Heat Pump Subcooling Control for Stable High COP Operation
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Solution Overview
Problem
Heat pump type floor heaters experience inefficient operation due to the significant influence of supercooling degree (SC value) on the Coefficient of Performance (COP), leading to potential efficiency deterioration, unlike air conditioners, where SC value changes have a lesser impact on COP.
Innovation Solution
Implementing a control system that determines and adjusts the objective subcooling value (SC value) based on both condensing pressure and compressor rotation number, using a subcooling table to optimize SC values for various operation conditions, ensuring efficient operation by maintaining high COP levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SC value is not strictly controlled in heat pump type floor heaters, then the operation is simpler, but the COP deteriorates significantly
Solution Approach 1:
The control system automatically adjusts the electronic expansion valve opening degree based on detected condensing temperature and refrigerant discharge temperature to maintain optimal SC value, eliminating the need for manual intervention and ensuring efficient operation
Solution Approach 2:
The system continuously monitors condensing temperature and refrigerant discharge temperature, calculates the actual SC value, and adjusts the electronic expansion valve accordingly to maintain the optimal SC value, creating a closed-loop control system that prevents COP deterioration
2Loss of energy
If the electronic expansion valve opening degree is adjusted to change the SC value, then the COP can be optimized, but the control system becomes more complex
Solution Approach 1:
The system replaces manual mechanical adjustment of the expansion valve with an electronically controlled valve that can be precisely adjusted by the control unit based on temperature sensor feedback, enabling automated optimization without manual intervention
Solution Approach 2:
The control system dynamically adjusts the opening degree parameter of the electronic expansion valve based on real-time temperature measurements and calculated SC value, optimizing the refrigerant flow and heat exchange efficiency adaptively
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 operational efficiency of heat pump apparatuses like heat pump type floor heaters and water heaters by delicately controlling subcooling, maintaining high COP levels even under varying conditions, thereby preventing efficiency deterioration.
Implementation Method 1
heat exchange is effected using water which circulates in a floor heating panel
Implementation Method 2
converting water into hot water by heat exchange
Implementation Method 3
an evaporator are sequentially connected by piping
Implementation Method 4
a compressor, a condenser, an electronic expansion valve, and an evaporator are sequentially connected by piping
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A heat pump apparatus includes: a refrigerant circuit including a compressor, a utilization-side heat exchanger for exchanging heat between water and refrigerant, an electronic expansion valve, and an outdoor heat exchanger; control means for controlling the compressor and the electronic expansion valve; subcooling value calculating means for calculating a subcooling value of the refrigerant circuit; condensing pressure detecting means for detecting condensing pressure of the compressor; compressor rotation number detecting means for detecting rotation number of the compressor; and objective subcooling value extracting means for selecting and extracting an objective subcooling value stored in advance, from the condensing pressure and the rotation number of the compressor. The control means adjusts an opening degree of the electronic expansion valve so that the calculated subcooling value of the refrigerant circuit reaches the objective subcooling value.