Refrigeration device
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Solution Overview
Problem
The refrigerating apparatus with an economizer system faces inefficiencies due to the subcooling process, where the branched refrigerant injected into the compressor reduces the flow rate through the utilization-side heat exchanger, leading to increased compressor work and energy wastage, especially during light cooling loads.
Innovation Solution
The system controls the subcooling temperature of the subcooling heat exchanger based on the cooling load, adjusting the opening of the subcooling expansion valve to optimize the flow rate of the refrigerant into the compressor, thereby adjusting the work done by the compressor and conserving energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the branched refrigerant is injected into the compressor from the suction side, then the subcooling effect is achieved, but the flow rate of refrigerant through the utilization-side heat exchanger decreases
Solution Approach 1:
The patent introduces an intermediate port on the compressor as a mediator for refrigerant injection. Instead of injecting directly into the suction side, the refrigerant is injected into the intermediate port, which serves as a buffer zone between the suction side and compression chamber. This allows the refrigerant to be introduced without directly reducing the suction flow rate, thereby maintaining better balance between subcooling effect and refrigerant circulation quantity.
2Quantity of substance
If the branched refrigerant is injected into the intermediate port of the compressor, then the refrigerant flow rate through the utilization-side heat exchanger is maintained, but the compressor work increases
Solution Approach 1:
The patent implements dynamic control of the subcooling expansion valve based on compressor operating conditions. The opening degree of the expansion valve is adjusted according to the compressor's suction pressure, suction temperature, and discharge temperature. This dynamic adjustment allows the system to optimize the balance between maintaining refrigerant flow rate and minimizing unnecessary compressor work, adapting to varying load conditions in real-time.
Solution Approach 2:
The system changes key operating parameters including the opening degree of the subcooling expansion valve, suction pressure, suction temperature, and discharge temperature to optimize performance. By monitoring and adjusting these parameters dynamically, the system can maintain appropriate refrigerant flow rates while preventing excessive compressor work, especially under light load conditions where the contradiction is most pronounced.
3Productivity
If the subcooling expansion valve opening is increased to enhance subcooling, then the cooling capacity increases, but the compressor energy consumption increases during light loads
Solution Approach 1:
The patent employs a feedback control mechanism where the controller continuously monitors compressor operating parameters (suction pressure, suction temperature, discharge temperature) and adjusts the subcooling expansion valve opening accordingly. This closed-loop feedback system ensures that subcooling is optimized for maximum cooling capacity during high loads, while automatically reducing subcooling degree during light loads to minimize unnecessary compressor energy consumption, thus resolving the contradiction between cooling capacity and energy 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
This approach allows for efficient energy usage by reducing the compressor work during light loads and maintaining cooling capacity by adjusting the subcooling degree according to the load, preventing unnecessary energy expenditure.
Implementation Method 1
The subcooling passage is provided with a subcooling expansion valve for reducing the pressure of the branched refrigerant
Implementation Method 2
the branched refrigerant subjected to a pressure reduction in the subcooling expansion valve flows into the subcooling heat exchanger and evaporates through a heat exchange with the liquid refrigerant inside of the connection liquid piping
Implementation Method 3
the branched refrigerant subjected to a pressure reduction in the subcooling expansion valve flows into the subcooling heat exchanger and evaporates through a heat exchange with the liquid refrigerant
Implementation Method 4
a compressor (21a, 21b, 21c), a heat-source-side heat exchanger (25) and a utilization-side heat exchanger (53), in which the refrigerant circuit (10) includes a branch pipe (34) used for branching a liquid refrigerant inside of a liquid pipe (33)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A refrigerating apparatus includes: a first branch pipe (34) used for branching a liquid refrigerant inside of a liquid pipe (33) and provided with a subcooling expansion valve (29); a subcooling heat exchanger (28) provided along the liquid pipe (33) and subcooling a liquid refrigerant inside of the liquid pipe (33) with a branched refrigerant flowing thereinto from the first branch pipe (34); and a refrigerant circuit (10) for injecting the branched refrigerant after the subcooling into an intermediate-pressure compression chamber of a compressor (21a, 21b, 21 c). A controller (80) determines a target temperature of the liquid refrigerant inside of the liquid pipe (33) after the subcooling according to a cooling load in an inside-cabinet heat exchanger (53) and controls the opening of the subcooling expansion valve (29) such that the temperature detected by a liquid temperature sensor (68) becomes the target temperature.