Intercycle Heat Exchanger in Cascade Cooling for Superheat Control
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Solution Overview
Problem
Cascade cooling systems face challenges in energy efficiency, system reliability, and safety, particularly when achieving very low temperatures and high pressures, with existing systems lacking effective inter-cycle cooling capacity and control over superheating.
Innovation Solution
The introduction of an intercycle heat exchanger that simultaneously subcools refrigerant from the top-side condenser and superheats vapor from the low-side evaporator, along with suction line heat exchangers, to enhance efficiency and control superheating, and a control system to regulate subcooling and superheating levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional cascade cooling systems are used without intercycle cooling, then system simplicity is maintained, but energy efficiency and refrigerating capacity are insufficient
Solution Approach 1:
The intercycle heat exchanger merges the subcooling function for the top-side refrigerant and the superheating function for the low-side refrigerant into a single integrated component. This allows heat transfer between the two cycles to occur simultaneously, improving energy efficiency by utilizing the temperature difference between cycles without adding separate heating or cooling devices.
Solution Approach 2:
The intercycle heat exchanger performs multiple functions: it subcools the condensed refrigerant from the top-side condenser, superheats the vapor from the low-side evaporator, and provides intercycle cooling capacity. This multi-functionality eliminates the need for separate subcooling and superheating devices, improving overall system efficiency while maintaining reasonable complexity.
2Reliability
If external heating devices are added to maintain superheating levels, then reliability is improved, but energy efficiency deteriorates
Solution Approach 1:
The intercycle heat exchanger combines the superheating function with the intercycle cooling process, eliminating the need for separate external heating devices. The hot refrigerant from the top-side condenser provides the necessary heat to superheat the low-side evaporator vapor, maintaining reliable operation while avoiding additional energy consumption from external heaters.
3Ease of operation
If additional suction line heat exchangers are added, then control over superheating is improved, but device complexity increases
Solution Approach 1:
The intercycle heat exchanger serves as both the intercycle cooling device and the suction line heat exchanger for superheating control. By integrating these functions, the system achieves precise control over superheating levels through the heat exchange process between cycles, without requiring additional separate suction line heat exchangers.
4Temperature
If cascade cooling systems operate at very high pressures, then cooling to very low temperatures is achieved, but system safety and equipment availability worsen
Solution Approach 1:
The intercycle heat exchanger merges the high-pressure top-side cycle with the low-pressure low-temperature cycle, allowing efficient heat transfer between them. This integration enables the system to achieve very low temperatures in the low-side cycle while the intercycle heat exchanger manages the pressure transition safely, reducing the need for separate high-pressure handling equipment.
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 configuration significantly improves the energy efficiency and refrigerating capacity of cascade cooling systems, ensuring reliable operation by maintaining desired superheating levels without external heating, thus enhancing system performance and safety.
Implementation Method 1
an intercycle heat exchanger that simultaneously subcools refrigerant leaving the condenser of the top-side cooling cycle, and further heats the vapor leaving the evaporator of the low-side cooling cycle
Implementation Method 2
when used in conjunction with additional suction line heat exchangers
Data Source
AI summary
A cascade refrigeration system comprising a first cycle for circulating a first refrigerant, a second cycle for circulating a second refrigerant and a heat exchanger. The first refrigerant and the second refrigerant are in thermal communication, and the second cycle includes a receiver that receives a liquid form of the second refrigerant from the heat exchanger.