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The purpose of this paper is to present and discuss the external factors of the solar dryer design that influenced the thermal efficiency of the solar dryer that contribute to the better quality of dried food products.

From the reviewed works of literature, the external factors including the drying temperature, airflow rate and relative humidity have significant effects to increase the rate of moisture diffusivity of the freshly harvested products during the drying process. The proper controls of airflow rate (Q), velocity (V), relative humidity (RH%) and drying temperature (°C) can influence the dried product quality. The dehydration ratio is the procedure to measure the quality of the dried food product.

The indirect solar dryer including the mixed-mode, hybrid and integrated was found shorter in drying time and energy-intensive compared to sun drying and direct drying. The recommended drying temperature is from 35.5°C to 70°C with 1–2 m/s velocity and 20%–60% relative humidity. The optimum thermal efficiency can be reached by additional devices, including solar collectors and solar accumulators. It gives a simultaneous effect and elongated the drying temperature 8%–10% higher than ambient temperature with 34%–40% energy saving. The recommended airflow rate for drying is 0.1204 to 0.0894 kg/s. Meanwhile, an airflow rate at 0.035–0.04 kg/m2 is recommended for an optimum drying kinetic performance.

This paper discusses the influence of the external factors of the solar dryer design on the thermal performance of the solar dryer and final dried food products quality. Therefore, the findings cannot serve as a statistical generalization but should instead be viewed as the quantitative validation subjected to fundamentals of the solar dryer design process and qualitative observation of the dried food product quality.

A well-designed of solar dryer with low operating and initial fabrication cost, which is simple to operate is useful for the farmers to preserve surplus harvested crops to an acceptable and marketable foods product. The optimization of the external and internal factors can contribute to solar dryer thermal performance that later provides an organoleptic drying condition that results in good quality of dried product and better drying process. The recommended drying temperature for a drying method is between 35°C up to 70°C. Drying at 65.56°C was effective to kill microorganisms. Meanwhile, drying at 50°C consider as average drying temperature. The recommended airflow rate for drying is 0.1204 to 0.0894 kg/s. Meanwhile, air flowrate at 0.035–0.04 kg/m² is recommended for optimum drying kinetic performance. The recommended value of aspect ratio and mass flow rate is 200 to 300 for an optimum evaporation rate. The good quality of dried products and good performance of solar dryers can be developed by proper control of airflow rate (Q), velocity (V), relative humidity (RH%) and drying temperature (°C).

The proper control of the drying temperature, relative humidity and airflow rate during the drying process will influence the final dried food products in terms of shape, color, aroma, texture, rupture and nutritious value. It is crucial to control the drying parameters because over-drying caused an increment of energy cost and reduces the dry matter. The quick-drying will disturb the chemical process during fermentation to be completed.

This study identifies the potential of the solar drying method for dehydrating agricultural produces for later use with the organoleptic drying process. The organoleptic drying process can reduce mold growth by promising an effective diffusion of moisture from freshly harvested products. The research paper gives useful understandings that well-designed solar drying technology gives a significant effect on dried product quality.

Refractance window drying (RWD) has been identified as the method that can give high-quality products at a relatively low production cost. However, knowledge about its use and adoption remains lacking both in academic curricula and industry in the developing world.

A lab-scale batch RWD of a closed-loop control system was designed, fabricated and evaluated for drying rates, evaporation rate, the energy of evaporation, energy efficiency and throughput. Testing was done using mango and tomato pulps.

Drying rates at 95°C of 1.32 gg⁻¹min⁻¹ and 0.854 gg⁻¹min⁻¹ at 2 and 3 mm, respectively, for tomato, 0.6 gg⁻¹min⁻¹ and 0.33 gg⁻¹min⁻¹ at 2 and 3 mm for mango pulp were obtained. The dryer had an evaporation rate of 4.63 × 10^–4 kg/s and 4.25 × 10^–4 kg/s, the energy of evaporation of 1.05 kW and 0.96 kW and thermal energy efficiency of 25.64% and 21.73% while drying tomato and mango pulps, respectively. Dryer throughput of 0.6 kg/h of dried mango Pulp and 0.47 kg/h of dried tomato pulp was obtained.

The designed RWD can be adequately used in laboratory experiments on different products to produce powders. This will enable the transfer of knowledge about RWD technology in developing countries.

