Refrigeration circuits, environmental control systems, and methods of controlling flow in refrigeration circuits
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Solution Overview
Problem
Existing refrigeration systems in vehicles, such as aircraft, face inefficiencies when cooling zones require different temperatures, as they often operate by cooling air to the lowest required temperature and intermixing it with warmer air, leading to suboptimal performance.
Innovation Solution
A refrigeration circuit with a primary and secondary loop, including independent expansion valves and an ejector system, allows for separate control of refrigerant flow to each heat load, using a pump to pressurize refrigerant and adding energy with waste heat before the ejector, optimizing refrigerant circulation and reducing work required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigeration system cools air to the lowest required temperature and intermixes it with warmer air to satisfy different zone temperature requirements, then the temperature requirements of each zone are met, but the system operates less efficiently
Solution Approach 1:
The system divides the refrigerant flow into multiple independent circuits, each equipped with its own expansion valve and evaporator, allowing separate temperature control for different heat loads/zones without requiring over-cooling and mixing
2Device complexity
If a single refrigerant circuit is used to serve multiple heat loads with different temperature requirements, then the system structure is simplified, but the ability to independently control temperature for each zone is lost
Solution Approach 1:
The system merges multiple refrigerant circuits into a unified architecture where circuits are combined after the expansion valves and evaporators, allowing independent temperature control for each zone while maintaining a relatively compact overall structure
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 efficient control of heat removal for zones with different temperature requirements, reducing the overall work needed to circulate refrigerant and improving system efficiency by utilizing waste heat, thereby enhancing the performance of environmental control systems.
Implementation Method 1
an ejector arranged to receive a primary refrigerant flow from the primary loop and a secondary refrigerant flow from the secondary loop, the ejector accelerating the secondary refrigerant flow using the primary refrigerant flow
Implementation Method 2
a pump arranged along the primary loop
Implementation Method 3
a heat exchanger arranged along the primary loop and in fluid communication with the pump through the primary loop to receive pressurized refrigerant from the pump
Implementation Method 4
an expansion valve, which decreases pressure of the liquid refrigerant by flash evaporation to form a cold liquid-vapor refrigerant mixture
Implementation Method 5
the evaporator vaporizing the liquid portion of the cold liquid-vapor refrigerant mixture with heat removed from the environmentally controlled zones
Implementation Method 6
a condenser, which superheats the refrigerant. The superheated refrigerant is provided to a condenser to remove heat and condense the refrigerant into a liquid
Data Source
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AI summary
A refrigeration circuit (100) includes a primary loop (104), a secondary loop (106) connected to the primary loop, a first expansion valve (108) connected to the secondary loop, and a second expansion valve (110). The second expansion valve is connected to the secondary loop and is in parallel with the first expansion valve to control thermal communication between the refrigeration circuit and a first heat load independent of thermal communication between the refrigeration circuit and a second heat load. Environmental control systems and methods (200) of controlling refrigerant flow in refrigeration circuits are also described.