scholarly journals Extending dew-point temperature scale up to +50 °C

2018 ◽  
Vol 9 ◽  
pp. 17
Author(s):  
Doaa Mohamed Abd El-Gelil ◽  
Mohamed Gamal Ahmed
Keyword(s):  
Temperature Scale ◽  
Scale Up ◽  
Temperature Stability ◽  
Dew Point ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Temperature Range ◽  
Saturator Efficiency ◽  
Uncertainty Of Measurements ◽  
First Time

Extension of dew-point temperature scale has been performed using a two-temperature (2-T), constant pressure humidity generator that is developed for the first time by the National Institute of Standard (NIS) in order to extend the calibration capabilities to the high dew-point temperature range at NIS. It relies on the saturation of a stream of gas flowing over a water surface maintained at constant, well-known, temperature. In this paper, primary realization of dew-point temperature scale in a dew-point temperature range up to +50 °C was performed to extend calibration capabilities and to improve the uncertainties of the dew-point temperature scale realization. Several experiments were carried out in order to characterize the generator. Characterization comprises studies of the saturator efficiency, temperature stability and a comparison with a calibrated chilled-mirror hygrometer. The results of the efficiency tests showed good performance of the generator. For uncertainty of measurements, a thorough analysis was also described representing estimations of contributions for all the sources that possibly affect measurements.

Evaluation of membrane-based air pre-dehumidification for a capillary radiant air conditioning system

2020 ◽  
pp. 1420326X2096738
Author(s):  
Zan-She Wang ◽  
Fang-Ting Yin ◽  
Ran Li ◽  
Zhao-Lin Gu
Keyword(s):  
Moisture Content ◽  
Air Conditioning ◽  
Dew Point ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Temperature Range ◽  
Libr Solution ◽  
The Ideal

The polyvinylidene fluoride hollow fibre membrane air dehumidification tests were carried out between the liquid desiccant solutions and the wet air. Three liquid desiccant solutions of LiBr solution (50%), LiCl solution (35%) and CaCl2 solution (40%) were tested under different wet air conditions. The results showed that all the membrane dehumidification processes were stable. The air moisture content in the outlet of the membrane was maintained as 6.5 g/kg (da)–8.2 g/kg (da) when the air moisture content in the inlet of the membrane was operated from 17.1 g/kg (da) to 32.4 g/kg (da). The dehumidification amount of LiBr solution (50%) and LiCl solution (35%) was more productive. On this basis, a membrane-based air pre-dehumidification process for the capillary radiant air conditioning system was built. Since the ideal dew point temperature range of the indoor air is below 14–17°C according to the cold supply water, all the air moisture content at the membrane outlet is much lower than that of the ideal dew point temperature range, which means non-condensing occurs in the capillary tube surface. The membrane-based air pre-dehumidification process can easily form an adaptive regulation process of humidity with the capillary radiant air conditioning system under different environmental parameters.

scholarly journals Improving efficiency and lowering operating costs of evaporative cooling

2021 ◽  
Vol 338 ◽  
pp. 01027
Author(s):  
Jan Taler ◽  
Bartosz Jagieła ◽  
Magdalena Jaremkiewicz
Keyword(s):  
Electricity Consumption ◽  
Open Circuit ◽  
Dew Point ◽  
Operating Costs ◽  
Water Evaporation ◽  
Total Water ◽  
Point Temperature ◽  
Dew Point Temperature ◽  
Adiabatic Cooling ◽  
Positive Effect

Cooling towers, or so-called evaporation towers, use the natural effect of water evaporation to dissipate heat in industrial and comfort installations. Water, until it changes its state of aggregation, from liquid to gas, consumes energy (2.257 kJ/kg). By consuming this energy, it lowers the air temperature to the wet-bulb temperature, thanks to which the medium can be cooled below the ambient temperature. Evaporative solutions are characterized by continuous water evaporation (approx. 1.5% of the total water flow) and low electricity consumption (high EER). Evaporative (adiabatic) cooling also has a positive effect on the reduction of electricity consumption of cooled machines. Lowering the relative humidity (RH) by approx. 2% lowers the wet-bulb temperature by approx. 0.5°C, which increases the efficiency of the tower, operating in an open circuit, expressed in kW, by approx. 5%, while reducing water consumption and treatment costs. The use of the M-Cycle (Maisotsenko cycle) to lower the temperature of the wet thermometer to the dew point temperature will reduce operating costs and increase the efficiency of cooled machines.

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