charging if heat removal is not effective enough. The findings provide useful insights into battery venting induced by fast charging, which can shed light on battery safety evaluation for fast charging techniques.Acknowledgements:This work is supported by the Faraday Institution BESAFE project (FIRG038), the Imperial College President’s PhD Scholarship Scheme (funded by EPSRC), the National Natural Science Foundation of China (Grant No. 52207241), China National Postdoctoral Program for Innovative Talents (grant no. BX20220171), China Postdoctoral Science Foundation (grant no. 2022M711760), and Shuimu Tsinghua Scholar Program (grant no. 2021SM130).

CURRENT LEADS FOR RESISTIVE CCCM HEATERS

The article justifies the necessity of taking into account the transient electrical resistance of the welding contact between the titanium current lead and the resistive element of the heater made of carbon-carbon composite material (CCCM) during its manufacturing.
 Carbon-carbon composite material possesses a unique set of technical characteristics that make it suitable as a structural material for manufacturing resistive heaters operating in the temperature range from 400°C to 2500°C in a vacuum or protective atmosphere. The use of CCCM heaters in the thermal chambers of electrothermal engines to convert electrical energy into thermal energy allows them to be employed for temperature measurement inside the engine's thermal chamber. The utilization of an integrated temperature assessment of the CCCM heater, which relies on the resistance change of the heater with increasing temperature and essentially involves measuring the electrical current passing through the heater, requires ensuring accurate values of both the electrical resistance of the heater itself and the electrical resistance at the point of contact with the current lead.
 The design of the heater has a particular feature, which is the need to supply electrical current to two lamellas of the resistive element of the CCCM heater, located on one side of the heater. For welding the joints between the titanium wire and the resistive element of the heater, TIG welding with a surface arc in an argon environment was applied, with argon being supplied between the welding point and the non-consumable tungsten electrode.
 Laboratory tests revealed that detachable connections of the titanium wire to the resistive element of the CCCM heater and separable connections (such as bolts, screws, and wedges) cannot meet the requirements for contact resistance stability for various reasons. Among non-detachable connections, only welded joints demonstrated stable electrical contact resistance characteristics.
 The electrical resistance of the heater with current leads should be 3.8±0.2 Ohms. The tolerance value for resistance is determined by several factors, including the physical properties of CCCM, the technology of mechanical processing, the method of applying protective coatings, the resistance of the welding joint, and others.
 During mechanical tests of the welding joint between the titanium wire and the heater, it was observed that the wire detachment from the heater occurs with residues of CCCM and a transitional layer of titanium carbide, which forms during welding and can contribute to additional electrical resistance of the heater. Thermal deformation of the CCCM heater in the welding zone does not occur.
 The results of the conducted research demonstrate that the installation of titanium current leads by welding increases the resistance value of the resistive element of the CCCM heater due to the chemical reaction between the titanium alloy and the resistive element, leading to the formation of an additional layer of titanium carbide. Therefore, the electrical resistance of the resistive element of the CCCM heater during its manufacturing, before welding two titanium wires for current leads, should be reduced, taking into account the transitional electrical resistance of the two welding contacts.

Experimental and numerical investigations of an open-cell copper foam (OCCF)/phase change material (PCM) composite-based module for satellite avionics thermal management in a thermal vacuum chamber (TVC)

Small satellites' thermal control in the space environment is crucial. Phase change materials (PCM) are promising options for satellite thermal management in space thermal conditions. The current work provides an experimental and numerical investigation of a thermal control module (TCM) using an open-cell copper foam (OCCF)/PCM combination. The experimental tests were carried out in a thermal vacuum chamber (TVC), which simulated the vacuum space environment. The PCM thermal conductivity was boosted using OCCF and aluminium fins. The metallic parallel fins divided the heat sink into six cuboid cavities and were filled with PCM. Two samples with different pores per inch (PPI) of OCCF were adopted, one with 10 PPI and the other with 20 PPI. For the experimental work, the adopted PCM was SP 31. Two levels of heating loads were applied to the TCM: 10 W and 7 W. The numerical model was verified using the experimental work findings. The experimental work concluded that the PCM capsulation sealing is a dominant factor for successful capsule design under vacuum operation. The thermal conductivity enhancers (TCEs) remarkably improved the thermal management performance of the PCM. The case with PCM reported a reduction in the maximum temperature by about 43.67 % and 41.4 % at 7 W and 10 W, respectively, relative to the case without PCM. The PCM/fins combination could improve the PCM performance and mitigate the maximum temperature from 41.7 °C to 39.6 °C with a reduction percentage of 5 %. The OCCF reported better thermal performance than the metallic fins. The OCCF with 10 PPI decreased the PCM maximum temperature by 10.3 %. The OCCF with 20 PPI reported a reduction in the PCM maximum temperature by 13.8 % at 10 W heating power.

