Refrigeration system
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Solution Overview
Problem
Traditional refrigeration systems have fixed refrigerant charge levels, which are sub-optimal for varying operating conditions, leading to inefficiencies and reduced performance over time.
Innovation Solution
A refrigeration system with a buffer tank and controllable valves that adjust refrigerant charge levels based on sub-cooling measurements, allowing for increased efficiency and expanded operating envelopes by transferring refrigerant between the main circuit and the buffer tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed refrigerant charge levels are used in traditional refrigeration systems, then the system structure remains simple, but the system efficiency decreases under varying operating conditions
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed refrigerant charge system into a dynamic adjustable charge system. A buffer tank is introduced connected to the refrigeration circuit through controllable valves, allowing the refrigerant charge to be dynamically adjusted based on operating conditions such as temperature, pressure, and sub-cooling measurements. This enables the system to adapt to varying loads and environmental conditions, optimizing efficiency without requiring complete redesign of the basic system architecture.
Solution Approach 2:
The patent implements parameter changes by modifying the refrigerant charge level as a variable parameter rather than a fixed value. Sensors monitor system parameters (temperature, pressure, sub-cooling) and feed back to a controller that adjusts the refrigerant charge accordingly. This allows optimal performance across different operating conditions by changing the refrigerant mass in the circuit based on real-time system state.
2Productivity
If additional heat exchangers and sub-circuits are added to enable variable refrigerant charge, then system efficiency improves, but device complexity increases
Solution Approach 1:
The buffer tank serves multiple functions: it acts as a refrigerant reservoir, a charge adjustment mechanism, and a system buffer. By making this single component multi-functional, the patent avoids the need for separate dedicated devices for each function, thereby reducing overall system complexity while still enabling variable refrigerant charge capability.
Solution Approach 2:
The buffer tank acts as an intermediary element between the fixed charge refrigeration circuit and the control system. It provides a simple interface through which refrigerant can be added or removed from the main circuit using controllable valves, avoiding the need for complex integrated charge management systems while still achieving dynamic charge adjustment.
3Reliability
If refrigerant charge is depleted over time, then system robustness decreases, but maintaining fixed charge levels avoids the need for active management
Solution Approach 1:
The patent implements a feedback control system where sensors continuously monitor refrigerant charge level, sub-cooling, temperature, and pressure. This information is fed back to a controller that automatically adjusts the refrigerant charge by controlling valves between the buffer tank and the refrigeration circuit. This closed-loop feedback ensures the system maintains optimal charge levels and compensates for depletion over time, enhancing reliability through automated management.
Solution Approach 2:
The system performs self-service by automatically monitoring and adjusting its own refrigerant charge levels. The control system detects charge depletion and autonomously replenishes refrigerant from the buffer tank without requiring external intervention, thereby maintaining system robustness and eliminating the need for manual charge top-ups.
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 system achieves enhanced efficiency and robustness by dynamically adjusting refrigerant charge levels, maintaining optimal sub-cooling and reducing maintenance needs, while avoiding the complexity and cost of additional heat exchangers or sub-circuits.
Implementation Method 1
When a refrigerant pressure in the buffer tank is lower or higher than a refrigerant pressure in the main refrigeration circuit then opening the respective valve will allow for transfer of refrigerant fluid to or from the buffer tank
Implementation Method 2
the cooling of the refrigerant fluid is done via a heat rejection heat exchanger rejecting heat to the atmosphere
Implementation Method 3
the heating of the refrigerant fluid is done via a heat absorbing heat exchanger that absorbs heat from an object to be cooled
Implementation Method 4
In both cases a full or partial phase change of the refrigerant fluid can be used to increase the possible temperature differential between the heat rejection and heat absorption stages
Data Source
AI summary
A refrigeration system includes a main refrigeration circuit for holding refrigerant fluid, the main refrigeration circuit including: a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16. In addition, the refrigeration system includes a buffer tank 20 attached to the main refrigeration circuit, with valves 22, 24 for controlling flow of refrigerant fluid between the main refrigeration circuit and the buffer tank 20. The refrigeration system is arranged such that the valves 22, 24 are controlled to transfer refrigerant fluid between the main refrigeration circuit and the buffer tank 20 based on a measure of sub-cooling in the main refrigeration circuit.