HVAC Enthalpy and Flow Monitoring Using Reduced Sensor Arrangement
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Solution Overview
Problem
HVAC installations face challenges in accurately measuring flow rates and enthalpy differences due to the limitations of existing sensor arrangements, which increase energy demands, incur high maintenance costs, and are prone to fouling and decreased measurement accuracy.
Innovation Solution
A method that reduces the number of sensors by using a subset of measured variables and mathematical or empirical relationships to determine the remaining variables, allowing for the omission or replacement of sensors with non-calibrated auxiliary sensors, thereby minimizing costs and maintaining flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of flow sensors is placed within ducts to provide a grid of sensors equally distributed along the cross-section, then measurement accuracy is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent extracts only the essential measurements needed for accurate control by placing a single flow sensor in the return air duct, rather than installing a comprehensive grid of sensors throughout the system. This selective extraction of measurement points maintains control accuracy while dramatically reducing system complexity.
Solution Approach 2:
The patent uses return air flow rate as an intermediary parameter to infer the performance of the entire HVAC system. By measuring this intermediate variable, the system can calculate heating and cooling performance without directly measuring all primary parameters, thus simplifying the sensor arrangement.
2Measurement precision
If rods with sensors are placed within fluid flow, then measurement capability is improved, but flow resistance increases and energy demands rise
Solution Approach 1:
The patent removes sensor rods from the primary fluid flow paths where they would create significant resistance. Instead, it places a single sensor in the return air duct, extracting measurement capability without the harmful interference of obstructing the main flow paths that move large volumes of air through the system.
3Measurement precision
If multiple sensors are installed in large ducts, then measurement accuracy is improved, but sensors and rods are prone to fouling and maintenance costs increase
Solution Approach 1:
The patent extracts the measurement function to a single location in the return air duct, removing multiple sensors from exposure to dirty primary air streams. This single sensor location is much easier to access, clean, and maintain compared to multiple sensors distributed throughout the system.
4Loss of information
If a comprehensive sensor arrangement is used to measure all variables, then measurement completeness is improved, but manufacturing costs and assembly complexity increase
Solution Approach 1:
The patent makes the single return air flow sensor perform multiple functions: it measures return air flow rate, enables calculation of heating performance, enables calculation of cooling performance, and provides system diagnostic capability. This multi-functionality eliminates the need for separate sensors for each measurement objective.
Solution Approach 2:
The patent uses mathematical models and calculations to create virtual representations of unmeasured parameters based on the single physical sensor measurement. Instead of installing physical sensors for every parameter, the system creates calculated copies of the required information through thermodynamic relationships.
Data Source
AI summary
A method, system (100), and a computer program product comprising a non-transient computer-readable medium (190) having stored thereon computer program code configured to control one or more processors (180) of a computer (170) for operating an HVAC installation (200, 300), wherein a set of enthalpies (H1,i, H2,i, H1,o, H2,o) and flow rates (ϕ1, ϕ2) as variables of the HVAC installation (200, 300) is monitored and used for controlling the operation of said HVAC installation (200, 300), comprising the steps of: (a) dividing said set of enthalpies (H1,i, H2,i, H1,o, H2,o) and flow rates (ϕ1, ϕ2) into a first and second subset; (b) measuring each variable of said first subset with a related sensor (110, 120) arranged in said HVAC installation (200, 300); and (c) determining the variables of said second subset from the measured variables of said first subset by using a mathematical and/or empirical relationship between the variables of said first and second subset.