Air-conditioning apparatus
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Solution Overview
Problem
Air-conditioning systems face challenges in detecting abnormal flow rates of heat media, which can lead to pump overheating, damage, or failure due to air entrainment and temperature changes, making it difficult to accurately identify leakage in heat medium circuits.
Innovation Solution
An air-conditioning apparatus with a controller that calculates an actual temperature efficiency ratio based on heat exchanger temperatures to determine abnormal flow rates in the heat medium circuit, allowing for efficient detection and prevention of pump issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heat medium leakage detection is performed based on temperature change, then leakage can be detected, but detection accuracy is insufficient because temperature change varies with water amount
Solution Approach 1:
The patent changes the detection parameter from temperature change to temperature efficiency ratio. The temperature efficiency ratio is calculated by dividing the temperature difference between heat medium inlet and outlet by the temperature difference between heat medium inlet and refrigerant. This parameter transformation eliminates the influence of water amount variations, enabling accurate leakage detection regardless of the volume of heat medium in the system.
2Object-affected harmful factors
If heat medium is circulated in indoor space, then health safety is improved, but leakage detection becomes difficult due to lack of adverse effects on users
Solution Approach 1:
The patent replaces traditional mechanical detection methods (such as pressure sensors or flow meters) with a thermal field-based detection method. By monitoring temperature differences and calculating the temperature efficiency ratio, the system can detect leakage without requiring additional mechanical sensing components in the heat medium circuit, thus maintaining safety while enabling reliable detection.
3Device complexity
If pump operates without flow rate monitoring, then device complexity is reduced, but pump reliability decreases due to overheating and damage risks
Solution Approach 1:
The patent enables the heat exchanger system to self-monitor its own performance by calculating the temperature efficiency ratio from temperature measurements taken during normal operation. This self-diagnostic capability allows the system to detect flow rate abnormalities and potential pump issues without requiring external monitoring devices, thus maintaining simplicity while improving reliability.
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
Accurate and efficient detection of abnormal flow rates in heat medium circuits helps prevent pump damage and ensures reliable operation by promptly identifying and addressing flow rate anomalies.
Implementation Method 1
at least one intermediate heat exchanger configured to exchange heat between the heat source side refrigerant and a heat medium different from the heat source side refrigerant
Implementation Method 2
a use side heat exchanger configured to exchange heat between the heat medium and air in an air-conditioning target space
Implementation Method 3
a compressor configured to compress a heat source side refrigerant
Implementation Method 4
an expansion device configured to regulate the pressure of the heat source side refrigerant
Data Source
AI summary
An air-conditioning apparatus includes a refrigeration cycle that includes one or more intermediate heat exchangers, exchanging heat between a heat source side refrigerant and a heat medium different from the heat source side refrigerant, a heat medium circuit that includes at least one pump configured to circulate the heat medium for heat exchange by the intermediate heat exchanger, a use side heat exchanger configured to exchange heat between the heat medium and air in an air-conditioning target space, and flow switching valves configured to switch between passing the heated heat medium through the use side heat exchanger and passing the cooled heat medium through the use side heat exchanger and in which the pump, the use side heat exchanger, and the flow switching valves are connected by pipes, and a controller configured to calculate an actual temperature efficiency ratio based on a temperature at a heat medium inlet of the heat exchanger in the heat medium circuit and determine whether a flow rate of the heat medium in the heat medium circuit is abnormal based on the actual temperature efficiency ratio and a set reference temperature efficiency ratio.