Moisture Removal Research Articles

Study of the kinetics of the process of intramolecular moisture removal from wheat grain by DSC thermal analysis

The article presents the results of a DSC study of the kinetics of the process of removing intramolecular moisture from wheat grains. For the experiments, four samples of wheat of the 3rd class of the 2021 harvest diff ering in technological indicators, including the “Mass of 1,000 grains” indicator, were selected. The studies were carried out on a DSC 204 F1 Phoenix diff erential scanning calorimeter. The data on the change in the mass of wheat samples when they are heated to critical temperatures of +200 and 250 °С are presented. It has been shown that a slight weight loss at 200 °С generally corresponds to a larger weight loss at 250 °С. This led to the assumption that the degree of intramolecular water retention depends on the individual characteristics of the variety. The kinetics of the process of dehumidifi cation of four samples of wheat, determined by the method of diff erential scanning calorimetry, is presented.

Investigating the impact of flow rate and moisture content for different concentration of liquid desiccant solution

The desiccant air conditioning system consists of two processes, namely cooling and dehumidification, in which the air temperature and humidity are controlled in order to provide comfortable thermal conditions. A typical system includes a dehumidifier, indirect evaporative cooler, and regenerator. The desiccant is selected depending on its ability to absorb water vapor present in the air. In this study, calcium chloride solution was used as a desiccant for the desiccant solution regeneration process, and a flat plate solar collector was employed. Different variables, such as the primary air flow rate, desiccant flow rate, and the concentration of the desiccant solution, were changed during the experiments. The impact of these variables on the performance parameters of the desiccant system such as moisture removal rate, moisture efficiency, enthalpy efficiency, sensible heat ratio, and the mass transfer coefficient was studied. The obtained results revealed that as the solution concentration and the flow rate of primary air increase, the moisture removal rate, sensible heat ratio, and mass transfer coefficient increase. A particular value of inlet primary air flow rate (0.18Kg/s), an increase in the inlet concentration of calcium chloride solution from 0.85 to 0.95 leads to a rise in moisture removal rate, sensible heat ratio, and mass transfer coefficient of (1.1 _1.65) g/s, (0.18-0.25), and (0.01075-0.0123) m/s respectively. While at a certain inlet concentration of a desiccant solution (0.95), increasing the inlet primary air flow rate from 0.1Kg/s to 0.18Kg/s leads to an increase in the moisture removal rate, sensible heat ratio, and mass transfer coefficient o (0.94-1.26) g/s, (0.24-0.26), and(0.0038 -0.011) m/s respectively.

Ultrahigh-Frequency Hop Dryer with Tiered Resonators

Introduction. From the analysis of hop dryers of different systems and designs follows the prospect of hop drying by complex influence of the energy of the electromagnetic field of ultrahigh frequency and convective heat. Aim of the Article. The article aims at developing a small-sized microwave convective hop dryer with justified parameters for intensive drying technology of freshly harvested hops. Materials and Methods. Taking into account the justified criteria for the design of a hop dryer and the analysis of existing resonators, there was proposed a methodology for the development of a hop dryer with an energy supply in an electromagnetic field, including requirements for structural design, operational and economic indicators, and technology. The electrodynamic parameters of the resonator were investigated according to the CST Studio 2017 program. Results. The dielectric parameters of hops are theoretically investigated and functional dependences on humidity at a frequency of 2,450 MHz are obtained. The dynamics of hop heating is investigated when its dielectric loss factor changes during the action of an ultrahigh frequency electromagnetic field. There has been developed a design and technological scheme of a radio-hermetic microwave convective hop dryer of continuous flow action with tiered resonators for low-power agricultural enterprises. Resonators are arranged in tiers in the screening cylindrical housing: the first and third resonators are hemispherical, and the middle one is made in the form of an ellipsoid to ensure a high electric field strength. The transportation of raw materials takes place by rotating the discs in a gentle mode. Discussion and Conclusion. The expected specific energy costs of a hop dryer with a capacity of 12–13 kg/h at the microwave generator power of 4.0 kW for drying freshly harvested hops with a humidity of 76–82% to a humidity of 11–14% are 0.30–0.33 kWh/kg. The required electric field voltage of 2 kV/cm in all three resonators is provided, therefore, disinfection of raw materials occurs at a temperature of 65–70°C for 5–6 minutes of stay in three resonators. The intensity of moisture release from hop cones during endogenous convective heating increases 5–6 times compared to the convective drying method. The introduction of microwave drying technology using a convective method of evaporation and removal of moisture from the drying chamber reduces the duration of the process, saves valuable components of cones for brewing.