Zinc‐wire Pistol. A new version of the Mark 30 heavy‐duty motorised pistol is being manufactured. Illustrated on this page is a unit in operation spraying 5‐mm.‐diam. zinc wire at the rate of 132 lb./hr. The two spraying heads are fitted with double air caps to ensure a superfine coating even at a high rate of spraying. The heads can be angled to provide adjustment of the focal point.

The purpose of this paper is to examine the impact of thread count in polyester reinforcing fabric on heterogeneous cation exchange membrane mechanical properties and electrochemical performance.

Seven polyester fabrics differing in thread count were used for membrane manufacture and mechanical properties such as ultimate force or ultimate strain of all fabrics and membranes were determined. Electrochemical and physical properties of produced membranes were evaluated as well.

It was found that with increasing weft density ultimate force became greater in the case of fabric and membrane as well. The impact of weft density on ultimate strain was not confirmed but changes in swelling ability mainly in width direction were observed. The assumption of worse electrochemical properties of membranes reinforced by fabric with lower open area was also validated and these membranes exhibited higher areal resistance.

Gained information is a useful tool in design process of new ion exchange membrane types with improved mechanical and swelling properties.

The formulation of industrial finishes to protect and improve the appearance of mass‐produced articles has become an increasingly complicated technique with the growing range of materials flow available. In this article Mr. Macrae, after discussing surface preparation and application methods, describes the formulation and performances of stoving enamels, cold‐curing finishes and air‐drying finishes. He concludes that even with the number of resins available today there is still much room for improvement.

This paper details the use of isophthalic acid and trimellitic anhydride for the design and production of water reducible alkyd coatings. The performance of these systems is equal to or better than conventional solvent based systems. The use of special processing, compounding or application equipment is not required for the production of these coatings, however, the raw materials must be carefully selected to ensure optimum performance. Both water reducible alkyds and water reducible acrylated alkyds for air drying and force cured applications will be discussed. Coatings manufacturers in the United States have commercialized these systems for applications varying from air dry implement enamels to interior can coatings.

The purpose of this paper is to evaluate the protective effects of Persian gum and gum Arabic on the survival of Lactobacillus plantarum subsp. plantarum PTCC 1896, Escherichia coli, Xanthomonas axonopodis, and Saccharomyces cerevisiae during freeze drying.

Cultures were harvested from the early stationary phase and enumerated after dilution according to the Milse Misra method. Bacterial suspensions were mixed with protective agents and frozen at –80°C before drying in a freeze dryer. Survival rates were determined both immediately during freeze drying and after 14 days of cold storage (at 4°C).

Compared to gum Arabic 5 and 10 percent (W/V) or skim milk 10 percent (W/V), Persian gum 1 percent (W/V) showed no significantly different effects on the survival of Lactobacillus plantarum subsp. plantarum PTCC 1896 (p<0.05). Similarly, no significant differences (p<0.05) were observed between Persian gum 6 percent (W/V), gum Arabic 6 percent (W/V), the combination of Persian gum 3 percent (W/V) and gum Arabic 3 percent (W/V), and skim milk 10 percent (W/V) in terms of their effects on the survival of Escherichia coli. Skim milk 10 percent (W/V) was, however, found to have significant (p<0.05) effects on the survival of Xanthomonas axonopodis and Saccharomyces cerevisiae. Statistically significant (p<0.05) effects were observed after 14 days of cold storage (4°C) by Persian gum 6 percent (W/V) on the survival of Escherichia coli and by gum Arabic 6 percent (W/V) on the survival of Xanthomonas axonopodis and Saccharomyces cerevisiae. It was concluded that protective agents could be replaced by Persian gum for its effect on the survival rate of Escherichia coli and by skim milk for its effects on the survival of Xanthomonas axonopodis and Saccharomyces cerevisiae. Persian gum 6 percent (W/V) seemed to be the best protective agent for Escherichia coli during 14 days of its storage as gum Arabic 6 percent (W/V) seemed to have the same performance for Xanthomonas axonopodis and Saccharomyces cerevisiae. Persian gum 1 percent (W/V) was also found an alternative protective agent for the freeze drying of Lactobacillus plantarum subsp. plantarum PTCC 1896.

As Iranian Persian gum is cheap due to its wide availability and seems to have effects similar to those of gum Arabic and skim milk at low concentrations, it may be considered a good candidate for industrial applications.

