Heat Pump Refrigerant Injection Without an Accumulator
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Solution Overview
Problem
Conventional heat pump devices face challenges in downsizing due to the need for large accumulators in low outside-air temperature environments, which hinder efficient operation and require additional components to prevent refrigerant stagnation.
Innovation Solution
A heat pump device with a main refrigerant circuit, an injection pipe, and multiple parallel-connected main circuit expansion devices, controlled by a controller to regulate refrigerant flow and pressure based on outside-air temperature and suction pressure, eliminating the need for an accumulator by injecting refrigerant directly into the compressor and adjusting expansion device openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an accumulator is installed in the refrigerant circuit to prevent liquid back phenomenon, then reliability is improved, but device complexity and volume increase
Solution Approach 1:
The patent removes the accumulator component from the refrigerant circuit by implementing a control strategy that prevents liquid back phenomenon through injection control and expansion device management, thereby simplifying the system structure while maintaining reliability
Solution Approach 2:
The controller monitors suction pressure and outside air temperature in real-time, and dynamically adjusts the injection expansion device and main circuit expansion devices based on feedback signals, preventing liquid back phenomenon without requiring an accumulator
2Volume of stationary object
If the heat pump device is downsized by removing the accumulator, then device volume is reduced, but reliability may deteriorate due to refrigerant stagnation risks
Solution Approach 1:
The controller continuously monitors suction pressure and outside air temperature, and dynamically adjusts the opening degrees of expansion devices and injection amount based on feedback signals, ensuring reliable operation in low temperature environments without requiring an accumulator
Solution Approach 2:
The system dynamically adjusts the opening degrees of the injection expansion device and main circuit expansion devices based on real-time operating conditions (suction pressure and outside air temperature), enabling adaptive control that maintains reliability while allowing downsizing
3Stress or pressure
If refrigerant flow through the evaporator is reduced to increase pressure, then suction pressure is improved, but heat exchange efficiency may decrease
Solution Approach 1:
The system dynamically adjusts the opening degrees of the injection expansion device and main circuit expansion devices based on real-time operating conditions, optimizing the balance between suction pressure and heat supply efficiency under varying temperature and pressure conditions
Solution Approach 2:
The controller changes operating parameters (opening degrees of expansion devices, injection amount) based on suction pressure and outside air temperature conditions, optimizing system performance to maintain both adequate suction pressure and heat supply efficiency
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 allows the heat pump device to operate effectively in low temperatures without an accumulator, reducing refrigerant flow through the evaporator and increasing pressure, enabling downsizing while maintaining heat supply efficiency.
Implementation Method 1
a compressor configured to compress and discharge the refrigerant
Implementation Method 2
the refrigerant exchanging heat with a load through the condenser
Implementation Method 3
the refrigerant exchanging heat with a load through the condenser
Implementation Method 4
a main circuit expansion device unit configured to reduce a pressure of the refrigerant
Implementation Method 5
the refrigerant exchanging heat with outside air through the evaporator
Implementation Method 6
the refrigerant exchanging heat with outside air through the evaporator
Implementation Method 7
an injection pipe connected at one end to a pipe between the condenser and an expansion device, and connected at an other end to the injection port
Implementation Method 8
an injection expansion device configured to regulate an opening degree to regulate an amount of the refrigerant flowing through the injection pipe
Data Source
AI summary
Provided is a main refrigerant circuit in which a compressor having an injection port, a condenser, a main circuit expansion device unit, and an evaporator are connected by pipes to allow refrigerant to circulate in the main refrigerant circuit; an injection pipe an injection expansion device; an outside-air temperature detection device; a suction pressure detection device; and a controller, wherein the main circuit expansion device unit includes a plurality of main circuit expansion devices with different capacities and in a parallel-connected relationship, and during operation, when the controller determines that the temperature of the outside air is equal to or lower than a set temperature, the controller is configured to open the injection expansion device to control an opening degree to select the main circuit expansion device based on the suction pressure to control an opening degree of the selected main circuit expansion device.