Research on the Process of Convective Drying of Apples and Apricots Using an Original Drying Installation

After being harvested, fresh apples and apricots have a high moisture content and are put through a drying process to reduce waste and lengthen shelf life. This study intends to evaluate the physicochemical parameters during moisture removal and product heating in order to conduct an experimental investigation of the convective drying of apples and apricots in a pilot drying installation. The drying agent’s temperature and/or speed can be adjusted using the pilot installation. About the raw materials: the apricots (Neptun variety) were dried and cut into halves, while the apples (Golden Delicious variety) were dried and cut into 4 mm thick slices. The fruits’ drying properties were observed at 50 °C, 60 °C, 70 °C, and 80 °C, air speeds of 1.0, 1.5, and 2.0 m/s, and relative air humidity levels of 40–45%. Findings of the ascorbic acid content, color, heating, and dimensional fluctuations are provided and examined. Increased air velocity and temperature had the expected effect of increasing water loss, solid gain, and shrinking. Depending on the drying conditions, different color characteristics were applied.

КУЛОНОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ ВОДЫ В ФАРМАЦЕВТИЧЕСКИХ СУБСТАНЦИЯХ

The water content is one of the mandatory criteria for the quality of pharmaceutical substances. Violation of the technological process for the manufacture of substances or their storage conditions can lead to undesirable outcomes: loss of crystallization water or dampness, which can cause processes such as hydrolysis, oxidation, decomposition, the formation of undesirable impurities that can have a toxic effect. The regulatory documentation regulates either only the upper limit of the water content, or the upper and lower limits (for substances containing water of crystallization in their structure), depending on the properties of the pharmaceutical substance. Coulometric Fischer titration is a promising method for the determination of water. The titrant is electrogenerated iodine, which is formed during the anodic oxidation of iodide ions contained in the anode solution. Further, iodine oxidizes sulfur (IV) in the presence of water according to the Fisher reaction and is reduced to iodide ions, from which iodine can be generated again. Measuring the current and time duration for electrolysis, on which the amount of iodine electrogenerated at the anode depends, makes it possible to calculate the water content in the pharmaceutical substance. Preliminary removal of moisture from the anolyte and the possibility of water determination only in the injected sample significantly increase the accuracy of the analysis. The advantages of this method are specificity, no need for preliminary standardization of the titrant and creation of calibration graphs, rapidity and simplicity of the experiment, possibility of full automation. A unified method for the determination of water by coulometric Fischer titration in substance of nicotinic acid, bendazole hydrochloride and lizinopril dihydrate has been developed. The relative standard deviation does not exceed 2%, the relative error of the mean is 1.8%. The methods can be used in the practice of analytical laboratories to assess the "Water" parameter in these pharmaceutical substances.

