Refrigeration Defrost Valve Control for Stable Evaporation Pressure
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Solution Overview
Problem
In refrigeration apparatuses, the amount of refrigerant in the first heat exchanger can fall below the proper value during defrosting operations, leading to unsatisfactory refrigeration cycles and prolonged defrosting times due to decreased evaporation pressure in the evaporator.
Innovation Solution
A refrigeration apparatus comprising a compressor, heat exchangers, electric valves, and a controller that executes defrosting preparatory control by narrowing the opening degree of the first electric valve and setting the second electric valve to a minimum opening degree before switching the passage-switching valve, ensuring adequate refrigerant accumulation in the first heat exchanger, thus maintaining proper evaporation pressure and facilitating a shorter defrosting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the passage-switching valve is switched to start the defrosting operation, then the defrosting process can begin, but the refrigerant amount in the first heat exchanger falls below the proper value causing evaporation pressure to decrease
Solution Approach 1:
The patent applies preliminary action by executing defrosting preparatory control before the actual defrosting operation. During this preparatory phase, the first electric valve is controlled to increase refrigerant accumulation in the first heat exchanger, ensuring adequate refrigerant amount is established before the passage-switching valve is actuated to begin defrosting. This prevents the refrigerant amount from falling below proper values during the subsequent defrosting operation.
2Ease of operation
If the evaporation pressure decreases in the first heat exchanger during defrosting, then the defrosting operation can proceed, but water freezes in the first heat exchanger
Solution Approach 1:
The patent applies preliminary action by establishing proper refrigerant accumulation in the first heat exchanger during defrosting preparatory control before the actual defrosting operation begins. By controlling the first electric valve to maintain adequate refrigerant levels in advance, the evaporation pressure is kept at appropriate levels, preventing water from freezing in the first heat exchanger when the defrosting operation commences.
3Speed
If the refrigerant amount in the first heat exchanger is insufficient, then the system responds quickly to defrosting demand, but the refrigeration cycle becomes unsatisfactory
Solution Approach 1:
The patent applies preliminary action by proactively increasing refrigerant accumulation in the first heat exchanger during defrosting preparatory control, which occurs before the actual defrosting operation. This advance preparation ensures that when the defrosting operation begins, the refrigerant amount is already at proper levels, maintaining satisfactory refrigeration cycle performance while still enabling quick response to defrosting demands.
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 a satisfactory refrigeration cycle during defrosting by preventing a sudden decrease in refrigerant evaporation pressure, thereby shortening the defrosting operation time and maintaining the proper refrigerant load in the first heat exchanger.
Implementation Method 1
The first electric valve is configured and arranged to depressurize refrigerant in accordance with the opening degree
Implementation Method 2
The second electric valve is configured and arranged to depressurize or block refrigerant in accordance with the opening degree
Implementation Method 3
The supercooling heat exchanger is configured and arranged to conduct heat exchange between refrigerant flowing through the first refrigerant passage and refrigerant flowing through the second refrigerant passage
Implementation Method 4
The supercooling heat exchanger conducts heat exchange between refrigerant flowing through the first refrigerant passage and refrigerant flowing through the second refrigerant passage
Implementation Method 5
The first heat exchanger is configured and arranged to conduct heat exchange between refrigerant and water
Implementation Method 6
The second heat exchanger is configured and arranged to conduct heat exchange between refrigerant and an air flow
Implementation Method 7
The compressor is configured and arranged to compress refrigerant
Data Source
AI summary
A refrigeration apparatus includes a compressor, first and second heat exchangers, first and second electric valves, a passage-switching valve, a supercooling heat exchanger, and a controller. The first and second valves are disposed in first and second refrigerant passages. The supercooling heat exchanger conducts heat exchange between refrigerant flowing through the first and second refrigerant passages. The controller transitions to a defrosting operation mode upon determining that frost has formed on the second heat exchanger during a heating operation mode. The controller executes a defrosting preparatory control and a defrosting control after the defrosting preparatory control during the defrosting operation mode. The controller switches the passage-switching valve during the defrosting control. The controller narrows the opening degree of the first electric valve and controls the opening degree of the second electric valve to a minimum opening degree during the defrosting preparatory control.