Indoor Unit Valve Control for Unequal Heat-Medium Pipe Lengths
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Solution Overview
Problem
In air-conditioning apparatuses using a heat medium, pipes of different lengths to indoor units result in varying pressure losses and flow rates, leading to unequal capacities among indoor units, affecting heating and cooling efficiency.
Innovation Solution
An air-conditioning apparatus with a controller that adjusts the opening degree of flow control valves in each indoor unit based on the length of the heat medium pipe, ensuring uniform flow rates and capacities across units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pipes of different lengths are used to connect the heat-medium transfer device to multiple indoor units, then the system can accommodate flexible installation layouts, but the pressure losses and flow rates become unequal among indoor units, resulting in different capacities
Solution Approach 1:
The patent applies local quality by making each indoor unit have differentiated characteristics based on its pipe length. Flow control valves with different opening-degree control ranges are assigned to different indoor units according to their specific pipe lengths, allowing each unit to be optimized for its local conditions while maintaining overall system balance
Solution Approach 2:
The patent changes the control parameter (valve opening-degree control range) according to the pipe length parameter. By adjusting the control range based on the specific pipe length connecting each indoor unit, the system compensates for pressure loss differences and achieves uniform capacity across all units despite varying installation distances
2Device complexity
If the flow control valve opening-degree control range is the same for all indoor units, then the control system is simple, but indoor units with different pipe lengths achieve different capacities
Solution Approach 1:
The control system applies local quality by assigning different valve opening-degree control ranges to different indoor units based on their pipe lengths. This localized differentiation ensures that each indoor unit operates within an optimal control range that compensates for its specific pressure loss characteristics
Solution Approach 2:
The patent implements preliminary action by pre-determining the appropriate valve opening-degree control range for each indoor unit based on its pipe length before operation. This advance configuration allows the system to automatically achieve balanced capacity distribution without requiring complex real-time adjustments
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 ensures that indoor units have uniform capacities despite varying pipe lengths, maintaining consistent heating and cooling performance across all units.
Implementation Method 1
a pump provided to transfer a heat medium that contains water or brine and transfers heat
Implementation Method 2
an indoor heat exchanger provided to cause heat exchange to be performed between indoor air and the heat medium
Implementation Method 3
a flow control valve provided to adjust a flow rate of the heat medium that flows through the indoor heat exchanger
Data Source
Figure 1
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AI summary
An air-conditioning apparatus includes: a heat-medium transfer device including a pump provided to transfer a heat medium that contains water or brine and transfers heat; a plurality of indoor units each of which includes an indoor heat exchanger provided to cause heat exchange to be performed between indoor air and the heat medium, and a flow control valve provided to adjust a flow rate of the heat medium that flows through the indoor heat exchanger, the plurality of indoor units being connected to the heat-medium transfer device by respective heat medium pipes; and a controller provided to control an opening degree of the flow control valve. The controller determines a valve opening-degree control range that is a control range of an opening degree of the flow control valve of each indoor unit, based on a flow-passage resistance depending on a length of a pipe that extends from the heat-medium transfer device to the indoor unit, such that the lower the flow-passage resistance, the smaller the valve opening-degree control range.