Temperature Control Model Research Articles

Green Granary Temperature Control System Modeling and Simulation

Abstract As an important link of food production and distribution process, Granary's temperature control performance seriously affects the food quality and storage costs. Based on the analysis of granary components, granary temperature control model is established. The simulation results show the validity of established model.

Dynamic Model of Thermoelectric Cooler and Temperature Control Based on Adaptive Fuzzy-PID

Thermoelectric cooler has dynamic thermoelectric performance under complex environment. A linear dynamic model of the thermoelectric cooler is derived using small-signal linearization method. It shows that the dynamic model of the thermoelectric cooler has one zero and two poles. The dynamic model of the thermoelectric cooler is showed to vary with operating conditions. Based of average linear dynamic model of a thermoelectric cooler, a temperature control system is designed for the cold end temperature of the thermoelectric cooler using fuzzy-PID algorithm. The step response tests show that the controller has satisfying dynamic and static performance. In room temperature environment, the response time for cooling down 18°C is around 340s and the steady error is very small. The cold-end temperature can be maintained at the setting value within 0.1°C. Experiment results also show that the setting temperature can reach to 23°C below the environment temperature, and the setting value is smaller and the step response time is longer.

Simple model for temperature control of glycolytic oscillations

We introduce the temperature-dependent autocatalytic coefficient into the Merkin-Needham-Scott version of the Selkov system and consider the resulting equations as a model for temperature-controlled, self-sustained glycolytic oscillations in a closed reactor. It has been shown that this simple model reproduces key features observed in the experiments with temperature growth: (i) exponentially decreasing period of oscillations; (ii) reversal of relative duration leading and tail fronts. The applied model also reproduces the modulations of oscillations induced by the periodic temperature change.

Automatic Control Model of Concrete Temperature

Most temperature control measurement methods are based on artificial work with anti-cracking during concrete construction. Automatic temperature control model proposed to implement computer control technology in concrete structural construction temperature control with anti-cracking to create an automatic concrete temperature control model. The model is based on temperature sensation technology, wireless transmission technology, water-pipe cooling technology, numerical simulation for the concrete structure of dynamic simulation and real-time monitoring. It can implement concrete inner temperature control to prevent temperature stress from producing cracks in concrete structure.

Autocontrol of Water Condenser Based on PID Controller

To maintain the outlet temperature at the desired set-point, a high-order outlet temperature control model is established for a water condenser, and different PID controller design methods are applied to its temperature control process. The control function model is based on the analysis of the heat balance equation and the heat transfer rate equation. The design process of three different PID control methods, including Ziegler-Nichols Method, Modified Ziegler–Nichols Formula and the Optimum PID Controller, together with the unit step response consequence are provided and compared, and the numerical simulation results show that the Optimum PID Controller has a favorable control performance.

Optimal PID Control of Heat Exchanger Temperature

To maintain the outlet temperature at the desired set-point, a high-order outlet temperature control model is established for a shell-and–tube heat exchanger, which is based on the analysis of its heat transfer process and dynamic properties .The Optimal PID control is applied to the temerature control system on the basis of this model, and the tuning parameters of the PID controller are obtained by numerical solving of a formulated optimization problem using Matlab/Simulink. An experimental control system is set up to testify the effect of the optimal PID control. The simulation result and the practice show that the control system has a favorable control performance.

Nonlinear MPC based on a Volterra series model for greenhouse temperature control using natural ventilation

Suitable environmental conditions are a fundamental issue in greenhouse crop growth and can be achieved by advanced climate control strategies. In different climatic zones, natural ventilation is used to regulate both the greenhouse temperature and humidity. In mild climates, the greatest problem faced by far in greenhouse climate control is cooling, which, for dynamical reasons, leads to natural ventilation as a standard tool. This work addresses the design of a nonlinear model predictive control (NMPC) strategy for greenhouse temperature control using natural ventilation. The NMPC strategy is based on a second-order Volterra series model identified from experimental input/output data of a greenhouse. These models, representing the simple and logical extension of convolution models, can be used to approximate the nonlinear dynamic effect of the ventilation and other environmental conditions on the greenhouse temperature. The developed NMPC is applied to a greenhouse and the control performance of the proposed strategy will be illustrated by means of experimental results.

