A numerical study of the effects of ambient temperature and humidity on the particle growth and deposition in the human airway

Ground source deicing system application in bridge decks is an alternative to salt use, which reduces corrosion and extends the deck service life. Herein, a preliminary parametric numerical analysis is performed to investigate the effects of several important parameters (tube spacing, inlet temperature, flow rate, and concrete cover) on heat transfer performance. Three evaluation indexes (average top surface temperature, snow melting proportion, and heat absorption power) are introduced, and a synthetic evaluation index is proposed to comprehensively consider factors. Mainly referring to the synthetic evaluation index, the optimal design scheme of a geothermally heated bridge deck system under various conditions (layout, lane number, ambient temperature, and tube spacing) is obtained and analyzed to determine the optimal inlet temperature and guide heated bridge deck design. Finally, the influence of wind speed and two adjustment methods are studied. The results indicate that the horizontal layout is the recommended circulating tube layout. The established empirical equations reveal that the optimal inlet temperature is linearly related to ambient temperature and exhibits a quadratic relationship with tube spacing. There is no need to add a heat insulation layer at the bridge deck bottom, and only tubes arranged near the wheels in lanes are recommended.

Download Full-text

Impact of Vitamins C and E Dietary Supplementation on Leukocyte Profile of Layer Hens Exposed to High Ambient Temperature and Humidity

Acta Veterinaria Brno ◽

10.2754/avb201079030377 ◽

2010 ◽

Vol 79 (3) ◽

pp. 377-383 ◽

Cited By ~ 5

Author(s):

Joachim Joseph Ajakaiye ◽

Alcides Perez-Bello ◽

Angel Mollineda-Trujillo

Keyword(s):

Vitamin E ◽

Vitamin C ◽

Ambient Temperature ◽

Harmful Effect ◽

Dietary Supplementation ◽

High Ambient Temperature ◽

Control Group ◽

Physiological Status ◽

Temperature And Humidity ◽

Layer Hens

A 30-day experiment involving 720 White Leghorn layer hens was carried out to evaluate the effects of vitamins C and E on leukocyte and heterophil/lymphocytes ratios of the layer hens during the natural summer conditions. The birds were divided into 4 groups, one control with basal diet and three experimental with diet supplemented with vitamin C, vitamin E, or combination of both vitamins. Each group was divided into 4 subgroups. Exposure of layer hens to 31 ± 3 °C and 33 ± 0 °C ambient temperature and 84.6% and 81.5% relative humidity during the experiment caused an increase in the value of temperature humidity index of 15.5 above the threshold value of 70 established for this species. Total white blood cells, lymphocytes, and eosinophil levels were significantly (p < 0.001) higher in all treated groups compared to control. Similarly, heterophil/lymphocyte ratios of 0.51, 0.52, and 0.50 for groups with diet supplemented with vitamin C, vitamin E and vitamins C + E, respectively, were significantly (p < 0.001) lower compared to 0.59 recorded in the control group. However, heterophil, basophil and monocyte values were significantly (p < 0.001) higher in the control group compared to all treated groups. The results of the present study showed that dietary supplementation of vitamins C and E, or their combination, reduces the harmful effect of high ambient temperature and humidity on the leukocyte indicators of exposed layer hens, thereby alleviating the stress imposed on their thermoregulatory mechanism and physiological status.

Download Full-text

Numerical Study and Experimental Validation of the Thermal Performance for a Parallel Channel Optical Module

2003 International Electronic Packaging Technical Conference and Exhibition, Volume 2 ◽

10.1115/ipack2003-35141 ◽

2003 ◽

Cited By ~ 1

Author(s):

Z. F. Shi ◽

Albert C. W. Lu ◽

Eric Tan ◽

Ronson Tan

Keyword(s):

Ambient Temperature ◽

Thermal Performance ◽

Numerical Study ◽

High Ambient Temperature ◽

Junction Temperature ◽

Cavity Surface ◽

Optical Interconnection ◽

Laser Array ◽

Optical Module ◽

Forced Air

To meet the insatiable demand for data bandwidth in VSR (very short reach up to 300m) applications including server and routers, parallel optical interconnection offers a promising solution in terms of performance and cost effectiveness. A 12-channel pluggable paralle optical transmitter module has been developed to achieve a data rate of 2.5 Gb/s per channel. To maintain the robustness of the optical signal integrity under different environmental conditions, the thermal management is crucial. In this paper the thermal performance evaluation of the optical module was carried out through both numerical simulation and experimental verification. The optical module mainly consists of a VCSEL (vertical cavity surface emitting laser) array, a driver IC and a heat sink. Three types of heat sinks were integrated into the transmitter module separately. The thermal environments used for this evaluation include the normal and high ambient temperature, and both still-air and forced-air conditions. The ambient temperature and the wind speed were controlled by using a Wind Tunnel. The simulation was performed by using a CFD (computational fluid dynamics) program. In all the three modules, the simulation and experimental results of the junction temperature have shown good agreements. For Module 1 under the high ambient temperature, a forced-air condition was required to keep the junction temperature below 70°C. For Module 2 and Module 3, the junction temperature can be controlled below 70°C even under the high ambient temperature without using a fan.

Download Full-text

Numerical Study on Humidification Performance of Fuel Cell Test Platform Humidifier

Energies ◽

10.3390/en12203839 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3839 ◽

Cited By ~ 1

Author(s):

Tiancai Ma ◽

Kai Wang ◽

Qiongqiong Zhou ◽

Weikang Lin ◽

Ming Cong ◽

...

Keyword(s):

Fuel Cell ◽

Water Temperature ◽

Numerical Study ◽

Proton Exchange ◽

Operating Conditions ◽

Air Velocity ◽

Humidity Control ◽

Test Platform ◽

Temperature And Humidity ◽

Cell Test

Temperature and humidity are important parameters in the operation of proton exchange membrane fuel cell (PEMFC), which have an important impact on the performance of fuel cell. Fuel cell test platform is an important tool to study the performance of fuel cells, and its temperature and humidity control module is also the key in the research process of the test platform, so that it can provide the gas with precise temperature and humidity control during the test process of the fuel cell. In this paper, a humidifier combined with bubbling and spraying is adopted for the application of test platform, and the numerical simulation model of the humidifier is established. According to the model, the influence of operating conditions of humidifier on humidification performance is verified, such as inlet air velocity and the humidifying water temperature. The results indicate that the inlet air velocity and the humidifying water temperature have great influence on the humidifying performance of the humidifier. The humidifying performance decreases with the increase of the inlet air velocity and increases with the increase of the humidifying water temperature respectively. In addition, the humidification performance of the humidifier is verified.

Download Full-text