A multi-stage heat pump drying system and its control method

Abstract

The invention discloses a multi-stage heat pump drying system and its control method, and relates to the technical field of heat pump drying. The system includes a multi-stage heat pump circulation subsystem and a drying medium circulation subsystem; the multi-stage heat pump circulation subsystem includes an R410a heat pump circulation sub-system System, R134a heat pump circulation subsystem, R744 heat pump circulation subsystem and heat pipe circulation subsystem. Using the control method of the above system of the present invention to control the opening and closing of the air volume regulating valve, 6 working modes can be realized for the drying medium, such as air supply up and down the drying box, bypass between the front and back of the condenser, and fresh air before and after the evaporator; control compressors at all levels It can realize the first-level dehumidification and heating and drying mode, the second-level dehumidification and heating and drying mode, and the third-level dehumidification and heating and drying mode; control the speed of multiple inverter compressors to achieve the optimal matching relationship between the evaporation and condensation temperatures of different units. It solves the problem of high pressure ratio and low efficiency of the compressor in the single-stage heat pump drying system, shortens the drying time and saves energy consumption.

Description

technical field [0001] The invention relates to the technical field of heat pump drying, in particular to a multi-stage heat pump drying system and a control method thereof. Background technique [0002] Drying is a process with high energy consumption. In China, the energy consumption of drying equipment accounts for 12% of the total energy consumption of GDP, but the energy utilization rate of drying technology is only 40% to 50%. Traditional hot air drying is widely used due to its low cost, and currently occupies a dominant position in my country. Because the air with high temperature and high humidity is continuously discharged through replacement, it has disadvantages such as large energy consumption and slow drying speed, and the drying room The uniformity of temperature and humidity is poor, and the hot and humid environment formed is not easy to control. The heat pump can recover the energy of the waste heat of the waste gas in the drying process, recycle it and reu...

AI Technical Summary

Problems solved by technology

However, its equipment consumes a lot of energy, requiring multiple compressors to run in series, and the system consumes a lot of energy

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