Interface Unit Heat Exchanger for Multi-Mode Refrigerant Sub-Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Refrigeration systems face limitations in achieving efficient cooling due to the natural limits of sub-cooling in vapour-compression cycles, which restricts the cooling capacity and increases energy consumption, especially when using refrigerants with specific phase change properties.
Innovation Solution
An interface unit with a dedicated sub-cooling heat exchanger, multiple refrigerant flow paths, and intercept valves controlled by a controller, allowing for selective operation modes, including sub-cooling, multi-stage cooling, and heat recovery, to extend the sub-cooling effect beyond natural limits and improve refrigeration system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If natural sub-cooling is used in vapour-compression cycles, then the refrigeration system operates with standard components, but the cooling capacity is limited and energy consumption increases
Solution Approach 1:
The condenser is divided into two separate heat exchangers: a primary condenser for vapor-to-liquid phase change and a secondary sub-cooling heat exchanger for additional cooling of the liquid refrigerant. This segmentation allows independent optimization of condensation and sub-cooling processes, extending sub-cooling beyond natural limits to increase cooling capacity while managing energy consumption through targeted heat exchange.
Solution Approach 2:
A liquid-suction heat exchanger is introduced as an intermediary component between the liquid line and suction line. This heat exchanger enables heat transfer from the suction gas to the liquid refrigerant, providing additional sub-cooling without requiring additional compression work. The intermediary device recovers waste heat from the suction side to enhance sub-cooling efficiency.
2Productivity
If sub-cooling is extended beyond natural limits, then cooling capacity increases, but system complexity increases with additional components
Solution Approach 1:
The sub-cooling heat exchanger and liquid-suction heat exchanger are integrated into the existing refrigeration cycle architecture, sharing common piping and control systems where possible. The secondary heat exchanger is positioned to utilize existing temperature differentials in the cycle, merging the sub-cooling function with the natural heat exchange pathways to minimize additional complexity while achieving extended sub-cooling.
Solution Approach 2:
The liquid-suction heat exchanger serves multiple functions: it provides sub-cooling to the liquid refrigerant, pre-heats the suction gas before compression, and recovers waste heat from the low-pressure side. This multi-functionality allows a single additional component to address multiple system needs, reducing the overall complexity increase despite extending sub-cooling capabilities.
3Adaptability or versatility
If multiple refrigerant flow paths are implemented, then operational versatility improves, but control complexity increases
Solution Approach 1:
Multiple electronic expansion valves are employed instead of a single mechanical valve, allowing dynamic and independent control of refrigerant flow to different heat exchangers. The electronic valves can be modulated in real-time based on system conditions, enabling flexible operation across multiple modes (standard cooling, enhanced sub-cooling, heat recovery) while being managed through a centralized control algorithm that simplifies the overall control strategy.
Solution Approach 2:
Temperature and pressure sensors are positioned at key locations in the refrigerant circuit to provide feedback to the control system. This feedback enables the controller to automatically adjust the opening of electronic expansion valves and compressor operation to maintain optimal refrigerant conditions, managing the complexity of multiple flow paths through closed-loop control that adapts to changing system conditions without requiring manual intervention.
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
The solution enables efficient sub-cooling of a wide variety of refrigerants, reducing power consumption, enhancing cooling capacity, and allowing operation in multiple modes, thereby making the refrigeration system more cost-effective and resilient to temperature changes.
Implementation Method 1
an interface unit heat exchanger; directing the refrigerant to the dedicated interface unit heat exchanger to reduce the enthalpy and therefore sub-cool the condensed liquid refrigerant
Implementation Method 2
a plurality of intercept valves engagable with a piping circuit of a thermal network; the plurality of refrigerant pipes defining at least two different refrigerant flow paths across the interface unit heat exchanger, the at least two different refrigerant flow paths being selectively activatable by the controller controlling a status of the plurality of intercept valves
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An interface unit (50) for a thermal network, the interface unit (50) comprising: an interface unit heat exchanger (54); a plurality of refrigerant pipes (58a, 58b, 58c, 60); a plurality of intercept valves (62a, 62b, 62c, 62d) engagable with a piping circuit (120) of a thermal network; and a controller (56) associated with the plurality of intercept valves (62a, 62b, 62c, 62d); the plurality of refrigerant pipes (58a, 58b, 58c, 60) defining at least two different refrigerant flow paths across the interface unit heat exchanger (54), the at least two different refrigerant flow paths being selectively activatable by the controller (56) controlling a status of the plurality of intercept valves (58a, 58b, 58c, 60).