Heat Pump Dryer Internal Heat Exchanger for Refrigerant Phase Stability
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Solution Overview
Problem
Heat pump clothes treatment apparatuses face issues with refrigerant phase changes during sudden indoor load changes, leading to potential compressor damage and reduced efficiency due to improper superheat and supercooling control, which affects drying time and energy efficiency.
Innovation Solution
Incorporating an internal heat exchanger within the evaporator to manage superheat and supercooling by exchanging heat between refrigerant discharged from the condenser and that passing through the evaporator, ensuring appropriate phase states and optimizing the heat pump cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the degree of superheat is increased to prevent liquid refrigerant from entering the compressor, then compressor reliability is improved, but evaporator dehumidifying ability deteriorates due to incomplete saturation of refrigerant
Solution Approach 1:
The patent applies preliminary action by pre-heating the refrigerant in the evaporator outlet region before it enters the compressor. The control unit increases the degree of superheat in advance when liquid refrigerant is detected or anticipated, preventing liquid slug formation while maintaining optimal evaporator performance during normal operation
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the degree of superheat based on real-time operating conditions. The control unit monitors refrigerant state and indoor load changes, continuously optimizing the superheat degree to balance compressor protection and evaporator dehumidifying efficiency under varying conditions
2Productivity
If the degree of superheat is decreased to maximize evaporator dehumidifying ability, then productivity is improved, but compressor reliability deteriorates due to risk of liquid refrigerant entry
Solution Approach 1:
The patent applies feedback by continuously monitoring the refrigerant state at the evaporator outlet and using this information to adjust the superheat degree. The control unit receives feedback on refrigerant temperature and pressure, and modifies the expansion valve opening or heating element power to maintain optimal superheat that protects the compressor while maximizing dehumidification
Solution Approach 2:
The patent implements parameter changes by dynamically varying the degree of superheat as a control parameter. The system adjusts this thermodynamic parameter based on operating conditions, transforming it from a fixed value to a dynamically optimized variable that resolves the contradiction between compressor safety and evaporator efficiency
3Stability of the object's composition
If the degree of supercooling is increased to prevent flash gas formation, then refrigerant flow stability is improved, but energy efficiency deteriorates due to excessive heat exchange requirements
Solution Approach 1:
The patent applies partial action by providing just enough supercooling to prevent flash gas formation without excessive cooling. The control unit optimizes the supercooling degree to the minimum necessary level (typically 3-7°C) required to ensure stable refrigerant flow into the expansion valve, avoiding the energy waste associated with over-cooling while maintaining flow stability
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 stabilizes the refrigerant phase, prevents compressor damage, enhances drying efficiency, reduces drying time, and improves energy efficiency by maintaining optimal superheat and supercooling levels throughout the drying cycle.
Implementation Method 1
Incorporating an internal heat exchanger within the evaporator to manage superheat and supercooling by exchanging heat between refrigerant discharged from the condenser and that passing through the evaporator
Implementation Method 2
The liquid refrigerant undergoes heat exchange with air discharged from the drum while passing through the evaporator, and absorbs heat from the air to evaporate and change into gas refrigerant
Implementation Method 3
the refrigerant of the condenser is cooled and condensed as it exchanges heat with air that has passed through the evaporator
Data Source
AI summary
A clothes treatment apparatus, including a drum rotatably provided within a cabinet to accommodate washing and drying objects; and a heat pump including an evaporator, a compressor, a condenser, and an expansion valve, through which refrigerant is circulated, to provide heat to air discharged from the drum and circulated to the drum, wherein the heat pump further includes an internal heat exchanger configured to exchange heat between refrigerant discharged from the condenser and refrigerant passing through the evaporator.