Variable air supply velocity of forced-air precooling of iceberg lettuces: Optimal cooling strategies

Author(s):  
Xi-Fang Wang ◽  
En-Hai Liu ◽  
Zhong-Yang Fan
2016 ◽  
Vol 26 (2) ◽  
pp. 226-237 ◽  
Author(s):  
Changsheng Cao ◽  
Jun Gao ◽  
Li Wu ◽  
Xihui Ding ◽  
Xu Zhang

This paper investigates the situation of residential kitchen ventilation and individual exposure in China and attempts to reduce the exposure through organizing local make-up airflow. Measurements were conducted in a kitchen chamber to reproduce the real exposure to the cooking-generated particles under the mode of natural make-up airflow surveyed. Measurements results show that an individual cooking in a kitchen could be exposed to a concentration of airborne particles at ∼10 mg/m3 within a simplified cooking process of oil heating, in the case of an experimental kitchen chamber with an open window or closed window/door. Local make-up airflow through upward make-up air supply or downward make-up air supply was further investigated to determine the effectiveness for reduction of the exposure level. When the air-supply velocity at the outlet of the upward make-up air supply or downward make-up air supply mode was well defined, the individual exposure level could be reduced by 2–3 orders of magnitude, as compared to the baseline case when all the make-up air was from open window. Intake fraction of cooking-generated particles could be as low as ∼10−5 and ∼10−6 under the two modes. This finding has illustrated that well-organized local make-up airflow could largely reduce an individual’s exposure to the cooking-generated particles in Chinese residential kitchen.


2014 ◽  
Vol 1008-1009 ◽  
pp. 1088-1091
Author(s):  
Lan Xia Guo ◽  
Xiao Yong Peng ◽  
Jian Xiang Liu ◽  
Xu Sheng Chai ◽  
Jing Jing Liang ◽  
...  

Airpak was applied to numerically simulate the air distribution under the same air supply temperature ,different air supply velocity (3.6m/s、2.7m/s and 1.8m/s ) and air supply angle (+15°、-45° and-75°) , and evaluate thermal comfort by Comparative analysis velocity fields, temperature fields, PMV—PPD. The results show that different air supply velocity and air supply angle have a significant impact on indoor air distribution under the same air supply temperature. Air supply angle Plays a vital role in pattern and distribution of indoor flow field,air supply velocity mainly effect the magnitude of indoor velocity and temperature. Synthetically comparied, the model’s best supply parameters are supply velocity 2.7m/s and supply angle75°,which mean value of indoor PMV is-0.09, PPD is 8.5%.


2020 ◽  
Vol 10 (6) ◽  
pp. 192-201
Author(s):  
Nataliiа Borodina ◽  
Serhii Cheberiachko ◽  
Yurii Cheberyachko ◽  
Оleg Deryugin ◽  
Dmytro Radchuk ◽  
...  

The aim of the work was to conduct experimental studies aimed at determining the protection factor of the filter respirator with forced air supply by volunteers in different modes of operation and to establish the dependence of the amount of air supplied by the fan from the air purification device to the filter’s resistance. Simulation studies to determine the protective effectiveness of the filter respirator on the testers were performed according to the procedure for determining the penetration coefficient of test aerosol – sodium chloride, as the ratio of the submask concentration of test aerosol to the ambient concentration formed in a special chamber that meets the requirements of DSTU EN 13274. Determination of the amount of air supplied by the air purification unit to the submask space and assessment of the value of positive pressure inside the mask was performed according to the procedure described in DSTU EN 12941: 2004. As a result of simulated laboratory tests to determine the protective effectiveness of filter respirators with forced air supply to the testers, it was found that the average result of the protection factor of the test samples ranged from 99.93 to 99.97, which meets the requirements of DSTU EN 12941: 2004. In addition, it was found that the amount of air treated by the fan of the air purification device for clean filters is 165 and 215 dm3/min for operating modes “Normal” and “Turbo”, while for the polluted filters it is reduced to 131 and 185 dm3/min, respectively. During the study, the compliance of the value of excess pressure in the submask space with the requirements of DSTU EN 12941: 2004, which should not exceed 2.5 mbar, was confirmed. It is also determined that the stability of the technical parameters of the air purification device is maintained in the specified range when charging the “Dinogy Li-Pol 11000mAh 14.8V 4S 25C” brand battery not less than 12 V to ensure the current value of not less than 1.6 A. The practical value of the results lies in determining the duration of protective action of the filter respirator, the choice of filter resistance to establish the scope and modes of operation in the developed personal respiratory protection equipment.


2013 ◽  
Vol 295-298 ◽  
pp. 532-535 ◽  
Author(s):  
Li Ping Xiang ◽  
Han Qing Wang

The RNG turbulence model and species transport model were employed to simulate the dispersion of CO2 contaminant in the road vehicle cabin. Three different air supply velocities were analysed, the results indicates that CO2 concentration at middle zone is higher, CO2 concentration at seat zone is higher and easy to gather at lower air velocity. When air velocity is smaller, the height concentration appear distinctly layering. The concentration layering gradually weaken when the air supply velocity increase 5m/s. Increasing the air supply velocity the air velocity is higher than the levels and energy cost.


Author(s):  
Essam E. Khalil ◽  
Ahmed A. Medhat

This paper focuses on both experimental investigation and numerical modeling of full-scale modelled air-conditioned multipurpose hall fully operable. Two methodologies were used, firstly full scale experimental setup was incorporated to map the hall making use of a well-developed fully automated wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second methodology was a numerical modeling using a well developed [CFD] 3DHVAC and FLUENT computer simulation programs. Physical and Numerical investigations enable the analyses of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split air-conditioning units. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room. One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modeling were reported. While the reported comparisons concluded that qualitative agreements were shown, some discrepancies were also observed in the thermal parameters for comfort conditions required by different occupants.


2011 ◽  
Vol 374-377 ◽  
pp. 475-479
Author(s):  
Da Hua Jiang ◽  
An Gui Li ◽  
Fa En Shi ◽  
Zhi Hua Wang

This article uses CFD to study the efficiency of ventilation and pollution discharge of double polluted sources in the lab, and investigate the effect of air exhaust outlet location and air supply velocity on the performance of side ventilation. Using non-dimensional analysis method to analyze change of temperature,velocity with room height, the change of temperature efficiency and pollutants emission efficiency with the air supply velocity. The results show that the efficiencies of temperature and pollutants emission are the highest when h/H=0.175 and v=0.4m/s.


2016 ◽  
Vol 15 (3) ◽  
pp. 78-81
Author(s):  
A.Yu. Grigoriev ◽  
◽  
K.A. Grigoriev ◽  
A.A. Raykov ◽  
K.A. Kargalsky ◽  
...  

Author(s):  
Zeqin Liu ◽  
Yongjie Yu ◽  
Yuan Chang ◽  
Jie Li ◽  
Yang Yang ◽  
...  
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document