Powered Capture Hood for HVAC Airflow Measurement
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Solution Overview
Problem
Existing airflow measurement devices for HVAC systems are cumbersome, inaccurate, and difficult to use, especially in residential settings due to the inherent complexities of ductwork, and require on-site construction of flow boxes with powered blowers, making them time-consuming and inefficient.
Innovation Solution
A powered capture hood assembly with a hood structure, a formed nozzle structure having flared ends and a venturi shape, and a blower apparatus with an adjustable fan and pressure sensors to measure volumetric airflow by conditioning airflow and compensating for pressure loss, allowing for easy and accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive measuring devices are used, then the device structure is simple, but the measurement precision is poor and the ease of operation is difficult
Solution Approach 1:
The patent combines multiple functions into a single integrated powered capture hood assembly: the hood structure for capturing airflow, the nozzle structure for flow conditioning, the blower apparatus for pressurization, and the measurement system for data acquisition are merged into one unified device that provides both flow conditioning and measurement capabilities
Solution Approach 2:
The patent introduces a nozzle structure as an intermediary component between the capture hood and the measurement system. This nozzle serves as a flow conditioning element that transforms the captured airflow into a measurable flow pattern, enabling accurate measurement while isolating the measurement system from the complexities of the captured airflow
2Measurement precision
If flexible duct structures with powered blowers are used, then the measurement precision is improved, but the ease of manufacture and ease of operation deteriorate due to requiring on-site construction of flow boxes
Solution Approach 1:
The patent incorporates flow conditioning nozzles and pressure reference systems into the device during factory manufacturing, eliminating the need for on-site construction of flow boxes. The device arrives pre-configured with all necessary flow conditioning elements, pressure taps, and measurement systems, requiring only installation and calibration at the measurement site
Solution Approach 2:
The patent divides the measurement system into modular components: a capture hood for airflow intake, a nozzle structure for flow conditioning, a blower apparatus for pressurization, and a measurement system for data acquisition. This segmentation allows for easier manufacturing, assembly, and on-site deployment compared to monolithic flow box constructions
3Productivity
If prior art devices are used, then the device complexity is low, but the productivity deteriorates due to being time-consuming to construct and utilize
Solution Approach 1:
The patent merges the capture hood, nozzle structure, blower apparatus, and measurement system into a single integrated assembly that can be deployed as one unit. This eliminates the time-consuming sequential construction of separate components and enables rapid deployment for airflow measurements
Solution Approach 2:
The device is pre-assembled and pre-configured with all necessary components including flow conditioning elements, pressure taps, and measurement systems before delivery to the site. This preliminary preparation significantly reduces on-site construction time and enables rapid deployment for measurements
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
The powered capture hood assembly provides easy and accurate measurement of volumetric airflow in heating and cooling systems and ventilation fans, overcoming the limitations of prior devices by simplifying the measurement process and improving accuracy.
Implementation Method 1
The formed nozzle structure is formed having flared ends and has a venturi shape or constricted middle section
Implementation Method 2
A pressure sensor which communicates with a pressure reference tap and a pressure gauge is provided to read pressure differentials
Data Source
AI summary
A powered capture hood assembly to measure volumetric airflow in heating and cooling systems and for ventilation fans. The capture hood assembly has a hood for capturing or providing airflow, a formed nozzle structure attached thereto for conditioning the airflow and a blower apparatus with an adjustable fan attached to the opposite end of the nozzle structure. Subsequent the positioning of the hood over a supply duct, for example, a fan speed controller is utilized to adjust the fan in the tubular blower member to provide a zero or null pressure reading between the venturi portion of the nozzle structure and the local ambient room pressure. A pressure gauge is utilized to measure the pressure differential between a pressure reference tap of the formed nozzle structure and the pressure tap of the blower apparatus to determine volumetric airflow.