Numerical Investigation on the Strategies for Reducing the Cell Temperature Gradient of an Indirect Internal Reforming Tubular SOFC

2004 ◽  
Author(s):  
Takafumi Nishino ◽  
Hiroshi Iwai ◽  
Kenjiro Suzuki
Keyword(s):  
Temperature Gradient ◽  
Distribution Pattern ◽  
Flow Rate ◽  
Air Flow ◽  
Maximum Temperature ◽  
Air Flow Rate ◽  
Internal Reforming ◽  
Average Temperature ◽  
Reforming Catalyst ◽  
Catalyst Distribution

Strategies to reduce the temperature gradient of the cell have been numerically examined by using a comprehensive analytical model of an indirect internal reforming tubular SOFC, the first generation of which was presented at the last conference in 2003 (1st ICFCSET). In particular, how the air flow rate, gas inlet temperature and density distribution of reforming catalyst affect the thermal field in the cell has been examined. Based on the calculated results, it has been confirmed that larger air flow rate reduces the maximum temperature and accordingly the temperature gradient of the cell, while lower inlet temperatures of gases reduce only the average temperature of the cell. For the reforming catalyst distribution, it has been determined that the temperature gradient of the cell can be fairly reduced by adjusting the amount and allocation of the catalyst. In addition, it has been revealed that the distribution pattern of the catalyst has little effect on the average temperature, so that the power generation performance of the cell is not affected by the adjustment of the catalyst distribution pattern substantially.

Experimental Study of a Solar Air Heater With a New Arrangement of Transverse Longitudinal Baffles

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Afaq Jasim Mahmood
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Air Flow ◽  
Maximum Temperature ◽  
Maximum Efficiency ◽  
Solar Air Heater ◽  
Air Flow Rate ◽  
Double Pass ◽  
Air Heater

This study presents a new design for improving the convection heat transfer coefficients of double-pass solar air heater. Three cases were described by using a different number of transverse baffles (three, five, and seven) in the lower channel of the collectors; steel mesh sheets were also used to enlarge the heat transfer area. All collectors have a space of 25 mm between its glass covers and a 50 mm depth of air channel. Furthermore, this work examined the effect of air flow rate and baffles number on device's thermal efficiency and outlet temperature. The experimental results indicate raises in the thermal efficiency as the air flow rate goes from 0.011 kg/s to 0.038 kg/s. A maximum efficiency of 68% was obtained from the case of seven baffles at the air flow rate of 0.038 kg/s. Moreover, the difference between collector's inlet and outlet temperatures, ΔT, indicated an inverse relationship with air flow rate. Thus, the results show ΔT increases as the air flow rate reduced. The maximum temperature difference recorded was 54 °C, which achieved using seven baffled solar air heater at 0.011 kg/s air flow rate in the middle of the day. It has also been found that thermal efficiency of double-pass solar air heater is greater than single-pass solar air heater, using same air flow rate and number of baffles. Finally, the pressure drop associated with increasing the number of baffles and air flow rate was deliberated.

Field Investigation of the Small House with the Ventilated Roof Tiles

2014 ◽  
Vol 931-932 ◽  
pp. 1233-1237 ◽  
Author(s):  
Onvalee Amornleetrakul ◽  
Withaya Puangsombut ◽  
Jongjit Hirunlabh
Keyword(s):  
Flow Rate ◽  
Natural Ventilation ◽  
Air Flow ◽  
Field Investigation ◽  
Air Flow Rate ◽  
Heat Gain ◽  
Average Temperature ◽  
Roof Tile ◽  
Small House ◽  
North And South

This paper investigates the thermal performances and heat gain reduction of a new roof tile design referred as Ventilated Roof Tile (VRT) compared with an ordinary corrugated concrete roof tiles (CCR). The outside dimension of each small house was 1.70 x 1.70 x 2.85 m3 (W x L x H) and inside dimension was 1.50 x 1.50 x 2.20 m3. The volume of each room was 4.95 m3. The gable roofs slope were 25o and surface area of VRT was 2.58 m2 per each side facing north and south. The VRT tile composed of upper cement plate 40 × 40 cm2 and lower cement plate 30 x 40 cm2. Between plates was 3 cm thickness air gap. The experimental results showed that the top surface of VRT was lower than CCR about 2.10°C for average temperature (from 6:00 18:00) and made VRT room temperature lower than CCR about 1.41°C for average temperature. VRT could reduce heat gain with air flow rate through the roof tiles gaps varied following the solar radiation, during time 8:00-17:00 the natural ventilation varied from 0.003-0.014 m3/s (10.6-50.0 m3/hr.). Observed that, during 17:00-18:00, the air flow rate is about 0.003 m3/s (10.8 m3/hr.) due to heat accumulated in the attic space and roof tiles.

scholarly journals Empirical Thermal Performance Investigation of a Compact Lithium Ion Battery Module under Forced Convection Cooling

2020 ◽  
Vol 10 (11) ◽  
pp. 3732
Author(s):  
Akinlabi A. A. Hakeem ◽  
Davut Solyali
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Air Flow ◽  
Lithium Ion ◽  
Operating Conditions ◽  
Battery Pack ◽  
Performance Criteria ◽  
Maximum Temperature ◽  
Air Flow Rate ◽  
Worst Case

