scholarly journals EFFECT OF AMBIENT TEMPERATURE AND AIR FLOW RATE ON THE TEMPERATURE INSIDE THE COMPOST PILE

2016 ◽  
Vol 33 (3) ◽  
pp. 1017-1032
Author(s):  
El-Sayed G. Khater
Keyword(s):  
Ambient Temperature ◽  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate

Analysis of Heat Transfer From a Photobioreactor

2016 ◽  
Author(s):  
Gary A. Anderson ◽  
Sarmila Katuwal ◽  
Anil Kommareddy ◽  
Stephen Gent
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Heat Loss ◽  
Growth Medium ◽  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate ◽  
Medium Temperature ◽  
Reactor Volume ◽  
Light Passing

A photobioreactor (PBR) was operated for sixteen days producing S. Leopoliensis. The PBR was lit by two LED panels, one on each of the long sides of the PBR. The PBR dimensions were nominally 51mm by 273mm with a height of 319mm (273mm liquid depth). Each LED panel was powered at 14.1W (11.2V and 1.26A). Measurements of ambient temperature, ambient relative humidity, water loss from the PBR, relative humidity of the exhaust gas from the PBR, air flow rate through the PBR, air pressure in the plenum, growth medium temperature, and LED panel temperature were made approximately daily. Measurements show that the growth medium (water) temperature was relatively insensitive to the ambient temperature which varied from 22.7C to 33.6C. The medium temperature ranged from 23.9C (beginning of the test) to 40.6C. The medium temperature mirrored the LED panel temperature staying 2–4C below the LED panel temperature after the first day. The elevated LED panel temperature was likely due to the inefficiency of the LED lights and the fact that much of the light passing through the reactor volume was incident on the LED panel on the opposite side of the reactor. The panels are black in color and absorbed a significant portion of the light passing through the reactor volume. The air flow rate through the PBR ranged from 1.33×10−5m3/s to 1.67×10−5m3/s. The parallel between panel temperature and PBR medium temperature indicate that the amount of air moving through the PBR was insufficient to affect the medium temperature significantly. The heat loss from the PBR to the ambient environment was also small likely due to the small area available to heat loss to the environment when the PBR walls with the LED panels are excluded. The LED panels covered nominally 88% of the PBR reactor volume area. The measured data and measurements of light intensity passing through the two short walls of the panel will be used to estimate heat loss parameters of the PBR. The exhaust air from the PBR varied from 42.6% to 99.1% with the higher measurements occurring days 6–11. Estimates of the energy stored in the algal biomass are also evaluated in the analysis.

scholarly journals Heating Performance Characteristics of an Electric Vehicle Heat Pump Air Conditioning System Based on Exergy Analysis

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2868 ◽  
Author(s):  
Xingwang Tang ◽  
Qin Guo ◽  
Ming Li ◽  
Mingzhe Jiang
Keyword(s):  
Ambient Temperature ◽  
Electric Vehicle ◽  
Flow Rate ◽  
Air Conditioning ◽  
Air Flow ◽  
Exergy Destruction ◽  
Air Flow Rate ◽  
Air Conditioning System ◽  
Heating Capacity ◽  
Expansion Valve

In this paper, a heat pump air conditioning system (HPACS) with refrigerant R134a based on the functional requirements of battery electric vehicle is designed and tested. Experiments were conducted to evaluate the effects of different ambient temperature, air flow rate of internal condenser, expansion valve (EXV) opening and compressor speed. The results demonstrate that air flow rate of internal condenser, EXV opening and compressor speed have important impact on heating capacity, compressor power consumption and coefficient of performance (COP) under several ambient temperatures. To verify the HPACS can also provide the heating capacity required by the battery electric vehicle cabin in cold climate, the system was also tested under a −5 °C ambient temperature, it was found that the heating capacity is 3.6 kW and the COP is 3.2, demonstrating that the system has high energy efficiency. In addition, heating process analysis of the HPACS under lower temperature is studied by exergy principle. The results indicate that compressor is the highest exergy destruction in all components, accounting for 55%. The percentage of exergy destruction in other components is about 28%, 12% and 5% for the expansive valve, condenser, and evaporator. Furthermore, air flow rate of internal condenser, ambient temperature and expansion valve opening have important impact on exergy destruction and exergy efficiency of the HPACS.

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

Model-Based Analysis of Transient Behavior of Large Scale CFB Boilers

2003 ◽  
Author(s):  
Ari Kettunen ◽  
Timo Hyppa¨nen ◽  
Ari-Pekka Kirkinen ◽  
Esa Maikkola
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Air Flow ◽  
Model Parameters ◽  
Air Flow Rate ◽  
Process Data ◽  
Cfb Boiler ◽  
Flow Rates ◽  
Load Change ◽  
Secondary Air

The main objective of this study was to investigate the load change capability and effect of the individual control variables, such as fuel, primary air and secondary air flow rates, on the dynamics of large-scale CFB boilers. The dynamics of the CFB process were examined by dynamic process tests and by simulation studies. A multi-faceted set of transient process tests were performed at a commercial 235 MWe CFB unit. Fuel reactivity and interaction between gas flow rates, solid concentration profiles and heat transfer were studied by step changes of the following controllable variables: fuel feed rate, primary air flow rate, secondary air flow rate and primary to secondary air flow ratio. Load change performance was tested using two different types of tests: open and closed loop load changes. A tailored dynamic simulator for the CFB boiler was built and fine-tuned by determining the model parameters and by validating the models of each process component against measured process data of the transient test program. The know-how about the boiler dynamics obtained from the model analysis and the developed CFB simulator were utilized in designing the control systems of three new 262 MWe CFB units, which are now under construction. Further, the simulator was applied for the control system development and transient analysis of the supercritical OTU CFB boiler.

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