Air conditioning device
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Solution Overview
Problem
Conventional air-conditioning systems face issues with draft discomfort and increased time to reach target indoor temperatures due to temperature fluctuations during transitions between anti-freezing and cooling modes, especially when the heat medium temperature deviates significantly from the required range.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle circuit, intermediate heat exchanger, and a control device that adjusts the compressor and pump operations to maintain the heat medium temperature within a predetermined range, while controlling the fan to minimize draft and optimize temperature adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor and pump are kept stopped for a long period to save energy, then energy consumption is reduced, but the heat medium temperature drops below the freezing point causing water to freeze in the pipe
Solution Approach 1:
The control device performs preliminary heating action by operating the compressor in heating mode before the heat medium temperature reaches the freezing point. This preliminary action prevents freezing by maintaining the temperature above the freezing point during the stopped period, resolving the contradiction between energy saving and freezing prevention.
2Reliability
If the outdoor unit starts in heating mode to prevent freezing when temperature drops to set point or lower, then freezing of heat medium is prevented, but transition from anti-freezing mode to cooling mode causes draft discomfort and increases time to reach target indoor temperature
Solution Approach 1:
The control device continuously monitors the heat medium temperature and uses feedback control to determine when to transition from anti-freezing mode to cooling mode. By basing the transition decision on real-time temperature feedback rather than fixed thresholds, the system avoids abrupt mode changes that cause draft discomfort and extends the cooling mode operation to ensure heat medium temperature is suitable before transitioning, thereby reducing temperature adjustment time.
Solution Approach 2:
The control device performs preliminary cooling operation by extending the cooling mode operation before transitioning to anti-freezing mode. This ensures the heat medium temperature is already within a suitable range before mode transition, preventing draft discomfort and reducing the time needed to reach target indoor temperature when switching modes.
3Use of energy by moving object
If HFC refrigerant is conveyed to the indoor unit to achieve energy saving performance, then energy saving is improved, but pipe damage causes refrigerant leakage into the room deteriorating indoor environment
Solution Approach 1:
The system uses an intermediate heat exchanger as a mediator between the refrigerant circuit and the heat medium circuit. The heat medium (water or antifreeze) circulates through the intermediate heat exchanger to absorb or release heat from the refrigerant, then conveys this thermal energy to the indoor unit. This intermediary approach eliminates direct refrigerant contact with indoor pipes, preventing leakage while maintaining energy saving performance.
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
The system ensures immediate comfort by reducing draft and shortening the time to reach the target indoor temperature by maintaining the heat medium temperature within a suitable range, even when compressor and pump operations are temporarily stopped.
Implementation Method 1
an intermediate heat exchanger configured to exchange heat between a refrigerant and a heat medium
Implementation Method 2
a pump configured to convey the heat medium
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An air-conditioning apparatus includes a heat medium temperature adjustment operation mode in which when the temperature of a heat medium falls outside a predetermined temperature range while a compressor and a pump are kept stopped, the compressor and the pump are driven to cause an intermediate heat exchanger to exchange heat between a refrigerant and the heat medium so that the heat medium is heated or cooled to have a temperature that falls within the temperature range.