Subcooling Heat Exchanger Control for High-Temperature Hot Water Capacity
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Solution Overview
Problem
Existing air-conditioning and hot water supply combination systems face challenges in maintaining high hot water supply capacity and efficient operation under high-temperature outside air conditions, with systems either requiring increased size or experiencing reduced hot water supply capacity and efficiency due to high compression ratios and pressure increases.
Innovation Solution
The system incorporates a heat source unit with a compressor, heat exchanger, pressure reducing mechanisms, a bypass for liquid refrigerant, an accumulator, and subcooling heat exchangers to control the degree of superheat and subcooling, allowing for efficient refrigerant flow management and pressure regulation, ensuring high hot water supply capacity and efficiency even under high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single refrigerant circuit performs hot water supply, then the system size is reduced, but the hot water supply capacity is reduced and operation efficiency is reduced under high-temperature outside air conditions
Solution Approach 1:
The patent implements dynamic control of the refrigerant circulation flow rate through a circulation flow rate controlling mechanism. This mechanism adjusts the refrigerant flow rate based on operating conditions, enabling the single refrigerant circuit to dynamically adapt its capacity. Under high-temperature outside air conditions, the system can increase refrigerant circulation to maintain hot water supply capacity while avoiding the need for multiple fixed-capacity circuits, thus resolving the contradiction between compact size and adaptable productivity.
Solution Approach 2:
The patent changes the operating parameters of the refrigerant circuit, specifically the refrigerant circulation flow rate and pressure, to optimize performance under different conditions. By controlling these parameters dynamically, the single refrigerant circuit can achieve high hot water supply capacity when needed while maintaining a compact system size, effectively resolving the contradiction between system size and productivity.
2Temperature
If high-temperature hot water supply is executed when outside air temperature is high, then the compression ratio of compressor increases, but the operation efficiency is reduced
Solution Approach 1:
The patent introduces an intermediary mechanism (circulation flow rate controlling mechanism and pressure controlling mechanism) between the compressor and the refrigerant circuit. These intermediaries regulate the refrigerant flow and pressure entering the compressor, preventing excessive compression ratios even when supplying high-temperature hot water. This allows the system to maintain high operation efficiency while achieving the desired hot water supply temperature under high-temperature outside air conditions.
Solution Approach 2:
The system performs preliminary control of refrigerant flow rate and pressure before the refrigerant enters the compressor. By pre-regulating these parameters through the circulation flow rate controlling mechanism and pressure controlling mechanism, the system prevents the compression ratio from becoming excessively high, thereby maintaining operation efficiency before the harmful effect occurs.
3Temperature
If high-temperature hot water supply is executed when outside air temperature is high, then pressure on high-pressure side and pressure on low-pressure side increase, but the hot water supply capacity is reduced
Solution Approach 1:
The patent implements feedback control through pressure controlling mechanisms that monitor and regulate the pressure on both the high-pressure side and low-pressure side of the refrigerant circuit. By continuously adjusting the refrigerant flow based on pressure feedback, the system prevents excessive pressure buildup that would reduce hot water supply capacity, while still maintaining the ability to supply high-temperature hot water. This feedback mechanism resolves the contradiction between temperature and productivity.
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 maintains high hot water supply capacity and achieves a highly efficient operation state by controlling refrigerant flow and pressure, preventing increases in pressure and discharge temperature, thus optimizing system performance under high-temperature outside air conditions.
Implementation Method 1
a subcooling heat exchanger that exchanges heat between the liquid refrigerant on the high-pressure side and the refrigerant on the low-pressure side flowing through the bypass
Implementation Method 2
a use side pressure reducing mechanism that controls the flow of the refrigerant flowing into the use unit in accordance with an operation state in the use unit, and a hot water supply pressure reducing mechanism that controls the flow of the refrigerant flowing into the hot water supply unit
Implementation Method 3
one or a plurality of heat source units connected to the use units and the hot water supply units, each heat source unit being equipped with a compressor
Data Source
AI summary
Provided is an air-conditioning and hot water supply combination system capable of maintaining a high hot water supply capacity and achieving high efficiency even under high-temperature outside air conditions by appropriately controlling the degree of superheat and the degree of subcooling of a heat exchanger. In an air-conditioning and hot water supply combination system, when an evaporating pressure or an evaporating temperature calculated from the evaporating pressure reaches a first predetermined value or higher, the degree of superheat of a refrigerant on a low-pressure gas side of a subcooling heat exchanger or the degree of subcooling of the refrigerant on a high-pressure liquid side of the subcooling heat exchanger is controlled by the opening degree of a low-pressure bypass pressure reducing mechanism, such that the evaporating pressure or the evaporating temperature calculated from the evaporating pressure is less than or equal to the first predetermined value.