Performance assessment of an evacuated tube solar-electric hybrid dryer for lotus seeds drying: Moisture removal behavior, GHG emission and thermodynamic analysis

A novel evacuated tube solar-electric hybrid dryer (ETSED) was developed and evaluated to contribute to global food security from the perspective of optimized processing while reducing energy consumption and greenhouse gas (GHG) emissions. The performance of the ETSED was assessed compared with solar heating drying (SHD), and mixed heating drying (MHD) at temperatures of 55, 65 and 75 °C by studying the drying behavior of the samples as well as the thermodynamic analysis and GHG emissions of the system. Results revealed that under all studied experimental conditions, the evacuated tube solar collector provided more than 60% of the thermal supply in the drying process, and significantly improved the fluid exergy. Moreover, the roller shutter mechanism and the heating tube were used together to achieve precise control of the drying temperature. In terms of thermodynamic analysis, the heating tube further enhanced the ETSED performance by providing high quality energy in combination with solar energy in MHD mode. Furthermore, compared with SHD, MHD-65 and 75 °C shortened the drying time by 10.4 and 28.2%, improved the drying efficiency by 0.7% and 6.29%, and increased the drying chamber's exergy by 14.99 and 19.36%, respectively. Remarkably, the lowest emissions of CO2 (872.06 g/kg removed water), SO2 (0.13 g/kg removed water) and NOx (0.19 g/kg removed water) were seen in the case of SHD. Based on the obtained results, the increased drying temperature in the MHD led to higher CO2, SO2 and NOX emission levels. Interestingly, when the lotus seeds were dehydrated, the accumulated electric energy generated by the photovoltaic cells almost met the electric consumption of mechanical energy. The results of this study identified the potential of ETSED equipment for food industrial production.

Development of FE modeling for hybrid greenhouse dryer for potato chips drying.

In this communication, a combination of heat and mass transfer model was developed using finite element (FE) model to explain the drying performance of the hybrid greenhouse dryer for potato chips. The hybrid greenhouse dryer is integrated with a single-pass solar air heater (SAH). A partial differential equation for a combined set of heat and mass transfer was numerically solved by the FE method. In order to see the spatial moisture distribution within the potato sample, a 3-dimensional FE model was created, and moisture removal takes place from the surface during drying of the products. Lagrange triangle FEs of extremely small size and second-order geometry shape were employed for meshing the geometry of model. Time-dependent study was express the fluctuation in time interval of 0-5h. The developed model showed the maximum crop and ground temperature are 67.1 and 79.1°C, respectively. Moisture ratio in dry basis is reduced from 1 to 0.005 in 03h and remains constant at 0.005. Thus, average moisture ratio in dry basis was found as 0.18902. Drying efficiency for the hybrid greenhouse dryer found to be 20.52%, whereas thermal efficiency for SAH was found 54.53%. Relative humidity inside the drying chamber found to be 26.50% in hybrid greenhouse dryer. The predicted versus the experimental results observed that hybrid greenhouse dryer having moderate inside temperature is suitable for crop drying as well as ith sustaining the environmental balance, hybrid greenhouse proves to be most effective.

Thermodynamic analysis of a food waste plasma gasification-based multigeneration system with dehumidification and carbon capture

The amount of food waste generated annually has increased due to rapid urbanization. Food waste that is not effectively treated not only pollutes the environment but also endangers human health indirectly. To realize the resource treatment of food waste, a novel combined cooling, heating, power, and dehumidification system based on food waste plasma gasification (PG) is proposed. First, the PG and solid oxide fuel cell (SOFC) models are validated, and then energy analysis and exergy analysis of the hybrid system are conducted. Finally, the influence of crucial parameters on energy output and efficiency is analyzed. It was found that the net electrical, thermal, and exergy efficiencies of the hybrid system were 54.60%, 84.22%, and 51.15%, respectively, under the designed conditions. The moisture removal rate, humidity efficiency, and CO2 removal rate of the hybrid system were 20.16 g/kg, 93.66%, and 97.17%, respectively. The largest part of the exergy destruction was that of the plasma gasifier that accounted for approximately 35.45% of the total exergy destruction related to the plasma torch's high power consumption. This system could efficiently and cleanly convert food waste into energy and could provide a new method for the efficient utilization of food waste.

