scholarly journals A Control Strategy of the Air Flow Rate of Coal-Fired Utility Boilers Based on the Load Demand

ACS Omega ◽  
2020 ◽  
Vol 5 (48) ◽  
pp. 31199-31208
Author(s):  
Zhuwei Liu ◽  
Shanjian Liu ◽  
Ruchao Shi ◽  
Jie Wang ◽  
Man Xie ◽  
...  
Keyword(s):  
Flow Rate ◽  
Control Strategy ◽  
Air Flow ◽  
Air Flow Rate ◽  
Load Demand ◽  
Utility Boilers

A control strategy for reducing aeration costs during low loading periods

2004 ◽  
Vol 50 (7) ◽  
pp. 61-68 ◽  
Author(s):  
C. Sahlmann ◽  
J.A. Libra ◽  
A. Schuchardt ◽  
U. Wiesmann ◽  
R. Gnirss
Keyword(s):  
Flow Rate ◽  
Control Strategy ◽  
Oxygen Transfer ◽  
Air Flow ◽  
Air Flow Rate ◽  
Transfer Rates ◽  
Diffuser Flow ◽  
Aeration System ◽  
Oxygen Transfer Efficiency ◽  
Biomass Activity

The efficiency of the aeration system in a full-scale activated sludge basin with 3 separately controlled aeration zones was improved for the low loading period in summer. The air flow rate to each aeration zone is currently regulated to hold a preset dissolved oxygen concentration (DO). Four different DO setpoint combinations were tested, each one for a one week period, using dynamic off-gas testing to measure the standardised oxygen transfer efficiency (αSOTE). As the DO setpoints were lowered, the total air flow rate to the basin decreased initially. A low DO in the first zones slowed biomass activity and pushed the load towards the end of the aeration basin. The relationship between αSOTE and the specific diffuser flow rate qD is different for each zone. In Zone 1 there was a strong decrease in αSOTE as qD increased, while Zones 2 and 3 were fairly independent of qD, Zone 2 at a higher level than Zone 3. Aeration costs were reduced by 15% for the most efficient combination. To achieve even more savings, a control strategy adjusting oxygen transfer rates over the aeration basin to the necessary oxygen transfer rates is suggested. It is based on changing the DO setpoints to reach the lowest total air flow rate while meeting the effluent requirements.

Coupling the SHARON process with Anammox: Model-based scenario analysis with focus on operating costs

2005 ◽  
Vol 52 (4) ◽  
pp. 107-115 ◽  
Author(s):  
E.I.P. Volcke ◽  
S.W.H. Van Hulle ◽  
B.M.R. Donckels ◽  
M.C.M. van Loosdrecht ◽  
P.A. Vanrolleghem
Keyword(s):  
Flow Rate ◽  
Control Strategy ◽  
Air Flow ◽  
Operating Cost ◽  
Ph Control ◽  
Ammonia Concentration ◽  
Air Flow Rate ◽  
Cost Index ◽  
Sludge Digestion ◽  
Sharon Process

The combined SHARON-Anammox process for treating wastewater streams with high ammonia concentration is discussed. Partial nitritation in the SHARON reactor should be performed to such an extent that an Anammox-optimal nitrite:ammonium ratio is generated. The SHARON process is typically applied to sludge digestion rejection water in order to relieve the ammonium load recycled to the main plant.A simulation study for realistic influent conditions on a SHARON reactor with a fixed volume and operated with constant air flow rate reveals that the actual nitrite:ammonium ratio might deviate significantly from the ideal ratio and might endanger operation of the subsequent Anammox reactor. It is further examined how the nitrite:ammonium ratio might be optimized. A cascade pH control strategy and a cascade O2 control strategy are tested. Simulation results are presented and the performance of the different strategies is assessed and quantified in an economic way by means of an operating cost index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2-set-point that is tracked by adjusting the air flow rate.

