Dry Chamber Research Articles

Banana slice drying using waste heat from an air conditioner for enhancing performance and sustainability

AbstractAs waste heat dryers (WHD) exhibit conservation of energy with environmental and economic benefits, the direct use of waste hot air rejected from the outdoor unit of a window air conditioning (AC) unit for drying banana slices is demonstrated experimentally in the present research work. For this purpose, a drying chamber was directly coupled to an AC unit (AC‐WHD) and analyzed its performance during banana slice drying by revisiting the concepts of generalized drying curve and drying performance index (DPI). The experimental data set of moisture content ratio obtained with AC‐WHD matched well with the generalized drying curve and the DPI value was found to be 0.999. It was found that the waste air supplied by the AC unit to the drying chamber was hot (≈ 50°C) and 28% dry, which aided the drying process. The thermodynamic performance of AC‐WHD was also evaluated using warm and wet exergy to provide insight into the mechanism of AC‐WHD drying. The exergy based sustainability index was higher while the exergetic destruction coefficient and environmental impact factor were lower for AC‐WHD when compared to literature values of the solar drying method. The findings of this research work indicate the practicality of coupling AC units with dryer units to address sustainable development goals (SDG).

The characteristics of Zn–5Al–2Mg coating on low carbon steel by two-step galvanizing method

The aim of this work is to characterize the complicated microstructure of a multilayer material that has been produced using a two-step batch galvanizing technique, with a particular focus on its extraordinary resistance to corrosion. The corrosion testing was performed using cyclic salt spraying, which involved the use of a salt mist chamber, wet chamber, and dry chamber. The results indicated that the Zn–5Al–2Mg (ZMA) coating system consists of four distinct layers: α, β, θ, and π layers. The top layer consisted of ternary and binary eutectic phases, whereas the central section had a branch-like Fe4Al13 phase. A continuous layer of Fe4Al13 was produced at an interface with the substrate. After undergoing 270 corrosion cycles, the coating demonstrated the capability to generate corrosion products that were dense and compact, including Zn5(OH)6Cl2H2O, Zn5(CO3)2(OH)6, and Mg6Al2(CO3)(OH)16⋅H2O. The corrosion products inhibited the corrosive substance from reaching the steel substrate, hence enhancing the durability of the coating.

A broad appraisal of decompression-induced physiological stress in different simulated dive profiles

Background: The present study was designed to observe if different decompression profiles, calculated as a function of tissue supersaturation during ascent, would result in significantly different outcomes, measured through different physiological stress indicators, even in the absence of symptoms of decompression sickness. Aim: The aim of this study was to evaluate if simulated decompression profiles would affect the immune system, oxidative stress indicators, and heart rate variability. Methods: A total of 23 volunteers participated in two different experimental protocols in a dry hyperbaric chamber. These simulated dives comprised two different compression–decompression arrangements with the same maximum pressure and duration but different decompression profiles. Results: The shallow decompression profile with shorter deeper stops and longer shallow stops presented an increase in the standard deviation of the normal-to-normal R-R interval (a wide indicator of overall variability); the deep decompression profile with longer deeper stops and shorter shallow stops did not exhibit such increase. The shallow decompression profile resulted in an increase in neutrophil count and its microparticles (MPs), but no changes were observed for platelet count and its MPs, as well as for endothelial-derived MPs. In contrast, the deep decompression profile resulted in no changes in neutrophil count and its MPs, but a decrease in platelet count along with an increase in MPs from both platelets and endothelial cells. The observed difference might be related to different levels of decompression-related activation of immune system responses and oxidative processes triggered by different levels of inert gas supersaturation upon surfacing. Conclusion: From previous results and literature data, we present a tentative schematic of how the velocity of ascent would trigger (or not) pro-inflammatory and immune system responses that could ultimately lead to the development of decompression sickness. Relevance for patients: Increasing safety in exposure to hyperbaric environments and subsequent decompression by evaluating individual physiological responses to the process.

