Heat Pump Dryer Control for Inlet Air Temperature Without Subcooler
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Solution Overview
Problem
Heat pump clothes dryers face challenges in controlling the temperature of the inlet air and discharge temperature during the drying process, leading to energy wastage and potential damage to materials due to high-temperature air, while conventional solutions like subcoolers dissipate heat into the atmosphere, reducing energy efficiency.
Innovation Solution
A clothes dryer with a variable speed compressor and electronic expansion valve, controlled by a controller with temperature and humidity sensors, adjusts the rotational speed and opening of the valve to manage heat quantity and air temperature, eliminating the need for a subcooler and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If energy provided by the refrigerant system remains constant during the drying process, then the temperature of the inlet air to the roller increases continuously, but this causes the materials to be broken by high-temperature air and increases compressor discharge temperature
Solution Approach 1:
The patent applies dynamics by making the compressor speed variable rather than fixed. The controller dynamically adjusts the compressor operating speed based on real-time temperature and humidity conditions in the drying chamber. This allows the system to adapt the refrigerant circulation rate to match the actual drying needs, preventing overheating of materials while maintaining effective drying when moisture is present
Solution Approach 2:
The patent implements feedback control through temperature and humidity sensors that continuously monitor the drying environment. The controller receives this feedback and adjusts the compressor speed accordingly - reducing speed when temperature becomes too high or humidity is low, and increasing speed when more cooling capacity is needed. This closed-loop control prevents material damage while optimizing drying efficiency
2Temperature
If a subcooler is added to control the temperature of inlet air to the roller, then the temperature control is achieved, but heat is dissipated into the atmosphere causing low energy utilization efficiency
Solution Approach 1:
The patent applies self-service by using the refrigerant system itself to provide both cooling and temperature control functions without requiring an external subcooler. The variable speed compressor and electronic expansion valve work together to modulate the refrigerant flow, allowing the system to control inlet air temperature by adjusting refrigerant circulation rather than dissipating heat externally. This eliminates the energy waste associated with traditional subcooling approaches
3Loss of time
If the compressor operates at high power consumption to rapidly increase air temperature, then the temperature rise phase is shortened, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by operating the compressor at different power levels during different phases of the drying cycle. During the temperature rise phase, the compressor operates at higher power to quickly establish effective drying conditions. Once the target temperature is reached, the controller reduces compressor speed to maintain temperature with lower energy consumption. This phased approach minimizes both time loss and overall energy consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively controls the air temperature, reduces energy consumption, and prevents energy wastage by dynamically adjusting the compressor speed and expansion valve opening, ensuring efficient drying without a subcooler.
Implementation Method 1
the condenser is configured to provide heat quantity, required for drying, to the roller
Implementation Method 2
the high-humidity air is cooled and dehumidified by a low temperature evaporator, and the condensate water formed in the above process is discharged
Data Source
AI summary
A clothes dryer and a control method thereof are provided. The clothes dryer includes an air circulation system and a refrigerant circulation system, the refrigerant circulation system includes a compressor, a condenser, a throttling element and an evaporator; the air circulation system includes a filter device, an air circulation power fan and a roller, and the refrigerant circulation system does not include a subcooler; the clothes dryer further includes a controller, a temperature sensor or a temperature-sensing element, and a temperature and humidity sensing element; the controller is configured to control an operation of the refrigerant circulation system, the operation of the clothes dryer includes a temperature rise phase and a basic drying phase, and the compressor of the clothes dryer is configured to have a higher power consumption in the temperature rise phase than in the basic drying phase, to rapidly rise a temperature in the clothes dryer.