Control method of closed variable frequency heat pump drying equipment

Abstract

The invention relates to a control method of closed variable frequency heat pump drying equipment. The control method comprises the following steps: a relation I of equivalent air inlet temperature T0' of a drying bin along with deviation change of actual air inlet humidity phi 1 and set air inlet humidity phi 0 is built; a controller adjusts the frequency of a variable frequency compressor through comparing the actual air inlet temperature T1 with the equivalent air inlet temperature T0'; the controller adjusts the openness of a throttling valve according to the optimal operation demands of aheat pump system and through comparing the actual air inlet humidity phi 1 with the set air inlet humidity phi 0; and the controller adjusts the frequency of a variable frequency fan through comparing the actual humidity change value delta phi of medium air entering and exiting from the drying bin with the set air humidity difference value delta phi' and comparing the actual temperature change value delta T with the set air temperature difference value delta T'. The control method has the following advantage: the drying equipment realizes the operation energy conservation under the conditionof satisfying drying process parameters.

Description

technical field [0001] The invention relates to a control method for frequency conversion heat pump drying equipment, and relates to the field of heat pump energy saving. Background technique [0002] Heat pump drying technology has been widely used in the drying process of food, agricultural products, etc. A notable feature in the drying process of these products is that the heating load changes greatly during the whole process. Speed ​​and product quality are also relatively large. [0003] At present, heat pump drying equipment mostly adopts fixed-frequency heat pump technology, which has poor adaptability to drying process requirements. Not only the drying rate and product quality are difficult to meet the design requirements, but also the energy consumption of drying equipment is relatively high. For this reason, the frequency conversion heat pump drying technology with better heating load adjustment ability has gradually begun to be applied. Although the frequency con...

AI Technical Summary

Problems solved by technology

In the closed frequency conversion heat pump drying equipment, the medium air temperature is generally controlled by adjusting the frequency of the frequency conversion compressor, and the humidity of the circulating air is controlled by adjusting the frequency of the frequency conversion fan. The air volume is too large or too small. When the air volume is too large, not only the power of the fan will increase, but also the energy consumption of the heat pump system will increase; when the air volume is too small, the drying rate and uniformity of the materials in the drying chamber will be poor.

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