Advances in heat pump systems: A review

http://maghaleh2012.persiangig.com/document/arsalan/zm1.pdf

Drying of eggplant and selection of a suitable thin layer drying model

http://paginas.fe.up.pt/~sereno/publ/2004/JFE_ShrinkReview.pdf

Modelling shrinkage during convective drying of food materials: a review

Mathematical modeling of thin layer solar drying of sultana grapes

Fruits and vegetables are dried to enhance storage stability, minimize packaging requirement and reduce transport weight. Preservation of fruits and vegetables through drying based on sun and solar drying techniques which cause poor quality and product contamination. Energy consumption and quality of dried products are critical parameters in the selection of drying process. An optimum drying system for the preparation of quality dehydrated products is cost effective as it shortens the drying time and cause minimum damage to the product. To reduce the energy utilization and operational cost new dimensions came up in drying techniques. Among the technologies osmotic dehydration, vacuum drying, freeze drying, superheated steam drying, heat pump drying and spray drying have great scope for the production of quality dried products and powders.

/pdf/recent-advances-in-drying-and-dehydration-of-fruits-and-5chud9fawi.pdf

Recent advances in drying and dehydration of fruits and vegetables: a review

Four generic trends of pore formation during drying are identified from the literature. The present prediction methods are mainly based on empirical correlations. It is common to correlate porosity with water content by quadratic, polynomial, or exponential forms of equations, which do not provide insight into the physics of the process. The glass transition theory is one of the proposed concepts to explain the process of shrinkage and collapse during drying. However, the glass transition theory does not hold true for all products. Other concepts, such as surface tension, structure, environment pressure, and mechanisms of moisture transport also play important roles in explaining the formation of pores. It is hypothesized that as capillary force is the main force responsible for collapse, so counterbalancing this force causes formation of pores and lower shrinkage.

Toward prediction of porosity in foods during drying: a brief review

Desorption isotherm and heat pump drying kinetics of peas

The state diagram of date flesh was developed by measuring its freezing points, glass transition temperatures, maximal-freeze-concentration condition ( and ), and solute melting points (or decomposition temperature) by Differential Scanning Calorimetry (DSC). The freezing curve and glass transition lines were developed using Clausius-Clapeyron equation by incorporating concept of unfrozen water, and Gordon-Taylor equation, respectively. The developed state diagram of date flesh can be used in determining its stability during storage as a function of temperature and moisture content (such as, frozen and dried conditions) as well as in designing drying and freezing processes.

State Diagram of Date Flesh Using Differential Scanning Calorimetry (DSC)

Although heat pumps have been used extensively in industry for many years, their use for drying, especially foods, has been limited. This article reviews the potential of heat pump dehumidifier (HPD) dryers for use in food drying. HPD dryers offer several advantages over conventional hot-air dryers for the drying of food products, including higher energy efficiency, better product quality, and the ability to operate independently of outside ambient weather conditions. In addition, this technology is environmentally friendly in that gases and fumes are not given off into the atmosphere. The condensate can be recovered and disposed of in an appropriate manner, and there is also the potential to recover valuable volatiles from the condensate.

M. Shafiur Rahman

Papers

Toward prediction of porosity in foods during drying: a brief review

Desorption isotherm and heat pump drying kinetics of peas

State Diagram of Date Flesh Using Differential Scanning Calorimetry (DSC)

Heat pump dehumidifier drying of food

Prediction of pores formation (porosity) in foods during drying: generic models by the use of hybrid neural network