VRF Outdoor Unit Refrigerant Switching for Suction Superheat
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Solution Overview
Problem
In heat recovery VRF air conditioning systems, the suction-superheat degree of the compressor is compromised during heating mode, leading to reduced energy efficiency due to excessive refrigerant in the gas-liquid separator and inadequate refrigerant in the pipe, which is typically addressed by opening a hot gas bypass solenoid valve, further reducing efficiency.
Innovation Solution
The outdoor unit incorporates a refrigerant flow direction switching device with throttling elements, one-way valves, and a gas-liquid separator, where all throttling elements are opened in heating mode to depressurize the refrigerant before it enters the outdoor heat exchanger, improving pressure and dryness, and reducing refrigerant in the separator, thereby enhancing suction-superheat and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hot gas bypass solenoid valve is opened to increase the suction-superheat degree of the compressor, then the suction-superheat degree is improved, but the energy efficiency of the heat recovery VRF air conditioning system is reduced
Solution Approach 1:
The patent introduces a gas-liquid separator as an intermediary device between the refrigerant flow and the compressor. This separator mediates the refrigerant distribution, allowing liquid refrigerant to be separated and stored in the gas-liquid separator while ensuring adequate refrigerant reaches the compressor for proper suction-superheat without requiring the hot gas bypass valve to be opened, thus avoiding the energy efficiency penalty
Solution Approach 2:
The patent changes the refrigerant distribution parameters by using a throttling element to control the refrigerant flow into the gas-liquid separator. By adjusting the throttling degree and pressure parameters, the system achieves optimal refrigerant distribution between the pipe and the separator, ensuring proper suction-superheat while maintaining energy efficiency
2Quantity of substance
If more liquid refrigerant is stored in the gas-liquid separator, then the refrigerant in the pipe is increased, but the suction-superheat degree of the compressor drops
Solution Approach 1:
The gas-liquid separator acts as an intermediary that buffers the refrigerant distribution. It allows the system to store liquid refrigerant while preventing excessive refrigerant from reaching the compressor, thereby maintaining proper suction-superheat degree even when refrigerant quantity in the system is increased
Solution Approach 2:
The patent uses a throttling element to control the refrigerant flow parameters into the gas-liquid separator. By adjusting the throttling degree, the system optimizes the balance between storing sufficient refrigerant in the separator and ensuring adequate refrigerant reaches the compressor for proper suction-superheat
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 improves the suction-superheat degree of the compressor and enhances the energy efficiency of the heat recovery VRF air conditioning system by optimizing refrigerant distribution and pressure within the system.
Implementation Method 1
a plurality of one-way valves, in which each one-way valve has a circulation end and a stop end, and each one-way valve is opened only in one direction from the circulation end to the stop end
Implementation Method 2
the refrigerant is throttled and depressurized by a throttling element in a refrigerant flow direction switching device
Implementation Method 3
more liquid refrigerant is stored in the gas-liquid separator
Implementation Method 4
an outdoor heat exchanger, having a first end connected to the fourth valve port, and a second end connected to the second connector
Implementation Method 5
a compressor having an exhaust port and a gas return port
Data Source
AI summary
An outdoor unit for a heat recovery VRF air conditioning system and a heat recovery VRF air conditioning system are provided. The outdoor unit comprises: a compressor, having an exhaust port and a gas return port; a reversing assembly, having a first valve port, a second valve port, a third valve port and a fourth valve port; an outdoor heat exchanger, having a first end connected to the first valve port, and a second end connected to the second connector; a plurality of one-way valves, wherein each one-way valve has a circulation end and a stop end, and each one-way valve is opened only in one direction from the circulation end to the stop end; a throttling element; and a gas-liquid separator.