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, as current defrosting methods either terminate too soon or too late, leaving residual ice that affects system operation and energy usage.
Innovation Solution
A method involving monitoring the temperature difference between the evaporator inlet and outlet using at least two sensors to determine when the rate of change of this difference approaches zero, indicating complete ice removal, allowing for precise termination of defrosting and ensuring optimal system performance.
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 leaving residual ice on the evaporator
Solution Approach 1:
The patent implements feedback control by continuously monitoring the temperature difference between evaporator inlet and outlet and using the rate of change of this difference to determine defrosting completion. The controller adjusts the defrosting termination decision based on real-time temperature data, ensuring complete defrosting while maintaining simple control logic.
Solution Approach 2:
The patent replaces the mechanical/time-based defrosting control with a thermal field-based control system. Instead of using a predetermined time timer, the system uses temperature sensors and computational analysis of temperature difference rates to detect defrosting completion, substituting mechanical timing with thermal measurement and calculation.
2Reliability
If defrosting is extended to ensure complete ice removal, then defrosting completeness is improved, but energy consumption increases
Solution Approach 1:
The feedback mechanism continuously monitors temperature differences and their rates of change, allowing the system to terminate defrosting precisely when complete ice removal is detected. This prevents unnecessary extension of the defrosting cycle, thereby reducing energy consumption while ensuring complete defrosting.
Solution Approach 2:
The patent employs dynamic monitoring of the temperature difference rate of change rather than a static predetermined time. The system adapts the defrosting duration to the actual ice accumulation conditions, extending defrosting only as long as necessary to remove all ice, thus optimizing energy usage based on real-time thermal conditions.
3Use of energy by moving object
If defrosting is terminated early to save energy, then energy consumption is reduced, but residual ice remains affecting system performance
Solution Approach 1:
The feedback control system prevents premature termination by continuously analyzing the temperature difference rate of change. The system only terminates defrosting when the rate of change indicates complete ice removal, ensuring system performance is maintained while avoiding unnecessary energy consumption from extended defrosting.
Solution Approach 2:
The patent replaces simple time-based or fixed-temperature control with a dynamic thermal analysis system that calculates the rate of change of temperature difference. This substitution enables precise detection of defrosting completion, preventing both premature and excessive defrosting termination.
4Measurement precision
If multiple temperature sensors are used to monitor evaporator temperatures, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the temperature measurement into two distinct locations: evaporator inlet and evaporator outlet. By placing sensors at these critical points, the system achieves comprehensive monitoring of the temperature difference across the evaporator, enabling accurate detection of defrosting completion without requiring excessive sensors.
Solution Approach 2:
The patent applies local quality measurement by focusing temperature monitoring at specific critical locations (inlet and outlet) rather than uniformly distributing sensors across the entire evaporator. This targeted approach provides sufficient measurement precision for defrosting detection while minimizing the total number of sensors required.
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, enhancing energy efficiency and maintaining high system performance by accurately determining when all ice has been melted, thereby preventing re-ice accumulation and reducing energy consumption.
Implementation Method 1
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
Implementation Method 2
monitoring a rate of change of a difference between Te,in and Te,out, and terminating defrosting when the rate of change of the difference between Te,in and Te,out approaches zero
Data Source
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,out, is monitored and defrosting is terminated when the rate of change of the difference between Te,in and Te,out approaches zero.