A method for terminating defrosting of an evaporator
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Solution Overview
Problem
Existing vapor compression systems, such as refrigeration and air conditioning systems, face inefficiencies and instability due to ice and frost buildup on evaporators, leading to suboptimal cooling performance and excessive energy consumption during defrosting, as current methods for terminating defrosting are either too short or too long, often leaving residual ice.
Innovation Solution
A method involving monitoring the temperature difference between the evaporator inlet and outlet using at least two sensors, terminating defrosting when the rate of change of this difference approaches zero, ensuring complete ice removal and optimizing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If defrosting is terminated after a predetermined period of time, then the control method is simple, but the defrosting may be incomplete or excessively long causing energy waste
Solution Approach 1:
The system continuously monitors the temperature difference between evaporator inlet and outlet during defrosting and uses this feedback to dynamically determine when defrosting is complete. The defrosting process is terminated when the rate of change of temperature difference approaches zero, providing real-time adaptive control that prevents both incomplete defrosting and excessive energy consumption.
Solution Approach 2:
The invention monitors changes in temperature parameters (inlet and outlet temperatures) and their rate of change to determine defrosting completion. By tracking how the temperature difference evolves over time and detecting when its rate of change approaches zero, the system adapts the defrosting duration based on actual thermal conditions rather than using a fixed predetermined time.
2Ease of operation
If defrosting is terminated when a certain temperature inside the evaporator is achieved, then the control is straightforward, but some parts of the evaporator may still have remaining ice
Solution Approach 1:
The system uses continuous temperature monitoring at both inlet and outlet with feedback control to detect when the rate of temperature change approaches zero. This provides comprehensive feedback about the defrosting state across the entire evaporator, ensuring reliable detection of complete defrosting rather than relying on a single temperature threshold that may not reflect conditions throughout the evaporator.
Solution Approach 2:
Instead of monitoring a single temperature parameter, the invention monitors the temperature difference between inlet and outlet and its rate of change over time. This adds temporal and spatial dimensions to the monitoring, creating a more comprehensive indicator of defrosting completion that accounts for heat propagation through the entire evaporator structure.
3Reliability
If defrosting lasts longer to ensure complete ice removal, then all ice is melted, but energy consumption increases and cooling of chamber items is reduced
Solution Approach 1:
The continuous monitoring of temperature difference and its rate of change provides real-time feedback on defrosting progress. The system terminates defrosting precisely when the rate of change approaches zero, indicating complete ice removal, thereby avoiding unnecessary extended defrosting that would waste energy and reduce cooling availability for chamber items.
Solution Approach 2:
The defrosting termination criterion is dynamic rather than static - it adapts to the actual thermal conditions by monitoring the rate of temperature change. This dynamic approach allows the system to terminate defrosting at the optimal moment when ice is completely removed, balancing reliable ice removal with minimal energy consumption and maximum cooling availability.
4Use of energy by moving object
If defrosting is terminated early to save energy, then energy consumption is reduced, but remaining ice degrades system performance and accelerates new ice accumulation
Solution Approach 1:
The feedback mechanism monitoring the rate of temperature change ensures that defrosting continues until complete ice removal is detected. This prevents premature termination that would leave residual ice degrading performance, while also avoiding unnecessary extension that would waste energy. The feedback ensures optimal termination timing that protects productivity.
Solution Approach 2:
The dynamic termination criterion based on rate of temperature change allows the system to adapt to varying ice accumulation conditions. This ensures complete ice removal is achieved regardless of the amount or distribution of ice, maintaining optimal cooling performance without excessive energy consumption.
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 ensures complete defrosting within an optimal time frame, maintaining high system performance and reducing energy consumption by accurately determining when all ice has been melted, thus preventing re-ice accumulation and maintaining efficient operation.
Implementation Method 1
During defrosting, the evaporator is heated in order to melt ice buildups
Implementation Method 2
monitoring, by at least two temperature sensors, an evaporator inlet temperature, Te,in, at a hot gas inlet of the evaporator and an evaporator outlet temperature, Te.out, at a hot gas outlet of the evaporator
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)
AI summary
A method for terminating defrosting of an evaporator (104) is disclosed. The evaporator (104) is part of a vapour compression system (100). The vapour compression system (100) further comprises a compressor unit (101), a heat rejecting heat exchanger (102), and an expansion device (103). The compressor unit (101), the heat rejecting heat exchanger (102), the expansion device (103) and the evaporator (104) are arranged in a refrigerant path, and an air flow is flowing across the evaporator (104). When ice is accumulated on the evaporator (104), the vapour compression system (100) operates in a defrosting mode. At least two temperature sensors (306, 307) monitor an evaporator inlet temperature, Te,in, at a hot gas inlet (304) of the evaporator (104) and an evaporator outlet temperature, Te,out, at a hot gas outlet (305) of the evaporator (104). A difference between Te,in and Te,ou,is monitored and defrosting is terminated when the rate of change of the difference between Te,in and Te,out approaches zero.