Thermal energy storage control using phase change materials in a rectangular energy storage chamber with metal foam gradient and magnetic field

Considering the low thermal conductivity of phase change materials (PCM) and the slowness of the melting process in the thermal energy storage chamber (TESC), a comprehensive study on the use of magnetic field and porous foam gradient in the phase change process of PCM in a rectangular chamber with a cylinder is presented. The numerical solution is done using the finite volume method. PCM, metal foam and nanoparticles are respectively lauric acids, aluminum and iron oxide. Porosity coefficient changes have been examined in the positive and negative directions of the coordinate axes during melting and compared to a uniform porosity coefficient in the common case. As a result of a constant magnetic field, melting does not take place as much, but when a non-uniform magnetic field is used, the process of melting in the TESC increases by about 35 times, and the intensity of the magnetic field can be used between 0.025 and 0.05 mT. The average thawing fraction of the PCM has augmented by 5.046, 6.86, 7.66 and 7.819 %, respectively, compared to the no-field. The metal foam gradient has an imperative efficacy in enhancing the process of melting and up to about 97 % reduces melting time. When the porosity coefficient is higher near the active wall, the heat transfer and liquifying are quicker. In the chamber, temperature changes of the cylinder can have a momentous efficacy on the thawing process. The greatest effect is observed when the changes of cylinder temperature with time are stepwise. The sensitivity analysis was done based on the Sobol method, which shows that the porosity coefficient has the greatest effect on the melting rate.

Structural thermal optical performance (STOP) analysis and experimental verification of an hyperspectral imager for the HYPSO CubeSat

The evaluation of space optical instruments under thermo-elastic loads is a complex and multidisciplinary process that requires integrating thermal, structural, and optical disciplines. This thorough analysis often requires substantial resources, leading small satellite projects to exclude it from their schedules. However, even though the instrument discussed in this paper is compact, its complex design and stringent dimensional stability requirements demand a comprehensive evaluation of its performance under thermal loads. The hyperspectral camera, which comprises 18 lenses, a grating, a slit, and a detector, is especially vulnerable to thermo-elastic distortions, as the deformation of even a single lens could significantly impact its performance. In this paper, we present the experimental validation of the STOP analysis applied to the HYPerspectral Small satellite for ocean Observation (HYPSO) Hypespectral Imager (HSI) model. Both the HSI Structural Thermal Optical Performance (STOP) numerical model and the HSI engineering model were subjected to identical thermal conditions in the simulations and in a Thermal and Vacuum Chamber (TVAC), and subsequently the optical results derived from simulations and the test campaign compared. To characterize the thermal field, an infrared camera and thermocouples were used. Moreover, to assess the thermal performance of the HSI, we measured the Full Width at Half Maximum (FWHM) of the main peaks in the intensity-wavelength spectra when the hyperspectral camera targeted a known spectral lamp. After individually calibrating the STOP models so that the FWHM and index of the intensity peaks are in close alignment with the experimentally measured FWHM and index, the lenses most sensitive for displacements were characterized.

Junction temperature of CMOS electronics cooled by a Stirling cryocooler

This case study addresses the practical challenges associated with operating cryo-CMOS electronics. Previous research has been largely confined to impractical liquid cryogen cooling and the few under-reported examples of implementing electric cryocoolers. This study further clarifies the operation of cryo-CMOS devices cooled by electric cryocoolers. It develops and experimentally validates an analytical relation between the junction temperature and the parameters of a cryogenic system. To validate this relationship, we placed a printed circuit board in a thermal chamber, cooled it to 173 K using a Stirling cryocooler, and varied input clock frequencies. The measured values of the junction temperature were compared with calculations, which showed good prediction accuracy with a coefficient of variance of ±2%, a mean biased error of −2%, and a determination coefficient of 0.92. In addition, the measurements provided evidence for a multi-fold increase in the clock frequency of cryo-CMOS electronics. The results of this study help estimate accurately the steady-state junction temperature of cryo-CMOS devices in a wide range of cryogenic temperatures for different types of cryocoolers.