Lithium ion batteries (LiBs) are considered one of the most suitable power options for electric vehicle (EV) drivetrains, known for having low self-discharging properties which hence provide a long life-cycle operation. To obtain maximum power output from LiBs, it is necessary to critically monitor operating conditions which affect their performance and life span. This paper investigates the thermal performance of a battery thermal management system (BTMS) for a battery pack housing 100 NCR18650 lithium ion cells. Maximum cell temperature (Tmax) and maximum temperature difference (ΔTmax) between cells were the performance criteria for the battery pack. The battery pack is investigated for three levels of air flow rate combined with two current rate using a full factorial Design of Experiment (DoE) method. A worst case scenario of cell Tmax averaged at 36.1 °C was recorded during a 0.75 C charge experiment and 37.5 °C during a 0.75 C discharge under a 1.4 m/s flow rate. While a 54.28% reduction in ΔTmax between the cells was achieved by increasing the air flow rate in the 0.75 C charge experiment from 1.4 m/s to 3.4 m/s. Conclusively, increasing BTMS performance with increasing air flow rate was a common trend observed in the experimental data after analyzing various experiment results.

scholarly journals CFD-modeling of the temperature field of the radiator casing of the transmitting module of the active phased antenna arrays with air cooling

2019 ◽  
pp. 27-33 ◽  
Author(s):  
Yu. E. Nikolaenko ◽  
A. V. Baranyuk ◽  
S. A. Reva ◽  
V. A. Rohachov
Keyword(s):  
Output Power ◽  
Flow Rate ◽  
Antenna Arrays ◽  
Air Flow ◽  
Cfd Modeling ◽  
Maximum Temperature ◽  
Technical Solution ◽  
Air Cooling ◽  
Air Flow Rate ◽  
Phased Antenna Arrays

Modern radar stations are widely used to obtain images of earth surface with high spatial resolution, to identify moving objects in the air, on sea and on the ground, and allow determining the coordinates and movement parameters accurately. Active phased antenna arrays with large number of transmitting modules are widely used as antenna systems in radar stations. The heat generated by the active microwave elements of the output amplifiers of the transmitting module, leads to an increase in their temperature and to decrease in reliability. In this regard, the task of increasing the cooling efficiency of active microwave elements of the output power amplifiers is important. The aim of this study is to assess the possibilities of air cooling of the active elements of the output power amplifier in relation to the transition from gallium arsenide to gallium nitride element base with increased heat generation. This paper presents the results of computer simulation for the temperature filed of the mounting base of the radiator casing, on which 8 heat-generating elements with a local heat release of 28 W each are installed. Cooling fins are made on the opposite base of the radiator casing. The finned surface of the radiator casing is blown by an air stream with an inlet air temperature of 40°C. The simulation was carried out for three values of the air flow rate in the interfin channels: 1, 6 and 10 m/s. It is shown that the maximum temperature of the mounting base of the radiator casing is 90.1°C and is observed at an air flow rate of 1 m/s inside the interfin channels. Increasing the air speed up to 10 m/s makes it possible to reduce the temperature at the installation site of the microwave elements down to 72.1°C. A new technical solution was proposed to further improve the efficiency of the applied cooling system and to reduce the temperature of the mounting surface of the radiator casing.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Modeling and optimization of radish root extract drying as peroxidase source using spouted bed dryer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shahrbanoo Hamedi ◽  
M. Mehdi Afsahi ◽  
Ali Riahi-Madvar ◽  
Ali Mohebbi
Keyword(s):  
Kinetic Parameters ◽  
Flow Rate ◽  
Air Flow ◽  
Cost Effective ◽  
Industrial Applications ◽  
Interactive Effects ◽  
Root Extract ◽  
Air Flow Rate ◽  
Spouted Bed ◽  
Radish Root

AbstractThe main advantages of the dried enzymes are the lower cost of storage and longer time of preservation for industrial applications. In this study, the spouted bed dryer was utilized for drying the garden radish (Raphanus sativus L.) root extract as a cost-effective source of the peroxidase enzyme. The response surface methodology (RSM) was used to evaluate the individual and interactive effects of main parameters (the inlet air temperature (T) and the ratio of air flow rate to the minimum spouting air flow rate (Q)) on the residual enzyme activity (REA). The maximum REA of 38.7% was obtained at T = 50 °C and Q = 1.4. To investigate the drying effect on the catalytic activity, the optimum reaction conditions (pH and temperature), as well as kinetic parameters, were investigated for the fresh and dried enzyme extracts (FEE and DEE). The obtained results showed that the optimum pH of DEE was decreased by 12.3% compared to FEE, while the optimum temperature of DEE compared to FEE increased by a factor of 85.7%. Moreover, kinetic parameters, thermal-stability, and shelf life of the enzyme were considerably improved after drying by the spouted bed. Overall, the results confirmed that a spouted bed reactor can be used as a promising method for drying heat-sensitive materials such as peroxidase enzyme.

Method to Determine an Optimal Air-Flow Rate in Solar Collectors

1979 ◽  
Vol 3 (6) ◽  
pp. 357-362
Author(s):  
H. C. Hewitt ◽  
E. I. Griggs
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Solar Collectors ◽  
Air Flow Rate
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