Multi-parallel carbon dioxide heat pump control method based on target load control
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Solution Overview
Problem
Current multi-parallel carbon dioxide heat pump systems face instability and low energy utilization due to pressure fluctuations caused by load additions and removals, leading to inefficient energy use.
Innovation Solution
A multi-parallel carbon dioxide heat pump control method based on target load control, which adjusts the opening degree of the electronic expansion valve according to temperature, flow, and target outlet temperature, and dynamically turns on or off compressors to maintain system stability and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If load is added or removed in the carbon dioxide heat pump system, then the heating or cooling capacity is adjusted, but pressure fluctuations occur causing system instability and energy waste
Solution Approach 1:
The patent applies dynamics by making the electronic expansion valve opening degree adjustable in real-time based on system conditions. The control method dynamically modifies the opening degree during operation to compensate for pressure fluctuations caused by load changes, thereby maintaining system stability while allowing capacity adjustment. This is evident in the control steps that monitor system parameters and adjust the expansion valve accordingly.
Solution Approach 2:
The patent changes the parameter of electronic expansion valve opening degree to control system pressure and maintain stability during load transitions. By modifying this parameter based on detected system conditions (such as suction pressure, discharge pressure, or superheat temperature), the system can adjust refrigerant flow to counteract pressure fluctuations, resolving the contradiction between capacity adjustment and system stability.
2Productivity
If load is added or removed in the carbon dioxide heat pump system, then the heating or cooling capacity is adjusted, but energy utilization rate decreases due to control method defects
Solution Approach 1:
The patent implements feedback control by continuously monitoring system parameters (such as suction pressure, discharge pressure, superheat temperature, or subcooling temperature) and using this information to adjust the electronic expansion valve opening degree. This closed-loop control ensures that the system responds optimally to load changes, minimizing energy waste while maintaining desired heating or cooling capacity. The control method compares actual system state with target state and makes corrective adjustments accordingly.
Solution Approach 2:
The dynamic adjustment of electronic expansion valve opening degree based on real-time system conditions allows the system to optimize refrigerant flow during load transitions. This dynamic control prevents energy waste that would occur with static or粗放 control methods, enabling efficient capacity adjustment while maintaining high energy utilization rate throughout the operating range.
3Stress or pressure
If conventional refrigerant heat pumps are used, then operating pressure is lower, but heating efficiency and application scope are limited compared to carbon dioxide heat pumps
Solution Approach 1:
The patent addresses the high-pressure operation of carbon dioxide heat pumps by implementing control methods that optimize system parameters (such as expansion valve opening degree, compressor frequency, or heat exchanger airflow) specifically for carbon dioxide's high-pressure characteristics. This enables the system to efficiently operate at 4-5 times higher pressure than conventional refrigerants while maintaining or improving heating efficiency through precise control of refrigerant flow and heat transfer conditions.
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 method achieves stable system energy adjustment, rapid convergence of target water temperature, and efficient energy utilization by minimizing pressure fluctuations and optimizing compressor operation.
Implementation Method 1
adjusting the opening degree of an electronic expansion valve according to the temperature of an inlet of the hot water pipeline, the temperature of an outlet of the hot water pipeline, the flow in the hot water pipeline and a target outlet temperature set by a user
Implementation Method 2
the evaporator evaporating pipe and the heat source pipeline are arranged together to exchange heat with each other, the hot water pipeline and the cooler condensing pipe are arranged together to exchange heat with each other
Implementation Method 3
the compressor unit comprises a plurality of variable-frequency carbon dioxide compressors arranged in parallel
Implementation Method 4
the carbon dioxide circulation loop comprises an evaporator evaporating pipe, a gas-liquid separator, a compressor unit, an oil-gas separator, a cooler condensing pipe and an electronic expansion valve which are arranged in series in the loop sequentially
Data Source
AI summary
A multi-parallel carbon dioxide heat pump control method based on target load control, wherein the multi-parallel carbon dioxide heat pump comprises a carbon dioxide circulation loop, a heat source pipeline and a hot water pipeline, and the control method comprises: adjusting the opening degree of an electronic expansion valve (3) according to the temperature of an inlet of the hot water pipeline, the temperature of an outlet of the hot water pipeline, the flow in the hot water pipeline and a target outlet temperature set by a user, such that the steady-state change of system pressure can be realized by adjusting the electronic expansion valve (3) on the basis of the fluctuation of parameters such as user side temperature and flow, thus a target outlet temperature change curve is rapidly and stably converged to a target value, and the outlet temperature can be rapidly stabilized.