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Coating Defects and Inspection
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
A dew point calculator (see Figure 4.25) is another device that is used to calculate the dew point by knowing the temperature and relative humidity. Dew point is used in addition to a surface temperature thermometer and a sling psychrometer. A dew-point calculator is used frequently during surface preparation, coating application and drying. It is recommended to use a dew-point calculator every 6 hours and when the weather condition changes. Dew point has an effect on condensate and rust formation on the metal surface, as explained earlier in this chapter.
Industrial Heat and Its Control
Published in John D. Constance, Controlling In-Plant Airborne Contaminants, 2020
Humidity is expressed as absolute humidity and relative humidity. For a quick explanation please refer back to Chapter 1. Dew point is another measure of humidity and is closely related to vapor pressure and absolute humidity. Various combinations of dry bulb temperature and relative humidity with the same vapor pressure also have the same dew point. To the heat loss by evaporation from the skin must be added that from the respiratory tract into the inspired air which is expired naturally. See Carroll, B. T. (1976).
Air conditioning systems
Published in Paul Tymkow, Savvas Tassou, Maria Kolokotroni, Hussam Jouhara, Building Services Design for Energy-Efficient Buildings, 2020
Paul Tymkow, Savvas Tassou, Maria Kolokotroni, Hussam Jouhara
The space humidity may also be controlled by a dry-bulb temperature sensor placed in the duct immediately after the cooling coil. This sensor controls the flow in the cooling coil to maintain the off-coil temperature constant. Although the apparatus dew point and the moisture content of the air leaving the coil will vary, the variation is very small. This method of control is therefore considered to provide a constant off-coil air dew point temperature and moisture content, which is known as dew point control.
Drying and Atterberg limits of Cochin marine clay
Published in International Journal of Geotechnical Engineering, 2020
Amal Azad Sahib, Retnamony G. Robinson
To verify the role of shrinkage stresses upon drying, suction values were measured in Cochin marine clay specimens using Dew point Potentiameter (WP4) that employs the chilled mirror hygrometer. The device is used as a rapid means of determining the total suction of unsaturated soils (Leong, Tripathy, and Rahardjo 2003; Vikas and Singh 2005). The specimens were filled in slurry state (about 1.5 times liquid limit) in a mould of 35 mm diameter and 7 mm height. The soil sample was placed in a sealed chamber containing a mirror with a detector of condensation. The dew-point is the temperature to which the air must be cooled so that the water vapour in the air condenses to liquid water. At the dew-point, the water vapour present in the air is just sufficient to saturate it. When equilibrium prevails, the relative humidity of the air in the chamber is equal to the relative humidity of the soil sample. Relative humidity is calculated as the ratio of the saturated vapour pressure of water at the dew-point to the saturated vapour pressure of water at the air temperature. This ratio can be substituted in the following thermodynamic equation to calculate the total suction pressure.
A comparative thermal properties evaluation for residential window retrofit solutions for U.S. markets
Published in Advances in Building Energy Research, 2021
Tim Ariosto, Ali M. Memari, Ryan L. Solnosky
Several shortcomings were also identified in this study that can be resolved through further research. These stem mainly from the inability of computer testing (using existing software) to properly evaluate the performance of window/window retrofit assemblies. Thermal transmittance of the complete assembly is based largely on the role of convection heat transfer through the window retrofit. While WINDOW developed algorithms to account for this, the variability of real systems and mounting methods can potentially significantly alter this behavior. Therefore, physical testing is needed for several reasons. First, physical testing would allow for the validation of the WINDOW analysis. Secondly, physical testing would allow for the determination of surface temperatures at several locations on the assembly. With sufficient physical testing, a set of isotherms could be determined. Condensation potential could then be evaluated by determining the location of the dew point on the window/window attachment assembly. If the dew point is located within the assembly itself, there will be potential for condensation. If the dew point lies on the exterior of the window assembly, there is no risk of condensation. Another shortcoming of the WINDOW analysis is a lack of detailed spectral data (interior and exterior reflectance, transmittance, and absorptance) for shading systems. Without detailed spectral data, the SHGC and Tvis could vary significantly. Physical testing of specimens could not only generate this spectral data, but could also be used to validate WINDOW modeling. Such data could also be used for energy analysis, thus allowing for a measurement of return on investment.
The impact of local variations in a temperate maritime climate on building energy use
Published in Journal of Building Performance Simulation, 2020
Ralph Evins, Ross Alexandra, Ed Wiebe, Michael Wood, Matthew Eames
The dew point temperature is a required variable in EPW weather files and as an input for the illuminance calculations. The observed weather data contains the dry bulb temperature and the relative humidity. The dew point temperature can be therefore estimated directly from psychrometric formulas (ASHRAE Fundamentals 2017). The dew point temperature is the point at which the air temperature must be lowered to become 100% saturated with water vapour. The dew point temperature is solved iteratively.