scholarly journals Distributed or centralized HVAC: a practical investigation into household heating systems.

2021 ◽  
Author(s):  
Morgan James Cunningham
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Energy Input ◽  
Scale Model ◽  
Mechanical Equipment ◽  
Empirical Testing ◽  
Time Constants ◽  
Heating Systems ◽  
State Models ◽  
Practical Investigation

Three main questions pertaining to household heating were and answered through rigorous empirical testing; • Is it more efficient to keep a house at constant temperature throughout the day, or should the temperature be allowed to dip when unoccupied? • Is it possible to build a scale-model house with proper thermal ballasting to simulate and verify the first question? • Can the empirical results be used to verify whether or not steady state models of heat transfer (for simplicity’s sake) can provide reasonably accurate results? It was observed that keeping a house at constant temperature is inefficient and causes over cycling of electro-mechanical equipment. Continuing on, it is possible to build a scale-model house to mimic reality, however, care is needed in the design process if you wish to have similar volumetric time constants. And finally, steady-state models can be implemented to predict energy input, but with a certain degree of error.

scholarly journals Distributed or centralized HVAC: a practical investigation into household heating systems.

2021 ◽  
Author(s):  
Morgan James Cunningham
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Energy Input ◽  
Scale Model ◽  
Mechanical Equipment ◽  
Empirical Testing ◽  
Time Constants ◽  
Heating Systems ◽  
State Models ◽  
Practical Investigation

Three main questions pertaining to household heating were and answered through rigorous empirical testing; • Is it more efficient to keep a house at constant temperature throughout the day, or should the temperature be allowed to dip when unoccupied? • Is it possible to build a scale-model house with proper thermal ballasting to simulate and verify the first question? • Can the empirical results be used to verify whether or not steady state models of heat transfer (for simplicity’s sake) can provide reasonably accurate results? It was observed that keeping a house at constant temperature is inefficient and causes over cycling of electro-mechanical equipment. Continuing on, it is possible to build a scale-model house to mimic reality, however, care is needed in the design process if you wish to have similar volumetric time constants. And finally, steady-state models can be implemented to predict energy input, but with a certain degree of error.

Control of the adiabatic flow reactor by feeding the catalyst solution

1979 ◽  
Vol 44 (8) ◽  
pp. 2352-2365
Author(s):  
Josef Horák ◽  
Zina Sojková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Reaction Temperature ◽  
Control Algorithm ◽  
Flow Reactor ◽  
Operating Temperature ◽  
Temperature Deviation ◽  
Adiabatic Flow ◽  
Dosing Frequency ◽  
Laboratory Reactor

Control algorithm of the operating temperature is described in the reactor, which is operated at constant temperature and composition of the inlet mixture. The temperature is controlled by dosing a constant volume of the catalyst solution. The dosing frequency is determined according to the reaction temperature (deviation of the temperature from the desired value and the sign of the derivative of temperature). The control algorithm has been verified experimentally for the laboratory reactor in unstable steady state.

Experimental Investigation of Power Umbilical Damping

2017 ◽  
Author(s):  
Torfinn Ottesen
Keyword(s):  
Steady State ◽  
Energy Input ◽  
State Energy ◽  
Seawater Temperature ◽  
Structural Damping ◽  
Stick Slip ◽  
Slip Regime ◽  
Free Decay ◽  
Vortex Induced Vibrations ◽  
Slip Transition

Ocean currents may cause vortex induced vibrations (VIV) of deep-water umbilicals and cables. Since the VIV response may give significant contributions to the total fatigue damage it is important to know the structural damping for relevant curvature levels. A laboratory test has been performed on a 12.5 m long test specimen to determine the damping for a range of curvature levels that are in the vicinity of the stick-slip transition region. The energy input to maintain steady state oscillations with curvature amplitudes in the range 0.0002–0.001 m−1 was measured. The steady state energy input is consistent with damping ratios obtained using the free decay method. The structural damping depends on construction temperature and curvature and is less for typically low seawater temperature and low curvatures. The transition between the stick- and the slip regime is seen for typical seawater temperature.

scholarly journals Flame Failures and Recovery in Industrial Furnaces: A Neural Network Steady-State Model for the Firing Rate Setpoint Rearrangement

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Tahmineh Adili ◽  
Zohreh Rostamnezhad ◽  
Ali Chaibakhsh ◽  
Ali Jamali
Keyword(s):  
Neural Network ◽  
Steady State ◽  
Optimization Problems ◽  
Network Models ◽  
Economic Loss ◽  
Neural Network Models ◽  
Firing Rates ◽  
State Models ◽  
Major Equipment ◽  
Artificial Neural Network Models

Burner failures are common abnormal conditions associated with industrial fired heaters. Preventing from economic loss and major equipment damages can be attained by compensating the lost heat due to burners’ failures, which can be possible by defining appropriate setpoints to rearrange the firing rates for healthy burners. In this study, artificial neural network models were developed for estimating the appropriate setpoints for the combustion control system to recover an industrial fired-heater furnace from abnormal conditions. For this purpose, based on an accurate high-order mathematical model, constrained nonlinear optimization problems were solved using the genetic algorithm. For different failure scenarios, the best possible excess firing rates for healthy burners to recover the furnace from abnormal conditions were obtained and data were recorded for training and testing stages. The performances of the developed neural steady-state models were evaluated through simulation experiments. The obtained results indicated the feasibility of the proposed technique to deal with the failures in the combustion system.

Variable-air-volume terminal units I: Steady-state models

1998 ◽  
Vol 19 (3) ◽  
pp. 155-162 ◽  
Author(s):  
I. Khoo ◽  
G.J. Levermore ◽  
K.M. Letherman
Keyword(s):  
Steady State ◽  
Variable Air Volume ◽  
Air Volume ◽  
Terminal Units ◽  
State Models

scholarly journals Analyse comparative de la productivité des cheptels de petits ruminants en élevage extensif tropical : une nouvelle approche par les modèles matriciels en temps discret

2001 ◽  
Vol 54 (1) ◽  
pp. 69 ◽  
Author(s):  
Matthieu Lesnoff ◽  
Renaud Lancelot ◽  
Emmanuel Tillard ◽  
Bernard Faye
Keyword(s):  
Steady State ◽  
State Models ◽  
Analyse Comparative

Une nouvelle méthode d’analyse comparative de la productivité des cheptels domestiques tropicaux est présentée ici. Cette méthode a utilisé les modèles démographiques matriciels et la méthode des modèles de production à l’équilibre (steady-state models). Les méthodes démographiques classiques utilisent des modèles à pas de temps annuel, peu adaptés pour les espèces à cycle de reproduction relativement court et dont les mises bas surviennent tout au long de l’année. Dans ce nouveau modèle, l’année a été décomposée en quinzaines. Trois apports opérationnels principaux ont été présentés. Premièrement, le pas de temps court a pu diminuer le biais dans l’estimation des paramètres démographiques (fécondité, mortalité, exploitation ou importation d’animaux). Deuxièmement, le modèle périodique a pu représenter conjointement les variations intra-annuelles et interannuelles des paramètres démographiques et d’autres paramètres comme le poids ou le prix de vente des animaux. Enfin, la méthode d’inférence proposée (utilisant le bootstrap non paramétrique) a permis de calculer des intervalles de confiance et de réaliser des tests pour comparer la productivité de cheptels différents. La méthode a été testée avec des données de terrain récoltées sur des cheptels d’ovins au Sénégal. Elle peut également être appliquée à d’autres espèces domestiques ou sauvages dans divers contextes zootechniques ou écologiques.

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