Cool Gas Dryer Valve Coordination for Stable Evaporator Control
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Solution Overview
Problem
The existing cool drying method for gases, which involves a complex system with two separate controls for the expansion valve and hot gas bypass valve, complicates the operation of the cooling circuit and makes it difficult to maintain optimal conditions due to interdependent valve adjustments.
Innovation Solution
A method that uses an experimentally determined formula to link the states of the expansion valve and hot gas bypass valve, allowing for either valve to be adjusted based on the other or both to be controlled together, simplifying the control process and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate controls are used for the expansion valve and hot gas bypass valve, then the cooling circuit can be controlled to maintain fixed superheating and desired evaporator pressure, but the system complexity increases and the control becomes difficult to operate
Solution Approach 1:
The patent combines the control of the expansion valve and hot gas bypass valve into a single integrated control system. The control unit receives signals from sensors monitoring evaporator pressure and temperature, then simultaneously adjusts both valves based on a mathematically determined relationship, merging two independent control loops into one coordinated system that simplifies operation while maintaining reliability
Solution Approach 2:
The control system uses feedback from sensors that continuously monitor evaporator pressure and temperature to dynamically adjust the states of both the expansion valve and hot gas bypass valve. This closed-loop feedback mechanism ensures that the mathematical relationship between the valves is maintained under varying operating conditions, preserving control stability while simplifying the user interface
2Reliability
If the expansion valve is adjusted to maintain fixed superheating with variable load, then the coolant superheating is optimized, but the evaporator pressure changes requiring additional adjustment of the hot gas bypass valve
Solution Approach 1:
The control system automatically compensates for evaporator pressure changes caused by expansion valve adjustments. When the expansion valve is adjusted to maintain fixed superheating, the control unit detects the resulting evaporator pressure change and automatically adjusts the hot gas bypass valve to restore the desired pressure, eliminating the need for manual intervention and simplifying operation
3Reliability
If the hot gas bypass valve is adjusted to control evaporator pressure, then the condensate freezing is prevented, but the expansion valve must also be adjusted to maintain fixed superheating
Solution Approach 1:
The control system uses feedback from evaporator pressure sensors to detect when the hot gas bypass valve is adjusted for pressure control. The system then automatically adjusts the expansion valve to maintain fixed superheating, ensuring that both control objectives are met simultaneously without requiring complex manual coordination between the two valves
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 reduces the complexity of the system to a single control, ensuring stable operation of the cooling circuit and preventing condensate freezing, thereby maintaining optimal drying efficiency.
Implementation Method 1
water vapour in the gas is condensed by guiding the gas through the secondary section of a heat exchanger whose primary section forms the evaporator of a closed cooling circuit
Implementation Method 2
a compressor that is installed in the cooling circuit downstream from the evaporator
Implementation Method 3
which is followed by a condenser and an expansion valve
Implementation Method 4
an expansion valve through which the coolant can circulate
Data Source
Figure 1~2
Figure 3
AI summary
Method for cool drying gas, making use of a heat exchanger (2) whose primary section forms the evaporator (3) of a cooling circuit (4) with a compressor (6), an expansion valve (8) and a bypass pipe (16) across the compressor (6) with a hot gas bypass valve (18), whereby the method makes use of a formula that makes the link between the state of the expansion valve (8) and hot gas bypass valve (18), whereby on the basis of this formula: - either the state of the expansion valve (8) is adjusted as a function of the state of the hot gas bypass valve (18); or - adjusting the state of the hot gas bypass valve (18) as a function of the state of the expansion valve (8) or vice versa; or - the states of both valves (8, 18) are controlled with respect to one another.