Heat-Medium Flow Control for Simultaneous Cooling and Heating
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Solution Overview
Problem
Conventional air-conditioning systems face challenges in maintaining efficient cooling and heating operations during simultaneous cooling and heating modes, leading to increased power consumption and reduced comfort due to limitations in heat exchanger capacity control and refrigerant flow management.
Innovation Solution
An air-conditioning apparatus with a compressor, heat source device-side heat exchanger, and multiple indoor units connected by a relay device, featuring a heat-medium flow control system that adjusts the flow rate based on the total cooling and heating capacities of the indoor units and the heat source device, allowing for efficient switching between cooling and heating operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the AK value is lowered to improve comfort and energy saving during heat recovery operation, then the heat exchange capacity is reduced, but the low pressure of refrigeration cycle decreases causing frequent start-stop of the device
Solution Approach 1:
The patent applies parameter changes by adjusting the flow rate of the heat medium supplied to the heat source device-side heat exchanger based on the total cooling capacity and total heating capacity of the indoor units. This dynamic parameter adjustment allows the system to optimize heat exchange efficiency while preventing excessive pressure drops that would cause frequent start-stop operations, thereby resolving the contradiction between energy saving and operational stability.
Solution Approach 2:
The control device implements feedback control by continuously monitoring the total cooling capacity and total heating capacity of the indoor units, and adjusting the heat medium flow rate accordingly. This feedback mechanism ensures that the heat exchange capacity is optimized in real-time without causing the low pressure to drop below acceptable levels, thus maintaining both energy efficiency and device reliability.
2Use of energy by moving object
If the flow rate of heat medium is reduced to match use-side heat exchanger capacity, then power consumption is reduced, but the heat exchange efficiency may be compromised
Solution Approach 1:
The patent dynamically changes the flow rate parameter of the heat medium based on the actual heat exchange requirements calculated from the total cooling capacity and total heating capacity of the indoor units. This ensures that the heat medium flow rate is optimized for each operating condition, reducing power consumption when less heat exchange is needed while maintaining sufficient efficiency when high capacity is required.
Solution Approach 2:
The system employs dynamic control of the heat medium flow rate rather than a fixed flow rate. The control device continuously adjusts the flow rate according to the varying heat exchange demands of the indoor units, allowing the system to adapt to changing conditions and optimize both energy consumption and heat exchange efficiency in real-time.
3Reliability
If the compression ratio is maintained at a predetermined value or larger to ensure device reliability, then the compressor operates safely, but the AK value cannot be lowered sufficiently at low outdoor temperatures
Solution Approach 1:
The patent introduces the heat medium flow rate as an intermediary control parameter between the compressor operation and the heat exchange capacity. By adjusting the heat medium flow rate rather than directly controlling the compressor or heat exchanger geometry, the system can optimize heat exchange efficiency without compromising compressor safety or requiring structural modifications.
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 enables stable and efficient cooling and heating simultaneous operations, reducing power consumption and maintaining comfort by optimizing refrigerant flow and heat exchange, thereby improving energy savings and operational reliability.
Implementation Method 1
a heat source device-side heat exchanger (103) configured to exchange heat between the refrigerant and a heat medium different from the refrigerant
Implementation Method 2
a plurality of use-side heat exchangers (105) configured to exchange heat between the refrigerant and use-side medium around the plurality of use-side heat exchangers
Implementation Method 3
a compressor (101) configured to compress and discharge refrigerant
Data Source
AI summary
An air-conditioning apparatus includes at least one system including a heat-medium conveying device, a heat-medium flow regulator, and a heat-medium flow control device, as a heat medium system capable of regulating a flow rate of a heat medium supplied to a heat source device-side heat exchanger exchanging heat between refrigerant and the heat medium. The air-conditioning apparatus switches each of a plurality of use-side heat exchangers to a cooling operation or a heating operation in accordance with a control command to perform a cooling and heating simultaneous operation. The refrigerant is caused to flow through the heat source device-side heat exchanger depending on a ratio of a total cooling capacity and a total heating capacity of the plurality of use-side heat exchangers. The heat-medium flow control device controls the flow rate of the heat medium supplied to the heat source device-side heat exchanger based on a difference between the total cooling capacity and the total heating capacity of the plurality of use-side heat exchangers and a total operation capacity of the heat source device-side heat exchanger.