A comprehensive review on dehumidification system using solid desiccant for thermal comfort in HVAC applications

In comfort, air-conditioning control over the humidity is essential in applications such as pharmaceutical industries, electronic gadgets manufacturing units, the food sector, paper industries, etc. Relative humidity of nearly 50% can effectively prevent the growth and abidance of biological pollutants. There are several methods using which dehumidification can be achieved. The most common method is subcooling air up to the condensation temperature of the moisture trapped and then cooling again, and the condensate is collected. This method is time-consuming and needs to be more effective. On the other hand, desiccants’ dehumidification process is suitable for maintaining humidity in air-conditioning systems and producing dry air. Desiccants with economical materials, high moisture removal rate, low regeneration temperature, and steadiness after many years make a desiccant system more successful in its performance and cost. The effect of change in process air temperature, process air humidity ratio, and regeneration temperature on the system's performance is studied. This research focuses on the functioning of various desiccant dehumidification systems and their applications. A comparative study of the different dehumidification systems found efficiency, low maintenance cost, and high sustainability.

Experimental evaluation of a 3D printed air dehumidification system developed with green desiccant materials

Energy-efficient dehumidification systems are necessary to reduce energy consumption and CO2 emissions into the atmosphere. Desiccant systems could be an alternative to conventional air dehumidification systems based on direct-expansion units. In the present work, the main objective was to develop and experimentally evaluate a 3D printed desiccant system manufactured using green desiccant materials. Hence, the adsorbent capacity of three 3D printed desiccant materials were studied: polylactic acid (PLA), pine wood with PLA (PW-PLA) and olive pit with PLA (OP-PLA). The results showed that PW-PLA was the material with the highest adsorption capacity of those analysed, up to 12.7 % higher than OP-PLA. A fixed bed desiccant system was fabricated using PW-PLA filament and its latent energy performance was investigated under different inlet air conditions and low regeneration temperature, 50 °C. The evaluation of the energy performance of the 3D printed desiccant system revealed adequate moisture removal capacity values, up to 30 g/sm3, with low pressure drop, less than 552 Pa. These results show the promising potential of 3D printing and green desiccant materials for manufacturing ecological air dehumidification systems.

Application of drying acceleration to study the forms of moisture bond in currant fruits

The article discusses issues related to the study of the forms of connection of moisture removed during the drying process in black currant fruits. A study was carried out to determine the quantitative moisture content of various forms of communication by two methods and a comparative analysis was carried out. It is shown that the existing methods for studying the forms of moisture-material bonding have significant drawbacks and generally give a qualitative assessment of the state of moisture in the material or are very laborious and require long-term laboratory studies. The efficiency of the approach to determining the forms of moisture connection in black currant fruits is shown on the basis of graphical-analytical analysis of the drying kinetics, which allows qualitatively and quantitatively assessing the state of moisture in the fruits. With the help of a graphical editor, the curves of the drying kinetics of black currant fruits were processed and the dependences of the quantity called "drying acceleration" characterizing the rapidity of the change in the drying rate of currant fruits on the moisture content of the product were obtained. The analysis of the obtained curves is carried out, indicating the presence of extrema and points of inflection to the corresponding critical moisture content, as well as the presence of areas with a slowdown or acceleration of the drying rate change, allowing to establish the intervals of moisture removal with different binding energies. The approach under consideration makes it possible to give a quantitative and qualitative assessment of the physical state of moisture not only in currant fruits, but also in other food products, as well as reduce the time for analysis and improve the accuracy of the results.