USING THE ACOUSTIC EMISSION METHOD, STRAIN GAUGE AND FRACTOGRAPHY TO ANALYZE THE PROCESSES OF DESTRUCTION OF SAMPLES FROM CARBON FIBER

Static loading of Torayca T800 carbon fiber samples to failure was carried out, during which defects were registered using a microprocessor-based diagnostic acoustic emission (AE) system. The location of AE signals began in the area of the stress concentrator at loads not exceeding 30 kN. The analysis of the destruction process of samples at negative (–50 C) and positive (+80 C) temperatures was carried out. During their heating and cooling, thermal chambers were used, located in the region of a stress concentrator with a diameter of 12 mm. In the process of testing at a temperature of T = –50 C, an active location of AE signals was observed, corresponding, as shown by fractography, to delamination and destruction of the upper monolayers of carbon fiber. During tests carried out at a temperature of T = +80 C, AE signals were localized, caused by lateral delaminations located at the edges of the samples. Using wavelet transforms, an analysis was made of the features of changes in the main informative parameters of AE signals, and their relationship with the growth of damage (matrix, fiber, delamination) of the carbon fiber material.

ПРОТИВОКОРРОЗИОННАЯ ЗАЩИТА СТАЛИ СОСТАВАМИ НА ОСНОВЕ БИТУМНОГО ПРАЙМЕРА

The use of anti-corrosion protection is necessary to extend the service life of agricultural equipment; bitumen compounds can traditionally be used for this purpose. The effectiveness of compositions based on a bitumen primer, into which white spirit solvent and a corrosion inhibitor were additionally introduced in an amount of 5 wt. %: CO-FFA, paraffin, Emulgin, has been studied. Studies have shown that the bitumen primer is frost-resistant, and the thickness of its coatings increases as expected when several layers are applied. Corrosion tests were carried out in a thermal and moisture chamber G-4, in a solution of 0.5 M NaCl and in a natural atmosphere (full-scale bench studies). According to the results of tests in the G-4 thermal and moisture chamber, all compositions, both in the presence of an inhibitor and without it, almost completely protect the steel surface. Corrosion test data in 0.5 M NaCl showed that the effectiveness of the bitumen primer is 75%, and the addition of paraffin, Emulgin or KO-SZhK to the additive increases the protective effect to 98, 94, 87%, respectively. The composition with the addition of paraffin turned out to be the most effective according to the results of full-scale bench tests (Z = 93%), as evidenced by the appearance of the plates after the experiment. It is recommended that production tests be carried out using the latest formulation.

Analisis Pengaruh Skala Warna dan UV-Vis Terhadap Tingkat Penuaan Isolasi Minyak

A transformer is a static device that can transfer electrical energy using the principle of electromagnetic induction. In operating conditions, the increase of temperature in the transformer will cause the oil insulation having disturbance, which will cause the quality of the insulation to decrease. In this research, oil isolation type shell diala b was chosen which was placed in an accelerated thermal aging chamber experiment device. Then shell diala b oil insulation is heated to a temperature of 120 °C and 160 °C with three sampling times. After this, the oil insulation characteristics were tested which includes oil color scale testing and UV-Visible spectrophotometric testing of the oil. The research method used refers to the IEC 60216-3 2006 standard for aging time and ASTM D-1500 COLOR SCALE for color scale testing. After testing the characteristics of shell diala b oil insulation, it was found that the value of the color scale had increased. Besides that, there has been an increase in the absorption of UV-Visible rays within the oil insulation, which causes the color of the insulation become darker as the temperature and the aging duration in the accelerated thermal aging chamber increases.

Temperature transition optimization in cryogenic systems: Application to liquid nitrogen expenditure reduction in a thermal vacuum chamber case study

This paper presents outcomes regarding liquid nitrogen consumption reduction in a thermal vacuum chamber, with the motivation of lessening operational costs during space equipment testing. The article briefly outlines the optimal control application to thermal and cryogenic-related control systems based on a gas cycle, and assesses liquid nitrogen savings opportunities for a chamber including six shrouds with independent temperature requirements. In this case study, optimization of temperature transition profiles and a proposed modification in the control setup yielded potential savings from 14.1% to 20.4% in the examined experimental transitions.

