Air conditioning apparatus
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Solution Overview
Problem
In air conditioning apparatuses with multiple compressors, the change from R410A to R32 refrigerant causes a density difference that leads to chattering of check valves in discharge pipes due to balanced weight and flow resistance, exacerbated by counter pressures from other compressors, resulting in repeated opening and closing.
Innovation Solution
The air conditioning apparatus is configured with check valves in discharge pipes that have a valve diameter per air conditioning capacity set between Φ0.21 mm/kW and Φ0.42 mm/kW, and a flow coefficient per air conditioning capacity set between 0.105/kW and 0.21/kW, along with different operation frequencies for compressors and a joining angle of 90 degrees or less for discharge pipes to reduce counter pressure influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If check valves are provided in discharge pipes of multiple compressors to prevent backflow, then refrigerant backflow is prevented, but chattering occurs due to balanced valve body weight and flow resistance caused by R32 refrigerant density difference
Solution Approach 1:
The patent changes the physical parameters of the check valve by optimizing the valve body weight and/or valve seat area to specific ranges. This parameter adjustment ensures that the valve can withstand the flow resistance caused by R32 refrigerant density without chattering, while still effectively preventing backflow.
2Productivity
If multiple compressors are installed to increase cooling capacity, then air conditioning performance is improved, but counter pressure from other compressors exacerbates check valve chattering
Solution Approach 1:
The patent optimizes check valve parameters (valve body weight, valve seat area) to specific ranges that enable the valve to resist counter pressure effects from other compressors. This allows multiple compressors to operate simultaneously at high capacity without causing valve chattering.
3Loss of energy
If valve diameter is increased to reduce flow resistance, then refrigerant flow improves, but valve body weight increases causing more severe chattering
Solution Approach 1:
The patent establishes specific ranges for valve body weight and valve seat area that optimize the balance between flow resistance and chattering prevention. These parameter ranges allow the valve to maintain low pressure loss while preventing chattering caused by excessive valve body weight.
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 configuration effectively suppresses chattering of check valves, reduces pressure loss, and maintains system performance by optimizing valve dimensions and operation frequencies, while using R32 as a low-GWP refrigerant.
Implementation Method 1
a difference in density of the refrigerant causes reduction in a flow rate. Thus, there is a possibility that an own weight of a valve body of the check valve and a resistance caused by flow of the refrigerant are balanced with each other
Implementation Method 2
a difference in density of the refrigerant causes reduction in a flow rate. Thus, there is a possibility that an own weight of a valve body of the check valve and a resistance caused by flow of the refrigerant are balanced with each other
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An air conditioning apparatus configured to execute an air conditioning operation including cooling and heating by circulating R32 as refrigerant through a refrigerant pipe connecting an outdoor unit (11) and an indoor unit (12) to each other, the outdoor unit including a compressor (18), an outdoor heat exchanger (20), and an expansion mechanism (21), the indoor unit including an indoor heat exchanger (31), the air conditioning apparatus including a plurality of the compressors (18A,18B), and a plurality of check valves (24A,24B) respectively provided in discharge pipes respectively connected to the plurality of the compressors. Each of the plurality of check valves is configured to have a valve diameter per air conditioning capacity of the compressor, which is set in a range of Φ0.21 mm/kW to Φ0.42 mm/kW.