Heat Source Unit Pre-Cooling for Stable CO2 Refrigerant Flow
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Solution Overview
Problem
Existing refrigeration apparatuses using carbon dioxide as a refrigerant face inefficiencies in maintaining high-pressure refrigeration cycles, leading to suboptimal cooling capabilities and refrigerant flow rates, especially under varying outdoor temperatures.
Innovation Solution
Incorporating a refrigerant cooler within the heat source unit that uses a secondary refrigerant to cool the primary refrigerant, allowing for a higher flow rate and enhanced cooling capabilities by maintaining the primary refrigerant in a liquid single-phase state, and dynamically switching between cooling and inactive modes based on temperature and operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a refrigeration apparatus uses carbon dioxide as a refrigerant at high pressure higher than critical pressure, then the refrigeration cycle can be maintained, but the cooling capability and refrigerant flow rate become suboptimal under varying outdoor temperatures
Solution Approach 1:
The patent applies preliminary action by cooling the primary refrigerant before it enters the expansion valve using a second cooler. This pre-cooling ensures the refrigerant is in an optimal liquid single-phase state before expansion, improving cooling capability and refrigerant flow rate regardless of outdoor temperature variations. The second cooler performs the cooling action in advance, before the refrigerant reaches the expansion valve.
2Temperature
If the primary refrigerant is cooled using outdoor air in the first heat exchanger, then the system structure is simple, but the cooling effectiveness is insufficient under high outdoor temperatures
Solution Approach 1:
The patent introduces a second cooler as an intermediary device between the first heat exchanger and the expansion valve. This second cooler uses a coolant other than outdoor air to cool the primary refrigerant further, achieving better cooling effectiveness without being limited by high outdoor temperatures. The second cooler acts as a mediator that enhances the cooling process beyond what the first heat exchanger alone can achieve.
3Productivity
If the refrigerant flow rate is increased to improve cooling capacity, then the cooling capability increases, but the refrigerant may not remain in a stable liquid single-phase state
Solution Approach 1:
The second cooler performs preliminary cooling action on the primary refrigerant before it enters the expansion valve. This ensures that even at increased flow rates, the refrigerant maintains a stable liquid single-phase state by being sufficiently cooled in advance. The pre-cooling action guarantees phase stability regardless of the flow rate.
Solution Approach 2:
The patent incorporates a controller that monitors the state of the primary refrigerant and dynamically adjusts the operation of the second cooler. This feedback mechanism ensures the refrigerant remains in a stable liquid single-phase state by adjusting the cooling intensity based on real-time conditions, allowing the system to maintain phase stability while optimizing cooling capacity.
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
The solution increases the refrigeration apparatus's cooling capacity, ensures sufficient refrigerant flow and refrigerating performance across different outdoor temperatures, and maintains reliability by managing the refrigerant's phase and flow effectively.
Implementation Method 1
a second cooler (155) configured to cool the primary refrigerant flowing from the first heat exchanger (13) functioning as a radiator toward the first expansion valve (14), using a coolant other than the outdoor air
Implementation Method 2
a first heat exchanger (13) configured to exchange heat between the primary refrigerant and outdoor air
Implementation Method 3
a compressor (22, 23) configured to suck and compress the primary refrigerant
Implementation Method 4
a first expansion valve (14) configured to decompress the primary refrigerant that has flowed out of the first heat exchanger (13) functioning as a radiator
Data Source
AI summary
A heat source unit connected to a utilization unit includes a compressor, a first heat exchanger, a first expansion valve, and a receiver. The heat source unit further includes a first cooler and a second cooler. The first cooler cools a primary refrigerant flowing from the receiver toward the utilization unit. The second cooler cools the primary refrigerant flowing from the first heat exchanger functioning as a radiator toward the first expansion valve, using a coolant other than outdoor air.