Investigation of the Combined Influence of Temperature and Humidity on Fatigue Crack Growth Rate in Al6082 Alloy in a Coastal Environment

The fatigue crack growth rate (FCGR) of aluminium alloys under the combined influence of temperature and humidity remains a relatively unexplored area, receiving limited attention due to its intricate nature and challenges in predicting the combined impact of these factors. The challenge was to investigate and address the specific mechanisms and interactions between temperature and humidity, as in coastal environment conditions, on the FCGR of aluminium alloy. The present study conducts a comprehensive investigation into the combined influence of temperature and humidity on the FCGR of the Al6082 alloy. The fatigue pre-cracked compact tension specimens were corroded for 7 days and then subjected to various temperature and humidity conditions in a thermal chamber for 3 days to simulate coastal environments. The obtained data were analysed to determine the influence of temperature and humidity on the FCGR of the Al6082 alloy. An empirical model was also established to precisely predict fatigue life cycle values under these environmental conditions. The correlation between FCGR and fracture toughness models was also examined. The Al6082 alloy exhibits a 34% increase in the Paris constant C, indicating reduced FCGR resistance due to elevated temperature and humidity levels. At the same time, fatigue, corrosion, moisture-assisted crack propagation, and hydrogen embrittlement lead to a 27% decrease in threshold fracture toughness. The developed model exhibited accurate predictions for fatigue life cycles, and the correlation between fracture toughness and FCGR showed an error of less than 10%, indicating a strong relationship between these parameters.

Effect of Graphene Nanoplatelets on Flexural Behavior of Glass Fiber Reinforced Polymer Composites Subjected to Different Temperatures

Glass Fiber Reinforced Polymer (GFRP) Composite are increasing rapidly in Aerospace Industry, Civil and Wind energy sectors, where they can frequently be exposed to different temperature conditions. As the constituent polymer matrix is highly affected by temperature, extreme temperature conditions are critical for GFRP composite structural design. Researchers have recently found nanofillers such as graphene and carbon nanotubes with excellent multifunctional mechanical properties. Graphene Nanoplatelets (GnP) consist of several layers of graphene. GnP is considering an attractive nanofillers as it has improved polymer matrix properties. In this study, the weight percentage of GnP added in GnP-GFRP laminate is 0.25% and 0.5%.GFRP and GnP-GFRP laminates are fabricated by using the hand lay-up method, and the specimens are subjected to a three-point bending test in a thermal chamber with varying the temperature, i.e., 30°C, 50°C, 75°C, and 100°C. This paper investigates the effect of graphene nanoplatelets on the flexural behavior of glass fiber-reinforced polymer composites subjected to different temperatures. Flexural strength and modulus are evaluated, and the appropriate conclusions are determined. GFRP with 0.25% GnP shows higher strength than the neat and 0.5% GnP-GFRP. Here, it has also been shown that flexural strength and modulus decrease significantly with increasing temperature.

An experimental case study of solar food dryer with thermal storage using phase change material

With ever expanding population and accelerating energy challenges, the ultimate need to adopt green-energy solutions for the preservation and storage techniques for fruits and vegetables has become vital. Sun drying is an age-old method to preserve food and it has revived the popularity within the industrial sector to overcome the high energy consuming operations. This work presents the experimental investigations of a solar dryer with integrated thermal storage chamber. The thermal storage chamber employed paraffin wax as a phase change material (PCM). Incorporating PCM enhances the efficiency and efficacy of the solar dryer. PCM absorbs heat, causing it to melt during peak sunshine hours. Then, during periods of reduced sunlight, the PCM releases the stored heat, enabling continuous product drying. Particularly, the solar dryer successfully dried onions, apricots, and peas, with moisture removal percentages of 69.6 %, 65 %, and 75 % respectively from the total mass.

Hospital mattresses: Thermal disinfection against bacteria, fungi and virus

Disinfection protocols for medical items play an important role in the prevention and con-trol of healthcare-associated infections. Regarding mattresses, disinfection with chemical products only cleans the surface, leading to failures in the execution of final processes of cleaning. This study aims to evaluate the antimicrobial activity of ECOSTOVE Thermal Chamber for the disinfection of hospital mattresses. Microbiological analyses were carried out under different experimental con-ditions, considering microbial viability, treatment time and position of inoculum on mattress. Staphylococcus aureus, Klebsiella pneumoniae, Candida albicans and Chikungunya virus were in-oculated at five pre-defined positions on the external and internal areas of hospital mattresses. Im-prints were done using RODAC plates, before and after heat treatment to evaluate colony-forming unit and microbial viability. The percentage of microbial inhibition obtained by heat treatment of the ECOSTOVE varied between 83.1 to 100%. The best results were observed for the enveloped Chikungunya (100% inhibition) and C. albicans (between 97.6 and 100%), followed by K. pneu-moniae (85.4-100%) and S. aureus (83.1-99.1%). Due to the significant antimicrobial activity of ECOSTOVE, it can be integrated into standard hospital hygiene and cleaning procedures as a prom-ising strategy in the control of healthcare-associated infections.