Refrigerating Circuit Selective Defrosting With Gaseous Refrigerant
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Solution Overview
Problem
Conventional refrigerating circuits with carbon dioxide as refrigerant face inefficiencies in defrosting evaporator coils, particularly in cold consumers of the freezing cycle, due to the need for additional heating units that consume energy and incur costs.
Innovation Solution
A refrigerating circuit with a booster system that includes a defrosting line with pressure reduction and solenoid valves, allowing selective and efficient defrosting by using pressurized gaseous refrigerant from the compressor units to maintain gaseous form and increase refrigerant flow, reducing the need for additional heating and maintaining refrigeration mode during defrosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical heating is used to defrost evaporators, then defrosting effectiveness is improved, but energy consumption and installation costs increase
Solution Approach 1:
The system uses the refrigeration system's own pressurized gaseous refrigerant to defrost the evaporators, eliminating the need for external electrical heating. The refrigerant serves dual purposes: cooling during normal operation and heating during defrosting, making the system self-sufficient and energy-efficient
Solution Approach 2:
The system changes the pressure parameter of the refrigerant to achieve defrosting. By pressurizing the gaseous refrigerant and directing it to the evaporators, the refrigerant temperature increases, effectively melting ice without requiring additional energy input
2Reliability
If electrical heating is installed for defrosting, then defrosting capability is improved, but device complexity and installation costs increase
Solution Approach 1:
The pressurized gaseous refrigerant system serves multiple functions: it provides cooling during normal refrigeration operation and provides heating during defrosting operation. This multi-functionality eliminates the need for separate electrical heating components, reducing device complexity while maintaining defrosting capability
Solution Approach 2:
The defrosting function is merged with the existing refrigeration system by utilizing the same pressurized gaseous refrigerant that is already part of the system. The solenoid valves and distribution network are integrated into the existing refrigerant circuit, combining two functions (cooling and defrosting) into a single unified system
3Productivity
If additional compressors are added to the freezing branch, then refrigerant flow and defrosting performance are improved, but device complexity and cost increase
Solution Approach 1:
The existing compressors in the refrigeration system perform dual functions: they compress refrigerant vapor during normal cooling operation and also generate pressurized gaseous refrigerant for defrosting operation. This eliminates the need for dedicated defrosting compressors while maintaining sufficient refrigerant flow for effective defrosting
Solution Approach 2:
The system achieves the required refrigerant flow for defrosting by changing operational parameters of existing compressors rather than adding new equipment. By adjusting pressure and temperature parameters of the pressurized gaseous refrigerant, the system achieves effective defrosting with the existing compressor infrastructure
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 enables efficient and selective defrosting of iced evaporator coils without additional heating, reducing energy consumption and costs, while maintaining refrigeration performance and avoiding the need for extra compressors, particularly suited for carbon dioxide systems.
Implementation Method 1
leading hot pressurized gaseous refrigerant into a cold consumer of the freezing branch to be defrosted
Implementation Method 2
the pressure of it has been reduced by the pressure reduction valve to an acceptable pressure range
Data Source
Figure 1
AI summary
A refrigerating circuit (2) according to exemplary embodiments of the invention comprises a first compressor unit (4), a condenser/gas cooler (6), and a collecting container (10), a normal refrigeration branch coupled between the collecting container (10) and the suction side of the at least one first compressor unit (4), the normal refrigeration branch comprising at least one cold consumer having an evaporator (18) with an expansion device (16) arranged before it; and a freezing branch coupled between the collecting container (10) and the suction side of the first compressor unit (4), the freezing branch comprising at least one cold consumer having an evaporator (24) with an expansion device (22) arranged before it, a second compressor unit (28) and a desuperheating device (32), the refrigerant circuit (2) further comprising refrigerant conduits for connecting said elements and for circulating a refrigerant therethrough, a defrosting line (36) connected between a branching-off point in the pressure line (6) after the first compressor unit (4) and at least one attaching point between the expansion device (16; 22) and the evaporator (18; 24) of one of the cold consumer units, wherein a pressure reduction valve (38) is arranged in the defrosting line (36), a control unit being configured to operate at least one of the evaporators (18, 24) in a defrosting mode, in which a partial flow of the pressurized gaseous refrigerant leaving the first compressor unit (4) is led to the respective evaporator (18, 24) through the defrosting line (36), wherein the pressure of the refrigerant is reduced by the pressure reduction valve (38) and the refrigerant defrosts the respective evaporator (18, 24) while maintaining its gaseous state and flows back to the respective compressor unit (4, 28).