Low-Temperature Drying Using a Versatile Heat Pump Dehumidifier

Sosle, Venkatesh; Raghavan, G.S.V.; Kittler, R.

doi:10.1081/drt-120018461

Cited by 50 publications

(14 citation statements)

References 9 publications

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“…As the drying progressed, most of the heat exchanged at the evaporator is sensible heat and the temperature of the air entering the drying chamber increased gradually. The results were similar to the fi ndings of Sosle et al (2003). The exhaust drying air temperature was less than that of the inlet air temperature as part of the heat was utilized for raising the temperature of product and its associated water.…”

Section: Smersupporting

confidence: 78%

Performance evaluation of heat pump dryer

Pal

Khan

2010

J Food Sci Technol

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A batch type heat pump assisted dehumidifi ed air dryer was developed successfully with a medium range of temperatures (30-41°C) for safe drying of heat sensitive crops. Dehumidifi cation system of the developed heat pump dryer (HPD) maintained the relative humidity (RH) of air entering the drying chamber below 40%. The inlet drying air temperature decreased during early hours of drying followed by rapid rise between the 2nd and 10th h, after which the temperature was almost stable. The RH of inlet and exhaust drying air increased initially and decreased subsequently with drying time as product became drier. The HPD was found to have a specifi c moisture extraction rate between 0.55 and 1.10 kg/kWh. Energy consumption for HPD for 24 h of operation was found less (4.48-5.05 kWh) than the hot air dryer (5.65-9.6 kWh) while operating under different drying conditions. Better quality dried sweet pepper (Capsicum annuum L.) was obtained in HPD owing to lower drying air temperature.

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Section: Smersupporting

confidence: 78%

Performance evaluation of heat pump dryer

Pal

Khan

2010

J Food Sci Technol

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“…SSD can produce a product with high porous structure at a higher drying rate during the first stage of drying; HPD could then be used to maintain the shape and preserve the color of the drying product. [8][9][10][11][12][13][14][15] The purpose of the present work was to study a two-stage SSD/HPD (superheated steam drying followed by heat pump drying). The effect of tempering between these two stages of drying was also investigated in order to possibly reduce the drying time.…”

Section: Reprintsmentioning

confidence: 99%

Drying Kinetics and Quality of Shrimp Undergoing Different Two-Stage Drying Processes

et al. 2004

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An innovative two-stage drying concept is presented in this article. The work considered drying of shrimp using a superheated steam dryer followed by a heat pump (SSD/HPD) or a hot air dryer (SSD/ AD) both from drying kinetics and dried product quality points of view. The experiments were performed using the first-stage superheated steam drying temperature of 140 C while the second-stage heat pump drying (or hot air drying) was performed at 50 C. The moisture content of shrimp at the end of the superheated steam ORDER REPRINTS drying stage was varied between 30 and 40% (w.b.). The effect of tempering between SSD/HPD was also investigated. Shrinkage, color, rehydration behavior, texture (toughness and hardness), and microstructure of dried shrimp were measured. The results showed that SSD/HPD dried shrimp had much lower degree of shrinkage, higher degree of rehydration, better color, less tough and softer, and more porous than single-stage SSD dried shrimp. It was also found that SSD/AD gave redder shrimp compared to shrimp dried in a single-stage superheated steam dryer. No improvement in terms of shrinkage and rehydration behavior was observed, however.

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“…So, selection of proper drying conditions is necessary to minimize thermal stress and to maintain the relevant compounds that determine the quality of the product. Many researchers have established the positive effect of low temperature drying in conjunction with low RH in improving the product quality (Prasertsan et al 1996;Adapa et al 2002;Alves-Filho 2002;Sosle et al 2003). Modern methods for designing air drying operations depend on the mathematical description of food moisture movement during the process (Hernandez et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Effect of drying conditions on drying kinetics and quality of aromatic Pandanus amaryllifolius leaves

Rayaguru

Routray

2010

J Food Sci Technol

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Pandanus amaryllifolius is a plant with aromatic leaves, which impart the characteristic flavour of aromatic rice. The quality of aromatic Pandanus leaves dried at low temperature (35 °C) and low RH (27%) in a heat pump dryer was evaluated and compared with those obtained from hot air drying at 45 °C. Thin-layer drying kinetics has been studied for both the conditions. To determine the kinetic parameters, the drying data were fitted to various semi-theoretical models. The goodness of fit was determined using the coefficient of determination, reduced chi square, and root mean square error. Aroma, colour, and overall acceptability determination of fresh and dried leaves were made using sensory evaluation. Drying of leaves took place mainly under the falling-rate period. The Page equation was found to be best among the proposed models to describe the thin-layer drying of Pandanus leaves with higher coefficient of determination. The effective moisture diffusivity values were also determined. The effect of low RH was prominent during the initial drying when the product was moist. The effect of temperature was prominent in the later part of drying, which acted as a driving force for moisture diffusion and hence the total drying time was reduced. Retention of aromatic compound 2-acetyl-1-pyrroline content was more in low temperature dried samples with higher sensory scores.

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Low-Temperature Drying Using a Versatile Heat Pump Dehumidifier

Cited by 50 publications

References 9 publications

Performance evaluation of heat pump dryer

Performance evaluation of heat pump dryer

Drying Kinetics and Quality of Shrimp Undergoing Different Two-Stage Drying Processes

Effect of drying conditions on drying kinetics and quality of aromatic Pandanus amaryllifolius leaves

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