Air conditioner
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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, especially when refrigerant leaks occur, and existing solutions increase system complexity and cost, limiting flexibility in installation.
Innovation Solution
The air-conditioning apparatus employs a closed heat medium circulating circuit with a compressor, heat-source-side heat exchanger, expansion device, and pump in the outdoor unit, and a heat medium relay unit with heat exchangers and flow control devices, maintaining a pump head of 150 kPa or more to ensure pressures above atmospheric levels, preventing air intrusion and ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-loop system with water or brine is used for the secondary side to prevent refrigerant leakage hazards, then safety is improved, but the system requires additional components such as pumps and tanks, increasing device complexity and installation cost
Solution Approach 1:
The invention extracts the harmful refrigerant from the secondary loop and confines it to the primary loop only. The secondary loop uses safe water or brine that cannot cause harm if leaked, while the primary loop contains the refrigerant in a closed system. This separation eliminates safety concerns about secondary loop refrigerant leakage while maintaining the benefits of a two-loop system.
Solution Approach 2:
The invention introduces a heat exchanger as an intermediary component between the primary refrigerant loop and the secondary water/brine loop. This heat exchanger enables thermal energy transfer between the two loops without allowing direct contact between refrigerant and water, thus preventing refrigerant leakage into the secondary loop while maintaining efficient heat transfer.
2Reliability
If open atmospheric tanks or water-level tanks are installed to prevent negative pressure and air intrusion in the secondary circuit, then reliability is improved, but the number of parts increases leading to cost increase and limited installation positions
Solution Approach 1:
The outdoor unit housing serves multiple functions: it contains the compressor, condenser, and expansion device for the primary refrigerant loop, and simultaneously houses the pump and chargeable reservoir for the secondary water/brine loop. This multi-functional integration eliminates the need for separate atmospheric tanks or water-level tanks, preventing air intrusion through proper pressure management while reducing part count and installation constraints.
Solution Approach 2:
The invention merges the primary refrigerant loop components and secondary water/brine loop components into a single integrated outdoor unit. The pump and reservoir are combined within the same housing space, and the system uses a single closed secondary loop that eliminates the need for separate atmospheric compensation tanks, thereby reducing device complexity while maintaining reliability.
3Reliability
If the pump head is set to 150 kPa or more to maintain positive pressure and prevent air intrusion, then air intrusion prevention is improved, but energy consumption increases
Solution Approach 1:
The invention optimizes the pump head parameter to be 150 kPa or more, which is the minimum threshold required to maintain positive pressure in the secondary loop and prevent air intrusion. This parameter setting balances reliability requirements with energy efficiency, avoiding excessive pump head that would unnecessarily increase energy consumption while ensuring sufficient pressure to keep air out of the system.
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 pressures above atmospheric levels, preventing air intrusion and enhancing the reliability of the air-conditioning system while reducing the risk of pump breakdowns, thus ensuring safe and flexible installation without increasing system complexity or cost.
Implementation Method 1
a heat exchanger related to heat medium (15) that exchanges heat with the refrigerant
Implementation Method 2
a pump (21) that circulates the heat medium in the heat medium circulating circuit B
Implementation Method 3
a compressor (10) that circulates the refrigerant in the refrigerant circulating circuit A
Data Source
Figure 1
Figure 2
Figure 3
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 21 of the heat medium circulating circuit is 150 kPa or more, and a pressure near at least a suction side of the pump 21 is set to a charged pressure that is maintained equal to or higher than the atmospheric pressure during operation of the pump 21.