Cascade Refrigeration Receiver Cooling for Pressure Rise Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing two-stage refrigeration apparatuses face issues with insufficient cooling when the low-stage compressor is inactive, leading to abnormal pressure rises and increased equipment size due to the need for additional refrigeration machines during defrosting operations.
Innovation Solution
A two-stage refrigeration apparatus with a first and second refrigeration cycle device, a cascade condenser, a receiver heat exchanging portion, and a pressure determining system, where the controller activates the first compressor to cool the receiver when the second refrigerant approaches a supercritical state, maintaining pressure below the critical-point pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the low-stage compressor is inactive, then energy consumption is reduced, but the refrigerant pressure rises abnormally due to insufficient cooling
Solution Approach 1:
The high-stage compressor is designed to perform dual functions: its primary function of compressing high-stage refrigerant and its secondary function of cooling the low-stage refrigerant in the receiver when the low-stage compressor is inactive. This multi-functionality eliminates the need for a separate refrigerating machine while ensuring reliable pressure control in the low-stage refrigerant circuit.
Solution Approach 2:
The high-stage refrigeration cycle device serves itself and the low-stage system by using its own evaporator to cool the receiver containing low-stage refrigerant. This self-service mechanism allows the system to maintain pressure control without external assistance or additional active cooling components when the low-stage compressor stops.
2Reliability
If a separate refrigerating machine is added to cool the collector, then pressure control reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The high-stage compressor and evaporator are designed to perform dual functions: compressing and cooling high-stage refrigerant, and cooling the low-stage refrigerant in the receiver. This multi-functionality eliminates the need for a separate refrigerating machine while ensuring reliable pressure control.
Solution Approach 2:
The cooling function for the low-stage refrigerant is merged with the high-stage refrigeration cycle components. The high-stage evaporator serves as the cooling device for the receiver, combining two functions into one integrated system rather than using separate independent components.
3Quantity of substance
If the cascade condenser is filled with liquid refrigerant, then refrigerant storage capacity is improved, but cooling effectiveness deteriorates when the low-stage compressor is inactive
Solution Approach 1:
The receiver heat exchanging portion acts as an intermediary between the liquid refrigerant in the receiver and the high-stage evaporator. This intermediary structure allows efficient heat transfer from the liquid refrigerant to the high-stage evaporator, enabling effective cooling even when the low-stage compressor is inactive and the receiver is filled with liquid refrigerant.
4Reliability
If equipment size is increased to prevent pressure rise, then pressure control reliability is improved, but manufacturing cost and installation space increase
Solution Approach 1:
The controller monitors the pressure in the low-stage refrigerant circuit and automatically activates the high-stage compressor when pressure exceeds a predetermined threshold. This feedback control mechanism ensures reliable pressure prevention without requiring oversized equipment, as the system dynamically responds to pressure conditions.
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 effectively suppresses pressure rises and improves reliability by cooling the refrigerant in the receiver heat exchanging portion, reducing the need for large equipment designs and additional refrigeration machines.
Implementation Method 1
The receiver heat exchanging portion is configured to cool the receiver by heat exchange with a portion in which the first refrigerant being low-pressure flows in the first refrigerant circuit
Implementation Method 2
The cascade condenser includes the first evaporator and the second condenser and is configured to cause the first refrigerant flowing in the first evaporator and the second refrigerant flowing in the second condenser to exchange heat with each other
Data Source
AI summary
A two-stage refrigeration apparatus includes a high-stage refrigeration cycle including a high-stage-side refrigerant circuit including a high-stage-side compressor, high-stage-side condenser, high-stage-side expansion valve, and high-stage-side evaporator connected by pipes, a low-stage refrigeration cycle including a low-stage-side refrigerant circuit including a low-stage-side compressor, low-stage-side condenser, low-stage-side receiver, low-stage-side expansion valve, and low-stage-side evaporator connected by pipes, a cascade condenser including the high-stage-side evaporator and low-stage-side condenser, a receiver heat exchanging portion configured to cool the low-stage-side receiver, and a high-stage refrigeration cycle controller configured to perform controlling so as to activate the high-stage-side compressor when estimating a low-stage-side refrigerant will reach a supercritical state when the low-stage-side compressor is inactive on the basis of the pressure of the low-stage-side refrigerant.