CO2 Refrigerant Charge Tank for High-Pressure Cooling Stability
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Solution Overview
Problem
Conventional refrigerating apparatuses using carbon dioxide as a refrigerant face issues with maintaining appropriate refrigerant circulation, preventing refrigerant dissolution in oil, and optimizing cooling efficiency, especially at varying outdoor temperatures, leading to abnormal high pressures and reduced cooling performance.
Innovation Solution
A refrigerating apparatus with a refrigerant amount regulation tank connected to the high-pressure side via communicating circuits, controlled by opening and closing means to manage refrigerant flow, an oil separator with an oil return circuit and bypass, and an exhaust heat recovery heat exchanger to optimize refrigerant circulation and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pressure blocking device is disposed to avoid abnormal rise of high pressure side pressure, then the system is protected from high pressure, but the compression means is forcibly stopped causing cooling to stop
Solution Approach 1:
A refrigerant amount regulation tank is introduced as an intermediary device between the high-pressure side and the compression means. This tank accumulates excess refrigerant when high pressure occurs, acting as a buffer that prevents the need to stop the compression means while still protecting the system from abnormal high pressure
Solution Approach 2:
The system changes the state of refrigerant by accumulating it in the regulation tank when high pressure occurs. By changing the location and state (from circulating to stored) of the refrigerant, the system maintains compression operation while preventing dangerous pressure buildup
2Adaptability or versatility
If the outdoor temperature rises to +25°C to +30°C or higher, then a gas cycle operation is performed, but the amount of refrigerant cannot be regulated in the receiver tank causing high pressure side pressure to abnormally rise
Solution Approach 1:
The refrigerant amount regulation tank serves multiple functions: it regulates refrigerant amount during gas cycle operation at high temperatures, accumulates excess refrigerant during saturation cycle at low temperatures, and prevents high pressure abnormalities in both operating modes, replacing the need for separate receiver tank functionality
3Loss of energy
If the oil cooler is installed in an air path with the gas cooler and air-cooled by the same blower, then energy is saved, but at low outdoor temperature the oil is excessively cooled causing refrigerant to dissolve in the oil and return efficiency to deteriorate
Solution Approach 1:
The system dynamically adjusts the cooling of oil based on outdoor temperature conditions. At low temperatures, the oil bypasses the cooler or receives reduced cooling to prevent excessive cooling and refrigerant dissolution. At normal temperatures, the oil is cooled efficiently. This dynamic adjustment maintains both energy efficiency and oil return efficiency
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 effectively regulates refrigerant circulation, prevents refrigerant overload, ensures smooth oil return, and enhances cooling performance by maintaining appropriate refrigerant levels and optimizing heat exchange, even at high outdoor temperatures.
Implementation Method 1
a refrigerant compressed by the compression means releases heat in the gas cooler, has a pressure thereof reduced by the reducing means, and is then evaporated in the evaporator, to cool ambient air by the evaporation of the refrigerant at this time
Implementation Method 2
a refrigerant compressed by the compression means releases heat in the gas cooler
Implementation Method 3
the refrigerant is compressed to obtain a supercritical state on the high pressure side of the refrigerating cycle
Implementation Method 4
the oil separated from the refrigerant by the oil separator is cooled by the oil cooler, and then returns to the compression means via the oil return circuit
Data Source
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AI summary
An object of the present invention is to keep an appropriate amount of a refrigerant to be circulated through a refrigerant circuit and prevent an overload operation of compression means due to high pressure abnormality in a refrigerating apparatus which obtains a supercritical pressure on a high pressure side. The refrigerating apparatus which obtains the supercritical pressure on the high pressure side comprises a refrigerant amount regulation tank (100) connected to the refrigerant circuit on the high pressure side via a communicating circuit; a communicating circuit (101) which connects the upper part of this tank to a medium pressure region of the refrigerant circuit; a communicating circuit (103) which connects the lower part of the tank to the medium pressure region of the refrigerant circuit; an electromotive expansion valve (102) of the communicating circuit; an electromagnetic valve (104) of the communicating circuit; an electromagnetic valve (106) of the communicating circuit; and control means (C) for controlling these valves to collect a refrigerant circulated through the refrigerant circuit in the tank and discharging the refrigerant to the refrigerant circuit.