Heat Pump Clothes Dryer Bypass Duct for Pressure Control
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Solution Overview
Problem
Conventional condensing type clothes dryers with heat pump cycles face issues due to increased evaporation and condensation pressures during the drying process, leading to inefficient energy use and prolonged drying times, often requiring additional components like inverter compressors or secondary condensers that increase fabrication costs.
Innovation Solution
A condensing type clothes dryer with a bypass flow path in the circulation duct, where a portion of the air discharged from the drum bypasses the evaporator to mix with air passing through it at the upstream side of the condenser, controlled by a solenoid-actuated damper, to manage evaporation and condensation pressures and reduce flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air is passed through the evaporator and condenser sequentially in a heat pump cycle, then heat exchange efficiency is enhanced and drying time is reduced, but evaporation pressure and condensation pressure increase to values exceeding compressor reliability limits
Solution Approach 1:
The air flow path is segmented into two separate paths: one path passes through the evaporator for heat exchange, while another path bypasses the evaporator. This segmentation allows control over the amount of air undergoing heat exchange, thereby managing pressure levels while maintaining drying efficiency.
Solution Approach 2:
A damper is introduced to dynamically adjust the bypass flow path, enabling real-time control of air flow distribution between the heat exchange path and bypass path. This dynamic adjustment allows optimization of pressure levels during different drying stages while maintaining system reliability.
2Temperature
If the circulation duct and heat exchanger are formed with no gap to maximize air passage, then heat transfer coefficient and air speed are increased, but evaporation pressure and condensation pressure rise beyond safe operating limits
Solution Approach 1:
The air flow is segmented into heat exchange flow and bypass flow, allowing the system to maintain the no-gap configuration for maximum heat transfer while controlling the proportion of air exposed to heat exchange, thereby managing pressure levels.
Solution Approach 2:
The bypass flow path acts as an intermediary mechanism that mediates between the conflicting requirements of maximum heat transfer (no-gap configuration) and pressure control, allowing the system to operate at optimal heat transfer efficiency without exceeding pressure limits.
3Stress or pressure
If additional components like inverter compressors or secondary condensers are added to control pressure, then pressure can be maintained below reference values, but fabrication cost increases
Solution Approach 1:
The system uses the existing air flow and heat exchangers to self-regulate pressure through the bypass mechanism, eliminating the need for additional active pressure control components like inverter compressors or secondary condensers, thereby maintaining pressure control while avoiding increased fabrication costs.
Solution Approach 2:
The bypass flow path and damper serve multiple functions: they control evaporation and condensation pressures, regulate air flow distribution, and maintain system reliability, all while using simple, cost-effective components rather than expensive specialized equipment.
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 solution maintains pressures below reference values, enhances air flow and heat transfer efficiency, shortens drying time, and saves energy without the need for additional components like inverter compressors, thereby reducing costs and improving thermal efficiency.
Implementation Method 1
thermal energy of air having passed through the drum 1 may be transferred to a refrigerant via the evaporator 5, and then the thermal energy of the refrigerant may be transferred to air introduced into the drum 1 via the condenser 6
Implementation Method 2
thermal energy of air having passed through the drum 1 may be transferred to a refrigerant via the evaporator 5
Implementation Method 3
the thermal energy of the refrigerant may be transferred to air introduced into the drum 1 via the condenser 6
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A condensing type clothes dryer having a heat pump cycle includes: a drum (110) where an object to be dried is accommodated; a circulation duct (120) which forms a circulation passage such that air circulates via the drum (110); a circulation fan (130) configured to circulate the air along the circulation duct (120); a heat pump cycle (140) having an evaporator (141) and a condenser (142) spaced from each other in the circulation duct (120), and configured to absorb heat of air discharged from the drum (110) through the evaporator (141), and to transfer the heat to air introduced into the drum (110) through the condenser (142), by using an operation fluid which circulates via the evaporator (141) and the condenser (142); a bypass flow path (150) formed at the circulation duct (120) such that part of air discharged from the drum (110) bypasses the evaporator (141) to thus be mixed with air having passed through the evaporator (141) at an upstream side of the condenser (142); and an opening and closing unit (151, 160, 161, 162, 163) installed at the bypass flow path (150), and configured to selectively open or close the bypass flow path (150).