Effect of Top Ventilation on Cooling Characteristics of Passenger Cabin

2021 ◽  
Author(s):  
Suifan Chen ◽  
Zhiwei Meng ◽  
Qipeng Li ◽  
Feng Huang
Keyword(s):  
Cooling Rate ◽  
Minimum Temperature ◽  
Natural Ventilation ◽  
Great Influence ◽  
Two Dimensions ◽  
Cooling Effect ◽  
Forced Ventilation ◽  
Inlet Velocity ◽  
Inlet Angle ◽  
Passenger Cabin

Abstract In order to solve the hot soak effect of car during summer parking, the CFD numerical method was used to simulate the cooling law of passenger cabin under different inlet area, inlet velocity and inlet angle at the top vent. From the two dimensions of cooling rate and cooling effect, the influence of top natural ventilation and top forced ventilation on the cooling characteristics of passenger cabin were studied. The results show that under the condition of top natural ventilation, the cabin can reach thermal balance at about 10 min under different vent area conditions, and the cooling rate is the largest when the vent is fully opened, and the minimum temperature can reach about 45 °C within 4 min, which is 10 °C higher than the ambient temperature. Under forced ventilation, the inlet velocity has a great influence on the cooling rate and cooling effect of cabin. When the inlet angle is 90° and the inlet velocity is 5 m / s, the cooling rate is the largest and the cooling effect is the best.

scholarly journals Optimizing air velocity for the underfloor forced ventilation to protect a refrigerated warehouse from frost heaving

2018 ◽  
Vol 38 (3) ◽  
pp. 321-327
Author(s):  
Jingfu Jia ◽  
Manjin Hao ◽  
Jianhua Zhao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Frost Heave ◽  
Forced Ventilation ◽  
Air Velocity ◽  
Set Up

Forced or natural ventilation is the most common measure of frost heave protection for refrigerated warehouse floor. To optimize air velocity for the underfloor forced ventilation system of refrigerated warehouse, a steady state three-dimensional mathematical model of heat transfer is set up in this paper. The temperature fields of this system are simulated and calculated by CFD software PHOENICS under different air velocity, 1.5m/s, 2.5m/s or 3.5m/s. The results show that the optimized air velocity is 1.5m/s when the tube spacing is 1.5m.

Modified Fuzzy Rule-Based Classification System for Early Warning of Student Learning

2019 ◽  
Vol 48 (3) ◽  
pp. 385-406 ◽  
Author(s):  
Qun Zhao ◽  
Jin-Long Wang ◽  
Tsang-Long Pao ◽  
Li-Yu Wang
Keyword(s):  
Student Learning ◽  
Classification System ◽  
Prediction Accuracy ◽  
Confusion Matrix ◽  
Great Influence ◽  
Fuzzy Rule ◽  
Two Dimensions ◽  
Learning Performance ◽  
Rule Based

This study uses the log data from Moodle learning management system for predicting student learning performance in the first third of a semester. Since the quality of the data has great influence on the accuracy of machine learning, five major data transmission methods are used to enhance data quality of log file in the data preprocessing stage. Furthermore, the modified FRBCS-CHI (fuzzy rule-based classification system using Chi's technique) algorithm, based on the weighted consequence, is proposed to improve the prediction accuracy of classification. Thereafter, the confusion matrix with two dimensions is employed to illustrate the prediction results, such as false positives, false negatives, true positives, and true negatives, which are further used to produce the parameters of prediction performance, including the precision rate, the recall rate, and the F-measure. From the results of experiment, the proposed modified FRBCS-CHI method will have higher prediction accuracy than the original FRBCS-CHI method.

scholarly journals Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

2018 ◽  
Vol 32 ◽  
pp. 01020 ◽  
Author(s):  
Sebastian Valeriu Hudişteanu ◽  
Cătălin George Popovici ◽  
Nelu-Cristian Cherecheş
Keyword(s):  
Wind Tunnel ◽  
Natural Ventilation ◽  
Cooling Effect ◽  
Experimental Program ◽  
Small Scale ◽  
Photovoltaic Panels ◽  
Building Integrated Photovoltaics ◽  
Building Model ◽  
Double Skin ◽  
Wind Influence

The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

Evaluation of a hybrid personal cooling system using a manikin operated in constant temperature mode and thermoregulatory model control mode in warm conditions

2016 ◽  
Vol 87 (1) ◽  
pp. 46-56 ◽  
Author(s):  
Dandan Lai ◽  
Fanru Wei ◽  
Yehu Lu ◽  
Faming Wang
Keyword(s):  
Cooling Rate ◽  
Constant Temperature ◽  
Cooling System ◽  
Cooling Effect ◽  
Control Mode ◽  
Air Velocity ◽  
Work Condition ◽  
Model Control ◽  
Thermoregulatory Model ◽  
Personal Cooling

