Research on Water Vapor Release and Adsorption Mechanism to Improve the Measurement of Dew Point Humidity Sensor

2021 ◽  
pp. 1-1
Author(s):  
Qinghui Li ◽  
Xiaolei Wang ◽  
Huibing Yang ◽  
Xichuan Liu
Keyword(s):  
Water Vapor ◽  
Humidity Sensor ◽  
Adsorption Mechanism ◽  
Dew Point

scholarly journals Evaluation of radiosonde humidity sensors at low temperature using ultralow-temperature humidity chamber

2018 ◽  
Vol 15 ◽  
pp. 207-212 ◽  
Author(s):  
Byung Il Choi ◽  
Sang-Wook Lee ◽  
Sang-Bong Woo ◽  
Jong Chul Kim ◽  
Yong-Gyoo Kim ◽  
...  
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Response Time ◽  
Humidity Sensor ◽  
Weather Prediction ◽  
Observation Data ◽  
Humidity Sensors ◽  
Ultralow Temperature ◽  
Humidity Chamber ◽  
Sensing Characteristics

Abstract. Accurate measurements of temperature and water vapor in the upper-air are of great interest in relation to weather prediction and climate change. Those measurements are mostly conducted using radiosondes equipped with a variety of sensors that are flown by a balloon up to lower stratosphere. Reference Upper Air Network (GRUAN) has identified water vapor pressure as one of the most important measurands and has set an accuracy requirement of 2 % in terms of the mixing ratio. In order to achieve the requirement, many errors in the humidity measurement such as a temperature dependency in sensing characteristics including measurement values and response time need to be corrected because humidity sensors of radiosondes pass through low-pressure (1 kPa) and low-temperature (−80 ∘C) environments in the upper-air. In this paper, the humidity sensing characteristics of Jinyang radiosonde sensors in relation to temperature dependencies were evaluated at low temperature using a newly developed ultralow-temperature humidity chamber. The sensitivity characteristic curve of the radiosonde sensors was evaluated down to −80 ∘C, and the calibration curves of the humidity sensor and the temperature sensor were obtained. The response time of humidity sensor slowly increased from 52 to 116 s at the temperature from 20 to −40 ∘C, respectively, and then rapidly increased to almost one hour at −80 ∘C. Those results will help to improve the reliability of the upper-air observation data.

Thickness of the Still Air Layer Adhering to Perforated Plastic Plates and Fabric

1988 ◽  
Vol 58 (2) ◽  
pp. 86-90 ◽  
Author(s):  
Kozo Tsubouchi
Keyword(s):  
Water Vapor ◽  
Humidity Sensor ◽  
Unit Area ◽  
Water Vapor Pressure ◽  
Sample Surface ◽  
Hole Diameter ◽  
Vapor Pressures ◽  
Wide Range ◽  
Vapor Pressure Gradient ◽  
Surface Construction

The thickness of the still air layer adhering to perforated plastic plates and a fabric was investigated in terms of the water vapor pressure gradient in the zone of diffusion above the samples. The water vapor pressures above the samples were determined from measurements using a temperature and relative humidity sensor. To analyze the thickness of the still air layer for a wide range of evaporation rates, the hole diameter and the number of holes per unit area were changed and the measurements were under different temperature and humidity/gradient conditions. The thickness of the still air layer corresponded to a distance of 10 mm from the sample surface and was not related to the surface construction and materials.

Dew Point Humidity Sensor for Instrumentation Engineering Classes

2018 ◽  
Author(s):  
Marta Barbosa ◽  
Marta Torres ◽  
Pedro Moreira ◽  
Sofia Magalhaes ◽  
Luis Coelho ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Dew Point

Heat and Mass Transfer in Double-Filmwise Heat Exchanger for Industrial Food Processing Applications

2011 ◽  
Author(s):  
Helen Skop ◽  
James Pezzuto ◽  
Valeriy G. Oleynikov-White ◽  
John F. Cavallo ◽  
Robert Fesjian
Keyword(s):  
Water Vapor ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cost Effective ◽  
Dew Point ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Gas Cooling ◽  
Stack Gas

The baking industry is considered as one of the major energy consuming food industries in North America. More than 40% of bakery fuel consumption is used to evaporate water in the processes [1]. In addition to the baking process’ vapor the oven stack gas contains water vapor from combustion products. Overall the content of water vapor in the typical oven stack gas is about 20% by volume. Most bakeries waste this vapor and its latent heat. Bakeries’ ovens have wide diversity in power and design. Off-the-shelve heat exchangers are not considered as cost effective equipment for stack gas cooling below gas’ dew point temperature. At typical oven stack gas composition water vapor condensation begins to condense at about 72° C. Not using the latent heat of stack water vapor and the heat from gas cooling from dew point temperature to ambient temperature results in low effectiveness of waste heat recovery. Mainly the effect from the recovery of stack gas cooling prior to condensation is considered as non cost effective and waste heat recovery is neglected.

Automatic dew-point temperature sensor

1982 ◽  
Vol 52 (6) ◽  
pp. 1658-1660 ◽  
Author(s):  
H. Graichen ◽  
R. Rascati ◽  
R. R. Gonzalez
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Water Vapor Pressure ◽  
Skin Surface ◽  
Dew Point ◽  
Pressure Gradients ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Peltier Module ◽  
Local Water

A device is described for measuring dew-point temperature and water vapor pressure in small confined areas. The method is based on the deposition of water on a cooled surface when at dew-point temperature. A small Peltier module lowers the temperature of two electrically conductive plates. At dew point the insulating gap separating the plates becomes conductive as water vapor condenses. Sensors based on this principle can be made small and rugged and can be used for measuring directly the local water vapor pressure. They may be installed within a conventional ventilated sweat capsule used for measuring water vapor loss from the skin surface. A novel application is the measurement of the water vapor pressure gradients across layers of clothing worn by an exercising subject.

Capacitance Humidity Sensor

1995 ◽  
Vol 382 ◽  
Author(s):  
Andrew R.K. Ralston ◽  
Paul E. Thoma ◽  
Carl F. Klein ◽  
Denice D. Denton
Keyword(s):  
Water Vapor ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Moisture Uptake ◽  
Free Standing ◽  
Sorption Model ◽  
Volume Calculations ◽  
Water Vapor Transmission ◽  
Design Construction

ABSTRACTA capacitance relative humidity (RH) sensor is described that has a design, construction, and material composition that result in an inexpensive and robust sensor. This sensor has a multilayer, free-standing film construction. It consists of a humidity sensitive polyimide (PI) dielectric core and conductive layers consisting of carbon filled polysulfone on each side of the polyirnide film to form a capacitor. The polyimide used is a BPDA-ODA type, and replaces a PMDA-ODA type polyimide used in a previous version of this sensor. The BPDA-ODA sensor has a nominal capacitance of 200 pF and a nominal sensitivity of 13% at 100% RH. The characteristics of this humidity sensor are discussed and compared to the characteristics of the PMDA-ODA type sensor. Characteristics considered include the PI film moisture uptake and water vapor transmission, and the sensors' sensitivity to relative humidity, frequency response, and aging at 85°C/85% RH. The dual-state sorption model and free volume calculations are used to demonstrate that observed differences in the film are due to differences in chemical composition between the films.

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