As the application range of air source heat pump drying becomes wider and wider, users gradually pay more attention to the quality of its drying. However, there are many factors that should go into drying quality other than the equipment and the system itself. So, what are the other factors that affect the drying quality of materials? What is the relationship between them?
1. Temperature: The impact of environmental conditions on air energy products is very important. In seasons or regions with low temperature, the heating efficiency and energy efficiency ratio of air energy products will be reduced. This is the case in the heating and hot water fields, as well as in the drying field. In the common open drying system, air is used as the drying medium to increase the air temperature, that is, the outlet air temperature, so that the drying speed of the material will be accelerated. As the temperature increases, the greater the temperature difference between the heat transfer medium and the material, the greater the rate of heat transfer to the material, and the faster the water escape rate.
2. Humidity: During drying, the lower the relative humidity of the air, the faster the drying rate of the material, and the degree of moisture drop of the material is also determined by the air humidity. In the open system, the humidity of the outside air directly affects the humidity of the air inside the drying room. The higher the humidity, the stronger the system's dehumidification capacity is required. Otherwise, the drying speed of the material will decrease, which will seriously affect the drying of the material. quality after. In the closed system, the effect of air humidity on drying of materials is more obvious, because the air in the drying room is limited, the higher the humidity, the more difficult it is for the moisture to come out of the material, and the dehumidification ability of the unit will become a success or failure. The essential. The moisture of the material should always be in balance with the humidity of the surrounding air. If the air humidity is high, the moisture of the material will not come out, and the purpose of drying will not be achieved.
3. Surface area: The larger the surface area of the material in contact with the air, the faster the water will be taken away. The lower the relative humidity of the air in the drying room, the faster the material will be out of water. The surface area is the paving thickness of the material. During the drying process, the placement of the material will also affect the drying quality. Too much material is placed, that is, the surface area is too large, and the circulating air may not reach in some places, and the uniformity will also be affected; and too little material is placed, that is, the surface area is too small, while wasting energy, it will also As a result, the drying rate is too fast, and the quality requirements of material drying cannot be met.
4. Atmospheric pressure and vacuum degree: Atmospheric pressure affects the balance of water, so it can affect the drying of materials. When drying under vacuum, the vapor pressure of the air is reduced, and the drying speed is faster in the constant temperature stage. In the constant temperature stage, in order to accelerate the moisture evaporation of the material, under the principle of ensuring that the evaporation rate does not exceed the moisture diffusion rate inside the material, the temperature of the air, that is, the drying temperature, should be increased as much as possible. During the cooling stage, efforts should be made to reduce the evaporation rate of water on the surface of the material, so that it can be consistent with the gradually reduced water diffusion rate inside the material, so as to avoid excessive heating of the material surface and affect the drying quality of the material.
5. Air flow rate: heat pump drying, the air flow rate is accelerated, the more heat absorbed by the material, and the faster the drying rate. Not only because the amount of water vapor that the hot air can hold will be higher than that of the cold air to absorb more water, but also the saturated moist air gathered near the surface of the material can be taken away in time, which is conducive to the further evaporation of water in the material. At the same time, due to the increase in the amount of air in contact with the surface of the material, the evaporation of the moisture in the material is significantly accelerated.
The above are the factors that affect the drying quality of materials that we have summarized. If you want to know more about the heat pump dryer, please feel free to leave a message online with us!
