Heat Pump Dishwasher Drying Duct to Prevent Refrigerant Flooding
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Solution Overview
Problem
Refrigerant flooding in heat pump dishwashers occurs due to insufficient evaporation in the evaporator, leading to irreversible compressor damage and reduced performance, as the refrigerant enters the compressor in both liquid and gaseous phases, causing viscosity issues and abrasion.
Innovation Solution
A dishwasher design that includes a hot air duct connected to the drying duct, with a flap or independent hot air fan directing hot and humid air from the tub to the evaporator, providing additional heat transfer to ensure the refrigerant evaporates completely before entering the compressor, thus preventing liquid flooding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refrigerant circulation amount is increased to improve heating performance, then the heating efficiency is improved, but the risk of refrigerant flooding to the compressor increases
Solution Approach 1:
The patent implements a feedback control system using a temperature sensor to detect the refrigerant temperature at the evaporator outlet. When the temperature is below a predetermined threshold indicating incomplete evaporation, the expansion valve opening is adjusted to increase refrigerant flow to the evaporator, ensuring complete evaporation before compressor intake and preventing flooding while maintaining heating efficiency
Solution Approach 2:
The patent dynamically adjusts the expansion valve opening degree based on real-time refrigerant temperature measurements. By changing the valve opening parameter according to evaporator outlet temperature conditions, the system optimizes refrigerant flow to ensure complete evaporation while preventing flooding, thus resolving the contradiction between heating performance and compressor reliability
2Reliability
If the refrigerant evaporation is accelerated to prevent flooding, then the compressor protection is improved, but the heating efficiency may be reduced
Solution Approach 1:
The feedback control system continuously monitors evaporator outlet temperature and adjusts the expansion valve opening accordingly. This ensures the refrigerant is completely evaporated before reaching the compressor (protecting reliability) while maintaining optimal refrigerant flow for efficient heat transfer (preserving heating efficiency)
Solution Approach 2:
The system dynamically adjusts the expansion valve opening degree based on real-time operating conditions rather than using a fixed setting. This dynamic adjustment allows the system to adapt to varying load conditions and ambient temperatures, ensuring complete evaporation for compressor protection while optimizing heating efficiency under different operating scenarios
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 ensures the refrigerant enters the compressor solely in the gaseous phase, preventing damage and maintaining compressor performance and durability by ensuring complete evaporation, even under varying ambient conditions.
Implementation Method 1
the refrigerant assuming a low temperature and low pressure, draws heat from the environment while passing through an evaporator, and evaporates by shifting from the liquid phase to gaseous phase
Implementation Method 2
The refrigerating fluid exiting from the compressor arrives to the condenser, begins losing heat by dissipating heat to the outer environment, and condenses
Implementation Method 3
the compressor enabling circulation of a refrigerant by pressurizing it. The refrigerating fluid reaches high pressures and temperatures by means of the compressor compressing and pressurizing the refrigerating fluid
Data Source
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AI summary
The invention relates to a dishwasher (1 ) in which refrigerant flooding problem is eliminated, comprising a tub (2) in which washing, rinsing and drying processes are performed, at least one basket (3) in which the items to be washed are placed, a circulation pump (5) enabling by means of at least one spray arm (4) sending the washing water on the items to be washed, a drying duct (6) enabling after washing process cycling the humid air in the tub (2) by discharging the humid air from the tub (2) and thereby drying the washed items, a drying fan (7) enabling flow of the air in the drying duct (6), and a heat pump system (8) provided on the lower side of the tub (2), enabling heating the washing water.