Cross-Flow Heat Exchanger Layout for Better Dryer Dehumidification

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Solution Overview

Problem

Current dryers are energy-intensive due to inefficient heat exchangers, which hinder effective moisture separation from warm, humid air, and the use of heat pumps increases costs and maintenance.

Innovation Solution

Designing the exhaust air duct and cross-flow heat exchanger to direct a larger proportion of process air to the cooling flow inlet side, where the cooling flow enters, enhancing moisture separation without increasing cooling capacity, using flow guide bodies to optimize air flow and heat exchange.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the process air flow is distributed uniformly over the heat exchanger surface, then heat exchange efficiency is improved, but device complexity increases due to additional flow guide bodies and duct design modifications

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidduct design complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The invention applies local quality by creating a dedicated first process air flow path with optimized geometry that directs process air preferentially to the cooling flow inlet side of the heat exchanger. This localized flow optimization in a specific region of the heat exchanger achieves improved heat exchange efficiency without requiring complex flow distribution across the entire heat exchanger surface, thus balancing energy efficiency with design simplicity.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If heat pump is used to improve energy efficiency, then energy consumption is reduced, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improveenergy consumptionVSAvoidsystem complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The invention applies self-service by utilizing the existing cooling air flow and heat exchanger components already present in the dryer system to achieve improved energy efficiency. The optimized process air duct geometry enables the system to recover and reuse heat from the cooling air stream without requiring external heat pump equipment, allowing the dryer to improve its own energy efficiency using its existing components.

Inventive Principle:
Principle #25Self-service

3Productivity

If cooling capacity is increased to improve moisture separation, then dehumidification efficiency is improved, but energy consumption increases

Engineering Contradiction:
Improvedehumidification efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The invention applies preliminary action by pre-optimizing the process air flow distribution before it reaches the heat exchanger. The specially designed first process air flow path with optimized geometry directs the process air to preferentially contact the cooling flow inlet side of the heat exchanger, where the temperature difference is greatest. This preliminary flow arrangement maximizes heat exchange efficiency and moisture separation without requiring additional cooling capacity or energy input.

Inventive Principle:
Principle #10Preliminary 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 configuration improves dehumidification efficiency, reducing energy consumption and eliminating the need for increased cooling, resulting in a more efficient and cost-effective dryer with lower maintenance requirements compared to heat pump systems.

Implementation Method 1

the process air is cooled in a heat exchanger, it being possible for a filter, in particular a fluff filter, to be connected upstream of the heat exchanger. Due to the cooling of the process air in the heat exchanger, the moisture contained in the process air generally condenses

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

Due to the cooling of the process air in the heat exchanger, the moisture contained in the process air generally condenses and can be discharged as condensate

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

the process air is heated before it enters the drying chamber

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 4

air (so-called 'process air') is usually conducted by means of a blower through a drying chamber

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP2565321B1Dryer with a cross-flow heat exchanger and method for operating same
Publication Date: 2015.01.14 BSH HAUSGERATE GMBH
  • EP2565321B1 patent drawingFigure 1
  • EP2565321B1 patent drawingFigure 2
  • EP2565321B1 patent drawingFigure 3

AI summary

The invention relates to a dryer 1, comprising a control device 11, a process air duct 2,12 in which a heater 27, a drying chamber 3 for objects to be dried, a blower 15 and a cross-flow heat exchanger 14 are arranged, with the process air duct 2,12 being a supply air duct 12 in front of the drying chamber 3 and an exhaust air duct 2 between the drying chamber 3 and the cross-flow heat exchanger 14, and the exhaust air duct 2 and/or the cross-flow heat exchanger 14 is/are designed in such a way that a larger proportion p*M of a process air volume M that passes through the exhaust air duct 2 flowing into the cross-flow heat exchanger 14, where p>0.5, is directed to a cooling flow inlet side 24 of the cross-flow heat exchanger 14. The invention also relates to a method for operating this dryer.