Temperature control and safety in air handling unit configured with a supplemental heater assembly
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Solution Overview
Problem
Existing temperature-based bimetal switches in heater assemblies require customization for each electric heating element, complicating manufacturing and increasing costs, and fail to adapt to dynamic operating conditions, posing safety risks and efficiency issues.
Innovation Solution
A system utilizing thermistors positioned around the heating element and a controller to monitor and adjust heating capacity and blower speed to maintain predefined temperatures, ensuring safety and efficiency by dynamically controlling temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-based bimetal switches are used in heater assemblies, then temperature control is provided, but customization is required for each heating element which complicates manufacturing and increases costs
Solution Approach 1:
The patent applies universality by using a standardized thermistor and controller assembly that can be used across multiple heating elements of different sizes and configurations. The thermistor is positioned at a standardized location relative to the heating element, and the controller uses algorithmic calculations to determine heating element temperature based on this single temperature sensor reading, eliminating the need for custom temperature control devices for each heating element.
Solution Approach 2:
The patent introduces an intermediary computational approach where the controller acts as a mediator between the single thermistor sensor and the heating element temperature control. Instead of directly measuring the heating element temperature with a custom sensor, the system uses the thermistor to measure air temperature and applies algorithmic corrections based on the relationship between air temperature and heating element temperature, providing universal temperature control without custom sensors.
2Reliability
If temperature-based bimetal switches are used, then temperature control is provided, but the system fails to adapt to dynamic operating conditions
Solution Approach 1:
The patent applies dynamics by implementing a controller that dynamically adjusts heating element power based on real-time thermistor readings and operating conditions. The system continuously monitors air temperature and uses algorithmic calculations to determine the appropriate heating element temperature setpoint and power level, allowing the system to adapt to changing operating conditions such as varying airflow rates, ambient temperatures, and heating demands.
Solution Approach 2:
The patent implements feedback control where the thermistor continuously monitors air temperature and feeds this information back to the controller. The controller processes this feedback along with information about desired air temperature and operating conditions, then adjusts the heating element power accordingly. This closed-loop feedback system enables the heater assembly to adapt to dynamic operating conditions and maintain optimal temperature control.
3Measurement precision
If multiple temperature sensors are positioned around the heating element, then temperature monitoring accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the temperature measurement function into two parts: a single physical thermistor sensor that measures air temperature, and a computational segmentation where the controller calculates the heating element temperature based on the air temperature reading and the known thermal relationship between the air and heating element. This segmentation allows accurate temperature monitoring without physically placing multiple sensors around the heating element.
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 system provides adaptable and reliable temperature control, preventing over-temperature conditions, enhancing safety and efficiency of the heater assembly and air handling unit.
Implementation Method 1
one or more thermistors configured at predefined positions around or adjacent to a heating element
Implementation Method 2
a heating element associated with the heater assembly
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A temperature control and safety system (100) for an air handling unit (102) is configured with a supplemental heater assembly (104). The system comprises one or more thermistors (112) configured at predefined positions around or adjacent to a heating element (204) associated with the heater assembly, and a controller (114) operatively connected to the thermistors (112), the heating element (204), and a blower (108) associated with the air handling unit (102), wherein the controller comprises one or more processors (114-1) coupled to a memory (114-2) storing instructions executable by the processors, which causes the controller to: monitor, using the thermistors (112), temperature of the heating element (204) and/or temperature of air leaving or flowing through the heating element (204), and control switching and/or adjust heating capacity of the heating element (204) based on the monitored temperatures, to maintain temperature of the heating element (204) at a first predefined temperature and/or the temperature of the air leaving the heater assembly at a second predefined temperature.