A Squeeze Casting Die Temperature Control System Based on Fuzzy Control

On account of difficulties of squeeze casting die temperature control, squeeze casting process and factors influencing squeeze casting die were analyzed. On the basis of current heating and cooling ways of squeeze casting die, multiple factors and variability of die temperature influence were studied, a new squeeze casting die temperature control model was established. Fuzzy Control was chosen as the control system pattern. After designing the fuzzy controller, simulation model of die temperature control system was set up in the Simulink block of Matlab, and moreover, simulation was performed in it. The simulation results show that the system has good control performance compared with the traditional PID control mode.

Development of a temperature control model used in HVAC systems in school spaces in Mediterranean climate

In this paper a temperature control model used in heating, Ventilating and air-conditioning (HVAC) systems in school spaces, in Mediterranean climate, is developed. This empirical model considers the indoor preferred environmental temperature, the outdoor environmental temperature and the adaptation to the seasons of the year and to the spaces. In the development of the empirical model, in a school building located in the Algarve region, in the South of Portugal, occupied spaces by the non-teacher staff (administrative and auxiliary), teachers and students were used. In these spaces, equipped with heating, ventilating and air-conditioning systems, the occupants can change, during one year of school activities, the indoor environmental conditions in order to obtain acceptable comfort conditions. The indoor air temperature and relative humidity inside four spaces, namely an office room, a secretary room, a teachers room and a library room, the outdoor air temperature and other parameters related to the spaces and heating, ventilating and air-conditioning systems were measured every minute during one year. This empirical model, based in a group of equations for different months and for several spaces, gives information that can be used in the control of a heating, ventilating and air-conditioning systems, in school spaces, in Mediterranean climate, in order to promote indoor acceptable conditions with energy savings. In this model the adaptation to the outdoor environment, for different seasons, the clothing level and the fact that occupants enter and leave frequently from spaces equipped with heating, ventilating and air-conditioning systems to others not equipped are analyzed.

열간압연 ROT에서 고강도강의 CSTC 개발

This paper proposes a cooling stop temperature control(CSTC) concept which aims at obtaining the uniform temperature and quality of the material along the longitudinal and lateral direction of the strip. The CSTC is designed using the experimental CCT(Continuous Cooling Transformation), TTT(Time Temperature Transformation) curves and the temperature control model by the heat transfer governing equation, and the temperature control simulator. The cooling pattern and the rolling speed can be solved by the CSTC. It is shown through the field test of the hot strip mill of POSCO that the phase transformation ratio of the high carbon steel is considerably improved by the proposed temperature control.

Self-Learning and Its Application to Laminar Cooling Model of Hot Rolled Strip

Abstract The mathematical model for online controlling hot rolled steel cooling on run-out table (ROT for abbreviation) was analyzed, and water cooling is found to be the main cooling mode for hot rolled steel. The calculation of the drop in strip temperature by both water cooling and air cooling is summed up to obtain the change of heat transfer coefficient. It is found that the learning coefficient of heat transfer coefficient is the kernel coefficient of coiler temperature control (CTC) model tuning. To decrease the deviation between the calculated steel temperature and the measured one at coiler entrance, a laminar cooling control self-learning strategy is used. Using the data acquired in the field, the results of the self-learning model used in the field were analyzed. The analyzed results show that the self-learning function is effective.

Predictive functional control based on fuzzy T-S model for HVAC systems temperature control

In heating, ventilating and air-conditioning (HVAC) systems, there exist severe nonlinearity, time-varying nature, disturbances and uncertainties. A new predictive functional control based on Takagi-Sugeno (T-S) fuzzy model was proposed to control HVAC systems. The T-S fuzzy model of stabilized controlled process was obtained using the least squares method, then on the basis of global linear predictive model from T-S fuzzy model, the process was controlled by the predictive functional controller. Especially the feedback regulation part was developed to compensate uncertainties of fuzzy predictive model. Finally simulation test results in HVAC systems control applications showed that the proposed fuzzy model predictive functional control improves tracking effect and robustness. Compared with the conventional PID controller, this control strategy has the advantages of less overshoot and shorter setting time, etc.

