Binary Refrigeration Cycle Defrosting Using Cascade Heat Storage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing binary refrigeration systems face challenges in efficiently melting frost on evaporators during heating cycles without compromising efficiency or requiring additional energy inputs.
Innovation Solution
A refrigeration cycle system with a primary and secondary refrigerant circuit, utilizing a cascade heat exchanger, where the secondary refrigerant circuit operates to store heat during a first operation, which is then used to melt frost on the primary refrigerant circuit's heat exchanger during a subsequent operation by reducing heat radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply unit continues to supply heating medium during defrosting operation, then heat radiation from the second refrigerant in the second heat exchanger prevents effective frost melting, but stopping or decreasing the supply quantity reduces heat radiation and enables frost melting
Solution Approach 1:
The system performs heat storage in the cascade heat exchanger before defrosting operation by stopping water flow in the water circuit and refrigerant flow in the secondary refrigerant circuit. This preliminary action stores thermal energy that will be used during defrosting, allowing the second compressor to operate and supply heat to melt frost without continuous heating medium supply
2Reliability
If the primary refrigerant circuit is switched to reverse cycle for defrosting operation, then frost can be melted effectively, but additional energy input and system complexity increase
Solution Approach 1:
The system uses itself to provide the heat needed for defrosting. The second compressor, which is already operating as part of the binary refrigeration system, continues to operate and provides heat through the cascade heat exchanger to melt frost on the primary evaporator. This eliminates the need for separate defrosting energy input or reverse cycle switching
Solution Approach 2:
The defrosting function is merged with the normal heating operation. The second refrigerant circuit, which normally provides heating, is utilized to also perform defrosting by directing heat through the cascade heat exchanger to the primary evaporator. This combines two functions into one operational mode
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
Effectively melts frost on the primary heat exchanger while maintaining system efficiency by utilizing stored heat from the secondary refrigerant circuit, reducing the need for additional energy during defrosting operations.
Implementation Method 1
a cascade heat exchanger, to enable heat exchange between the first refrigerant and the second refrigerant
Implementation Method 2
It is thus possible to melt frost adhering to the first heat exchanger during the third operation by means of heat stored in the second circuit during the second operation
Data Source
AI summary
A primary refrigerant circuit allows circulation of a primary refrigerant and includes a primary compressor, a cascade heat exchanger, a primary heat exchanger, and a primary switching mechanism. A secondary refrigerant circuit allows circulation of a secondary refrigerant and includes a secondary compressor, the cascade heat exchanger, and a utilization heat exchanger; and an indoor fan configured to supply air to exchange heat with the secondary refrigerant flowing in the utilization heat exchanger When a defrosting condition is satisfied during normal operation, the primary refrigerant circulates in the order of the primary compressor, the primary heat exchanger, and the cascade heat exchanger after the indoor fan is stopped and the secondary compressor is operated.