ABSTRACT

Heat pump (HP) dryers have been used as one of the useful and promising drying techniques in food industries owing to their low energy consumption and costs, high coefficient of performance (COP), high energy efficiency, high drying efficiency, low drying temperature, and time, and less quality loss of dried products. It can be operated over a wide range of temperatures and humidity, providing the optimum conditions for drying of heat-sensitive food materials (vitamins). Many studies were done on food products drying by various HP drying systems such as simple HP, solar-assisted HP, infrared- assisted HP, vacuum HP and ultrasound intensified HP dryers. This paper reviews the effect of different and recent HP drying methods on the drying performance and quality of dried apple, banana, grape, jujube, kiwifruit, and pineapple. Also, this study reported the suitable mathematical models for HP drying modeling of various fruit crops. The HP dryer provides high-quality dried fruits as their drying conditions can be controlled. In addition, combination of solar/infrared/vacuum/ultrasound techniques and HP dryer has been used as an efficient and rapid drying method compared to HP drying alone. The effective moisture diffusivity (D_eff) values lie within in range of 10⁻⁷ to 10⁻¹¹ m²/s for some fruit crops during drying by HP dryer.

Abbreviations: COP: Coefficient of performance; D_eff: Effective moisture diffusivity; HP: Heat pump.

摘要

由于热泵（HP）的能耗低，成本低，性能系数（COP）高，能源效率高，干燥效率高，干燥温度低，因此在食品工业中已成为有用且有前途的干燥技术之一。和时间，减少干燥产品的质量损失。它可以在很宽的温度和湿度范围内运行，为热敏性食品材料（维生素）的干燥提供了最佳条件。通过各种HP干燥系统对食品干燥进行了许多研究，例如简单的HP，太阳能辅助的HP，红外辅助的HP，真空HP和超声强化的HP干燥机。本文概述了不同和最新的HP干燥方法对干燥的苹果，香蕉，葡萄，枣，猕猴桃和菠萝的干燥性能和品质的影响。还，这项研究报告了适用于各种水果作物的HP干燥建模的数学模型。HP干燥机可提供高质量的干燥水果，因为它们的干燥条件可以控制。此外，与单独的HP干燥相比，太阳能/红外/真空/超声波技术与HP干燥器的组合已被用作一种高效，快速的干燥方法。有效水分扩散率（D_eff）值在使用HP干燥机进行干燥的某些水果作物中处于10 ^-7至10 ^-11 m ² / s的范围内。

缩写：COP：性能系数；D _eff：有效水分扩散率；HP：热泵。