High Dew Point Humidity Sensor With Automated Tube Heating
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Solution Overview
Problem
Humidity sensors face challenges in high dew point environments, such as commercial ovens, where condensation forms due to temperature differences, leading to inaccurate data and labor-intensive trial-and-error preheating methods, making it difficult to maintain effective humidity sensing in multi-zone equipment.
Innovation Solution
A high dew point humidity sensor system with an enclosure assembly, ambient temperature sensor, fluid-moving device, heater block assembly, and controller that adjusts the heater block operation based on measured ambient and internal temperatures to prevent condensation, using a PWM duty cycle to maintain the air sample intake tube temperature above the dew point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the humidity sensor chip is cooled by passing air through a sample air channel, then the sensor is protected from extreme oven temperatures, but condensation forms on the sensor or blocks the sample air channel
Solution Approach 1:
The system performs preliminary heating of the air sample intake tube before inserting the humidity sensor into the thermal barrier. The controller activates the heater block assembly to heat the tube to a temperature above the dew point, preventing condensation from forming when the sensor is later inserted into the thermal barrier for operation in high dew point environments.
Solution Approach 2:
The system uses an internal temperature sensor to continuously monitor the temperature of the air sample intake tube and provides feedback to the controller. The controller adjusts the heater block assembly operation based on this feedback, maintaining the tube temperature above the dew point to prevent condensation while optimizing energy consumption.
2Object-affected harmful factors
If a heating pad is used to pre-heat the humidity sensor, then condensation can be prevented, but labor-intensive trial-and-error procedures are required to achieve proper heating
Solution Approach 1:
The system automatically controls the heating process without requiring manual intervention. The controller monitors the internal temperature sensor readings and autonomously adjusts the heater block assembly to maintain the air sample intake tube temperature above the dew point, eliminating the need for manual trial-and-error preheating procedures.
Solution Approach 2:
The patent replaces manual mechanical adjustment of heating with an automated electronic control system. The controller uses electronic feedback from the internal temperature sensor to automatically regulate the heater block assembly, substituting the manual mechanical trial-and-error process with an automated electronic control loop.
3Temperature
If the humidity sensor is inserted into a thermal barrier, then the sensor is protected from extreme temperatures, but it becomes difficult to maintain the sensor temperature above the dew point
Solution Approach 1:
The system heats the air sample intake tube to a temperature above the dew point before inserting the humidity sensor into the thermal barrier. This preliminary heating ensures that when the sensor is later operated within the thermal barrier in high dew point environments, condensation will not form on the sensor or block the sample air channel, maintaining sensing reliability.
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 effectively prevents condensation and ensures accurate humidity measurements in high dew point environments without labor-intensive preheating, allowing for reliable operation in commercial ovens and multi-zone equipment.
Implementation Method 1
a heater block assembly located within the enclosure assembly and in thermal communication with at least a portion of the air sample intake tube
Implementation Method 2
condensation is likely to form and block the sample air channel or contact the humidity sensor chip
Data Source
AI summary
A high dew point humidity sensor includes an enclosure assembly, an ambient temperature sensor, air sample intake and exhaust openings, a fluid-moving device, a heater block assembly, an internal temperature sensor, a humidity sensor chip, and a controller. The controller is configured to: (i) collect a measured ambient temperature from the ambient temperature sensor; (ii) collect a measured humidity of sample air from the humidity sensor chip; (iii) collect a measured temperature from the internal temperature sensor; and (iv) control operation of the heater block assembly based, at least in part, on the measured ambient temperature and the measured temperature from the internal temperature sensor.