Ejector Heat Pump Needle Actuation for Wide-Temperature Performance
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Solution Overview
Problem
Ejector operation in heat pumps deviates from the design or optimum operating point during varying conditions, leading to diminished performance, particularly in applications with wide temperature ranges, necessitating the use of additional expansion devices that increase system complexity and cost.
Innovation Solution
A method and system for operating heat pumps that involve switching between heating and cooling modes by adjusting fan speed and actuating the ejector needle based on refrigerant pressure measurements, eliminating the need for parallel expansion devices and optimizing ejector performance across different operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ejector operation conditions deviate from the design point during varying temperatures, then performance diminishes, but adding parallel expansion devices increases system complexity and cost
Solution Approach 1:
The patent implements dynamic control of the ejector by adjusting the motive flow rate in response to varying operating conditions. The controller modifies the ejector's operation based on real-time conditions, allowing the single ejector to adapt to different temperature ranges and maintain optimal performance without requiring multiple parallel devices.
Solution Approach 2:
The system changes the operating parameters of the ejector, specifically the motive flow rate, to optimize performance under varying conditions. By dynamically adjusting this parameter, the ejector can operate efficiently across a wide temperature range without deviating from its design point, eliminating the need for additional expansion devices.
2Reliability
If ejector operation conditions deviate from the design point during varying temperatures, then performance diminishes, but adding parallel expansion devices increases system cost
Solution Approach 1:
The dynamic control capability allows a single ejector to replace multiple parallel devices, reducing manufacturing costs. The controller adjusts the ejector's operation in real-time, enabling one device to perform the function that would otherwise require several fixed-design devices.
Solution Approach 2:
The ejector is designed to perform multiple functions across different operating conditions through dynamic control. A single ejector with adjustable motive flow rate can handle various temperature ranges and load conditions, replacing the need for multiple specialized expansion devices.
3Power
If ejector motive flow potential is low in mild winter conditions, then work recovery is insufficient, but using expansion valve bypass increases system complexity
Solution Approach 1:
The system dynamically adjusts the motive flow rate to the ejector based on outdoor temperature conditions. In mild winter conditions where natural motive flow potential is low, the controller increases the motive flow rate to maintain sufficient work recovery, eliminating the need for bypass valves or additional complexity.
Solution Approach 2:
The controller uses feedback from temperature sensors and system performance data to adjust the motive flow rate. This closed-loop control ensures that the ejector receives adequate motive flow even when natural potential is low, maintaining efficiency without requiring mechanical bypass arrangements.
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 enhances the efficiency and cost-effectiveness of heat pumps by maintaining optimal performance across varying conditions without the need for additional expansion devices, thereby improving the coefficient of performance and reducing system complexity.
Implementation Method 1
A primary or motive flow of high pressure refrigerant from the condenser enters the primary or motive port (inlet) and passes through the motive nozzle of the ejector where it accelerates. It exits the motive nozzle with a high velocity and generates low pressure area around the exit.
Implementation Method 2
A secondary or suction flow of refrigerant vapor from the evaporator is entrained (i.e., sucked) into the secondary or suction port (inlet) of the ejector and is thereby accelerated.
Implementation Method 3
High velocity motive flow refrigerant decelerates and mixes with accelerating suction flow refrigerant in the mixing section (mixer) of the ejector.
Implementation Method 4
After mixing, the two phase refrigerant mixture enters the diffuser of the ejector, decelerates thereby recovering pressure.
Implementation Method 5
The resulting two-phase refrigerant stream enters the separator where the vapor and liquid phases are separated.
Implementation Method 6
Vapor is sucked into the compressor where it is compressed and discharged to the condenser or gas cooler.
Implementation Method 7
In the condenser, the compressed high pressure, high temperature vapor is cooled and condensed.
Implementation Method 8
Liquid from the separator enters the evaporator after passing through an expansion valve, evaporates and vapor flows to the suction port of the ejector.
Implementation Method 9
Liquid from the separator enters the evaporator after passing through an expansion valve, evaporates and vapor flows to the suction port of the ejector.
Data Source
AI summary
A method for operating a heat pump (20; 300) includes operating in a cooling mode wherein heat is absorbed by refrigerant in the indoor heat exchanger (26) and rejected by refrigerant in the outdoor heat exchanger (24). The heat pump switches to operation in a heating mode wherein heat is rejected by refrigerant in the indoor heat exchanger, heat is absorbed by refrigerant in the outdoor heat exchanger, and there is an ejector (60) motive flow and ejector secondary flow. In the heating mode a refrigerant pressure (PH) or temperature (TL) is measured and, responsive to the measured refrigerant pressure or temperature, at least one of a fan speed is changed and a needle (132) of the ejector is actuated.