Creation of a methodology for determining the intensity of moisture evaporation within vacuum drying of fruits

The study objects were the Republic of Kazakhstan selection apple sorts: “Baiterek”, “Sarkyt” and “Saya”, also pear sorts: “Syilyk”, “Zhazdyk” and “Nagima”. Study of the process of moisture evaporation within vacuum drying of the fruits has essential value in the nutritional value saving. Basically, the product evaporative capacity is characterized by the evaporation resistance coefficient ‒ µ. Also during moisture removal, thermodynamic state of moisture changes that is described by water activity indicator ‒ aw. Experimental determination of these parameters allows for the analyzing moisture evaporation during vacuum drying process. Studies have established the following evaporation resistance coefficients: µ=2.03±0.07 for apple sorts and µ=2.3±0.05 for pear sorts. Either water activity decreases from 1.0 to 0.62±0.01 for apple sorts and from 1.0 to 0.65±0.04 for pear sorts. Two drying periods are discovered. The first drying period: 5.45–6.10 h for apple sorts; and 6.12–6.25 h. for pear sorts. The second drying period duration: 4.15–3.50 h for apple sorts; and 4.35–4.48 h for pear sorts. The critical humidity value: 27.1±2.1 % for apple sorts; and 30.1±2.5 % for pear sorts. Comparative analysis of calculated and experimental data shows maximum deviations 22.5 % for apple sorts and 23 % for pear sorts. The proposed equation for the calculating a moisture evaporation rate, considering the product properties and the hygroscopic parameters of air, can be used in practice to study the moisture evaporation dynamics from the product surface. The study results allow for the selecting an optimal mode for vacuum drying of apples and pears sorts in order to safe nutritional value and to produce biologically active additives for the food industry

Parametric investigations on a novel bubble column liquid desiccant dehumidifier with internal cooling

Increasing demand for space cooling and proportionate demand for electrical power call for less power intensive technology with lower carbon footprint. The liquid desiccant (LD) based air conditioning systems can remove latent heat more efficiently, mainly using heat energy coming from waste or renewable energy source. A novel, simple and corrosion-free bubble column liquid desiccant air dehumidifier (BCLD_ADH) with provision for internal cooling of LD has been developed in this work. The advantages of providing internal cooling and effect of LD concentration as well as ambient conditions are evaluated in this experimental work. Two new type of effectiveness, one based on ambient wet bulb temperature and the other on crystallization temperature of LD are proposed here to give due credit to higher potential of moisture removal available in internally cooled dehumidifier. At 40% concentration of LD, the dehumidifier effectiveness at wet bulb temperature was 67% for adiabatic dehumidifier, but could be increased to 95% using internally cooled dehumidifier. Using higher concentration is necessary for adiabatic dehumidifier but less important for internally cooled dehumidifier as lower LD temperature helps retain higher potential for mass transfer. The inlet air humidity ratio helps to increase change in humidity ratio while higher mass flow rate also helps increase moisture removal rate proportionately.

Numerical and experimental study on the regeneration performance of a liquid desiccant system coupled with rotating packed bed and vacuum

High moisture load generated during the air quality control process introduces a considerable energy consumption, liquid desiccant air-conditioning system has some constrains during the application although it provides an opportunity to save energy. Therefore, a novel regeneration system of liquid desiccant coupled with rotating packed bed (RPB) and vacuum technique was proposed in this study. A numerical model of RPB was developed and validated in order to characterize the heat and mass transfer process during the regeneration and correlate to its performance, furtherly, an experimental rig was built to study its feasibility of RPB application in regenerators. To facility the investigation, the moisture removal rate was introduced to evaluate the regeneration performance and thereafter the effects of three key factors, rotating speed, regeneration pressure and initial concentration of liquid desiccant, were investigated accordingly. The results show that the moisture removal rate increases with the rotating speed for which the maximum of 17.395 g·L-1·min−1 was reached; meanwhile it decreases with the regeneration pressure and initial concentration of desiccant, among which the concentration has a greater impact on moisture removal rate. Compared to traditional packed bed regenerators, the rotating packed bed can significantly enhance the heat and mass transfer rate. In overall, the proposed system can reduce the energy consumption by 10.6%, the regenerate performance was improved significantly, and the feasibility of proposed system was verified to prompt its application.