In this study, the cooling effect of a portable hybrid personal cooling system (PCS) was investigated on a sweating manikin operated in the constant temperature (CT) mode and the thermoregulatory model control (TMC) mode. Both dry (i.e., no sweating) and wet manikin tests (i.e., sweating) were performed in the CT mode in a warm condition (30℃, 47% relative humidity (RH), air velocity va = 0.4 m/s). For the TMC mode, two case studies were simulated: light work condition (30℃, 47% RH, air velocity va = 0.15 m/s, duration: 60 min, metabolic rate: 1.5 METs) and construction work condition (30℃, 47% RH, va = 1.0 m/s, 40 min exercise [5.5 METs] and 20 min rest [1.2 METs]). Four test scenarios were selected: fans off with no phase change materials (PCMs) (i.e., Fan-off, the Control), fans on with no PCMs (i.e., Fan-on), fans off with fully solidified PCMs (i.e., PCM+Fan-off) and fans on with fully solidified PCMs (i.e., PCM+Fan-on). Under the dry condition, the cooling rate in PCM+Fan-off during the initial stage (e.g., 55 and 50 W for the first 15 min and 20 min, respectively) was higher than that in Fan-on (i.e., 45 ± 1 W); under the wet condition, the cooling rate in PCM+Fan-off (e.g., 45 W for 10 min) was much lower than that in Fan-on (i.e., 282 ± 1 W). The hybrid PCS (i.e., PCM+Fan-on) provided a continuous strong cooling effect. Simulation results indicated that ventilation fans or PCMs alone could provide sufficient cooling while doing light work. For the intensive work condition, the PCS in all three scenarios (i.e., PCM+Fan-off, Fan-on and PCM+Fan-on) exhibited beneficial cooling, and the hybrid PCS showed an optimized performance in alleviating heat strain during both exercise and recovery periods. It was thus concluded that the PCS could effectively remove body heat in warm conditions for moderate intensive activities.

scholarly journals A Forced Ventilation Micropropagation System for Photoautotrophic Production of Sweetpotato Plug Plantlets in a Scaled-up Culture Vessel: I. Growth and Uniformity

2001 ◽  
Vol 11 (1) ◽  
pp. 90-94 ◽  
Author(s):  
Jeongwook Heo ◽  
Sandra B. Wilson ◽  
Toyoki Kozai
Keyword(s):  
Ipomoea Batatas ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Photon Flux ◽  
Air Distribution ◽  
Culture Vessel ◽  
Forced Ventilation ◽  
Photoautotrophic Growth ◽  
Plantlet Growth ◽  
Ventilation Rates

An improved forced ventilation micropropagation system was designed with air distribution pipes for uniform spatial distributions of carbon dioxide (CO2) concentration and other environmental factors to enhance photoautotrophic growth and uniformity of plug plantlets. Single-node stem cuttings of sweetpotato [Ipomoea batatas (L.) Lam. `Beniazuma'] were photoautotrophically (no sugar in the culture medium) cultured on a mixture of vermiculite and cellulose fibers with half-strength Murashige and Skoog basal salts in a scaled-up culture vessel with an inside volume of 11 L (2.9 gal). CO2 concentration of the supplied air and photosynthetic photon flux on the culture shelf were maintained at 1500 μmol·mol-1 and 150 μmol·m-2·s-1, respectively. Plantlets grown in forced ventilation systems were compared to plantlets grown in standard (natural ventilation rate) tissue culture vessels. The forced (F) ventilation treatments were designated high (FH), medium (FM), and low (FL), and corresponded to ventilation rates of 23 mL·s-1 (1.40 inch3/s), 17 mL·s-1 (1.04 inch3/s), and 10 mL·s-1 (0.61 inch3/s), respectively, on day 12. The natural (N) ventilation treatment was extremely low (NE) at 0.4 mL·s-1 (0.02 inch3/s), relative to the forced ventilation treatments. On day 12, the photoautotrophic growth of plantlets was nearly two times greater with the forced ventilation system than with the natural ventilation system. Plantlet growth did not significantly differ among the forced ventilation rates tested. The uniformity of the plantlet growth in the scaled-up culture vessel was enhanced by use of air distribution pipes that decreased the difference in CO2 concentration between the air inlets and the air outlet.

scholarly journals Impact of Temperature on Cooling Structural Variation of Forging Dies

2014 ◽  
Vol 11 (2) ◽  
pp. 21-25
Author(s):  
Marianna Piesova ◽  
Andrej Czan
Keyword(s):  
Carbon Steel ◽  
Cooling Rate ◽  
Automotive Industry ◽  
Structural Variation ◽  
Cooling Effect ◽  
Effect Of Temperature ◽  
Theoretical Knowledge ◽  
Final Structure ◽  
Die Forging

