Effect of greenhouse on crop drying under natural and forced convection I: Evaluation of convective mass transfer coefficient

Jain, Dilip; Tiwari, G.N.

doi:10.1016/s0196-8904(03)00178-x

Cited by 99 publications

(37 citation statements)

References 11 publications

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“…Similar results were observed by Jain and Tiwari (2004). The total energy for moisture removal from the crop, at any given temperature and pressure, is the sum of the latent heat of vaporisation and the binding energy of the moisture in the crop.…”

Section: Discussionsupporting

confidence: 84%

“…The vapour pressure in the crop increases with increase of crop temperature. On the other hand, the vapour pressure in the air reduces as the relative humidity (RH) of the air reduces, and this can be achieved by increasing the air temperature (Rogers and Mayhew, 1993;Jain and Tiwari, 2004). Thus crop drying becomes very effective when both the crop and the surrounding air are constantly warm.…”

Section: Introductionmentioning

confidence: 99%

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Field Drying of Cassava in a Solar Tent Dryer equipped with a Solar Chimney

Afriyie¹,

Achaw²,

Aikins³

et al. 2016

IJSEA

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Abstract:The performance of a solar tent dryer equipped with a solar chimney, as against that of open sun drying, was examined in the drying of cassava. An initial no-load trial was done, followed by trials with the dryer loaded with cassava. One drying trial was performed with the crops on the lower shelf, another with the crops on the upper shelf and a third trial with the dryer loaded on both the lower and upper shelves. In each drying trial, some cassava were also dried in the open sun which results were compared to that of the dryer. In the no-load process, the temperature inside the dryer increased with height due to thermo-syphon effects. But this trend was distorted by the evaporation of moisture from the crops during the drying processes, especially at the initial stages. About 75% to 80% of the drying process occurred within the first two days and nights of the drying periods. The open-sun drying was faster at the initial stages of drying, especially when the crops were on the lower shelf or the dryer was fully loaded. But the performance of the dryer overtook that of the open sun drying at later stages of drying. Thus, the dryer started more slowly but finished earlier than the open-sun drying. The best drying performance was observed when the crops were high up the dryer, though only a small amount of crops could be allowed at this height due to the design of the dryer.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Field Drying of Cassava in a Solar Tent Dryer equipped with a Solar Chimney

Afriyie¹,

Achaw²,

Aikins³

et al. 2016

IJSEA

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“…It concluded that the drying operation allow the exploitation of polyethylene greenhouses in summer time when not used [9].Jain and Tiwari studied of convective mass transfer coefficient and performed moisture removal rate from cabbage and peas for open sun and inside greenhouse drying. It concluded in natural mode, the convective mass transfer coefficient was lower inside the greenhouse drying as compared to open sun drying and in the initial stage of drying, its value was doubled below forced mode inside greenhouse drying than natural convection [10].Tiwari et al made an attempt to check out the convective mass transfer coefficient by regression analysis during jaggery drying in the roof type even span greenhouse under natural and forced convection mode. It was found that the complete drying of jaggery under forced convection as quicker than under natural convection as expectable and convective mass transfer coefficient in forced convection was greater than in natural convection mode [11].Jain and Tiwari presented mathematical model to investigate the effect of greenhouse on crops drying (Cabbage and Peas) under natural and forced convection and for open sun drying (natural convection) [12].…”

Section: Literature Reviewmentioning

confidence: 99%

A Review Paper on Solar Greenhouse Dryer

Nidhi¹

2016

IOSR

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“…The heat and mass transfer coefficients are important parameters in the simulation of drying rates, since the temperature difference between the air and food product varies with these coefficients. Jain D [28] evaluated the convective heat-transfer coefficient for some of the crops (green peas, green chillies, white gram, onion, onions and potatoes) under solar drying condition and developed a mathematical model to predict the drying parameters [29]. Further studies the dependence of convective heat-transfer coefficient on the drying time during complete solar drying process of green peas and cauliflower.…”

Section: Effect Of Drying Characteristic On Quality Of Garlicmentioning

confidence: 99%

Effect of Drying Characteristics of Garlic-A Review

Singh¹,

Singh²,

Singh³

et al. 2014

J Food Process Technol

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Natural sun drying is one of the most common ways to preserve agricultural products. The main purpose in drying farm produce is to reduce its water activity from the harvest level to the safe storage level in order to extend its shelf life. Once the produce has been dried, its rate of deterioration due to respiration, insects, and microbial activity and biochemical reactions should diminish leading to maintenance of quality of the stored product. It is improve bargaining position of the farmer to maintain relatively constant price of his product. Drying reduces post-harvest losses and transportation costs since most of the water are taken out from the product during the drying process. In India, sun drying is the most commonly used method to dry the agricultural material like grains, fruits and vegetables. In sun drying, the garlic is spread in a thin layer on the ground and exposed directly to solar radiation, ambient temperature, wind velocity, relative humidity, initial moisture content, absorptive, exposure time and mass of product per unit exposed area. Direct sun drying has been a popular method of crop drying in the farms and villages. Sun drying allows for the production of a product rich in colour and translucent in appearance, but it has some disadvantages (e.g. it is a time-consuming process, weather depended, labour demanded and it is greatly exposed to possible environmental contamination. Solar driers using natural convection or forced circulation have been investigated to overcome these problems. For commercial applications, the ability of the dryer to process continuously throughout the day is very important to dry the garlic to its safe storage level and to maintain the its quality. Garlic (Allium sativum L.) is a nutritional herbaceous plant known for its medicinal as well as culinary benefits, which originated from the mountains of Central Asian regions Globally, China is by far the largest producer of garlic, producing over 75% of world tonnage followed by India, Korea, and the USA (FAOSTAT, 2005). Food drying is one of the oldest methods of preserving food for later use.

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Effect of greenhouse on crop drying under natural and forced convection I: Evaluation of convective mass transfer coefficient

Cited by 99 publications

References 11 publications

Field Drying of Cassava in a Solar Tent Dryer equipped with a Solar Chimney

Field Drying of Cassava in a Solar Tent Dryer equipped with a Solar Chimney

A Review Paper on Solar Greenhouse Dryer

Effect of Drying Characteristics of Garlic-A Review

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