Online Optimal Ventilation Control of Building Air-conditioning Systems

2010 ◽  
Vol 20 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Shengwei Wang ◽  
Zhongwei Sun ◽  
Yongjun Sun ◽  
Na Zhu
Keyword(s):  
Energy Consumption ◽  
Flow Rate ◽  
Control Strategy ◽  
Air Conditioning ◽  
Air Flow ◽  
Air Flow Rate ◽  
Ventilation Control ◽  
Occupancy Detection ◽  
Critical Zones ◽  
Air Conditioning Systems

This paper presents a ventilation control strategy for multi-zone variable air volume (VAV) air-conditioning systems; integrating the sequential split-range control strategy for air-handing units with an aim to optimise the fresh air flow rate by compromising the indoor air quality and energy consumption. In this strategy, a CO2 -based adaptive demand-controlled ventilation scheme would employ a dynamic multi-zone ventilation equation for multi-zone air-conditioning systems, in which a CO2-based dynamic occupancy detection scheme would be used for online occupancy detection. The strategy would identify the critical zones online, and fully consider the outdoor air demand of critical zones, while, a model-based fresh air flow rate optimal control scheme is employed for VAV air-conditioning systems with the primary air handling units. An adaptive optimisation algorithm would be used for optimising the fresh air flow rate to minimise the energy consumption. The energy saving potentials in the Hong Kong climate condition by optimising fresh air ventilation and the practical implementation of the control strategy are also discussed in this paper.

scholarly journals Analysis of Defogging Performance, Thermal Comfort, and Energy Saving for HVAC System Optimization in Passenger Vehicles

2019 ◽  
Vol 111 ◽  
pp. 01033 ◽  
Author(s):  
Taro Ono ◽  
Hideaki Nagano ◽  
Suguru Shiratori ◽  
Kenjiro Shimano ◽  
Shinsuke Kato
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Flow Rate ◽  
Control Strategy ◽  
Energy Savings ◽  
Air Flow ◽  
Energy Condition ◽  
System Optimization ◽  
Hvac System ◽  
Air Flow Rate

The heating, ventilation, and air-conditioning (HVAC) system in a vehicle is used for both defogging the windshield and ensuring the thermal comfort of passengers. A challenge is that energy savings in the HVAC system lead to decreased system performance. The three objective functions, i.e. defogging performance, thermal comfort, and energy savings, these must be considered in parallel to find the optimized control strategy. In the present study, a transient numerical simulation of the in-vehicle environment is performed and the dependency of performance on the air flow rate and supplied air temperature is analyzed. The criteria of defogging performance and thermal comfort are determined as the constrained conditions. The results show a trade-off relationship between the air flow rate and air temperature in defogging performance and thermal comfort; however, their sensitivities depend on the conditions and the time elapsed. As for transient defogging performance, the air flow rate has greater impact than airflow temperature. The air flow rate and the air temperature are comparable in their effects on equivalent temperature, which is employed as the index of the thermal environment. The blowing condition range that fulfills the criteria makes a transition to a low-energy condition with time elapsed. A control strategy for the air flow rate and temperature is derived considering the transient and steady-state conditions.

Model-based Optimal Control of Outdoor Air Flow Rate of an Air-Conditioning System with Primary Air-Handling Unit

2011 ◽  
Vol 20 (6) ◽  
pp. 626-637 ◽  
Author(s):  
Zhongwei Sun ◽  
Shengwei Wang ◽  
Na Zhu
Keyword(s):  
Optimal Control ◽  
Energy Consumption ◽  
Energy Saving ◽  
Flow Rate ◽  
Control Strategy ◽  
Air Conditioning ◽  
Air Flow ◽  
Outdoor Air ◽  
Air Flow Rate ◽  
Optimal Control Strategy

This paper presents a model-based outdoor air flow rate optimal control strategy for multi-zone variable air volume air-conditioning systems with the primary air-handling units. An adaptive optimisation algorithm is adopted for optimising the set point of the outdoor air flow rate to minimise the energy cost, which could compromise the energy consumption of the primary fan and the cooling energy saving by the cold outdoor air. The primary fan energy consumption can be predicted using a simplified incremental fan model and the main parameters of this model are identified online. The cooling energy saving by the outdoor air is estimated online using the enthalpies of the air streams. The lower limit of the outdoor air flow rate is determined by a CO2-based adaptive demand-controlled ventilation strategy using the dynamic multi-space equation to maintain the satisfied indoor air quality (IAQ). Tests were conducted to evaluate the performance of the control strategy applied to a practical building system in simulation environment. The results show that the proposed optimal control strategy can reduce energy consumption significantly, while maintaining a satisfactory IAQ.

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.

Sign in / Sign up

Export Citation Format

Share Document