Energy contribution and loss of greenhouse-type drying chamber in multi-energy drying system: Heat distribution and exergy efficiency

In this paper, the relationship between the structural design of the greenhouse drying chamber and energy contribution and loss is discussed from the perspective of energy saving and system performance, and the rationality of their design is analysed based on the exergy efficiency. Taking the multi-energy drying system of kelp as an example, the airflow and temperature distributions of different greenhouse-type drying chambers were simulated and optimized by using the computational fluid dynamics (CFD) method, and the heat transfer and loss were analyzed. The results show that the optimized drying chamber has an increase of about 40% in The results show that the optimized drying chamber has an increase of about 40% in exergy efficiency and a reduction of about 37% in exergy damage. The average energy efficiency of the greenhouse-type drying chamber was more than 80% with a size of 5000×2500×2300 mm, a tilt angle of 22.5°, and fans of 7. In addition, the energy efficiency was negatively correlated with the temperature difference between the inlet and outlet and positively correlated with the ambient temperature. Despite the heat loss in the drying chamber, its contribution to the system's overall energy efficiency is significant.

Adjustments of mathematical models for drying maize seeds on cobs

The present study aimed to select the mathematical models that best fit the drying kinetics of maize seeds on the cob. A 50- and 150-cm maize layer was used in the dryer for four airflows: 5. 10, 15 and 20 m 3.min -1.t -1 was used for stationary drying. The ears were dried in four prototypes of stationary perforated false-bottom dryers with a diameter of 0.92 m, height of 1 m and axial fan. The temperature of the drying air was controlled at the base of the dryer chamber using a thermostat. The mathematical models were analyzed via linear regression. The model of Page and Handerson & Pabis was used. The results showed that the Page model was more satisfactory for predicting the data for the 50 cm layer of ears than the Henderson & Pabis model was for predicting the data for the 150 cm layer. However, both models can be used to represent the drying phenomenon of maize seeds on cobs

Exergy efficiency and sustainability indicators of forced convection mixed mode solar dryer system for drying process

The study investigates the effectiveness of a mixed-mode solar dryer (MSD) featuring two double-pass solar air collectors in series, with a focus on dehydrating cluster figs characterized by high moisture content and rapid deterioration. Exergy analysis is a powerful tool to assess the efficiency and sustainability of drying systems. The study involves experimental data obtained from the drying process under different air mass flow rates (0.018–0.062 kg/s). The solar radiation intensity ranged from 120 W/m2 to 750 W/m2 during these experiments. The solar air collectors and mixed mode dryer exergy efficiency is found to be dependent on solar radiation intensity, showing increased efficiency with higher air mass flow rates due to enhanced heat removal and reduced losses to the surroundings. The findings reveal that the optimal air mass flow rate of 0.062 kg/s yields the highest exergy efficiency in the solar air collectors. The overall exergy efficiency of the mixed-mode solar drying chamber increases with higher air mass flow rates, ranging from 18.8 % to 41.4 %. Improvement potential (IP) analysis indicates that, as the air mass flow rate increases, the potential for reducing exergy losses decreases. The sustainability index (SI), measures the environmental impact, and it ranges from 1.26 to 1.71, with higher values associated with higher exergy efficiency.

Assessment of an indirect solar dryer for small-scale resin production: Energy, exergy, economic (3E), and sustainability analysis

This study evaluates an innovative domestic indirect solar dryer (ISD) for drying grapes (Vitis Vinifera L.), focusing on energy, exergy, economic, and sustainability performance. Two trials with crop loads of 15% (Trial-1) and 33% (Trial-2) were conducted. Trial-2 exhibited higher energy efficiencies in the solar collector (SC) and drying chamber (DC) compared to Trial-1, with efficiencies of 61.4% and 58.5% for SC, and a 13% increase in DC efficiency. The daily average exergy efficiencies for SC and DC ranged from 11%–13% and 54%–58%, respectively. Trial-2 also showed a 113% higher life cycle savings, a 54.4% decrease in payback period, and a 23% lower waste exergy ratio compared to Trial-1. Pre-treatment of grapes resulted in superior dried product quality. The study highlights the ISD’s potential as an economically and environmentally sustainable solution for small-scale agricultural ventures, providing insights for renewable energy sectors

