A method of deciding when to terminate a defrosting cycle within a refrigerated container
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Refrigerated transport containers face challenges in preventing frost and ice formation on components above and upstream of the evaporator, particularly on the return air grid, and in the supply air ducts, which can lead to air circulation blockages and require costly repacking of cargo, especially during frozen mode operations with moist loads.
Innovation Solution
A method to extend defrosting cycles until all frost and ice have melted from the return air grid and other components, utilizing indicators such as temperature sensors and natural convection to ensure complete defrosting without additional hardware, allowing the container to operate efficiently without modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If defrosting cycles are extended to melt all frost and ice from the return air grid and other components, then reliability of air circulation is improved, but loss of time increases due to longer defrosting duration
Solution Approach 1:
The patent applies preliminary action by extending the defrosting cycle to proactively melt frost and ice on the return air grid and other components before they can accumulate to block air circulation. This preventive approach ensures that the container is ready for the next cooling cycle without risk of air circulation failure, resolving the contradiction by prioritizing reliability over time efficiency.
2Device complexity
If temperature sensors and natural convection are used to detect complete defrosting, then device complexity is reduced, but measurement precision deteriorates compared to additional specialized sensors
Solution Approach 1:
The patent applies self-service by using existing temperature sensors and natural convection processes to detect when defrosting is complete. The system leverages the container's own thermal environment and existing measurement capabilities rather than requiring additional specialized sensors, thereby maintaining low device complexity while achieving sufficient measurement precision for operational needs.
3Productivity
If defrosting cycles are prolonged to prevent ice buildup in supply air ducts, then productivity is maintained by avoiding cargo repacking, but use of energy increases due to extended heating
Solution Approach 1:
The patent applies feedback by using temperature sensor data to monitor the defrosting process and determine when it is complete. This feedback mechanism allows the system to extend defrosting cycles only as long as necessary to prevent ice buildup in supply air ducts, thereby maintaining productivity by avoiding cargo repacking while minimizing energy consumption by terminating heating once the defrosting objective is achieved.
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 approach prevents frost and ice buildup in critical areas, maintaining air circulation and preventing cargo damage, reducing repacking needs and operational costs, while maintaining the container's multi-purpose functionality.
Implementation Method 1
The evaporator is the part of the refrigeration system in which the refrigerant absorbs heat from the transport volume and thereby cools air forced over or through the evaporator
Implementation Method 2
moist and water carried by the air passing over or through the evaporator may settle on the cold surfaces of the evaporator thereby initiating frost and/or ice build-up
Implementation Method 3
means for actively heating said evaporator (16) during defrosting cycles
Implementation Method 4
means for sensing temperature indicative of the return air temperature of air returning to said cooling space (41) from said transport volume (45) or the temperature of the return air grid (45)
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a method, a device and a computer program for deciding when to terminate a defrosting cycle within a refrigerated transport container (1) where the container (1) includes: - a transport volume (45), - a cooling unit comprising at least an evaporator (16) arranged in a cooling space (41), - a return air grid (42) arranged to separate said cooling space (41) from said transport volume (45), - means for sensing temperature indicative of the return air temperature of air returning to said cooling space (41) from said transport volume (45) or the temperature of the return air grid (45), - means for actively heating said evaporator (16) during defrosting cycles, and - a processor configured for controlling at least the duration of said defrosting cycles, The method includes the steps of: - establishing one or more indicators indicative of frost and/or ice build-up on said return air grid (42), and - deciding to terminate a defrosting cycle only when said one or more indicators indicative of frost and/or ice build-up on said return air grid (42) indicate that said return air grid (42) is free of frost and/or ice.