A comparative study on intermittent heat pump drying process of Chinese cabbage (Brassica campestris L.ssp) seeds

Yang, Zhao; Zhu, Enlong; Zhu, Zongsheng; Wang, Juan; Li, Si-Yuan

doi:10.1016/j.fbp.2013.02.006

Cited by 52 publications

(36 citation statements)

References 18 publications

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“…However, an empirical equation does not makes it possible to explain this aspect. According to Silva et al (2012) and several authors, such as Carmo et al (2012) and Yang et al (2013), the quality of a dried product depends on several factors and, among them, the internal stresses produced by the distribution of moisture (and temperature) within the product during the transient process. Thus, information on the moisture distribution within the infinite cylinder that represents the banana is important because it permits a subsequent analysis of internal stresses during the drying process.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, it also leads to a change in the water absorbance capacity as well as the transfer of the solutes from the internal part of the product to the surface because of the long drying period and high temperature. According to Yang et al (2013), during drying by heating, the occurrence of moisture content gradients cannot be avoided, which can influence uniformity of moisture diffusion. This effect, together temperature gradients, increases probability of stress concentration and fissure.…”

Section: Introductionmentioning

confidence: 99%

“…Yang et al (2013) showed for heat pump drying at 40°C of Chinese cabbage seeds that 48% energy can be save using the sequence: drying for 400 s and stop for 800 s. In order to simulate the process, Yang et al (2013) used a diffusion model to determine moisture and temperature within the grains at any instant. Other authors have also used diffusion models to describe intermittent drying and, among them, Baini and Langrish (2007) and Dong et al (2009) can be cited.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Comparison between continuous and intermittent drying of whole bananas using empirical and diffusion models to describe the processes

Silva

Rodrígues

Silva

et al. 2015

Journal of Food Engineering

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison between continuous and intermittent drying of whole bananas using empirical and diffusion models to describe the processes

Silva

Rodrígues

Silva

et al. 2015

Journal of Food Engineering

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“…Heat pump (HP) drying can improve energy efficiency and independently control the drying temperature and air humidity (Minea, 2013;Yang et al, 2013;Zielinska et al, 2013;Artnaseaw et al, 2010), which is especially suitable for temperature sensitive vegetables and fruits as drying can occur at low temperature (Fan et al, 2014;Hossain et al, 2013;Hii et al, 2012). However, heat pump drying is a rather slow drying process.…”

Section: Introductionmentioning

confidence: 99%

Drying characteristics of Chinese Yam ( Dioscorea opposita Thunb .) by far-infrared radiation and heat pump

Song

Zhang

2018

Journal of the Saudi Society of Agricultural Sciences

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Chinese Yam chips were dried using a heat pump (HP) dryer alone or in combination with far infrared radiation (FIR) at 500, 1000 and 2000 W (500 FIR, 1000 FIR, and 2000. The experimental results were presented in terms of the drying characteristics, and dried product qualities (shrinkage, color, texture, percentage of rehydration, and moisture content). Samples with initial moisture content of approximately 76% (w.b.) were dried to a final moisture content of <17% (w.b.) at the drying temperature of 50°C and at an air flow rate of 1.0 m s À1 for all of the experiments. The data showed that FIR + HP drying increased the drying rate by reducing the drying time, and the resulted dried Chinese Yam chips generally had higher values of lightness and comparable values of redness and yellowness than the HP-treated samples. In the case of HP + 1000FIR, the dried Chinese Yam chips had lower shrinkage, improved rehydration ability, lower hardness and higher brittleness than those dried by HP, HP + 500FIR and HP + 2000FIR. It is worth noting that the total energy used for FIR-assisted drying processes decreased with the increase of FIR intensity. The present data suggest that HP + FIR drying is an effective and economical method for Chinese Yam chip drying, and HP + 1000FIR can obtain the best dried product. Ó 2016 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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“…[7,8] Intermittent drying has been developed in order to reduce drying time, minimize energy consumption, and maintain product quality. [9] During intermittent drying process, the temperature, relative humidity, pressure, velocity of drying air and the mode of heat input were changed over drying time. [10] Intermittent drying has been applied for different vegetables and fruits.…”

mentioning

confidence: 99%

Drying characteristics and modeling of yam slices under different relative humidity conditions

El‐Mashad

Fang

et al. 2015

Drying Technology

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The drying characteristics of yam slices under different constant relative humidity (RH) and step-down RH levels were studied. A mass transfer model was developed based on Bi-Di correlations containing a drying coefficient and a lag factor to describe the drying process. It was validated using experimental data. Results showed that the drying air with constant RH levels of 20%, 30%, and 40%, temperature of 60 o C and air velocity of 1.5 m/s had insignificant effect on drying time. This phenomenon was likely attributed to the fact that higher RH lead to rapidly increment of sample's temperature. Afterwards, higher sample's temperature could provide an additional driving force to water diffusion and thereby promoted the moisture movement which could minimize the negative effect of lower drying rate in the initial drying stage. Applying air with 40% RH for 15 min in the initial stage achieved the desired color and reduced the drying time by 25% compared to Downloaded by [University of Otago] at 12:28 07 October 2015 2 the drying time under continuous dehumidification from an initial RH of 40%. Using the developed Bi-Di correlation, the estimated Biot number, effective moisture diffusivity and mass transfer coefficient ranged from 0.1024 to 0.1182, from 1.1133×10 -10 to 8.8144×10 -9 m 2 /s and from 1.8992×10 -9 to 1.7364×10 -7 m/s, respectively. A rather high correlation coefficient of determination (R 2 ranged from 0.9871 to 0.9971) was determined between the experimental and predicted moisture contents. The present findings contributed to a better understanding of the effect of relative humidity on drying characteristics. The developed Bi-Di correlation provided a new method to determine the effective diffusivity of moisture in drying. A, B constants in Eq. (14)A p the surface area of the particles exposed to hot air (m 2 ) Bi Biot number for moisture transfer (dimensionless) Di Dincer number (dimensionless) DR drying rate (g·g -1 ·h -1 ) Fo Fourier number for moisture transfer (dimensionless) G lag factor (dimensionless) k moisture transfer coefficient (m·s -1 ) Downloaded by [University of Otago] at 12:28 07 October 2015 3 L characteristic dimension, slab half-thickness (m) M moisture content (dry basis) MR moisture ratio (dimensionless) MR exp,i the ith experimental moisture ratio MR e the equilibrium moisture ratio MR pre,i the ith predicted moisture ratio N the number of observation R 2 correlation coefficient RH relative humidity (%) S drying coefficient (s -1 ) T drying air temperature ( o C) t drying time (h) v flow velocity of drying air (m·s -1 ) μ characteristics coefficient depending on the product geometry CIELAB Parameters

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A comparative study on intermittent heat pump drying process of Chinese cabbage (Brassica campestris L.ssp) seeds

Cited by 52 publications

References 18 publications

Comparison between continuous and intermittent drying of whole bananas using empirical and diffusion models to describe the processes

Comparison between continuous and intermittent drying of whole bananas using empirical and diffusion models to describe the processes

Drying characteristics of Chinese Yam ( Dioscorea opposita Thunb .) by far-infrared radiation and heat pump

Drying characteristics and modeling of yam slices under different relative humidity conditions

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