Closed variable-frequency heat pump drying equipment with heat regenerator, and control method of closed variable-frequency heat pump drying equipment

Abstract

The invention relates to closed variable-frequency heat pump drying equipment with a heat regenerator. The closed variable-frequency heat pump drying equipment is characterized in that the drying equipment comprises a variable-frequency compressor, a condenser, a throttling valve, an evaporator, the heat regenerator, a three-way valve, a variable-frequency fan, an air inlet temperature sensor, anair inlet humidity sensor, a drying bin, an air outlet temperature sensor, an air outlet humidity sensor and a controller. A control method comprises the steps: the controller adjusts the frequency ofthe variable-frequency compressor by comparing the magnitudes of the actual air inlet temperature T1 and the set air inlet temperature T0; the controller adjusts the ratio of the straight flux of thethree-way valve to the regenerative air volume by comparing the magnitudes of the actual air inlet humidity phi1 and the set air inlet humidity phi0; and the controller adjusts the frequency of the variable-frequency fan by comparing the magnitudes of the actual air humidity change value delta phi and the set air humidity difference value delta phi' and the magnitudes of the actual air temperature change value delta T and the set air temperature difference value delta T' of medium air entering and exiting from the drying bin. The closed variable-frequency heat pump drying equipment has the advantages that energy-saving operation of the drying equipment is achieved in the case of meeting drying process parameters.

Description

technical field [0001] The invention relates to a closed frequency conversion heat pump drying equipment with a regenerator and a control method thereof, 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...

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.

In addition, some researchers have proposed heat recovery technology to further save energy in drying equipment, but the process parameters are still difficult to control

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