Fast switching multiple evaporator system for an appliance
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Solution Overview
Problem
Conventional multi-evaporator sealed systems for appliances face limitations in energy efficiency, particularly in achieving simultaneous parallel operation with separate evaporating pressures, which often require multiple compressors or complex designs like ejectors for pressure equalization.
Innovation Solution
A sealed system with a single compressor, a condenser, multiple evaporators in series or parallel configuration, and a flash tank, utilizing valves to switch refrigerant flow between vapor and liquid phases to maintain negligible temperature increase across evaporators, allowing for efficient operation with a single compressor and no ejectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If simultaneous parallel operation with two separate evaporating pressures is implemented, then energy efficiency is improved, but device complexity increases due to requiring multiple compressors or complicated ejector designs
Solution Approach 1:
The system divides the refrigeration load into two separate evaporators operating at different pressures (high-pressure evaporator and low-pressure evaporator), each serving different temperature zones. This segmentation allows simultaneous parallel operation with optimized evaporating pressures for each zone, improving overall energy efficiency without requiring a single complex high-capacity compressor
Solution Approach 2:
The system dynamically switches between different operational modes (sequential operation, simultaneous parallel operation, simultaneous series operation) based on cooling demands. The dynamic valve controls refrigerant flow distribution in real-time, allowing the system to adapt to varying load conditions and maintain optimal efficiency while avoiding the need for fixed complex hardware configurations
Solution Approach 3:
The system changes operational parameters (refrigerant flow paths, evaporator activation states, pressure levels) to achieve simultaneous parallel operation. By dynamically adjusting these parameters through the dynamic valve, the system can operate evaporators at their optimal evaporating pressures without requiring permanent complex hardware modifications
2Device complexity
If sequential operation of evaporators is used, then device complexity is reduced, but energy efficiency is limited
Solution Approach 1:
The system transitions from static sequential operation to dynamic operational control. The dynamic valve enables real-time switching between sequential and simultaneous parallel modes, allowing the system to maintain simple hardware architecture while achieving high energy efficiency when conditions permit simultaneous operation
3Productivity
If series mode operation with flash tank is implemented, then capacity improvement is achieved, but device complexity increases due to requiring multiple compressors or vapor injection capability
Solution Approach 1:
The system segments the refrigeration capacity into two independent evaporator circuits that can operate simultaneously in series through the flash tank. This segmentation allows each evaporator to be optimized for its specific temperature zone while maintaining overall system capacity, avoiding the need for a single oversized complex compressor with vapor injection capability
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 enhances energy efficiency by enabling simultaneous multi-stage cooling with negligible temperature swings, achieving over 10% efficiency improvement compared to conventional systems, while simplifying the design by eliminating the need for multiple compressors or ejectors.
Implementation Method 1
a flash tank positioned between the first evaporator and the second evaporator and having a vapor outlet and a liquid outlet
Implementation Method 2
a first expansion device positioned between the condenser and the first evaporator... a second expansion device positioned between the flash tank and the second evaporator
Implementation Method 3
The compressed refrigerant flows to an evaporator where heat exchange between the chilled chambers and the refrigerant cools the chilled chambers
Implementation Method 4
The sealed system includes a compressor having an inlet and an outlet... The compressed refrigerant flows to an evaporator
Data Source
AI summary
Various embodiments of a multi-evaporator sealed vapor compression system for an appliance are provided. In one example aspect, a sealed system charged with a refrigerant fluid includes a single compressor and a first and second evaporator fluidly coupled in series. A flash tank is positioned between the evaporators. One or more valves are fluidly coupled with and positioned downstream of the flash tank and the second evaporator. The valves are operable to selectively switch the flow of refrigerant fluid between the two evaporators at a frequency such that the temperature rise in the evaporators is negligible. In another aspect, a sealed system charged with a refrigerant fluid includes a single compressor and a first and second evaporator fluidly coupled in parallel. One or more valves positioned upstream of the evaporators and one or more valves are positioned downstream of the evaporators for controlling the refrigerant flow through the sealed system.