HVAC Air Flow Calculation Using Electrical Circuit Analogy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The complexity of modern vehicle HVAC systems makes it difficult to design and control air flow, as traditional methods require time-consuming measurements and simulations, and each modification necessitates new calculations, consuming computational resources.
Innovation Solution
A simplified model treats HVAC components as electrical circuits, using flow resistance and pressure differences to calculate air flow, allowing for easier design and control by determining total equivalent flow resistance and pressure differences, and adjusting flap positions and fan speed to achieve desired air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement methods are used to model HVAC systems, then measurement precision is improved, but loss of time increases due to time-consuming measurements of all relevant combinations
Solution Approach 1:
The HVAC system is segmented into individual components (ducts, flaps, outlets, heat exchangers) each characterized by its own flow resistance parameters. This allows the complex system to be modeled by combining simple component models rather than requiring comprehensive measurements of all possible combinations, significantly reducing modeling time while maintaining accuracy.
Solution Approach 2:
The system uses variable flow resistance coefficients that change based on flap positions and component characteristics. By parameterizing the system with these variable coefficients, the model can accurately represent different system configurations without requiring new measurements for each configuration, thus reducing time loss while maintaining precision.
2Measurement precision
If CFD calculations are used to build a system model, then measurement precision is improved, but use of energy increases due to computer intensive calculations
Solution Approach 1:
Instead of performing energy-intensive CFD calculations on the entire system, the approach segments the system into simple components with analytically determined flow resistance parameters. This eliminates the need for comprehensive CFD simulations while maintaining modeling accuracy through the combination of individual component characteristics.
Solution Approach 2:
The patent uses simple, computationally inexpensive component models with fixed flow resistance coefficients rather than expensive CFD simulations. These simple models can be rapidly calculated and combined to achieve system-level accuracy without the high energy cost of detailed computational fluid dynamics.
3Adaptability or versatility
If system complexity increases with more outlets and flaps, then adaptability is improved, but device complexity increases making design and control more difficult
Solution Approach 1:
The complex HVAC system with multiple outlets and flaps is segmented into standardized components, each with its own flow resistance parameters. This segmentation allows the system to handle increased complexity through modular parameter combinations rather than requiring complex integrated models, making design and control more manageable while maintaining high adaptability.
Solution Approach 2:
The patent develops a universal modeling approach that can handle any configuration of ducts, flaps, and outlets using the same fundamental equations and parameter types. This universal method allows the system to scale to increased complexity without requiring different modeling techniques, thereby improving adaptability while keeping the underlying model structure simple.
4Measurement precision
If each modification requires new measurements or calculations, then measurement precision is maintained, but loss of time increases due to repeated measurements
Solution Approach 1:
The patent determines flow resistance coefficients for individual components during the initial system design phase. These pre-determined parameters can then be reused for any system modification or configuration change without requiring new measurements or calculations, thus maintaining measurement precision while eliminating repeated measurement time loss.
Solution Approach 2:
The system uses parameterized flow resistance coefficients that can be adjusted to reflect different configurations, modifications, or operating conditions without requiring new measurements. By changing parameters rather than remeasuring, the system maintains accuracy while significantly reducing the time required for 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 approach reduces computational resources needed for controlling the system, simplifies modeling and redesign, and allows for efficient control of air flow in multi-zone systems without the need for extensive simulations, enabling less expensive on-board computers and freeing up resources for other tasks.
Implementation Method 1
determining a pressure difference P between a predetermined location in the system and the interior of the vehicle
Implementation Method 2
each air duct being characterized by a predetermined flow resistance coefficient; at least one flap being characterized by a flow resistance based on a degree of opening of the flap
Data Source
AI summary
A method is provided for determining an air flow in a vehicle air conditioning system that comprises an inlet; a plurality of outlets; at least one air duct for guiding air from the inlet to the outlets, each air duct being characterized by a predetermined flow resistance coefficient; at least one flap characterized by a flow resistance based on a degree of opening of the flap; and a fan for creating an air flow from the inlet to an outlet. The method comprises determining a total equivalent flow resistance between a predetermined location in the system and an interior of the vehicle, wherein flow resistances are treated as resistances in an electric circuit, and a total equivalent flow resistance is determined. Treating a pressure drop as equivalent with a voltage drop, the air flow can be determined, as the pressure is equal to the resistance times the flow squared.