Heat Pump Ejector with Needle Control for Multi-Mode Operation
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Solution Overview
Problem
Existing heat pump systems face inefficiencies in switching between cooling and heating modes, particularly with ejector systems, where efficiency drops at lower temperature differences, necessitating a solution for adaptable operation across varying ambient temperatures.
Innovation Solution
A controllable ejector system with a needle that shifts between closed and open positions, combined with a single four-port switching valve and check valves, allows for alternative operation in cooling, first heating, and second heating modes, enabling efficient switching based on sensed outdoor temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an ejector is used as an expansion device in heat pump systems, then efficiency is improved in high temperature difference conditions, but efficiency drops in low temperature difference conditions
Solution Approach 1:
The ejector is designed with a movable needle that can dynamically adjust its position between fully open and fully closed states. This dynamic adjustment allows the system to switch between ejector mode (for high temperature difference efficiency) and disabled mode (for low temperature difference operation), making the heat pump adaptable to varying ambient temperature conditions throughout the year
2Adaptability or versatility
If a controllable ejector with needle adjustment is implemented, then adaptability to different temperature differences is improved, but device complexity increases
Solution Approach 1:
The ejector control system is segmented into discrete operational states (fully open, fully closed, and intermediate positions) rather than requiring continuous complex control. The needle can be positioned at specific discrete locations, simplifying the control mechanism while maintaining the ability to adapt to different temperature difference conditions
Solution Approach 2:
The single ejector device with needle adjustment serves multiple functions: it can operate in fully open position for maximum ejector effect in high temperature difference conditions, be partially adjusted for intermediate conditions, and be fully closed to disable the ejector for low temperature difference operation. This multi-functionality reduces the need for multiple separate components
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 system efficiently transitions between modes, optimizing performance by using the ejector as an expansion device in high temperature differences and disabling it in low differences, thereby maintaining efficiency across a range of ambient temperatures.
Implementation Method 1
The ejector has a motive/primary refrigerant flow which enters the inlet and then passes into a convergent section of the motive nozzle. It then passes through a throat section and an expansion (divergent) section and through an outlet of the motive nozzle. The motive nozzle accelerates the flow and decreases the pressure of the flow.
Implementation Method 2
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 3
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.
Data Source
AI summary
A system (20; 300) comprises: 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 (26; 302). Conduits and valves are positioned to provide alternative operation in: a cooling mode; a first heating mode; and a second heating mode. In the cooling mode and second heating mode, a needle (60) of the ejector is closed.