Closed-Loop HVAC Valve Control to Prevent Flow Oscillations
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Solution Overview
Problem
In combined cycle ventilation systems, vibrations occur during dynamic balancing due to valves alternately switching between fully open and fully closed positions, as they are partially connected in series, failing to assign the correct volume flow to each heat exchanger based on its operating state.
Innovation Solution
The method involves shifting at least one valve in the heat absorption area and one in the heat emission area into their fully open positions, while keeping others not fully open, decoupling control circuits to prevent interference and ensuring each heat exchanger receives the required volume flow, with sensors and controlled pumps regulating the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If valves are controlled dynamically to adjust carrier medium flow through heat exchangers, then the system can adapt to different operating states and load ratios, but vibrations occur as valves alternately switch between fully open and fully closed positions
Solution Approach 1:
The system divides the heat exchanger network into multiple parallel heat exchangers with individual valve control. By segmenting the flow control into separate controllable units, the system can adjust each heat exchanger's contribution independently, enabling smooth transitions between operating states without causing vibrations in the overall system.
Solution Approach 2:
The control system dynamically adjusts valve positions based on current operating conditions and load ratios. Rather than fixed valve positions, the system continuously adapts valve opening degrees to match changing thermal demands, preventing the oscillatory behavior that occurs with static control settings.
2Manufacturing precision
If multiple heat exchangers are arranged in parallel with controllable valves, then precise flow distribution to each heat exchanger is possible, but the valves become partially connected in series causing interference between control circuits
Solution Approach 1:
The control system introduces intermediate control elements that mediate between the parallel valve circuits. By using a centralized control algorithm that coordinates valve actuation sequences and opening degrees, the system eliminates direct interference between control circuits while maintaining precise individual flow distribution to each heat exchanger.
3Productivity
If the regulated pump dynamically adjusts the total carrier medium flow, then the system can respond to changing thermal loads, but the coordinated control of multiple parallel heat exchangers becomes difficult
Solution Approach 1:
The control system implements feedback mechanisms that continuously monitor thermal loads, carrier medium temperatures, and flow rates. Based on this real-time data, the system automatically coordinates pump speed adjustments with individual heat exchanger valve positions, simplifying the operation of parallel heat exchangers while maintaining rapid response to changing thermal demands.
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 approach stabilizes the operation by preventing valve position oscillations, allowing precise control of carrier medium flow, ensuring each heat exchanger operates efficiently based on its state, and maintaining system balance without negative valve interactions.
Implementation Method 1
heat is transferred from a warm air volume flow to the carrier medium flowing in the line by means of the heat exchanger arranged in the heat absorption area
Implementation Method 2
heat is transferred from the carrier medium flowing in the line to a cold air volume flow by means of the heat exchanger arranged in the heat dissipation area
Implementation Method 3
At least one regulated pump is arranged in the line in such a way that the carrier medium is conveyed in a circle
Data Source
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AI summary
The invention relates to a method for adjusting an operating state of a closed-loop system of an air handling, preferably room air handling, system, wherein the closed-loop system has a heat absorption area (1) and a heat emission area (2), and wherein the heat absorption area (1) and the heat emission area (2) are connected via at least one line (3) forming a closed circuit and through which a carrier medium flows, wherein at least one heat exchanger (4) is arranged in the heat absorption area (1), by means of which heat is transferred from a warm air volume flow to the carrier medium flowing in the line (3), wherein a valve (6) controllable by means of an actuator (5) is assigned to the heat exchanger (4) for changing the amount of carrier medium flowing through this heat exchanger (4), and wherein at least one heat exchanger (4) is arranged in the heat emission area (2).by means of which heat is transferred from the carrier medium flowing in the line (3) to a cold air volume flow, wherein the heat exchanger (4) is assigned a valve (6) controllable by means of an actuator (5) to change the amount of carrier medium flowing through this heat exchanger (4), - wherein at least one controlled pump (14) is provided in the line (3) to achieve a flow, preferably in one of the two transition areas (9), and - wherein each actuator (5) can be controlled by means of a control device or regulating device, - wherein at least one further heat exchanger (4) is arranged in the heat absorption area (1) and/or in the heat emission area (2) in a flow-technical sense parallel to the heat exchanger (4) located there,wherein the heat exchanger (4) is assigned a valve (6) controllable by means of an actuator (5) to change the amount of heat transfer medium flowing through this further heat exchanger (4). In order to specify a method by which, during operation of the closed-loop system, each heat exchanger (4) is assigned the volume flow rate that it requires due to its current operating state,During operation of the closed-loop system, at least one valve (6) of a heat exchanger (4) arranged in the heat absorption area (1) shall be fully moved to its open position and remain unchanged in its open position, and at least one valve (6) of a heat exchanger (4) arranged in the heat absorption area (1) shall not be fully open, and at least one valve (6) of a heat exchanger (4) arranged in the heat discharge area (2) shall be fully moved to its open position and remain unchanged in its open position, and at least one valve (6) of a heat exchanger (4) arranged in the heat discharge area (2) shall not be fully open.