Central air-conditioning system and control method thereof
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Solution Overview
Problem
Central air-conditioning systems face issues with temperature uniformity, energy inefficiency, and comfort due to water flow imbalance and pressure differential problems in circulating water loops, leading to increased energy consumption and complex debugging requirements.
Innovation Solution
The implementation of regional flow balancing valves and energy balancing valves in a central air-conditioning system, which adjust flow and energy supply based on detected return water temperatures and set values, ensuring balanced water distribution and adapting to changing heat loads, thereby maintaining comfort and reducing energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a direct return transmission and distribution manner is adopted, then the system structure is simple and installation is easy, but water flow cannot be reasonably distributed leading to temperature unevenness and poor comfort
Solution Approach 1:
The system divides the circulating water loop into multiple independent control zones (first circulating water loop, second circulating water loop, etc.), each with its own flow balancing valve. This segmentation allows independent flow regulation in different regions, solving the water flow distribution problem while maintaining system simplicity.
Solution Approach 2:
Flow balancing valves are installed at specific locations (tail-end devices, branch connections) to locally adjust water flow distribution. This targeted approach addresses temperature unevenness in specific areas without requiring complete system redesign, maintaining overall system simplicity while improving temperature uniformity.
2Reliability
If a reverse return transmission and distribution manner is adopted, then system pressure balance is improved, but pipeline length increases consuming more materials and energy
Solution Approach 1:
The circulating water loop is segmented into multiple smaller loops with independent flow control. This allows pressure balance to be achieved in each segment rather than requiring a complex reverse return configuration, reducing pipeline length while maintaining pressure balance through localized flow regulation.
3Reliability
If differential pressure balancing valves are added, then system pressure balance is achieved, but debugging complexity increases and requires experienced personnel
Solution Approach 1:
The flow balancing valves are designed with flow indicators and adjustment mechanisms that allow operators to directly observe and adjust flow rates without complex debugging procedures. The valves enable self-service flow balancing by comparing flow indicators at different locations, eliminating the need for experienced personnel and complex differential pressure debugging.
4Manufacturing precision
If static flow balancing is performed, then initial flow distribution is optimized, but the system cannot adapt to dynamic load changes
Solution Approach 1:
The system employs multiple flow balancing valves distributed throughout the loop that can be dynamically adjusted based on changing load conditions. Unlike single-point static balancing, this multi-point adjustable approach allows the system to adapt to dynamic load changes by regulating flow at various locations, maintaining both precision and adaptability.
5Ease of operation
If flow balancing valves are installed at tail ends, then flow control is improved, but the valves may block and require frequent maintenance
Solution Approach 1:
The flow balancing function is merged with existing pipeline components such as branch connections and tail-end devices. By integrating flow control into the pipeline structure itself rather than adding separate vulnerable valves, the system maintains ease of flow control while reducing maintenance requirements through fewer discrete moving parts.
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 stabilizes heat exchange efficiency, reduces energy consumption, simplifies system debugging, and ensures consistent comfort by automatically adjusting flow and energy supply, eliminating static and dynamic hydraulic imbalances and reducing the need for complex hydraulic balance calculations.
Implementation Method 1
adjust the opening degrees of the valves by using the differential pressure effect and compensate the resistance change of pipelines by using the pressure drop change of valve elements
Implementation Method 2
the flow balancing valve respectively receives a signal output by a temperature sensor and a set value
Data Source
AI summary
In a central air-conditioning system, regional flow balancing valves for controlling flow of water return branch pipes are arranged on the water return branch pipes, and energy balancing valves are arranged on water return pipes of tail-end fan coils respectively. A control method includes: detecting flow in the water return branch pipes, and adjusting the flow in the return branch pipes to be smaller than or equal to a branch pipe set flow value; and detecting the temperature of return water in the water return pipes of the tail-end fan coils, controlling the temperature of the return water in the water return pipes of the tail-end fan coils to be greater than or equal to a tail-end return water set temperature value, detecting the room temperature and adjusting the opening degree of the energy balancing valves in temperature controllers.