Heat pump laundry dryer
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Solution Overview
Problem
Conventional laundry dryers, particularly condense dryers, have inefficient heat transfer due to non-uniform air flow and turbulence within the air conduit, leading to longer drying cycles and higher energy consumption compared to vented dryers.
Innovation Solution
The design incorporates a heat pump system with optimized heat exchanger modules featuring stacked heat exchange layers and common fins connecting adjacent modules, which enhance heat exchange surface area while minimizing turbulence and maintaining the same overall volume, thereby improving air flow uniformity and heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat exchangers are used in laundry dryers, then the structure is simple, but the heat transfer efficiency is low due to non-uniform air flow and turbulence
Solution Approach 1:
The heat exchanger is divided into multiple stacked heat exchange layers, each layer consisting of multiple channels. This segmentation allows the air flow to be distributed more uniformly across multiple parallel paths, reducing turbulence and improving heat transfer efficiency while maintaining a manageable structural complexity through modular design.
Solution Approach 2:
The patent transitions from a single-plane heat exchanger to a three-dimensional stacked structure with multiple layers arranged in the vertical dimension. This dimensional change increases the heat exchange surface area and allows air to flow through multiple levels simultaneously, improving heat transfer efficiency without significantly increasing the horizontal footprint.
2Loss of energy
If heat exchange surface area is increased, then heat transfer efficiency improves, but the volume of the heat exchanger increases
Solution Approach 1:
Multiple heat exchange layers are stacked vertically one on top of another within a compact housing, creating a nested arrangement. This nesting approach packs a large total heat exchange surface area into a small vertical space, increasing efficiency without proportionally increasing the overall volume occupied by the heat exchanger assembly.
Solution Approach 2:
The heat exchange surface area is expanded primarily in the vertical dimension through stacking, rather than expanding horizontally. This allows the heat exchanger to achieve high surface area-to-volume ratio by utilizing the vertical space efficiently, maintaining a compact overall volume while maximizing heat transfer capability.
3Productivity
If air flow velocity is increased to reduce drying time, then productivity improves, but turbulence increases and heat transfer efficiency decreases
Solution Approach 1:
The air flow is divided into multiple parallel streams through the multiple channels in each layer and across multiple layers. This segmentation allows air to move at higher velocities through each individual channel without creating excessive turbulence, as the flow is distributed across many paths rather than concentrated in a single stream.
Solution Approach 2:
The air flow path is extended in the vertical dimension by passing through multiple stacked layers, allowing the air to maintain higher velocities over a longer effective path length. This increases productivity by reducing drying time while the multi-layer structure maintains laminar flow characteristics that preserve heat transfer efficiency.
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 results in a more efficient heat transfer process, reducing energy consumption and drying time by optimizing the geometry of the heat exchanger modules within the laundry dryer, enhancing the control of air flow and maximizing the heat exchange surface area.
Implementation Method 1
a condenser where the refrigerant is cooled off and the process air stream is heated up
Implementation Method 2
thermally coupled to the process air conduit to perform heat exchange between said refrigerant flowing in said heat pump circuit and said process air stream
Implementation Method 3
an evaporator where the refrigerant is heated up and the process air is cooled off
Implementation Method 4
thermally coupled to the process air conduit to perform heat exchange between said refrigerant flowing in said heat pump circuit and said process air stream
Implementation Method 5
a compressor and a pressure-lowering device; said layers being stacked one above the others in a predetermined stacking direction
Implementation Method 6
optimized heat exchanger modules featuring stacked heat exchange layers and common fins connecting adjacent modules, which enhance heat exchange surface area while minimizing turbulence and maintaining the same overall volume
Implementation Method 7
minimizing turbulence and maintaining the same overall volume, thereby improving air flow uniformity and heat transfer efficiency
Data Source
Figure 1~3
Figure 2~10
Figure 4a~4b
AI summary
The invention relates to a laundry dryer (1) comprising: a casing (2) supporting a drying chamber (3) for receiving a load to be dried; a process air conduit (11) in communication with the drying chamber (3) where a process air stream is apt to flow, a heat pump (30) having a heat pump circuit in which a refrigerant (R) can flow, said heat pump circuit including a first heat exchanger (31) where the refrigerant is cooled off and the process air stream is heated up, and a second heat exchanger (32) where the refrigerant is heated up and the process air is cooled off; said first and/or second heat exchanger being thermally coupled to the process air conduit (11) to perform heat exchange between said refrigerant flowing in said heat pump circuit and said process air stream; said first and/or second heat exchanger (31;32) further comprising a first (10) and a second heat exchanger module (10'), each module (10; 10') including an inlet header (5; 5') to direct a flow of said refrigerant (R) into said module (10, 10'); an outlet header (6; 6') to discharge said refrigerant (R) from said module (10, 10'); and a plurality of heat exchange layers (8; 8') fluidly connecting said inlet (5; 5') to said outlet header (6; 6') to enable said refrigerant (R) to flow from said inlet to said outlet header and/or vice versa; said layers (8; 8') being stacked one above the others in a predetermined stacking direction (Z; Z') and each layer (8; 8') including a plurality of channels (7); wherein said first and said second heat exchanger modules (10,10') are mounted adjacent one to the other and a first heat exchange layer (8) of the first module (10) and a second heat exchange layer (8') of the second module (10) are separated by a gap (g) in a direction incident to said stacking direction (Z, Z'), said first and said second heat exchanger modules (10, 10') including a plurality of fins (50) arranged on both said first and said second heat exchange layers (8, 8') and extending through said gap (g).