Abstract The article is focused on the issue of die forging in the automotive industry. The cooling effect of temperature on the structure of forged die are under review. In the article, there is elaborated the analysis of theoretical knowledge in the field, focusing on die forging and experimentally proven effect of the cooling rate on the final structure of forged dies made of hypoeutectic carbon steel C56E2.

scholarly journals Electron-phonon decoupling in two dimensions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
George McArdle ◽  
Igor V. Lerner
Keyword(s):  
Electron Temperature ◽  
Cooling Rate ◽  
Two Dimensions ◽  
Electronic Systems ◽  
Two Dimensional ◽  
Many Body ◽  
Current Voltage ◽  
Current Voltage Characteristics

AbstractIn order to observe many-body localisation in electronic systems, decoupling from the lattice phonons is required, which is possible only in out-of-equilibrium systems. We show that such an electron-phonon decoupling may happen in suspended films and it manifests itself via a bistability in the electron temperature. By studying the electron-phonon cooling rate in disordered, suspended films with two-dimensional phonons, we derive the conditions needed for such a bistability, which can be observed experimentally through hysteretic jumps of several orders of magnitude in the nonlinear current-voltage characteristics. We demonstrate that such a regime is achievable in systems with an Arrhenius form of the equilibrium conductivity, while practically unreachable in materials with Mott or Efros–Shklovskii hopping.

Thermal-Mechanical Simulation of the Controlled Rolling and Cooling Process by Orthogonal Design for Pipeline Steel

2012 ◽  
Vol 557-559 ◽  
pp. 2355-2360 ◽  
Author(s):  
Min Jiang ◽  
Li Na Chen ◽  
Wei Pang ◽  
Chong He Li ◽  
Xiong Gang Lu
Keyword(s):  
Cooling Rate ◽  
Heating Temperature ◽  
Pipeline Steel ◽  
Great Influence ◽  
Control Process ◽  
Controlled Rolling ◽  
Rolling Temperature ◽  
Cooling Temperature ◽  
Finish Rolling Temperature ◽  
Finish Rolling

A novel pipeline steel was prepared by the vacuum inducting technology, using Gleeble-3500 hot simulator, its parameters of thermo-mechanical control process (TMCP), such as heating temperature, finish rolling temperature, finish cooling temperature and cooling rate, have been studied by the orthogonal experiment with four factors and three levels. Through the orthogonal theoretical analysis, it is found that the sequence of the effect of parameters on the mechanical property is: Cooling rate > Heating temperature > Finish cooling temperature > Finish rolling temperature, the cooling rate is the most important factor affecting the inspection target and possesses a great influence on the hardness of the pipeline steel.

scholarly journals Experimental Study on Catalytic Combustion of Methane in a Microcombustor with Metal Foam Monolithic Catalyst

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 536 ◽  
Author(s):  
Yanxia Li ◽  
Chaoming Luo ◽  
Zhongliang Liu ◽  
Feng Lin
Keyword(s):  
Catalytic Combustion ◽  
Equivalence Ratio ◽  
Metal Foam ◽  
Great Influence ◽  
Porous Matrix ◽  
Stoichiometric Ratio ◽  
Inlet Velocity ◽  
Monolithic Catalyst ◽  
Conversion Of Methane ◽  
Catalytic Combustion Of Methane

Utilizing catalysts in microcombustors is probably an excellent practical solution to stabilize fuel combustion because of the relatively fast reaction speed. In the present work, the monolithic catalyst Pd/A2O3/Fe-Ni with metal foam as matrix was used inside a 5 mm in diameter microcombustor. Then the effects of inlet velocity and equivalent ratio on catalytic combustion characteristics of methane were studied experimentally. The results showed that the methane and air mixture with the stoichiometric ratio Φ = 1.0 could be ignited at v = 0.2–0.6 m/s. The velocity of premixed mixture had a great influence on the catalytic combustion of methane. The larger the inlet velocity, the higher the temperature and the brighter the flame were. The experiment results also showed that the equivalence ratio had a large essential impact on the catalytic combustion, especially for the lean mixture of methane and air. It seemed the addition of the porous matrix with catalysts could significantly extend the limits of stable combustion. In the detection of exhaust gas, CO selectivity increased and CO2 selectivity decreased with the equivalence ratio. When Φ was between 0.94 and 1.0 m/s, a little amount of hydrogen was produced due to the lack of oxygen. The measured conversion of methane to CO and CO2 was very high, usually greater than 99%, which indicated the excellent performance of the catalyst.

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