Influencing Factors Used for Performance Evaluation of Solar Dryers

Due to the rapid growth in human energy demand, research and development in renewable energy sources have become a top priority. Solar energy, as a renewable energy source, is widely used in the drying industry. This study examines the factors that influence the performance evaluation of solar dryers. The dryer consists of an air collector, a drying chamber, and a chimney. Experiments were conducted at the Solar Energy Laboratory of the Hungarian University of Agriculture and Life Sciences in Hungary (47.59° N, 19.36° E). The drying behaviour of single-pass and double-pass solar dryers was compared under the same environmental conditions. The analysis results indicate that the maximum solar radiation value is 950 W/m2 at 12:00. The maximum temperature difference between the top and bottom channels of the double-pass solar air collector is 9.5 °C. The average humidity in the environment, single-pass, and double-pass drying chambers is 31%, 26.5%, and 24%, respectively. The instantaneous efficiency of the single-pass solar collector reaches a peak of 56%, while the double-pass collector’s instantaneous efficiency peaks at around 60%. The collector performance curves show that the double-pass collector has a more stable performance.

Application of CFD Simulation to the Design of an Innovative Drying Chamber

Drying and sanitising equipment has been very common in industrial plants since the pandemic. These are devices that consume significant amounts of energy. The best solution is to use a drying chamber equipped with a heat pump, which allows partial recovery of the energy. In the design of the drying chamber, the drying time is important, which depends both on the parameters of the heat pump itself, and the geometry and airflow of the drying chamber. The geometry and airflow supply should be arranged to ensure a uniform distribution of velocity throughout the drying area. For this purpose, the use of CFD simulations has been proposed. A model was developed in ANSYS/FLUENT where all model parameters, including the optimal mesh density, turbulence models, etc., were determined. The model was verified on the experimental results of the basic design of the chamber. Then an innovative design was proposed that was modelled and optimised in terms of the distribution of the inlet’s perforation. The final design was made, and, at the same time, the simulation’s results were verified by measuring the velocity of airflow in the new design. Together with the optimisation of the heat pump, this made it possible to reduce the drying time by 50%, with a simultaneous reduction in the energy consumed.

P-274 Humid or dry culture with medium renewal: impact on A-Grade Day 5 blastocysts. Randomized prospective cohort study

