Heat Medium Valve Sequencing for Stable Air-Conditioning Pressure
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Solution Overview
Problem
Existing air-conditioning systems for large buildings face challenges in efficiently controlling heat medium passages with limited input-output ports, leading to increased costs and potential abnormal heat medium pressure issues due to the need for multiple valve control circuits and synchronized pump operations.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit and a heat medium circuit, utilizing refrigerant flow switching devices and heat medium flow control devices, where the actuation control means delays the start of pump operation relative to the activation of heat medium flow switching and control devices, allowing for reduced valve driving time and pressure suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple valve control circuits are provided to simultaneously operate multiple valves, then the valve control capability is improved, but the device complexity and cost increase
Solution Approach 1:
The control device opens valves in a predetermined sequence before starting the pump, ensuring that all valves are fully opened and heat medium passages are established before pump operation begins. This preliminary valve opening action eliminates the need for complex simultaneous control circuits while preventing pressure abnormalities.
Solution Approach 2:
The valve opening process is segmented into sequential steps rather than simultaneous operation. The control device opens each valve one after another in a predetermined order, breaking down the complex simultaneous control requirement into manageable sequential actions that can be handled by a single control circuit.
2Productivity
If valves are opened simultaneously to reduce operation time, then the productivity is improved, but the heat medium pressure increases abnormally
Solution Approach 1:
The system performs preliminary valve opening actions before pump startup, allowing heat medium passages to be established gradually. This prevents sudden pressure spikes that would occur if all valves opened simultaneously while the pump was already running, while still achieving quick overall operation.
Solution Approach 2:
The control device prevents pressure abnormalities by opening valves in a predetermined sequence that avoids creating pressure conflicts. By controlling the order of valve opening, the system preemptively prevents the harmful pressure increase that would result from simultaneous valve opening during pump operation.
3Loss of time
If the pump starts immediately with valve opening, then the response time is reduced, but the heat medium pressure increases due to synchronized operation
Solution Approach 1:
The control device opens all required valves in a predetermined sequence before starting the pump, ensuring that heat medium passages are fully established before pump operation begins. This preliminary action prevents pressure abnormalities while maintaining efficient system response.
Solution Approach 2:
The system uses periodic sequential valve opening followed by pump startup, creating a timed sequence of operations. This periodic pattern of valve opening then pump activation prevents pressure conflicts while maintaining efficient overall response time.
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 solution reduces the time and cost associated with driving pumps and switching heat medium passages while minimizing heat medium pressure increases, enhancing the operational efficiency and safety of the air-conditioning system.
Implementation Method 1
heat source side refrigerant circulated in a refrigerant circuit including a compressor, a heat source side heat exchanger, a plurality of expansion devices, refrigerant passages of a plurality of intermediate heat exchangers, and a plurality of refrigerant flow switching devices
Implementation Method 2
a pump, a plurality of use side heat exchangers, a plurality of heat medium flow switching devices, a plurality of heat medium flow control devices, and heat medium passages of the intermediate heat exchangers
Data Source
AI summary
An air-conditioning apparatus includes actuation control means including an actuation unit that sequentially opens heat medium flow switching devices or heat medium flow control devices on a one-by-one basis. The actuation control means performs control in such a manner that start time of driving of pumps is later than start of actuation of the heat medium flow switching devices and the heat medium flow control devices.