Demands for coatings with superior technical characteristics have induced the use of composite coatings, which usually represent an extremely strong product. The resin blend technique is a simple and useful method for improving paint properties. Coal tar resins are the most economical coating extensively used in the industry; short oil‐length alkyd resins are usually used for air and force‐dry industrial coatings for metal surfaces. The purpose of this paper is to evaluate coating blends composed of these resins, in particular, the effects of short oil‐length alkyd additive on the properties of coal tar binder.

One way to achieve new types of binders is to make combinations of the existing ones, in an ideal case retaining the desirable properties of both. The alkyd has important properties over the original drying oil. To achieve the goal of improving coal tar resin properties, short oil‐length alkyd was blended with it. The prepared short oil‐length alkyd was characterised using IR and ¹HNMR spectroscopy. The mixing ratio of short oil‐length alkyd with coal tar was up to 25 per cent. The compatibility of coating blend was characterised by scanning electron microscope. The physical, mechanical and chemical properties of the coating blend in addition to the corrosion resistance were determined according to ASTM methods.

In spite of a large number of synthetic resins being available for use in paint formulations, the alkyd resins surpassed all of them in versatility and low cost. The blend of short oil‐length alkyd resin with coal tar has yielded better coating blend properties. The coating blend showed significant enhancement of physical, mechanical and chemical properties such as gloss, drying time, adhesion, scratch hardness, acid and solvent resistance because the coating blend combines the properties of thermosetting and thermoplastic resins.

Alkyd resins are the most extensively used synthetic polymers in the coating industry. Modification of coal tar blend based on other type of polyester resins could also be studied in order to assess the applicability of the coal tar blend system found for other applications.

These types of alkyd resins can be applied in other bitumen composites as additives and reinforce agent.

The paper shows how the low‐cost modified coal tar binder can be used for air and force‐dry industrial coatings for metal surfaces.

Food loss and wastage is an issue of global concern and the household sector is one of the biggest contributors to this. Solar drying has been explored by many eminent researchers as a solution to this problem but there have been concerns about the lack in designs, higher cost, lower performance, and consumer acceptability. The present research aims to design a small-scale domestic solar dryer by using computer software.

Response surface methodology (RSM) and computational fluid dynamics (CFD) are used to design the domestic solar dryer. Initially, design variables (inlet and outlet vent height) are identified and a design of experiments has been created using RSM for set of experimental runs. The experimental runs suggested by RSM were carried out using CFD simulation in COMSOL Multiphysics software and the results were used for optimization of response variables (outlet velocity and drying chamber temperature) in RSM.

Outlet vent height was found to be most significantly affecting parameter to both the responses. The optimum values of inlet and outlet vent heights were 0.5 and 2.5 cm, respectively with the overall desirability of 0.728. The model accuracy was tested by conducting a confirmation test as post processing in design expert software.

Designing a solar dryer is a complex, costly and time consuming process, this study presents an easy, economic and fast method to design a new solar dryer. It would help researchers to design and develop new domestic as well as large size industrial solar dryer.

The purpose of this paper is to investigate the friction and wear mechanisms in lubricated sliding conditions of additively manufactured SS316L parts. The different viscous oils 5W30, 15W40, 20W50 and SAE140 are used. These investigations provide a theoretical basis for the high performance of printed and postheattreated SS316L.

Tribological tests were carried out on selective laser melting-made SS316L printed specimens and heat-treated specimens. The parameters in 15 min of test duration are 20 N of load, 200 rpm, 8 mm of pin diameter, 25 mm length, 80 mm of track diameter and EN31 counter disc body. This work presented the phenomena of lubrication regimes and their characterization, as identified by the Stribeck curve, and these regimes affect the tribological properties of additively manufactured SS316L under the influence of industrial viscous lubricants. The results are observed using Scanning electron microscope (SEM), X-ray diffraction (XRD) and wear tests.

The observations indicate that additively manufactured SS316L shows a reduced coefficient of friction (COF) and specific wear rate (SWR). This is credited to the utilization of different viscous lubricants.

This exclusive research demonstrates how various viscous lubricants affect the COF and SWR of printed and post-heat-treated SS316L parts. Lambda (λ), lubricant film thickness (h₀), surface roughness and wear mechanisms are studied and reported.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0110/