Control of metabolic rate is a hidden variable in the allometric scaling of homeotherms

The allometric scaling exponent of the relationship between standard metabolic rate (SMR) and body mass for homeotherms has a long history and has been subject to much debate. Provided the external and internal conditions required to measure SMR are met, it is tacitly assumed that the metabolic rate (B) converges to SMR. If SMR does indeed represent a local minimum, then short-term regulatory control mechanisms should not operate to sustain it. This is a hidden assumption in many published articles aiming to explain the scaling exponent in terms of physical and morphological constraints. This paper discusses the findings of a minimalist body temperature (Tb) control model in which short-term controlling operations, related to the difference between Tb and the set-point temperatures by specific gains and time delays in the control loops, are described by a system of differential equations of Tb, B and thermal conductance. We found that because the gains in the control loops tend to increase as body size decreases (i.e. changes in B and thermal conductance are speeded-up in small homeotherms), the equilibrium point of the system potentially changes from asymptotically stable to a centre, transforming B and Tb in oscillating variables. Under these specific circumstances the very concept of SMR no longer makes sense. A series of empirical reports of metabolic rate in very small homeotherms supports this theoretical prediction, because in these animals B seems not to converge to a SMR value. We conclude that the unrestricted use of allometric equations to relate metabolic rate to body size might be misleading because metabolic control itself experiences size effects that are overlooked in ordinary allometric analysis.

The funnel model for accurate slab temperature control in reheating furnaces

This paper gives a brief overview of process control in slab reheating furnaces, zooming on the so-called “funnel-concept”, as this is implemented at Corus IJmuiden this year. The control automation in reheating furnaces at Corus started in 1970. In 1985-1990 an on-line slab temperature calculation and control system has been developed and implemented at pusher-and walking-beam furnaces. Ongoing development of this model resulted in a control strategy where the target-heating curve of each individual slab was extended by an upper and lower limit, of which the interval at the entrance gradually diminished to the end of a zone: the funnel model.

Thermal homeostasis in systemic inflammation: modulation of neuronal mechanisms.

Fever can be defined as a specific model of body temperature control, modified by action of humoral substances released due to bacterial infection. Under laboratory conditions exogenous and endogenous pyrogens affect nervous endings in the body periphery, as well as thermosensitive neurons in the hypothalamus, which first manifests as a shock reaction and then as shifts of temperature thresholds for activation of thermoregulatory effectors (cold thermogenesis, vasomotion, sweating or panting) to higher body temperatures. During the later phase of fever, the temperature threshold for cold thermogenesis starts to move downwards, while the thresholds for other thermoregulatory outputs remain elevated, the result being enlarging of the interthreshold zone. This creates conditions for cooling of the body and for termination of the fever. During different phases of fever cytokines, prostaglandins, neuropeptides and catecholamines participate in modulation of mechanisms regulating thermoregulatory functions. This paper aims to specify the role of individual cytokines in induction of fever, as well as in activation of thermoregulatory centers as well as individual thermoregulatory effectors and to define differences in their mode of action. The paper further attempts to summarize our knowledge on humoral modulation of the cytokine release. It is concluded that cytokines are not the primary factors responsible for setting of the body thermostat during fever.

Temperature control of electrohydrodynamic micro heat pipes

Active thermal control was achieved by using an electrohydrodynamically (EHD) assisted micro heat pipe array. A simulation model of temperature control of EHD micro heat pipes was established in a Matlab Sinulink environment. An experimental model was designed and fabricated to verify the model and identify the factors most influential to the thermal control via EHD micro heat pipe array. Good correspondence between simulations and experiments was achieved. Electric field intensity, set-point temperature and the gap between the upper and lower set-point temperatures were shown to have a dramatic influence on the temperature control.

