Refrigeration appliance and method for the operation thereof
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Solution Overview
Problem
Existing refrigeration devices with multiple temperature zones struggle to maintain stable temperature control due to unsatisfied cooling demands leading to undesirable temperature fluctuations, as they redistribute cooling capacity without accounting for changing cooling requirements across zones.
Innovation Solution
A refrigeration device with a compressor and evaporators connected in series, featuring a controllable throttle point and independent compressor and throttle controllers that adjust compressor speed and throttle opening based on temperature zone setpoints, allowing for separate control of each zone without affecting others, using proportional-integral (PI) controllers for quick adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the throttling on the controllable expansion valve upstream of the evaporator in a temperature zone is increased to satisfy unsatisfied cooling requirement, then the evaporation temperature in the relevant evaporator decreases, but the throttling in downstream expansion valves must be reduced to maintain unchanged overall throttling, causing cooling capacity redistribution and temperature fluctuations in other zones
Solution Approach 1:
The patent divides the control of the refrigeration system into independent segments: each expansion valve is controlled independently based on its own evaporator's temperature feedback, rather than controlling the entire refrigerant circuit as a single unit. This segmentation allows local optimization without causing system-wide temperature fluctuations.
Solution Approach 2:
The control strategy applies local quality by making each expansion valve's throttling independent of others, allowing each evaporator to maintain its own optimal evaporation temperature based on local cooling demands. The controllable expansion valves are positioned upstream of each evaporator to enable localized control.
2Productivity
If the cooling capacity is redistributed to satisfy cooling demand in one temperature zone, then the cooling capacity available in other temperature zones is reduced, but this leads to unsatisfied cooling demand and temperature fluctuations in other zones
Solution Approach 1:
The system dynamically adjusts the throttling of each controllable expansion valve in real-time based on the specific cooling demand of each evaporator. This dynamic control allows the system to adapt to changing cooling requirements in different temperature zones simultaneously, rather than statically redistributing cooling capacity.
Solution Approach 2:
Temperature sensors in each evaporator provide feedback to their respective expansion valve controllers, enabling each zone to independently adjust its cooling capacity based on actual temperature conditions. This feedback mechanism ensures that each temperature zone can adapt to its own cooling demands without being constrained by fixed capacity allocation.
3Device complexity
If a single controllable expansion valve is used in the refrigerant circuit, then the device complexity is reduced, but it is not possible to independently control the cooling capacity for multiple temperature zones with different cooling requirements
Solution Approach 1:
The patent implements local quality by placing controllable expansion valves upstream of specific evaporators that serve specific temperature zones, enabling zone-specific cooling control. The controllable expansion valves are strategically positioned to allow independent adjustment of cooling capacity for each temperature zone based on its unique requirements.
Solution Approach 2:
The controllable expansion valves serve multiple functions: they regulate refrigerant flow to their associated evaporators, respond to temperature feedback from sensors, and enable independent control of cooling capacity for different temperature zones. This multi-functionality allows a single valve to handle both flow control and adaptive cooling management.
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 enables simple and stable temperature control across multiple zones by independently managing the compressor speed and throttle points, ensuring that each zone's cooling demand is met without causing temperature fluctuations, optimizing energy efficiency and humidity control.
Implementation Method 1
a first evaporator for cooling the first temperature zone and a second evaporator for cooling the second temperature zone
Implementation Method 2
evaporator for cooling the first temperature zone
Implementation Method 3
a refrigerant circuit which comprises a compressor
Implementation Method 4
a first controllable throttle point in the refrigerant circuit being upstream of the first evaporator and downstream of the second evaporator
Data Source
Figure 1~3
Figure 4~5
AI summary
A refrigeration appliance comprises at least a first and a second temperature zone (1, 2) and a refrigerant circuit that includes a compressor (10), a first evaporator (6) for cooling the first temperature zone (1) and a second evaporator (7) for cooling the second temperature zone (2). The first evaporator (6) is serially connected downstream of the second evaporator (7) in the refrigerant circuit, and a controllable throttle point (21) is arranged upstream of the first evaporator (6) and downstream of the second evaporator (7) in the refrigerant circuit. A compressor controller (29) is designed to control the rotational speed of the compressor (10) on the basis of the temperature in the first temperature zone (1).