Refrigerating machine and control method therefor
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Solution Overview
Problem
Current refrigeration machines using HFO refrigerants face challenges in accurately detecting and effectively extracting noncondensable gases like air, which accumulate inside the system, leading to performance deterioration and potential machine failure due to unclear air accumulation positions in shell-and-tube type condensers.
Innovation Solution
Incorporating a temperature sensor to measure the cooling medium outlet temperature, determining the air bleeding start state based on temperature differences, and using a control unit to manage expansion and hot gas bypass valves to extract noncondensable gases, ensuring accurate detection and timely air bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If air bleeding is performed only when a certain amount of noncondensable gas accumulates and performance clearly decreases, then the refrigeration machine can operate without frequent maintenance, but the performance deterioration and potential machine failure occur before air bleeding can be performed
Solution Approach 1:
The patent performs air bleeding in advance based on operating time or operating cycle count, before performance clearly deteriorates. The control unit determines that air bleeding is needed when the operating time exceeds a predetermined threshold or when the operating cycle count reaches a predetermined value, preventing performance deterioration rather than responding to it after occurrence.
2Reliability
If air bleeding is performed frequently to maintain performance, then the refrigeration machine maintains effective performance, but the complexity of the control system and operation increases
Solution Approach 1:
The control unit determines air bleeding timing in advance based on simple criteria such as operating time thresholds or operating cycle counts, rather than continuously monitoring complex performance parameters. This preliminary determination based on straightforward metrics maintains performance stability while avoiding the need for complex real-time detection and control systems.
3Loss of substance
If air bleeding is performed in a shell-and-tube type condenser where air accumulates inside pipe groups, then noncondensable gases can be extracted, but the position of air accumulation cannot be specified and reliable air bleeding cannot be performed
Solution Approach 1:
Instead of attempting to precisely detect air accumulation position in the complex shell-and-tube condenser, the control unit determines air bleeding timing in advance based on operating time or cycle count thresholds. This preliminary timing determination bypasses the need for precise spatial detection of air pockets within the pipe groups, enabling reliable air extraction despite the complex geometry.
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 allows for precise detection and effective extraction of noncondensable gases, maintaining refrigeration machine performance, preventing corrosion, and ensuring stable operation by moving gases to the condenser for removal.
Implementation Method 1
a temperature sensor which measures a cooling medium outlet temperature which is a temperature of the cooling medium which flows out from at least one heat transfer pipe configuring the pipe group
Implementation Method 2
a condenser which includes at least one pipe group configured of a plurality of heat transfer pipes through which a cooling medium flows and condenses the refrigerant compressed by the compressor
Implementation Method 3
an evaporator which evaporates the refrigerant expanded by the expansion valve
Data Source
AI summary
This refrigerating machine is equipped with: a turbocompressor which compresses a refrigerant; a condenser which is equipped with one or more pipe groups configured from a plurality of heat transfer pipes through which cooling water flows, and condenses the refrigerant compressed by the turbocompressor; an expansion valve which causes the refrigerant condensed by the condenser to expand; an evaporator which causes the refrigerant expanded by the expansion valve to evaporate; a temperature sensor which detects cooling water exit temperature, which is the temperature of the cooling water flowing from at least one of the heat transfer pipes constituting the pipe group(s); and a control unit which determines, on the basis of the detection temperature of the temperature sensor, air bleeding start conditions for starting an air bleeding operation to bleed and discharge air to the outside.