HVAC Airflow Measurement Bypass Partition for Low-Flow Accuracy

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Solution Overview

Problem

HVAC systems face challenges in accurately measuring volumetric fluid flow rates, particularly in rooftop systems, where existing devices may not meet industrial standards for accuracy, such as LEED requirements, and may not function properly if the fluid flow rate is below the minimal sensitivity requirement.

Innovation Solution

A method and system that include a fluid flow passage with a measuring section and a bypass/flow-through section, where a partition is configured to ensure the fluid flow measuring passage operates at a minimal sensitivity flow rate, using a flow rate measuring device to measure parameters like pressure drop and correlating them to determine the total flow rate, ensuring compliance with industrial accuracy standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the fluid flow passage is equipped with a flow rate measuring device to measure volumetric airflow, then measurement precision is improved, but the device complexity increases

Engineering Contradiction:

Improvevolumetric airflow measurement accuracyVSAvoidfluid flow passage structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The fluid flow passage is segmented into a measuring section and a bypass section. The partition divides the passage so that only a portion of the fluid flow passes through the measuring section equipped with the flow rate measuring device, while the rest bypasses through the bypass section. This segmentation allows the measuring device to operate within its optimal sensitivity range without requiring the entire passage to be modified, thus improving measurement precision while limiting the increase in device complexity.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If the partition is configured to direct minimal fluid flow through the measuring section, then measurement precision is improved, but the fluid flow rate through the measuring section decreases

Engineering Contradiction:

Improveflow rate measurement accuracyVSAvoidfluid flow rate through measuring section

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The partition is specifically configured to change the flow distribution parameter, directing a controlled portion of the total fluid flow through the measuring section. By adjusting the partition geometry and position, the system ensures that the fluid flow rate through the measuring section reaches the minimal sensitivity flow rate required for accurate measurement, while the bypass section handles the remaining flow. This parameter optimization resolves the contradiction by achieving both adequate flow rate for measurement precision and sufficient flow volume through strategic flow distribution.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the flow rate measuring device operates at minimal sensitivity flow rate, then measurement precision is improved, but the pressure drop in the fluid flow passage increases

Engineering Contradiction:

Improveminimal flow rate measurement accuracyVSAvoidpressure drop in fluid flow passage

Core Design Contradiction:

Measurement precisionVSStress or pressure

Solution Approach 1:

The partition segments the fluid flow passage into measuring and bypass sections, allowing the measuring section to operate at minimal sensitivity flow rates for improved measurement precision while the bypass section handles the majority of the fluid flow. This segmentation isolates the pressure drop impact to only the measuring section, preventing system-wide pressure increase.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system applies partial action by directing only a portion of the total fluid flow through the measuring section at the minimal sensitivity flow rate required for accurate measurement. The bypass section carries the excess flow, ensuring that the pressure drop experienced by the measuring device remains minimal while still achieving the required measurement precision for the overall fluid flow passage.

Inventive Principle:

Principle #16Partial or excessive action

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 allows for accurate and sensitive measurement of volumetric fluid flow rates, meeting industrial standards like ASHRAE 62.1-2004, while minimizing pressure drop and ensuring proper system operation by adjusting the partition to maintain the required minimal sensitivity flow rate.

Implementation Method 1

obtaining a flow rate measurement in the measuring section of the fluid flow passage by measuring a parameter of the fluid flow (e.g. a pressure drop)

Methodology Applied

Scientific EffectPressure drop measurement: Pressure Drop

Data Source

PatentUS9261388B2Methods and systems to measure fluid flow

Publication Date: 2016.02.16 TRANE INTERNATIONAL INC

AI summary

Methods and systems to measure a volumetric fluid flow rate through a fluid flow passage, such as an air handler of a HVAC system, are described. The method may include obtaining a flow rate measurement in a measuring section, and calculating a total flow rate based on a correlation between the obtained flow rate measurement and the total flow rate. The method may also include blocking a portion of the fluid flow passage so that when a minimal volumetric fluid flow rate is provided, the flow rate measurement obtained in the measuring section is at about a minimal sensitivity flow rate requirement.