Heat pump system and control method thereof
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Solution Overview
Problem
Air-to-water heat pump systems face challenges in maintaining operation reliability and heating capacity due to varying outlet and outside temperature conditions, particularly with the R290 refrigerant which has a wider temperature range than traditional refrigerants.
Innovation Solution
The system controls the expansion valve based on an optimized target discharge temperature, calculated using a combination of outlet and outside temperature sensors, as well as discharge and suction pressure sensors, to ensure optimal efficiency and reliability across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion valve is controlled based on conventional target discharge temperature settings, then the system operates within standard parameters, but the operation reliability decreases and heating capacity becomes insufficient under varying temperature conditions
Solution Approach 1:
The patent implements dynamic adjustment of the target discharge temperature based on real-time detection of outside temperature and water outlet temperature. The controller continuously modifies the target discharge temperature within a predetermined range (e.g., 100°C to 120°C) according to the detected temperature conditions, rather than using a fixed conventional setting. This dynamic adaptation resolves the contradiction by enabling the system to maintain high operation reliability across varying temperature environments.
Solution Approach 2:
The system employs feedback control by detecting the actual discharge temperature of the compressor and comparing it with the dynamically adjusted target discharge temperature. The controller then adjusts the expansion valve opening degree based on the difference between actual and target values, creating a closed-loop control system. This feedback mechanism ensures the system adapts to changing conditions while maintaining reliable operation.
2Productivity
If the expansion valve is controlled with fixed parameters, then the control system remains simple, but the heating capacity becomes insufficient under diverse temperature conditions
Solution Approach 1:
The patent introduces dynamic control parameters for target discharge temperature that adjust automatically based on outside temperature and water outlet temperature detections. The controller modifies the target discharge temperature within a predetermined range according to the specific operating conditions, enabling the system to maintain optimal heating capacity across diverse temperature environments without requiring complex additional hardware.
Solution Approach 2:
The system changes the target discharge temperature parameter dynamically based on detected temperature conditions. By adjusting this key parameter within a predetermined range rather than using a fixed value, the system optimizes heating capacity for different operating conditions. This parameter change approach maintains relatively simple control logic while significantly improving heating performance.
3Reliability
If conventional target discharge temperature settings are used, then the control logic remains simple, but the compressor operation reliability decreases under varying temperature conditions
Solution Approach 1:
The patent establishes predetermined ranges for target discharge temperature adjustments before operation begins. Based on the detected outside temperature and water outlet temperature, the controller selects appropriate target discharge temperature values within these pre-established ranges. This preliminary preparation of control parameters simplifies the real-time decision-making process while ensuring reliable compressor operation under varying temperature conditions.
Solution Approach 2:
The system continuously monitors the actual discharge temperature and compares it with the target value, creating a feedback loop that adjusts the expansion valve accordingly. This feedback mechanism ensures the compressor operates within safe temperature parameters, preventing overheating and maintaining reliability. The feedback control automatically adapts to temperature condition changes without requiring complex monitoring algorithms.
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 operation reliability of the compressor and maintains optimal heating capacity by adjusting the expansion valve according to optimized target discharge temperatures, even under diverse temperature conditions.
Implementation Method 1
an outlet temperature sensor configured to detect an outlet temperature of the water-refrigerant heat exchanger
Implementation Method 2
an outside temperature sensor configured to detect an outside temperature
Implementation Method 3
a discharge pressure sensor configured to detect pressure of a refrigerant discharged from the compressor
Implementation Method 4
a suction pressure sensor configured to detect pressure of a refrigerant that enters the compressor
Implementation Method 5
a water-refrigerant heat exchanger connected to a compressor
Implementation Method 6
heat is exchanged between water and a refrigerant through the internal heat exchanger
Implementation Method 7
Changing a high-pressure refrigerant into a low-pressure refrigerant through a phase change of the refrigerant is accomplished through a throttling process
Implementation Method 8
a compressor; a discharge pressure sensor configured to detect pressure of a refrigerant discharged from the compressor
Data Source
AI summary
A heat pump system may include a compressor, a water-refrigerant heat exchanger, an expansion valve, an outdoor heat exchanger, an outlet temperature sensor configured to detect an outlet temperature of the water-refrigerant heat exchanger, an outside temperature sensor, a discharge pressure sensor, a suction pressure sensor, and at least one processor. The at least one processor may obtain, during a heating operation, a first target discharge temperature of the compressor based on an output value from the outlet temperature sensor and an output value from the outside temperature sensor, obtain a second target discharge temperature of the compressor based on an output value from the discharge pressure sensor and an output value from the suction pressure sensor, set any one of the first target discharge temperature or the second target discharge temperature to a final target discharge temperature, and control the expansion valve based on the final target discharge temperature.