Laundry Dryer Moisture Control for Thick Load Drying Uniformity
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Solution Overview
Problem
Existing methods for controlling rotatable-drum laundry dryers fail to ensure uniform drying of laundry with large sizes, high thicknesses, or special fabrics like GORETEX, as they prematurely end the drying cycle based on outer surface moisture measurements, leading to incomplete drying of the inner parts.
Innovation Solution
A method that calculates the quantity/weight of laundry using the behavior of an electrical signal during an initial measuring interval, extends the drying cycle interval based on this calculation, and adjusts the cooling phase duration to ensure uniform drying, using moisture sensors and electronic control systems to manage the drying and cooling processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drying cycle is stopped when the impedance measurement reaches a certain value associated with predetermined final moisture, then the drying process is efficient and timely, but the inner portion of the laundry remains damp due to premature termination
Solution Approach 1:
A multiplicative extension coefficient is introduced as an intermediary factor between the measured drying time and the actual required drying time. This coefficient, determined based on laundry weight and type, extends the drying cycle duration to ensure that the inner portions of thick or bulky laundry items are thoroughly dried, while maintaining efficiency for lighter loads.
Solution Approach 2:
The drying cycle duration is dynamically adjusted by changing the time parameter based on laundry characteristics. The system calculates an extended drying time by multiplying the base drying time (when impedance reaches threshold) by an extension coefficient that varies with laundry weight, thickness, and material type, thereby adapting the drying process to different laundry conditions.
2Reliability
If the drying cycle is extended to ensure uniform drying of inner portions, then drying uniformity is improved, but energy consumption increases
Solution Approach 1:
The drying cycle duration is made dynamic rather than fixed. The system continuously monitors impedance and calculates the appropriate drying time extension based on real-time measurements and laundry characteristics. This dynamic adjustment ensures that each drying cycle is optimized for its specific load, extending time only when necessary for uniform drying while avoiding unnecessary energy consumption for loads that dry quickly.
Solution Approach 2:
The time parameter of the drying cycle is adjusted based on calculated extension coefficients derived from laundry weight and type. By changing the duration parameter dynamically, the system achieves uniform drying when needed while minimizing energy consumption for lighter or more breathable laundry, thereby resolving the contradiction between drying uniformity and energy efficiency.
3Reliability
If the drying cycle duration is extended for all laundry types, then uniform drying is achieved, but the drying time for simple laundry types is unnecessarily increased
Solution Approach 1:
The drying cycle extension is applied locally based on laundry characteristics rather than universally. The system differentiates between various laundry types (cotton, synthetic, thick, thin) and applies appropriate extension coefficients to each category. This localized approach ensures that extended drying time is applied only where necessary for uniform drying, while maintaining efficient, shorter cycles for laundry types that dry uniformly and quickly.
Solution Approach 2:
The drying cycle duration is dynamically adapted to match the specific requirements of different laundry types. By making the time parameter variable and dependent on laundry characteristics, the system achieves uniform drying for complex loads while maintaining optimal efficiency for simple loads, thereby resolving the contradiction between drying uniformity and drying time.
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 approach ensures uniform moisture levels both inside and outside the laundry, even with varying drying capacities and special fabrics, by extending the drying cycle and adjusting the cooling phase based on the calculated weight and moisture levels.
Implementation Method 1
the impedance of the laundry is measured by measuring electrodes positioned contacting the laundry; the moisture of the laundry is determined on the basis of the impedance measurement
Data Source
Figure 1
Figure 2~5
Figure 3~4
AI summary
A method of controlling a rotatable-drum laundry drier (1) for drying laundry; the rotatable-drum laundry drier (1) comprises a rotatable drum (3) for laundry (5) and moisture sensors (22) generating an electrical signal (SM) indicatives of the loaded laundry moisture/quantity. The method comprises the steps of: feeding a flow of air into the drum (3) so that it blows on the laundry (3), rotating the drum (3) about an axis of rotation (6), calculating the quantity/weight of the laundry on the basis of a first quantity (OFFSET) indicative of the behaviour of the electrical signal (SM) in an predetermined initial measuring interval (TTM) of the drying cycle, determining a main cycle interval (TTC) indicative of the time that the electrical signal (SM) takes from the beginning of the drying cycle to meet a relation with a predetermined threshold (TSH), extending the main cycle interval (TTC) on the basis of the calculated quantity/weight of the laundry and the determined main cycle interval (TTC), and interrupting the drying cycle at the end of the extended main cycle interval (TEND).