Abstract Study question Could the humid embryo culture impact the development of top-graded blastocysts? Summary answer While no differences were observed in the overall blastocyst development rate, humidity conditions emerged as a significant factor influencing the achievement of A-Grade D + 5 blastocysts. What is known already In recent years, several publications have highlighted the advantages of humid culture (HC) over dry culture (DC) (<45% relative humidity, RH). HC, with its lower risk of media evaporation and consequent osmolality changes. Nevertheless, to the best of our knowledge, this is the first prospective study addressing this aspect through oocytes from the same cohort. Study design, size, duration We have been conducting a randomized control trial (RCT) consisting on 379 MII oocytes from 30 patients from August 2022 until January 2024 (and ongoing). After ICSI procedure, sibling oocytes were divided following 1:1 ratio into both humid (>70% HR) and dry (0% HR) chambers of a Geri incubator (Genea Biomedx, Australia). Ejaculated sperm ICSI cycles with >5 fresh MII were included in the analysis. Time-lapse cleavage timings were manually gathered. Participants/materials, setting, methods Extended culture to the blastocyst stage (D + 5, D + 6 or D + 7) was performed in 80μL of single step G-TL medium (Vitrolife, Sweden). HC remained undisturbed while medium was renewed on D + 3 in DC by changing the culture dish. Fertilization, overall blastocyst development and A-Grade Day 5 blastocysts rates (ASEBIR’s morphology criteria) were compared. Statistical analysis consisted on Chi-squared test, t-student test and logistic regression for computation of Odds Ratio (OR, 95%CI). Main results and the role of chance While no statistically significant differences were observed in the fertilization rate (DC: 76.4%; HC: 69.1%, NS) or the overall usable blastocyst development rate (DC: 48.6%; HC: 53.1%, NS), noteworthy distinctions emerged in the proportion of top-graded embryos based on ASEBIR’s morphology criteria. Specifically, the A-Grade Day 5 blastocyst development rate displayed significant disparities when comparing all fertilized embryos in each culture type (DC: 19.9%; HC: 32.3%; p < 0.05) and also among all usable blastocysts (DC: 40.8%; HC: 60.9%, p < 0,05). The Odds Ratio for achieving A-Grade Day blastocysts depending on type of humidity conditions was 1.87 (1,099 – 3,235) for the humid culture. Moreover, time-lapse imaging facilitated the detection of direct cleavage presence, which was similarly distributed between both incubation types (DC: 27/146; HC: 23/130, NS). However, only 3 embryos showing direct cleavage and cultured in HC reached the blastocyst stage at Day 6, while in dry incubator, 10 embryos with direct cleavage were able to develop to usable blastocysts, three of them being A-Grade on Day 5. Limitations, reasons for caution This study is currently ongoing, aiming to increase the sample size. Future analyses will explore clinical outcomes, especially for underrated embryos, day 6 blastocysts, and those with morphodynamic phenomena. While A-grade blastocyst rate variations may not impact pregnancy outcomes directly, they could influence cumulative success rates. Wider implications of the findings These data highlight that day+3 medium renewal doesn’t equalize conditions to humid culture. Ongoing efforts involve validating these insights through an expanded sample size and extensive outcome analysis. Investigating the long-term impact on clinical outcomes and refining culture protocols can amplify the relevance of these findings in assisted reproductive technologies. Trial registration number pending_protocolOK

Efficacy of RCI001 as a therapeutic candidate of dry eye disease in a modified mixed dry eye model

BackgroundTo evaluate the therapeutic effects of topical RCI001 (RCI) and compare its efficacy with that of 1% prednisolone acetate (PDE) and 5% Lifitegrast in a modified mixed dry eye disease (DED) model.MethodsThe environmental DED model was induced in BALB/c mice in a dry chamber with scopolamine. The eyes of the mice were treated topically with phosphate buffered saline (PBS), PDE, Lifitegrast or RCI twice daily for 1 week. Ocular surface staining (OSS), tear secretion, inflammatory cytokines in the ocular surface and lacrimal gland, and immunofluorescence staining in the conjunctiva and cornea(CC) were assessed.ResultsThe RCI group demonstrated better improvement of OSS and tear secretion than the PBS group (OSS, PBS: 13.0 ± 1.6, RCI: 9.4 ± 3.0; tear secretion, PBS: 5.0 ± 0.4 mm, RCI: 7.0 ± 0.3 mm, each P < 0.001) and better clinical efficacy than PDE and Lifitegrast groups on Day 7 (improvement rate of OSS, RCI: 32.45%, Lifitegrast: 13.13%, PDE: 12.25%). The RCI group resulted in significantly lower expression of oxidative stress markers in the CC than the PBS group (4-HNE, NOX2, and NOX4 in the conjunctiva; NOX2 in the cornea, each P < 0.05). However, the PDE and Lifitegrast groups did not show significant differences compared with the PBS group. There were no significant differences of inflammatory cytokines in the ocular surface and lacrimal gland between all groups.ConclusionTopical RCI001 showed excellent therapeutic effects in environmental DED models by stimulating tear secretion, modulating oxidative stress and improving corneal epithelial healing compared to 1% PDE and 5% Lifitegrast.

