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The distinctive pharmacological characteristics of Chinese medicinal herbs are rendering them increasingly popular as functional foods. However, fresh herbs are prone to mold and decay. Currently, drying processing is primarily employed to extend the storage time and effectively preserve the bioactive constituents of these herbs. After examining of the recent literatures on drying Chinese medicinal herbs, this paper provides a comprehensive overview of various drying technologies, including shade drying, hot air drying, solar drying, heat pump drying, microwave drying, far-infrared drying, vacuum drying, vacuum freeze drying, radio frequency drying, high voltage electric field drying and some combined techniques. While, an extensive illustration for each drying method principles, advantages/disadvantages, potential improvements and deep investigation of its energetic performance and the influence on the main active components in the drying process, such as polysaccharides, polyphenols, flavonoids, saponins, volatile oils, were summarized. The results showed that the combined drying technology not only had high efficiency and low energy consumption, but also preserved the bioactive medicinal components and sensory quality at the best. This paper provides a theoretical foundation and vast technical support for enhancing the value of Chinese medicinal herbs utilization and drying industry. [ABSTRACT FROM AUTHOR]

Poria cocos has been dried in an indirect solar drying system composed of a roughened solar air heater (RSAH), a shell and tube storage unit assisted with flat micro heat pipes fins, and a drying chamber. The main novelty in this study is using FMHPs as fins in shell and tube storage unit with paraffin wax and lack of investigations on Poria cocos solar drying as medicinal material used in Chinese medicine. First and second laws of thermodynamics are used to assess the performance of the system and the results indicated that the RSAH average thermal (η ) and exergy efficiency ( η Ex ) were 73.9% and 5.1%, respectively, with averaged incident solar radiation of 671 W/m2 under airflow rate of 0.0381 m3/s. Furthermore, the storing system showed 37.6% as averaged overall η and 17.2% as averaged overall η Ex , as well as, discharging prolonged to 4 h with effective drying temperature. The overall η of the dryer was 27.6% with specific energy consumption (SEC) of 8.629 kWh/kg moisture. The payback period of the system is 1.7 years. [ABSTRACT FROM AUTHOR]

Susceptibility of airborne ultrasonic power to augment heat and mass transfer during hot air dehydration of peppermint leaves was investigated in the present study. To predict the moisture removal curves, a unique non-equilibrium mathematical model was developed. For the samples dried at temperatures of 40‒70 °C and the power intensities of 0‒104 kW m−3, the diffusion of moisture inside the leaves and coefficients for of mass and heat transfer varied from 0.601 × 10–4 to 5.937 × 10–4 s−1, 4.693 × 10–4 to 7.975 × 10–4 m s−1 and 49.2 to 78.1 W m−2 K−1, respectively. In general, at the process temperatures up to 60 °C, all the studied transfer parameters were augmented in the presence of ultrasonic power. [ABSTRACT FROM AUTHOR]

Household biogas-digesters are a prospective technique that can help minimal-income rural families to meet their basic energy requirements and enhance their living standards. Nevertheless, due to the cold temperature of the digesters, the biogas generation is decreased and the digestion efficiency is generally low. The current work proposes a solar-greenhouse (SGH) heating technique united with a north wall to heat a semi-buried tubular digester, as a solution. Two similar semi-buried digesters were used in this experiment; one (DA) was heated by a SGH attached to a north wall, while the other (DB) was heated by direct sunlight (without a greenhouse), which used as a control, and both digesters were fed with cattle manure. The average slurry temperature for DA and DB was 24.9 °C and 23.45 °C, respectively, and both digesters were warmer than the outside air temperature of 22 °C. Moreover, there were no appreciable differences in the methane concentration (62.2–62.76%) between the mean specific biogas production of DA and DB, which were 173 and 155.3 L/kg VS, individually. The study showed that using combined SGH technique is enhanced the process of biogas output more than control. [ABSTRACT FROM AUTHOR]

The productivity and efficiency of harvesting forage crops depend on the sharpness and quality of the mower blades. Therefore, studying blade wear during Alfalfa harvesting is crucial to sharpening and maintaining blades. This research aims to create mathematical models to predict the wear of mower blades and assess the wear rate of mower blades, fuel consumption, and CO2 emissions during the harvesting operation. Blade wear was measured by the weight loss method and examined by scanning electron microscopy (SEM) before and after the field experiment. The results showed that the weight of the mower blade decreased from 103.82 to 98.39 g after 37.5 working hours. Over time, fuel consumption and operating costs increased due to the wear of blades. Also, CO2 emissions were 17.7 kg h−1 at the beginning of the experiment and increased to 29.5 kg h−1 after 37.5 working hours. Due to wear in the blades, the increase in fuel consumption, cost, and CO2 emissions reached 67% at the end of the experiment. From the obtained mathematical equations, the sharp part of the blade has worn out after 34 ± 3 working hours.Article Highlights: Drum mower blades wear rate is investigated for alfalfa in Egyptian condition. Microscopic and SEM techniques are clearly showed the morphological changes on the mower blades. Wear rate has a significant influence on fuel consumption and CO2 to the environment. A mathematical model is developed to predict blades lifetime. [ABSTRACT FROM AUTHOR]

Enhancements in heat transfer, and consequently the thermohydraulic performance of solar air heaters (SAHs), are necessary to widen and optimize their use in many applications such as solar drying or heating buildings. In this investigation, two techniques were used. A novel solar selective coating combined with broken arc ribs roughness was employed with a SAH and the evaluation of the energetic and exergetic performance was applied under four airflow working conditions compared to a smooth absorber SAH coated with the same coating. The results revealed that the Nusselt number of roughened SAH with the new coating exhibited a notable improvement compared to a smooth absorber SAH and a roughened SAH without a coating. Furthermore, the thermal efficiency increased with the increase in the air flow rate and the maximum rise was 18.8% compared to a smooth SAH. The highest increase in exergy was 51.6% with minimum values of exergy destruction and improvement potentials. In brief, the roughened SAH with 4% CNTs/CuO-black paint under the airflow rate of 0.0244 m3/s (condition C) exhibited the best energetic and exergetic performance. [ABSTRACT FROM AUTHOR]