Thermally Choked Expansion Device for Refrigerant Flow Control
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Solution Overview
Problem
Conventional refrigeration systems in appliances face inefficiencies in regulating refrigerant flow rates and cooling capacity, particularly due to the limitations of capillary tubes in controlling flow rates across varying operating conditions.
Innovation Solution
A suction line heat exchanger with a first conduit for refrigerant liquid flow from the condenser to the evaporator and a second conduit for refrigerant vapor flow from the evaporator to the compressor, where a heating device is used in thermal communication with both conduits to regulate the flow rate by converting a portion of the refrigerant liquid to vapor, controlled by a refrigeration control system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a capillary tube is used to regulate refrigerant flow, then the refrigeration system can maintain simple structure, but the flow rate regulation capability deteriorates under varying operating conditions
Solution Approach 1:
The patent applies the dynamics principle by introducing a movable piston within the expansion device that can dynamically adjust the opening size of the refrigerant passage. The piston position is controlled by a diaphragm responding to pressure changes, enabling the device to adapt its flow regulation characteristics to varying operating conditions while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent implements parameter changes by varying the opening area of the refrigerant passage through piston displacement. The effective opening area changes in response to pressure differential across the diaphragm, allowing the device to optimize flow rate regulation for different operating conditions without requiring complex external control systems.
2Reliability
If heating is applied to the second conduit to prevent liquid refrigerant reaching the compressor, then compressor protection is improved, but energy efficiency deteriorates due to unnecessary heating
Solution Approach 1:
The patent extracts the heating function from a continuous operation mode and applies it selectively only where needed. The heating element is positioned to heat only the first conduit containing liquid refrigerant, separating the heating action from the second conduit where vapor refrigerant already flows, thereby preventing compressor damage while avoiding unnecessary energy consumption.
Solution Approach 2:
The system utilizes the inherent temperature difference between the hot condenser outlet and the suction line to create a heat exchanger effect. The hot refrigerant liquid in the first conduit naturally heats the surrounding components, including the second conduit, providing self-protection without requiring active heating in both conduits.
3Productivity
If a heating device is used to convert refrigerant liquid to vapor for flow rate regulation, then cooling capacity control is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated device: the expansion device combines flow regulation, phase change induction, and temperature control functions. The heating element is integrated within the expansion device housing, and the diaphragm mechanism serves both as a flow control actuator and a temperature sensing element, reducing overall system complexity.
Solution Approach 2:
The expansion device is designed as a multi-functional component that performs throttling, heating, phase change induction, and flow rate regulation simultaneously. The same piston mechanism that controls the refrigerant passage opening also responds to temperature and pressure conditions to modulate the heating effect, creating a universal device that handles multiple control objectives.
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 enhances energy efficiency by dynamically adjusting the cooling capacity and preventing liquid refrigerant from reaching the compressor, thereby improving temperature recovery and pull-down performance across a wide range of operating conditions.
Implementation Method 1
a heating device is used in thermal communication with both conduits to regulate the flow rate by converting a portion of the refrigerant liquid to vapor
Implementation Method 2
apply heat along a portion of one or, more typically, both the first conduit and the second conduit adjacent to the heating device
Implementation Method 3
a suction line heat exchanger having a first conduit including a refrigerant liquid which flows inside of the first conduit from the condenser to the evaporator. Also, the refrigeration system includes a second conduit in thermal communication with the first conduit
Data Source
AI summary
A refrigeration system including a suction line heat exchanger having a first conduit including a refrigerant liquid which flows inside of the first conduit from the condenser to the evaporator. Also the refrigeration system includes a second conduit in thermal communication with the first conduit and includes a refrigerant fluid, typically a vapor, which flows inside of the second conduit in an opposite direction of flow from the first conduit from the evaporator to the compressor. Additionally, at least one heating device is in thermal communication with at least one of the first conduit and second conduit and is configured to communicate with a refrigeration control system to apply heat along a portion of both the first conduit and the second conduit adjacent to the heating device thereby regulating the flow rate of the refrigerant liquid in the first conduit and the second conduit.