Heat pump device
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat pump devices used as hot-water heaters face efficiency and reliability issues due to improper subcooling adjustment, which is influenced by discharge temperature variability and refrigerant type, leading to potential compressor damage.
Innovation Solution
A heat pump device with a refrigerant circuit and control system that includes discharge temperature and subcooling detection, along with load detection, to adjust the electronic expansion valve and compressor rotation speed based on predetermined discharge temperature limits, ensuring stable subcooling within a target range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electronic expansion valve is adjusted based on subcooling to improve operation efficiency, then the coefficient of performance increases, but the discharge temperature becomes unstable and compressor reliability decreases
Solution Approach 1:
The control device implements a feedback mechanism by detecting discharge temperature and using it to adjust the electronic expansion valve opening degree. The control device determines the opening degree based on the detected discharge temperature to maintain it within a predetermined range, creating a closed-loop control system that simultaneously optimizes efficiency and ensures compressor reliability.
Solution Approach 2:
The patent changes the control parameter from subcooling-based adjustment to discharge temperature-based adjustment. By using discharge temperature as the primary control parameter instead of subcooling, the system achieves both efficient operation and stable compressor performance, resolving the contradiction between efficiency optimization and reliability assurance.
2Adaptability or versatility
If the discharge temperature is not controlled within optimal limits, then the system operates without temperature constraints, but the compressor may suffer from excessive wetness or overheating
Solution Approach 1:
The control device takes preliminary anti-action by proactively controlling the electronic expansion valve to prevent discharge temperature from exceeding safe limits. By anticipating potential harmful conditions and adjusting the opening degree in advance, the system prevents compressor damage from excessive wetness or overheating before these conditions can occur.
Solution Approach 2:
The electronic expansion valve serves as an intermediary component between the refrigerant circuit and the compressor. By precisely controlling the opening degree of this intermediary device, the system regulates refrigerant flow to maintain discharge temperature within safe boundaries, protecting the compressor from harmful 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
Ensures efficient operation and reliability of the compressor by maintaining discharge temperatures within optimal limits, thereby enhancing the coefficient of performance (COP) and preventing excessive wetness or overheating.
Implementation Method 1
a use-side heat exchanger that exchanges heat between water and a refrigerant
Implementation Method 2
a compressor... causes a high-temperature gas refrigerant compressed by the compressor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A heat pump device according to an embodiment of the present invention includes: a compressor, a use-side heat exchanger that exchanges heat between water and a refrigerant, an electronic expansion valve, a heat source-side heat exchanger, and control means for controlling a rotation speed of the compressor and an opening degree of the electronic expansion valve. The control means controls the electronic expansion valve on the basis of predetermined upper-limit discharge temperature and lower-limit discharge temperature, sets the upper-limit discharge temperature in accordance with the magnitude of the load of the compressor, reduces the opening degree of the electronic expansion valve such that the discharge temperature is equal to or larger than the lower-limit discharge temperature when the discharge temperature is less than the lower-limit discharge temperature, increases the opening degree of the electronic expansion valve such that the discharge temperature is less than the upper-limit discharge temperature when the discharge temperature is equal to or larger than the upper-limit discharge temperature, and controls the opening degree of the electronic expansion valve such that the subcooling is a target subcooling when the discharge temperature is equal to or larger than the lower-limit discharge temperature and less than the upper-limit discharge temperature.