Subcooling Heat Exchanger Control for High-Temperature Hot Water Supply
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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, particularly due to increased pressures and reduced efficiency in hot water supply at temperatures above 60 degrees C.
Innovation Solution
The system incorporates a subcooling heat exchanger and pressure reducing mechanisms to control the degree of superheat and subcooling, allowing for efficient refrigerant flow management through bypass mechanisms, ensuring that evaporating pressure or temperature remains within predetermined limits, thus maintaining high hot water supply capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single refrigerant circuit is used for hot water supply, then the system size is reduced, but the hot water supply capacity decreases and operation efficiency is reduced under high-temperature outside air conditions
Solution Approach 1:
The refrigerant circuit is segmented into multiple independent circuits, each capable of performing hot water supply functions. This allows the system to maintain compact overall size while providing multiple parallel pathways for refrigerant flow, thereby preserving hot water supply capacity under high-temperature conditions.
Solution Approach 2:
The patent introduces a bypass circuit that operates in parallel with the main refrigerant circuit, effectively adding another dimension to the refrigerant flow paths. This bypass circuit enables additional heat exchange capacity without significantly increasing the physical footprint of the system.
2Temperature
If high-temperature hot water supply is executed under high-temperature outside air conditions, then the evaporating pressure and condensing pressure increase, but the hot water supply capacity is reduced and compression ratio increases
Solution Approach 1:
The patent employs dynamic control mechanisms including electronically controlled expansion valves and variable speed compressors that can adjust their operating parameters in real-time based on ambient temperature and hot water demand. This dynamic adaptation allows the system to maintain optimal performance across varying temperature conditions without sacrificing capacity.
Solution Approach 2:
The bypass circuit acts as an intermediary pathway that provides alternative refrigerant flow routes when the main circuit experiences excessive pressure or temperature conditions. This intermediary circuit helps balance the load and prevents the system from operating in inefficient high-compression-ratio states.
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 enables the system to maintain high hot water supply capacity and efficient operation even under high-temperature outside air conditions by controlling pressures and temperatures, preventing increases in pressure and discharge temperature, and optimizing refrigerant flow.
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 heat source side pressure reducing mechanism, a low-pressure bypass pressure reducing mechanism disposed in the bypass... a use side pressure reducing mechanism that controls the flow of the refrigerant flowing into the use unit
Data Source
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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 100, 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 18 or the degree of subcooling of the refrigerant on a high-pressure liquid side of the subcooling heat exchanger 18 is controlled by the opening degree of a low-pressure bypass pressure reducing mechanism 23, such that the evaporating pressure or the evaporating temperature calculated from the evaporating pressure is less than or equal to the first predetermined value.