HVAC Preheat Control Using Wind and Tracer Gas Airflow Data
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Solution Overview
Problem
HVAC systems face challenges in accurately determining the preheat period due to miscalculations, leading to either insufficient start-of-occupancy temperatures or unnecessary energy usage, as they typically rely on constant air change rate assumptions rather than real-time air flow characteristics.
Innovation Solution
The method involves receiving wind condition data and tracer gas concentration data to calculate air flow characteristics, correlating this data to determine an operating air flow characteristic, and using it to calculate a more accurate preheat time interval for temperature control in HVAC systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant air change rate assumptions are used in HVAC control, then device complexity is reduced, but measurement precision of air flow characteristics deteriorates
Solution Approach 1:
The patent replaces mechanical measurement devices with a computational approach using tracer gas concentration measurements and wind condition data processed through a controller to calculate air flow characteristics. This substitution of physical measurement mechanisms with computational methods resolves the contradiction by maintaining system simplicity while achieving precise air flow characterization through mathematical modeling rather than complex mechanical sensors.
2Reliability
If preheat period is extended to ensure start-of-occupancy temperature, then temperature reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of the preheat period by calculating real-time air flow characteristics using tracer gas concentration data and wind condition information. The controller dynamically determines the optimal preheat duration based on current atmospheric conditions, building envelope characteristics, and thermal mass properties. This dynamic approach ensures reliable start-of-occupancy temperatures are achieved while minimizing energy consumption by avoiding excessive preheating, directly resolving the contradiction between temperature reliability and energy efficiency.
Solution Approach 2:
The system employs feedback mechanisms by continuously monitoring tracer gas concentration to calculate air flow characteristics and using this information to adjust the preheat period calculation. The controller uses the calculated air flow characteristics as feedback to determine the precise preheat duration needed, ensuring that heating is maintained just long enough to achieve the desired temperature without unnecessary energy expenditure, thereby resolving the contradiction between temperature reliability and energy consumption.
3Use of energy by moving object
If preheat period is shortened to reduce energy usage, then energy consumption is reduced, but temperature reliability deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the preheat period by calculating real-time air flow characteristics using tracer gas concentration data and wind condition information. The controller dynamically determines the optimal preheat duration based on current atmospheric conditions, building envelope characteristics, and thermal mass properties. This dynamic approach ensures reliable start-of-occupancy temperatures are achieved while minimizing energy consumption by avoiding excessive preheating, directly resolving the contradiction between temperature reliability and energy efficiency.
4Measurement precision
If real-time wind condition data and tracer gas measurements are collected, then air flow characteristic measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs a controller that performs multiple functions: it monitors wind condition data from external sources, measures tracer gas concentration within the building, calculates air flow characteristics from these measurements, and determines the optimal preheat period. By using a single multi-functional controller rather than separate specialized devices for each measurement and calculation task, the system achieves high measurement precision through comprehensive data collection while minimizing device complexity through functional integration.
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 precise determination of the preheat period, optimizing energy usage by accounting for real-time air flow characteristics, thereby ensuring accurate start-of-occupancy temperatures and reducing energy wastage.
Implementation Method 1
receiving measured tracer gas concentration data in the control zone for the at least one sample time interval, calculating an air flow characteristic for the at least one sample time interval based on the measured tracer gas concentration data
Implementation Method 2
receiving measured wind condition data external to the building for at least one sample time interval, calculating an air flow characteristic based on wind conditions and tracer gas concentration
Data Source
AI summary
According to various aspects and embodiments, a system and method for controlling temperature in a control zone within a building is provided. According to some embodiments, the method includes receiving measured wind condition data external to the building and measured tracer gas concentration data in the control zone for a sample time interval and calculating an air flow characteristic for the sample time interval based on the measured tracer gas concentration data. The method further includes using the air flow characteristic in a temperature control loop for the control zone. According to some embodiments, the air flow characteristic is an air change rate (ACR) that may be used in determining a preheat time interval.