Intermediate Heat Exchanger Switching for Stable HVAC Capacity
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Solution Overview
Problem
Existing air-conditioning apparatuses face challenges in maintaining consistent cooling and heating capacities when load conditions vary, due to limitations in the number of intermediate heat exchangers and their inability to continuously adjust heat exchange capacity in response to indoor unit operations.
Innovation Solution
The air-conditioning apparatus includes a heat source unit, indoor units, and a relay unit with multiple intermediate heat exchangers and flow passage switching valves, allowing for dynamic control of refrigerant flow and heat exchanger operation to maintain capacity and efficiency across varying loads, by adjusting the number of intermediate heat exchangers operating as evaporators or condensers and controlling the compressor frequency and heat-source-side heat exchanger capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of intermediate heat exchangers is reduced to simplify device complexity, then device complexity decreases, but the cooling and heating capacities cannot be maintained when load conditions vary
Solution Approach 1:
The patent applies dynamics by making the configuration of intermediate heat exchangers adjustable rather than fixed. The control unit dynamically changes which intermediate heat exchangers operate as evaporators or condensers based on the operation modes of indoor units, enabling the system to adapt to varying load conditions while maintaining capacity with fewer exchangers.
Solution Approach 2:
The patent implements multi-functionality by enabling intermediate heat exchangers to serve multiple roles. Each intermediate heat exchanger can function as either an evaporator or a condenser depending on control signals, allowing a reduced number of exchangers to handle both cooling and heating loads across different operational scenarios.
2Device complexity
If the number of intermediate heat exchangers is reduced, then device complexity decreases, but the adaptability to different load conditions deteriorates
Solution Approach 1:
The control unit dynamically reconfigures the intermediate heat exchangers based on real-time operation modes of indoor units. This dynamic adaptation allows the system to maintain high versatility with fewer components by optimally assigning each intermediate heat exchanger's function according to current cooling and heating demands.
Solution Approach 2:
The patent changes the operational parameters of intermediate heat exchangers by switching their functional state (evaporator/condenser) based on load conditions. This parameter change enables the system to adapt to different operational scenarios without requiring a fixed large number of exchangers for all possible conditions.
3Device complexity
If the heat exchange capacity of intermediate heat exchangers is not continuously adjustable, then device complexity decreases, but the precision of capacity matching with indoor unit loads deteriorates
Solution Approach 1:
The system achieves dynamic capacity matching by controlling which intermediate heat exchangers operate and in what mode (evaporator or condenser). This dynamic configuration allows the heat exchange capacity to be continuously adjusted to match the combined load of cooling and heating indoor units without requiring physically adjustable heat exchangers.
Solution Approach 2:
The patent changes the operational parameters of the intermediate heat exchangers by switching their functional state and selecting different combinations of active exchangers. This parameter-based control enables precise capacity matching with varying indoor unit loads while maintaining simple heat exchanger designs.
4Stability of the object's composition
If the compressor frequency and heat exchanger capacity are controlled to maintain predetermined temperatures, then temperature stability improves, but the cycle efficiency deteriorates when load conditions vary
Solution Approach 1:
The patent applies dynamics by dynamically reconfiguring which intermediate heat exchangers serve as evaporators or condensers based on indoor unit operation modes. This dynamic adaptation allows the system to maintain temperature stability while optimizing cycle efficiency for varying load conditions, avoiding the energy losses associated with fixed-configuration systems operating outside their optimal range.
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 ensures that cooling and heating capacities are maintained even with changing load conditions, while operating at a high cycle efficiency, such as COP, by optimizing the operation of intermediate heat exchangers and compressor settings.
Implementation Method 1
heat exchange is performed between the primary-side cycle and the secondary-side cycle in the intermediate heat exchangers
Implementation Method 2
heat source unit including a compressor
Data Source
AI summary
When indoor units are performing a cooling operation, an air-conditioning apparatus controls four flow passage switching valves, for example a first solenoid valve, a second solenoid valve, a third solenoid valve, and a fourth solenoid valve, so that a number of intermediate heat exchangers operating as evaporators is greater than in a cooling main operation. During the cooling main operation, a target value for suction pressure or evaporating temperature at a compressor is set equal to or lower than that in a case in which the indoor units are performing the cooling operation, and a frequency of the compressor and a capacity of a heat-source-side heat exchanger are controlled.