An atmospheric water harvester with fast and energy‐saving water removal and recovery

Moisture removal and water recovery from the air are vital for regulating indoor humidity and mitigating water scarcity. Most atmospheric water harvesters (AWH) focus primarily on increasing the moisture capture rate, but for it to be economical and sustainable, it is essential to consider the energy required to recover and harvest the captured water. Here, a mechanically flexible, biphilic sorption-based AWH made of green, environmentally friendly material is presented. It consists of a hygroscopic chitosan polymer embedded within a flexible, hydrophobic silica xerogel that can harvest 86.3 g water/g chitosan at 97% relative humidity and 25°C reaching saturation after 30 days (i.e. 2.88 g water/g chitosan/day). Roughly 88% of the sorbed moisture was recovered by mechanical squeezing (ca. 0.020 MPa) within 150 s. Repeated water harvesting experiments and uniaxial compression tests demonstrate that chitosan-silica xerogel is durable for long-term operations, providing a fast, reliable, and sustainable moisture removal and water harvesting tool.

Thermodynamic analyses of an innovative system combined dehumidification, cooling and heating driven by solar energy

For the sake of improving the utilization of solar energy in hot summer and cold winter areas of China, an innovative system combined liquid dehumidification with absorption refrigeration driven by solar energy is proposed in this paper. Solar energy is applied to three subsystems in a cascade utilization approach. Energy, exergy, and dehumidification performances of the system in three typical seasons of hot summer and cold winter areas in China are analyzed and compared. The key parameters including solar radiation intensity, ambient temperature, segment temperature and air relative humidity are investigated to obtain the optimization design of the proposed system. The objective indicators, including dehumidification coefficient of performance, refrigeration coefficient of performance, exergy efficiency, moisture removal rate, humidity efficiency, cooling capacity and heating capacity are discussed, respectively. The results show that, as the ambient temperature and solar radiation intensity increase, the dehumidification coefficient of performance (COPD) declines but the refrigeration coefficient of performance (COPR) rises. The COPD in rainy season is increased by 33.66 % and 50.15 % respectively, compared with that in cooling season and heating season. But the COPR in cooling season is 35.32 % higher than that in rainy season. The minimum of COPD reaches 1.31 at 12 noon. The maximum of COPR in the proposed system is 0.95. The exergy efficiency of the proposed system is improved by combining the liquid dehumidification subsystem and absorption refrigeration subsystem, with the maximum reaching 16.64 %. The proposed system shows better dehumidification performance in rainy season, and the maximum moisture removal rate and humidity efficiency in the proposed system are 27.98 g/kg and 0.83. The proposed system is also used for cooling and heating, with the highest cooling capacity and heating capacity achieving 217.31 kW and 36.58 kW, respectively. The obtained results state that the proposed system has excellent performance for dehumidification, cooling, and heating in hot summer and cold winter areas of China.

Recent Advances in the Drying Process of Grains

AbstractGrain drying is a vital operation in preparing finished grain products such as flour, drinks, confectioneries and infant food. The grain drying kinetics is governed by the heat and mass transfer process between the grain and the environment. Incomplete, improper and over-drying are crucial to the grain quality and negatively influence the acceptance of the grain by the consumers. Dried grain moisture content is a critical factor for developing grain drying systems and selecting optimal performance by researchers and the grain processing industry. Many grain drying technologies such as fluidised bed dryers, fixed bed dryers, infrared dryers, microwave dryers, vacuum dryers and freeze dryers have been used in recent years. To improve the drying process of grain, researchers have combined some drying technologies such as microwave + hot air, infrared + hot air and microwave + a fluidised bed dryer. Also, they introduce some treatments such as ultrasound dielectric and dehumidification. These methods enhance the dryer performance, such as higher moisture removal, reduced processing time, higher energy efficiency and nutrient retention. Therefore, this review focused on the drying conditions, time, energy consumption, nutrient retention and cost associated with the reduction of moisture content in grain to a suitable safe level for further processing and storage.

