Heat Pump Ejector Needle Control for Multi-Mode Heating Efficiency
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Solution Overview
Problem
Conventional heat pump systems face inefficiencies in switching between cooling and heating modes, particularly with ejector systems, where the ejector's efficiency drops at lower temperature differences, leading to suboptimal performance across varying ambient temperatures.
Innovation Solution
A controllable ejector system with a needle that shifts between closed and open positions, combined with a controller to switch between cooling, first heating, and second heating modes based on outdoor temperature, utilizing a single 4-way switching valve and check valves to alter refrigerant flow paths through heat exchangers, allowing for efficient operation in different temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional ejector is used in heat pump systems, then cooling mode operation is achieved, but heating mode efficiency drops at lower temperature differences
Solution Approach 1:
The ejector needle is made movable between different positions (fully open, partially open, fully closed) to dynamically adjust the ejector's operation or disable it entirely. This dynamic adjustment allows the system to adapt to different temperature conditions, maintaining heating efficiency across varying outdoor temperatures by switching between ejector-assisted and non-ejector modes.
Solution Approach 2:
The system changes the operational parameters of the ejector by adjusting the needle position based on outdoor temperature. At lower temperatures where the ejector would be inefficient, the needle is closed to disable the ejector function. At higher temperatures where the ejector is more effective, the needle is opened to enable ejector operation, thus optimizing heating efficiency across different temperature ranges.
2Adaptability or versatility
If multiple expansion devices are used to enable different heating modes, then system adaptability improves, but device complexity increases
Solution Approach 1:
The single ejector is designed to perform multiple functions by adjusting its needle position. It can operate as a fully open ejector for high-temperature heating, as a partially open ejector for moderate-temperature heating, and as a closed valve disabling the ejector function for low-temperature heating. This multi-functionality eliminates the need for separate expansion devices for different heating modes, reducing system complexity while maintaining adaptability.
Solution Approach 2:
The invention merges the functions of multiple expansion devices into a single ejector with a controllable needle. By combining the roles of what would traditionally require separate expansion devices (fully open ejector, partially open ejector, and closed valve) into one component, the system achieves the same adaptability with reduced complexity.
3Productivity
If the ejector needle is kept fully open for heating mode, then refrigerant flow is maximized, but performance deteriorates at lower outdoor temperatures
Solution Approach 1:
The ejector needle position is dynamically adjusted based on outdoor temperature conditions. Rather than remaining statically fully open, the needle can be positioned partially open or fully closed depending on the temperature. This dynamic control allows the system to maintain optimal refrigerant flow at high temperatures while preventing performance deterioration at lower temperatures by reducing or eliminating ejector operation.
Solution Approach 2:
The system uses outdoor temperature as feedback to control the ejector needle position. When outdoor temperature drops below a certain threshold, the controller closes the needle to disable the ejector function. When temperature rises above the threshold, the needle is opened to enable ejector operation. This feedback mechanism ensures optimal heating performance across varying temperature conditions by automatically adjusting refrigerant flow through the ejector.
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
Enables efficient operation across different modes by optimizing refrigerant flow and pressure management, enhancing performance by selecting the appropriate heating mode based on sensed outdoor temperatures, thus improving overall system efficiency and adaptability.
Implementation Method 1
The motive nozzle accelerates the flow and decreases the pressure of the flow. The pressure reduction caused to the primary flow by the motive nozzle helps draw a suction flow or secondary flow into the outer member through the suction port.
Implementation Method 2
The outer member also has a divergent section or diffuser downstream of the elongate throat or mixing section. The resulting combined flow is a liquid/vapor mixture and decelerates and recovers pressure in the diffuser while remaining a mixture.
Implementation Method 3
An exemplary outdoor heat exchanger is a refrigerant-air heat exchanger wherein fan-forced outdoor air acquires heat from refrigerant. Again, the evaporator may be a refrigerant-air heat exchanger across which a fan-forced interior/indoor airflow is driven with the interior/indoor airflow rejecting heat to the refrigerant.
Implementation Method 4
By rejecting heat, the refrigerant may condense from vapor to liquid in the heat rejection heat exchanger. Accordingly, such exchangers are often referred to as condensers.
Implementation Method 5
The reduced temperature of the refrigerant thus absorbs heat in the heat absorption heat exchanger (e.g., evaporator).
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A system 300 has: a compressor 22 having a suction port 40 and a discharge port 42; an ejector 32 having a motive flow inlet 50, a suction flow inlet 52, and an outlet 54; a separator 34 having an inlet 72, a vapor outlet 74, and a liquid outlet 76; a first heat exchanger 24; an expansion device 28; and a second heat exchanger 302. Conduits and valves are positioned to provide alternative operation in: a cooling mode and a heating mode. In the cooling mode, a needle of the ejector 32 is closed. In the heating mode refrigerant passes sequentially from a first section of the second heat exchanger to a second section. In the cooling mode refrigerant passes in parallel through the first section and the second section.