Сушилка для селекционных семян сои

As a result of the study of existing methods and devices for drying seeds, their poor adaptation for drying soybean breeder seeds was revealed, namely: the impossibility of effective drying of small batches of seeds (1–5 kg); increased injury during loading and unloading; unsuitable regime of specific moisture removal, which leads to loss of sowing qualities of valuable breeding seed samples. Analysis of the designs of previously developed dryers, as well as research carried out in the mechanization department at the V.S. Pustovoit All-Russian Research Institute of Oil Crops, made it possible to develop a new method for drying soybean breeder seeds and a device for its implementation – a chamber dryer for soybean breeder seeds in fabric bags. Drying seeds in fabric bags prevents direct contact of seeds with the structural elements of the dryer, which prevents damage from mechanical influences, as well as local overheating of the surface of the seeds. This saves the breeder seeds from mechanical trauma, leading to micro- and macrocracks in the seed shells and the surface tissues of the cotyledons located directly under the shell, and the axial organs of the embryos – the embryonic root, which leads to their death, which is extremely undesirable in breeding work. Blowing bags with seeds from two opposite sides provides the possibility of a softer drying mode – at a coolant temperature of 38 ºС, smoother removal of seed moisture, a more productive drying process, ensuring the absence of seeds cracking, which is very important in breeding. This is explained by the fact that when blowing bags with seeds from two opposite sides of the bags, the removal of moisture from the entire volume of seeds will be smoother and at the same time more productive than when blowing the same volume of seeds with a coolant. Analyzing the experimental data obtained, we can draw the following conclusion: a dryer design was created for soybean breeder seeds, which implements a soft drying mode, ensuring uniform drying with smooth moisture removal, preventing cracking of soybean seeds, as well as their mechanical damage.

A Simulation Study of Hybrid Solar Drying Chamber for Agriculture Product

Hybrid solar drying chamber is an application that is widely used today for agriculture products because it can promise the hygiene of the product. However, drying chambers nowadays still lack uniformity in drying products within a drying chamber, leading to food wastage and compromised product quality. This study aims to design an innovative hybrid solar drying chamber system and investigate the uniformity of temperature and velocity within the chamber using Computational Fluid Dynamics (CFD). The methodology involves validating the simulation results by comparing them with existing journal data, with a validation error of less than 5%. A new design is proposed after the validation process, considering factors such as tray arrangement and air inlet size. The results show that a tray arrangement with 0.20 m spacing between each tray provides better uniformity in temperature and air velocity distribution compared to other arrangements. Additionally, an inlet size of 0.05 m2 demonstrates the most suitable temperature distribution for drying purposes, falling within the ideal range of 318 K to 343 K. The study showed that the performance of the drying chamber under different operating conditions has consistent temperature distribution and is suitable for uniform drying. Overall, the proposed hybrid solar drying chamber system offers improved temperature control and uniformity for effective drying process.

Characteristics of temperature uniformity system in multi-tier drying equipment with sharp turning technology

Drying is a process of heat and mass transfer that occurs on the surface and within the material to be dried. It helps reduce the internal moisture of the material, inhibiting the growth, damage, and chemical changes of microorganisms during storage, thus extending the shelf life of dry materials and improving the quality of raw materials. This study aims to test multi-level drying equipment using combustion heat with a square shape and racks inside it used as the drying space for the material. The raw material was placed on racks made of perforated metal. This research started from designing the drying equipment system, fabricating and testing system. The drying system was tested using fish and cocoa beans as sample materials. The tested equipment system included temperature distribution in the combustion chamber, distribution system of hot combustion gases through sharp turning technology, uniform temperature distribution in the drying chamber with 8 levels of racks, each capable of holding a load of 10 kg, and testing of the chimney system. The research findings concluded that to maintain a drying chamber temperature of 90⁰C, an average combustion chamber temperature of 339⁰C was required. The average combustion chamber temperature needed to maintain a drying chamber temperature of 80⁰C was 290⁰C. For a drying chamber temperature of 70⁰C, an average combustion chamber temperature of 314⁰C was required. The temperature distribution inside the drying chamber moves horizontally, indicating that the temperature distribution in the drying chamber was uniform for each drying rack.

