Heat Pump Dryer Load Detection Using Humidity and Motor Current
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Solution Overview
Problem
Existing dryers face inaccuracies in detecting dryness due to irregular material contact with electrode sensors, leading to over-drying or under-drying issues, especially with varying material types and quantities, and inefficient energy usage.
Innovation Solution
A dryer system that includes humidity and current detectors to determine the drying load, allowing for controlled motor and heat source operations based on detected humidity and current, using a heat pump with a compressor, condenser, expansion valve, and evaporator to adjust drying conditions, and an electrode sensor for additional drying time calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If electrode sensor is used to detect dryness, then drying process can be automated, but measurement precision deteriorates due to irregular material contact
Solution Approach 1:
The patent introduces an intermediary mechanism (rotating drum with multiple contact points) between the electrode sensor and the drying material. This mediator ensures consistent electrical contact by bringing different portions of the material into contact with the sensor during rotation, thereby improving measurement precision while maintaining automation.
2Loss of energy
If drying process is based on flow passage temperature, then energy consumption is reduced, but manufacturing precision deteriorates due to insufficient internal drying
Solution Approach 1:
The patent implements dynamic control of the drying process by continuously monitoring both flow passage temperature and drying material humidity, and adjusting drying parameters in real-time. This dynamic approach ensures that energy-efficient temperature-based drying does not compromise the internal drying quality of the material.
Solution Approach 2:
The system incorporates feedback mechanisms where humidity sensors monitor the actual drying progress of the material and provide this information back to the control system. The controller then adjusts the heating and airflow parameters to ensure thorough internal drying while maintaining energy efficiency, resolving the contradiction between energy savings and drying quality.
3Productivity
If high rpm is maintained for large load, then productivity is improved, but use of energy worsens due to excessive motor power consumption
Solution Approach 1:
The patent implements dynamic rpm control where the motor speed is automatically adjusted based on the detected load size and drying progress. For large loads, the system initially maintains high rpm for rapid drying but dynamically reduces speed as the material approaches target humidity, optimizing the balance between productivity and energy consumption.
Solution Approach 2:
The system changes operational parameters (motor rpm, heater power, airflow rate) based on detected conditions. When processing large loads, the controller adjusts these parameters to maintain high productivity initially, then gradually reduces them as drying progresses, preventing excessive energy consumption while maintaining efficient drying rates.
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 system improves drying accuracy and energy efficiency by adjusting drying conditions based on detected humidity and current, preventing over-drying and ensuring thorough drying across different materials, while optimizing energy consumption.
Implementation Method 1
a heat pump configured to circulate a refrigerant in order of the compressor, the condenser, the expansion valve, and the evaporator
Implementation Method 2
control moisture included in air discharged from the drum through heat exchange in the evaporator
Implementation Method 3
an evaporator connected to the expansion valve
Implementation Method 4
a motor configured to apply a rotating force to the drum
Implementation Method 5
a heat source configured to supply hot air to the drum
Data Source
AI summary
A dryer according to the disclosure may detect current flowing through a motor for rotating a drum, detect humidity of a drying material accommodated in the drum, compare the detected humidity to a plurality of pieces of reference humidity and compare the detected current to a plurality of pieces of reference current to obtain a drying load, control a revolutions per minute (rpm) of the motor, a frequency of a compressor provided in a heat pump, and a degree of superheat of an evaporator provided in the heat pump based on the drying load, perform a drying process, detect humidity of the drying material while the drying process is performed, and finish the drying process in response to the detected humidity determined to be target humidity.