Air-conditioning apparatus
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Solution Overview
Problem
Existing air-conditioning systems for buildings face challenges in preventing air intrusion into secondary circuits, which can lead to pump breakdowns and safety concerns due to refrigerant leaks, especially with long pipe lengths and diverse installation requirements.
Innovation Solution
An air-conditioning apparatus with a closed heat medium circulating circuit where the pump's maximum head is set to 150 kPa or more, ensuring the pressure near the pump's suction side remains equal to or higher than atmospheric pressure, using a heat medium relay unit to maintain constant pressure and prevent air intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a two-loop system is employed with water or brine for the secondary loop, then safety and harmful effects to humans are improved, but device complexity increases due to requiring a transfer unit such as a pump
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary component between the refrigerant loop and the water/brine loop. This allows heat transfer without direct mixing of fluids, maintaining safety while managing system complexity through functional separation. The heat exchanger mediates the interaction between the two loops, enabling independent optimization of each loop's characteristics.
2Reliability
If the maximum pump head Pp is set to 150 kPa or more, then air intrusion into the secondary circuit is prevented, but the pressure requirement increases the system design constraints
Solution Approach 1:
The patent specifies a minimum pump head parameter (Pp ≥ 150 kPa) to ensure that the pump can maintain positive pressure in the secondary circuit, preventing air intrusion. This parameter change directly addresses the reliability issue by ensuring adequate pressure margin. The design accepts the resulting system constraints as necessary to achieve the desired reliability level.
Solution Approach 2:
The system is designed with preliminary pressure establishment through the pump, creating a positive pressure environment in the secondary circuit before operation begins. This preliminary action of pressurizing the circuit prevents air from intruding during operation, addressing the reliability concern proactively rather than reactively.
3Adaptability or versatility
If diverse installations are assumed for multi-air-conditioning apparatuses, then adaptability is improved, but ensuring safety and reliability across all installations becomes more difficult
Solution Approach 1:
The patent designs the system with universal components and standardized interfaces that can accommodate diverse installation scenarios. The heat exchanger, pump, and control system are configured to function reliably across different installation configurations, making the system adaptable while maintaining consistent safety and reliability performance. This multi-functionality approach allows the same basic design to serve various installation needs.
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 enhances the reliability of the air-conditioning system by preventing air intrusion and pump breakdowns, ensuring safe operation and flexibility in system installation.
Implementation Method 1
a heat exchanger related to heat medium (15a, 15b)
Implementation Method 2
heat medium circulating circuit in which a heat-medium-side flow of the heat exchanger related to heat medium, a pump, a use-side heat exchanger, and a heat medium flow control device are connected and through which a heat medium circulates
Implementation Method 3
a pump, a use-side heat exchanger, and a heat medium flow control device are connected and through which a heat medium circulates
Data Source
AI summary
In an air-conditioning apparatus including a refrigerant circulating circuit A and a heat medium circulating circuit B that performs passing of heat to and from the refrigerant circulating circuit A, the heat medium circulating circuit is a closed circuit, the maximum pump head Pp of a pump of the heat medium circulating circuit is 150 kPa or more, and a pressure near at least a suction side of the pump is set to a charged pressure that is maintained equal to or higher than the atmospheric pressure during operation of the pump.