HEAT PUMPS AS AN ENERGY-EFFICIENT MEANS OF GRAIN DRYING

Large energy costs for the process of drying grain crops associated with the increase in the price of energy carriers pose the task of reducing the energy component to the developers. The presented article focuses on the development of measures to reduce energy costs for the grain drying process using heat pumps. The considered advantages of heat pumps indicate the possibility of using these units for drying grain crops. Especially noteworthy is the increase in energy efficiency of heat pumps due to the conversion of ambient heat with a low temperature potential into heat with a high temperature potential. Thus, heat pumps are characterized by the heat pump conversion factor, which indicates their efficiency. The presented schemes with a heat pump implement the drying process in convective dryers, in particular in chamber, tunnel, shaft and drum dryers. Different schemes of heat pumps can be used for different types of dryers. The use of alternative drying sources for grain drying, in particular solar energy in the heat pump system, dramatically increases the efficiency of this installation. Also presented is a comprehensive scheme for the utilization of spent coolant in heat exchangers, an economizer, and a heat pump, which comprehensively addresses the issue of coolant utilization in a chamber dryer. In the drum dryer, the utilization of the spent coolant in heat exchangers and a heat pump is provided, increasing the temperature of the drying agent at the entrance to the dryer. For drying plant raw materials in a two-zone tunnel dryer, a heat pump scheme with two temperature levels of the heat carrier was developed for drying the material at different temperatures in the dryer zones.

Machine learning, mathematical modeling and 4E (energy, exergy, environmental, and economic) analysis of an indirect solar dryer for drying sweet potato

A developed indirect solar dryer is built and operated to dry sweet potato cubes. Since, numerous instruments have gathered experimental data to comprehensively evaluate the system's energy, exergy, environmental, and economical aspects. Additionally, four machine learning algorithms, namely Decision Trees (DT), Gradient Boosting Regression (GBR), Multiple Linear Regression (MLR), and Random Forest (RF), are evolved to forecast the solar collector's energy (RSAH,η) and exergy efficiency (RSAH,ηEX) as well as the drying chamber's mean drying temperature and exergy efficiency (DC,ηEx). In addition, ten drying kinetics mathematical models were employed to fit with sweet potato moisture ratio variation over the experiment. Also, Color and bioactive compounds were analyzed. Results show that, RSAH,η and RSAH,ηEX was 72.9 %, and 5.6 %, respectively. Storage unit thermal (ηTh.,SUPCM)and exergy efficiency (ηEx,SUPCM) were 43.4 %, and 18.4 %, respectively, the discharging lasted around 5.5 h. Theoretical drying chamber thermal efficiency (DC,ηth) was from 21.9 to 97.2 %. And av. DC,ηEx was 46.1 %. RF algorithm achieved the best results for RSAH,η, RSAH,ηEX , DC,Tmean, and DC,ηEx forecasting, because of its superior adaptability and generalization. The overall dryer efficiency was 15 % with a specific energy consumption of 4.509 kWh/kg moisture. The Page model showed the best fitting with sweet potato moisture ratio data. In addition, CO2 mitigation reached 20.2 with earned carbon credit is 56771 RMB. The economic payback period is 29.24 months, the annual total revenue is 8464 RMB and 0.7 RMB as a Return on investment.

Transport phenomena in pasta drying: a dough-air double domain advanced modeling

In the realm of pasta drying, where precise prediction of temperature and water-content distribution is crucial, the application of modeling and simulation emerges as highly significant. This study endeavors to evaluate operational conditions ensuring the production of a safe, high-quality pasta product. An advanced two-domain model was devised and solved to estimate transport phenomena in both the food and air domains. Unlike conventional models relying on specified interfacial heat and mass transfer coefficients, the proposed model serves as a versatile tool applicable across a broad spectrum of process and fluid-dynamic conditions in real pasta driers. The system of non-linear unsteady-state partial differential equations governing the behavior of a “Rigatone" pasta sample in a drier was solved using the finite elements method to estimate how air characteristics influence drying performance. A pilot-scale drying chamber was used for model validation for inlet air temperature Ta,in=80°C at relative humidity values (RHin) of 50 % and 60 %, with error consistently below 10 %.

