Dishwasher Evaporator Segmentation for Compressor-Safe Superheating
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Solution Overview
Problem
Existing dishwasher heat pump devices face issues with proper operation due to incomplete evaporation of the working fluid, leading to potential compressor defects and freezing of water in the tank, which affects overheating and overall efficiency.
Innovation Solution
The design incorporates a section of the evaporator's pipe coil within the air duct path above the water level, creating two temperature zones to ensure efficient overheating of the working fluid, preventing liquid residues from entering the compressor and maintaining efficient evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the evaporator pipe coil is completely submerged in water within the tank, then heat transfer efficiency is improved, but the working fluid cannot be sufficiently overheated and liquid residues may enter the compressor
Solution Approach 1:
The evaporator pipe coil is segmented into two distinct zones: a lower portion submerged in water for heat transfer, and an upper portion exposed to air for overheating. This segmentation allows each zone to perform its specific function optimally without interfering with the other, resolving the contradiction between heat transfer efficiency and compressor protection.
Solution Approach 2:
Different portions of the evaporator pipe coil are placed in environments with different thermal properties (water vs. air). The lower portion benefits from water's high heat capacity for efficient heat transfer, while the upper portion benefits from air's lower heat capacity for effective overheating, ensuring complete evaporation and preventing liquid residues from reaching the compressor.
2Productivity
If ambient air is introduced into the tank to accelerate water regeneration, then water regeneration speed is improved, but the water temperature drops and freezing occurs, affecting overheating
Solution Approach 1:
The upper portion of the evaporator pipe coil is pre-positioned in the air-filled upper region of the tank before water regeneration begins. This preliminary arrangement ensures that when ambient air is introduced to accelerate water regeneration, the evaporator is already configured to utilize the air for overheating the working fluid, preventing water temperature drop and freezing while maintaining overheating effectiveness.
3Reliability
If the evaporator is positioned to ensure complete evaporation of working fluid, then compressor reliability is improved, but heat transfer efficiency decreases
Solution Approach 1:
The evaporator is segmented vertically with the lower portion optimized for heat transfer in water and the upper portion optimized for overheating in air. This segmentation allows the system to achieve both complete evaporation (protecting the compressor) and efficient heat transfer simultaneously, as each segment operates in its optimal thermal environment.
Solution Approach 2:
The thermal environment parameters are changed along the length of the evaporator pipe coil, transitioning from water immersion (high heat capacity) to air exposure (low heat capacity). This parameter change enables the working fluid to first absorb heat efficiently from water and then be sufficiently overheated by air, achieving both heat transfer efficiency and complete evaporation.
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 ensures complete evaporation of the working fluid, prevents compressor damage, and increases the overall efficiency of the heat pump device by utilizing ambient air to enhance overheating, thus maintaining reliable operation.
Implementation Method 1
a section of the evaporator's pipe coil within the air duct path above the water level, creating two temperature zones to ensure efficient overheating of the working fluid
Implementation Method 2
these air ducts, as provided for in EP 3 375 345 A1, enable the transfer of heat energy from the air in the flushing tank to the water stored in the heat pump unit's tank
Implementation Method 3
it can absorb heat from the surroundings in the subsequent evaporator before being directed to the compressor
Implementation Method 4
heat is extracted from the working fluid by means of the condenser and transferred to the purge fluid. After passing through the condenser, the working fluid passes through the expansion element, which reduces its pressure. Since the working fluid is significantly colder than the ambient temperature in this state, it can absorb heat from the surroundings in the subsequent evaporator
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a dishwasher, in particular a household dishwasher, with a washing container (3) providing a washing chamber (4) for receiving items (5) to be cleaned, and a heat pump device (9) with an evaporator (13) having a coiled pipe (22) through which a working fluid flows, which is arranged within a tank (16) filled with water (21), wherein the tank (16) has an air supply opening (24) connected to an air supply channel (23) and an air discharge opening (26) connected to an air discharge channel (25), wherein an air guide path (32) extending within the tank (16) is provided, which fluidically connects the air discharge opening (26) with the air supply opening (24), wherein the coiled pipe (22) has a section arranged within the air guide path (32).