Comparative study of hot air drying and microwave drying for dewatered sludge

Wulyapash, Wittawat; Phongphiphat, Awassada; Towprayoon, Sirintornthep

doi:10.1007/s10098-021-02242-5

Cited by 16 publications

(5 citation statements)

References 50 publications

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Section: Discussionmentioning

confidence: 99%

“…The results showed that the number of macropores increased gradually with the increase in the particle size of soil aggregates, which was consistent with previous studies. Then, the method of hot air drying [10,11] was used to blow hot air into the wet soil to solve the problem of excessive moisture in the soil pores. The study found that hot air would produce different forms of heat flow under different sized pore structures, thus producing different heat and mass transfer rules.…”

Section: Discussionmentioning

confidence: 99%

“…The hot air dehumidification of porous media mainly uses hot air as the drying medium and uses high temperature hot air to heat liquid water into steam to remove excess water in porous media [10,11]. Among them, the pore structure has a significant effect on the dehumidification effect of hot air.…”

Section: Discussionmentioning

confidence: 99%

“…To solve the problem of steam condensation blocking soil pores, the first thing is to remove the condensation that is clogging the pores in the soil. According to previous research on the sludge drying process, hot air heating is used to remove excess water from the sludge [10,11]. Building on the concept of hot air heating for dehumidification, to more effectively clear blocked pores and improve steam diffusion efficiency, it is essential to further investigate the impact of hot air on water heating and evaporation in soil pores of different sizes.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

Yang,

Ameen,

Yang

et al. 2024

Agriculture

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In recent years, the problematic circumstances of the constant cropping problem in facility crops have become increasingly serious. Compared to chemical disinfection, soil steam disinfestation offers the benefits of environmental protection and being pollution-free, which can effectively reduce the problem of constant cropping in crops. However, during the steam disinfection procedure, a large quantity of liquid water is formed due to the condensation of high-temperature steam, which causes soil pore blockage, seriously affecting the mass and heat transfer efficacy of steam and, thus, affecting the disinfection efficiency. Therefore, to solve this problem, this paper proposes the use of hot air dehumidification to remove excess water from soil pores and achieve the goal of dredging the pores. However, further exploration is needed on how to efficiently remove excess water from different pore structures through hot air applications. Therefore, this paper first used CFD simulation technology to simulate and analyze the hot air flow field, mass, and heat transfer in soil aggregates of different sizes (<2 mm to >8 mm). Then, based on the soil hot air heating experimental platform, research was conducted on the mass and heat transfer mechanism of hot air under diverse soil pore conditions. The results show that as the soil particle size increases from <2 mm to >8 mm, the number of soil macropores also increases, which makes the soil prone to the formation of macropore thermal currents, and the efficiency of hot air heating for dehumidification first increases and then decreases. Among them, the 4–6 mm treatment has the best dehumidification effect through hot air heating, with a deep soil temperature of up to 90 °C and a water content reduction of 6%. The 4–6 mm treatment has a high-temperature heating and dehumidification area of 15–20 cm deep. The above results lay the theoretical foundations for the parameters of hot air heating and dehumidification operations, as well as the placement of the hot air pipe. This paper aims to combine hot air dehumidification technology, for the removal of excess water from soil, and dredging soil pores, ultimately achieving the goal of improving soil steam disinfection efficiency.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

Yang,

Ameen,

Yang

et al. 2024

Agriculture

View full text Add to dashboard Cite

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“…It has also been applied in ginger drying to determine the appropriate microwave power and drying temperature for the final product (Zeng et al, 2023). Similarly, microwave drying was applied for dewatered sludge, and it was found that the application of microwaves reduced the drying time by at least 37.5% compared to using hot air (Wulyapash et al, 2022). In addition to quality prospectus, concerns that producers are preoccupied with are energy usage that influences drying costs.…”

Section: Introductionmentioning

confidence: 99%

Quality and bioactive compound accumulation in two holy basil cultivars as affected by microwave-assisted hot air drying at an industrial scale

Wiset,

Poomsa-ad,

Jindamol

et al. 2023

Front. Sustain. Food Syst.

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Holy basil (Ocimum Tenuiflorum L.) contains several bioactive compounds useful to the pharmaceutical and food industries. Microwave drying (MD) is a powerful technique for rapid drying of food or plant materials while preserving bioactive compounds during the process. However, little is known about the optimal combination of MD power with hot air drying (HAD) that can preserve the quality and yet only consume reasonable energy when drying holy basils. For that purpose, the effects of drying methods using MD combined with HAD at 45°C were examined to prevent losses in quality, antioxidant activities, and volatile flavor compounds in two holy basil cultivars (green and red cultivars). Holy basil leaves were dried at different MD powers of 200, 400, and 600 W combined with HAD and compared with a traditional tray drying (TD) at 45°C. Drying using MD at 600 W with HAD displayed significantly high levels of color retention, chlorophyll, and carotenoid content in both cultivars. The green cultivar showed a greater accumulation of total phenolic compounds (TPC), terpenoids, and DPPH free radical scavenging at 400 W with HAD. However, the red cultivar had the highest TPC, flavonoid, and terpenoid content at 600 W with HAD. The accumulation of major volatile organic compounds (VOCs) was also affected, and treatment at 600 W exhibited the highest methyl eugenol and β-caryophyllene content in both cultivars. The use of the highest power of MD (600 W) with HAD for leaf drying reduced the effective drying time and energy consumption among both cultivars. Taking into consideration the dried quality of antioxidant accumulation and energy consumed for drying, we recommend using MD at 400 or 600 W with HAD for the green cultivar and 600 W for the red.

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Study on efficient drying process of industrial silicon powder

Li,

Xu,

et al. 2024

Env Prog and Sustain Energy

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The drying procedure is an important consideration for the silicon powder processing. Herein, a comparative investigation of the drying efficiency, drying performance, and energy consumption of silicon powder after separation and purification of monocrystal silicon cutting slurry by using the hot air, far‐infrared and microwave drying treatments. The results show that microwave drying of 30 g silicon powder takes only 12 min, which is much shorter than hot air drying of 200 min and far infrared drying of 40 min. The water evaporation energy consumption of microwave drying reached 73.5 g/kW·h, which was 3.3 times than that of far infrared drying and 16.5 times than that of hot air drying. For 1 kg of silicon powder, the power consumption of microwave drying was 8 kW·h, while the far‐infrared drying was 26.7 kW·h, and the hot air drying was 133.4 kW·h, respectively. Therefore, effects of microwave power, drying temperature and drying time on the dehydration rate of silicon powder were investigated and optimized by response surface method, demonstrating that the microwave drying dehydration rate of 30 g silicon powder could reach 97.65%, and the power consumption could be reduced to 6.7 kW·h/kg under the conditions of microwave power of 1000 W, drying temperature of 89°C and drying time of 12 min. The present study shows that microwave drying of silicon powder is an energy‐saving and efficient process with good industrial application prospects.

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Comparative study of hot air drying and microwave drying for dewatered sludge

Cited by 16 publications

References 50 publications

Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

Study on the Temperature and Water Distribution of Hot Air in Red Loam Based on Soil Continuous Cropping Obstacles

Quality and bioactive compound accumulation in two holy basil cultivars as affected by microwave-assisted hot air drying at an industrial scale

Study on efficient drying process of industrial silicon powder

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