Design and Optimization of a Mixed-Flow Drying Chamber for Tiger Nuts Based on CFD-DEM Heat and Mass Transfer Model

In order to solve the problem of inconsistent moisture content in particles during the drying process of tiger nuts (Cyperus esculentus) due to uneven air flow and temperature distribution in the drying chamber, an open-hole corner box was designed based on the principle of negative pressure micro-perforated air supply. Using computational fluid dynamics (CFD) and discrete element method (DEM) simulation, coupled with the basic theory of interphase heat and mass transfer, a mathematical model for interphase heat and moisture coupling transfer was established. The effects of different aperture rates of corner boxes in the drying chamber, spatial location arrangement, and other related variables on the airfield distribution, temperature field distribution, tiger nut temperature, and moisture content changes were investigated. The results show that the average air velocity below the air inlet gradually increases as the opening ratio increases. When the opening rate is 0.33%, the wind field uniformity is better, and the inhomogeneity of the drying chamber wind field is improved. As the lateral distance increases, the consistency of the moisture content distribution increases and then decreases, and the flow rate of the tiger nuts gradually increases when the grain is discharged. The rate of decrease in water content decreases gradually with the increase in longitudinal distance. When the wind speed reaches 4 m/s, the drying chamber wind field is more uniform, and the water vapor diffusion efficiency at the outlet is basically the same. Therefore, the appropriate corner box has a horizontal distance of 320 mm and a longitudinal distance of 420 mm, providing a basis for the design of tiger nut drying equipment.

Investigation of dry environment construction Equipment's medium displacement system for submarine pipelines

Innovative underwater pipeline repair and inspection technologies utilising a dry chamber represent a novel approach. This technique involves injecting high-pressure air into a chamber to displace the surrounding medium. However, sealing becomes very challenging owing to the irregularity of the sealing surface, and diver operations pose significant risks at high gas pressures. This study presents a novel design that integrates inflation and drainage methods. It employs an air compressor for chamber inflation and submersible pumps, along with an air-operated diaphragm pump for water drainage. This system could effectively manage various degrees of leakage and maintain continuous drainage, thus establishing a normal pressure environment. Consequently, the sealing requirement is significantly reduced, and divers are allowed to perform multiple tasks within the chamber at atmospheric pressure. Furthermore, the inflation parameters were optimized during the inflation and drainage processes through a numerical method, and the designed system was validated via offshore experiments. The results indicated that the system could handle a leakage rate of 50 m3/h and maintain a dry chamber for at least 5 h.

Embedded Wireless Sensor for In Situ Concrete Internal Relative Humidity Monitoring.

The moisture content within the concrete pore network significantly influences the mechanical, thermal, and durability characteristics of concrete structures. This paper introduces a novel fully embedded wireless temperature and relative humidity sensor connected to an automatic acquisition system designed for continuous concrete monitoring. Relative humidity measurements from this new sensor are compared with those obtained by a commercial system based on the borehole method at different depths (2.5 and 4.0 cm) and exposure conditions (oven drying and humid chamber). The results allow for proving that both systems provide consistent internal relative humidity measurements aligned with the exposure conditions and highlight the capability of fully embedded wireless sensors as a practical and reliable alternative to the conventional borehole method. Additionally, the continuous monitoring of the wireless cast-in sensor exhibits reliability during unintended temperature fluctuations, emphasizing the effectiveness of permanently installed sensors in promptly detecting unintended curing variations in real time. The continuous real-time information provided combined with the practicality of these sensors might assist construction managers to improve the quality control of the concrete curing process and shrinkage behavior, and ensure the integrity of concrete surface finishing.