Laundry Dryer Temperature Staging for Energy-Saving Final Drying

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Solution Overview

Problem

Conventional drying machines experience reduced water extraction efficiency towards the end of the drying cycle, leading to increased energy consumption and potential damage to delicate garments due to excessive heating.

Innovation Solution

The method involves a three-step drying process with progressively lower target temperatures and adjusted blower speed and cooling fluid intake, optimizing energy consumption and reducing heat exposure to prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drying cycle continues until the humidity threshold is met, then the laundry is almost dry, but energy consumption increases and water extraction efficiency decreases towards the end of the cycle

Engineering Contradiction:
Improvedrying completenessVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The drying cycle is divided into multiple phases with different temperature profiles. The method implements a multi-stage drying process where the temperature is adjusted according to the drying progress, segmenting the continuous drying process into distinct operational stages that optimize energy efficiency at each phase.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating element operates dynamically by adjusting its power output based on the current drying phase. The system transitions from high-power heating during initial drying stages to reduced-power operation in later stages, creating a dynamic control strategy that adapts to the changing moisture content and thermal conditions of the laundry.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the heating element continues to heat the laundry towards the end of the drying cycle, then the laundry is dried completely, but the temperature increases excessively which could damage delicate garments

Engineering Contradiction:
Improvedrying completenessVSAvoidtemperature damage to laundry
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary cooling action by reducing the heating power before the laundry reaches the final dry state. This preliminary reduction in thermal input prevents the temperature from rising to damaging levels while still achieving the desired drying completeness through the accumulated effect of earlier high-temperature phases.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The heating element operates in periodic cycles with varying intensity levels. During later drying stages, the system employs periodic heating pulses or reduced-duty-cycle operation, allowing the laundry to cool between heating intervals and preventing continuous temperature buildup that would damage sensitive fabrics.

Inventive Principle:
Principle #19Periodic action

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 reduces energy consumption and minimizes the risk of damaging laundry by controlling temperature, ensuring efficient drying without excessive heat exposure.

Implementation Method 1

an electrical heating element which enables the fluid for drying the laundry to be heated

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

a blower which moves the fluid long the movement line

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 3

a condenser which, along the direction of flow of the fluid, is interposed between the drum and the electrical heating element

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

a humidity sensor which measures the level of humidity of the laundry and of the fluid for drying the laundry

Methodology Applied
Scientific EffectHumidity sensing: Hygrometer

Data Source

PatentEP2492388B9A method for drying laundry
Publication Date: 2015.03.18 INDESIT COMPANY SPA
  • EP2492388B9 patent drawingFigure 1

AI summary

Described is a method for drying laundry in a drying machine comprising: a drying fluid movement line (2), a rotatable drum (4) designed to receive the laundry to be dried, heating means (3) for heating the drying fluid, the fluid being designed to enter the drum (4). The method comprises the steps of: -performing a first step of drying the laundry in the drum (4) for a duration equal to a predetermined value; the heating means (3) being controlled for the entire duration of the first drying step in order to take the fluid, in a predetermined zone of the movement line (2), to a target temperature equal to a predetermined value; -performing a second step of drying the laundry in the drum (4) for a duration equal to a predetermined value; the heating means being controlled for the entire duration of the second drying step in order to take the fluid, in the predetermined zone of the movement line (2), to a target temperature equal to a predetermined value; the second drying step following the first drying step and the predetermined value of the target temperature in the second drying step being lower than the predetermined value of the target temperature in the first drying step.