The Rate and Extent of Fouling in a Single-Tube Wort Boiling System

Wort is the fermentation feedstock that provides all the necessary sugars and nutrients required for successful brewing. It is boiled to stabilize its composition prior to fermentation, a process that leads to the coagulation and subsequent flocculation of proteins and tannins, and fouling of the heat transfer surfaces. Fouling by commercially-supplied wort was studied in a single-tube (15 mm × 0.2 mm wall thickness, with wall temperature control) model wort boiling system, at wall temperatures of 130, 150 and 170°C and flow velocities of 0.07, 0.14 and 0.18 ms –1 , with the overall objective being to identify modes of operation which prolong operating times. Heat transfer was quantified in terms of the amounts of heat transferred to the liquid and vapour phases. The influence of operating conditions on the fouling process was determined by calculating the decrease in heat transfer coefficient with the increasing number of batches of wort processed. The work quantified the influence of wall temperature, wort velocity (and hence circulation time) and the duration of the boil. Fouling showed little temperature dependence as for all wall temperatures, a constant rate of fouling (d R f / dt ) was determined; d R f /d t = 1 × 10 –5 m 2 kW –1 h –1 , in the absence of vapour condensation and d R f /d t = 2 × 10 –5 m 2 kW –1 h –1 , with vapour condensation. The rate of fouling in the system was more affected by wort velocity, particularly under conditions where vapour was condensed. Under these conditions, curves obtained for velocities 0.07 and 0.14 ms –1 showed an initial, more rapid rate of fouling, which then continued at a reduced rate. The initial rate of fouling doubled as the wort velocity halved (at wort velocity 0.07 ms –1 initially d R f /d t = 4 x 10 –5 m 2 kW –1 h –1 compared to d R f /dt = 2 × 10 –5 m 2 kW –1 h –1 at velocity 0.14 ms –1 ), whereas the final rate was the same at both velocities (d R f / dt = 8 × 10 –6 m 2 kW –1 h –1 ).

Oscillatory pattern in oxygen consumption of Hummingbirds

Mammals and birds offer the most conspicuous example of homeothermic endothermy, a metabolic feature that implies maintenance of a constant body temperature along broad ranges of ambient temperature. The concept of homeothermic endothermy has been developed in close association with the terms thermoneutral zone and basal metabolic rate. These two metabolic parameters, however, are not easily estimated in micro-endotherms, a difficulty that might emerge from intrinsic aspects of endothermy in minute animals. To address this issue, we used empirical work derived from theoretical considerations. Our theoretical analysis is based on a model of body temperature control by shifts in metabolic rate, and assumes that micro-endotherms lose heat very quickly due to body size, and exhibit a remarkable capacity to rapidly increase metabolic output. We found that these two metabolic traits can lead to non-equilibrium metabolic rate and body temperature. We then measured metabolic rate and body temperature during euthermia in two species of hummingbirds, and analyzed data using the χ 2 periodogram statistic and a power spectral analysis. We found long-range correlation in both oxygen consumption and body temperature during euthermia, a finding that suggests non-random 1/ f oscillations. A similar pattern was not found in the rat, a much larger endotherm. Hummingbirds, then, do not appear to maintain steady-state metabolic conditions during euthermia. If, as we suggest, this pattern applies to micro-endotherms in general, the traditional concepts of thermoneutral zone and basal rate of metabolism might not apply to these animals.

Essential of the environmental control of insect seasonality as reference points for comparative studies in other invertebrates

A great body of knowledge of photoperiodic and other developmental reactions, governing seasonality in insects, may be helpful for similar investigations which are or will be conducted with other animal groups. The following principles, based on a recent hypothesis, seem the most significant to be tested in comparative studies. (1) On the level of the photoperiodic clock only quantitative perception of photoperiod takes place. (2) The following, presumably neuroendocrine, ‘managing’ level of the mechanism discriminates between long and short days, determines the type of the response, and integrates photoperiodic and temperature reactions. (3) A working hypothesis, to be tested with both insects and other invertebrates, is that the ‘managing’ mechanism described in the model of photoperiodic and temperature control of development may have several sensory inputs and, therefore, plays a central role in governing developmental reactions to different environmental cues.

Macromolecule hydration and the effect of solutes on the cloud point of aqueous solutions of polyvinyl methyl ether: A possible model for protein denaturation and temperature control in homeothermic animals

The effects of strong, neutral, 1:1 electrolytes; MgSO 4; urea, tetraalkylammonium salts, sucrose, and alcohols on the cloud point temperature of aqueous solutions of polyvinyl methyl ether have been examined and are interpreted in terms of (1) the two types of water structure, coulombic and hydrophobic, comprising the hydration sheath of polymer, (2) the selective exclusion of solute from the polymer's hydration sheath, and (3) the solute's stabilization or destabilization of the polymer's hydration sheath. The last two of these processes are related to the viscosity B-coefficient of the solute ions. The behavior of the polymer exhibits both similarities to and differences from proteins, and caution must be exercised in the use of the cloud point phenomenon as a model of protein denaturation. The solute effects described in this paper suggest a possible experimental test of the hypothesis that the thermal destruction of a biopolymer's hydration sheath might provide the basis of temperature control in homeothermic animals.