By controlling the working conditions of the device, the temperature of the hot dry air in the drying chamber is between 20 and 80 °C, which can meet the high-quality drying requirements of most heat-sensitive materials; the closed cycle of the drying medium can avoid the exchange of air with the outside world. Possible contamination of materials by impurities, which is especially important for food, pharmaceuticals, or biological products. In addition, when the material is sensitive to oxygen in the air (easy to oxidize or burn and explode), an inert medium can also be used instead of air as the drying medium to achieve oxygen-free drying.

The heat of heating the air in the heat pump dryer mainly comes from the sensible heat and latent heat contained in the warm and humid air discharged from the recovery drying room. The energy that needs to be input is only the power consumption of the heat pump compressor, and the heat pump can consume a small amount of work Taking advantage of a large amount of heat, the SMER (the amount of moisture in the wet material removed by the unit energy consumed) of the heat pump drying device is usually 1.0 ~ 4.0kg/kWh, while the SMER value of the traditional convection dryer is about 0.2 ~ 0.6kg/kWh.

When the material has high requirements on the temperature and humidity of the air entering the drying room (such as wood, etc.), the evaporating temperature and condensation temperature of the working fluid in the evaporator and condenser can be adjusted to meet the material’s texture, appearance, and other aspects. Require.

Some materials contain volatile components (such as fragrance and other volatile components). When drying with a heat pump, the volatile components and moisture are vaporized into the air together in the drying room, and the air containing the volatile components passes through the evaporator. When it is cooled, the volatile components in it are also liquefied and discharged together with the condensed water. The condensed water containing the volatile components is collected, and the useful volatile components can be separated by an appropriate method.

In the heat pump drying device, the drying medium is closed and circulated, and there is no pollution caused by material dust, volatile substances and odors discharged to the environment with the drying exhaust gas; the waste heat in the exhaust gas of the drying chamber is directly recovered by the heat pump to heat the cold and dry air, and there is no pollution. Thermal pollution of the unit to the environment.

The heat pump in the heat pump drying device also has a cooling function. In the season with fewer drying tasks, the cooling function can be used to achieve low-temperature processing (such as quick freezing, refrigeration) or fresh-keeping of various materials, and it can also expand the heating function of the heat pump in cold weather. Season heating for cultivation (eg greenhouses) or farms.

The materials suitable for drying are mainly a large class of materials that can withstand temperatures between 20 and 80 °C during the drying process or materials that can withstand higher temperatures but are more energy-efficient or safe to use heat pumps to dry. Materials that have been researched and applied such as wood (such as oak), grains, seeds, edible fungi (such as mushrooms, fungus), medicinal materials (such as ginseng, etc.), seafood (such as fresh oysters, scallops, etc.), biologically active products ( Such as cells, enzymes), tea, paper, etc.

Compared with other low-temperature (air temperature into the drying chamber <40℃) drying devices (such as microwave drying, vacuum drying, and freeze-drying), due to the small initial investment of equipment and low operating costs, the heat pump dryer device has the obvious economy. The equipment cost of the heat pump drying device is mainly the heat pump part and the drying chamber part. The drying chamber part has the same requirements as the ordinary convection drying chamber, and there are no special air tightness and pressure bearing requirements.