Combustion performance of lignite after efficient upgrading via deep eutectic solvent‐assisted hydrothermal dewatering

AbstractIn order to increase the efficiency of hydrothermal dewatering (HD), a deep eutectic solvent (DES, synthesized by ChCl and ZnCl2) was employed to promote the removal of moisture and oxygen from lignite. The variation of physicochemical structure of upgraded coals greatly affected the combustion performance. The effects of addition amount of DES, upgrading temperature, and the molar ratio by ChCl and ZnCl2 on combustion performance of upgraded coals were analyzed via thermogravimetric analysis. Compared with HD lignite upgraded at 280°C, the combustion curves of DES‐HD lignite were shifted and delayed toward a higher temperature zone as DES additions increased. DES‐HD lignite had lower spontaneous combustion tendency and higher combustion reactivity. When upgrading temperature increased from 250 to 300°C, the combustion curves of lignite upgraded with 3.0‐g DES (ChCl:ZnCl2 = 1:1) first moved to the low‐temperature zone and then shifted to the high‐temperature zone. DES‐HD lignite maintained the advantages of raw coal in terms of combustion characteristics. For lignite upgraded with different molar ratios of ZnCl2 in DES, the difference in combustion behavior was mainly manifested in the burnout stage. The burnout stage was advanced slightly as the molar ratio of ZnCl2 increased.

Microwave-Osmo-Dehydro-Freezing and Storage of Pineapple Titbits—Quality Advantage

Osmotic dehydration is a pre-treatment given prior to finish drying or freezing preservation to improve quality and/or minimize the damaging effects on quality parameters, by partially reducing the moisture content of the sample. Pineapple titbits were partially dried using microwave assisted osmotic dehydration under continuous flow medium spray condition (MWODS) and then frozen with or without a sodium alginate–calcium chloride-based edible coating. The effects of MWODS pre-treatment and edible coating on the quality parameters of pineapple titbits frozen and stored at −20 °C for 10 and 50 days were evaluated after thawing. Both treatments (MWODS and alginate) resulted in superior quality products as compared to the control sample. MWODS, with its advantages over the conventional osmotic dehydration (COD) of rapid and higher moisture removal (16% in 10 min vs. 4 h in COD), while limiting solids gain (2.5% MWODS vs. 4.5% in COD), resulted in improved quality over the control during the frozen storage. The sodium alginate–calcium chloride edible coating treatment further reduced the drip loss in MW-osmo-dehydro-frozen pineapple titbits, possibly due to the effect of the calcium cross linked firming of the fruit texture. Both resulted in enhanced appearance, color and textural properties.

Performance investigation and exergy analysis of a novel recirculated regenerative solid desiccant dehumidification system

Vapor compression dehumidification (VCD) is limited by the wet-bulb temperature, which results in high-energy consumption, especially in enclosed hot and humid spaces. An improved recirculated regenerative solid desiccant-vapor compression (RRSD-VC) hybrid dehumidification system was proposed to achieve highly efficient dehumidification in enclosed cabins, such as those in marines, spacecraft, and underground shelters. An experimental study of the RRSD-VC system was carried out to analyze the dehumidification characteristics and exergy performance. The results indicate that the regenerative airflow ratio (γ) was the most crucial performance indicator of the proposed system. The system moisture removal capacity (Dtot) increased with decreasing precooling temperature and increasing regeneration air temperature, and the highest Dtot was obtained when the optimal γ was reached. The exergy efficiency of the RRSD-VC system (ηex) was inversely proportional to γ. Therefore, a balance of high dehumidification capacity and low energy consumption could be maintained in the system design. Moreover, ηex could be improved by 55.7% when the electric heating was replaced by heating with waste heat recovered from the engine exhaust gas for air regeneration. The results of further parametric analysis showed that the RRSD-VC system was more adaptable than the VCD system to hot and humid conditions.