Approach For Temperature Control Research Articles

An Enhanced Temperature Control Approach to Simulate Profile Extrusion.

Thermoplastic extrusion, a widely used method for processing thermoplastic materials, requires precise temperature control to ensure product quality. However, existing computer-aided engineering tools often oversimplify the temperature distribution calculations, leading to additional discrepancies between simulations and the actual processes. This study introduces a novel multi-region modeling approach to address this issue. By employing realistic temperature control conditions, the methodology overcomes the limitations of current numerical modeling tools. The key contributions include the development of a transient, incompressible, non-isothermal solver integrated into the OpenFOAM computational library and the implementation of a specialized boundary condition that emulates Proportional-Integral-Derivative (PID) control using real-time thermocouple measurements. The findings highlight temperature deviations at the flow channel walls and total pressure drop while demonstrating a smaller impact on velocity and flow uniformity at the outlet under steady-state conditions. This research substantially advances the understanding of thermal dynamics in extrusion processes, offering crucial insights for enhancing temperature control and laying the groundwork for more effective and precise operational strategies.

Thermal stresses of large-dimension lithium hydride ceramics during the sintering process and strength analysis based on process-based failure assessment diagram

Lithium hydride (LiH) is an important hydrogen storage, heat storage and neutron shielding material. When used in neutron shielding structure, its size and strength have certain requirements, which would be met by LiH ceramics. However, it fails easily during sintering due to severe thermal stress and high brittleness. In this study, the influences of the dimension, furnace temperature cooling rate, and convection condition on the mechanical behavior were systematically examined. The results indicated that larger dimensions and faster furnace temperature cooling rates resulted in higher maximum stresses. Furthermore, convection was beneficial for reducing the thermal stress. Accordingly, a process-based failure assessment diagram method was proposed to evaluate the safety of LiH ceramics, and a bilinear precise temperature control approach was proposed. Based on this method, the tube thickness was increased by 25 % and the cooling time was reduced by 32 % compared to those using linear temperature control in an example. The conclusion and method could be applied to optimize the temperature control for more practical large-dimension sintering.

Cascaded reinforcement learning based supply temperature control

In this work, a Q-learning based supply temperature control approach for a demonstrator building is proposed. The purpose is to improve the temperature behaviour inside the building and to tackle comfort problems such as overheating and undercooling which cannot be coped with by the standard heating curve. The Q-learning controller considers predicted future weather data as system states. This can be shown to be superior to Q-learning controllers without weather prediction. Furthermore, in order for the controller to capture different thermal effects of different time constants, a cascaded control structure is designed: An inner Q-learning based controller deals with thermal effects of smaller time constants. It is wrapped by an outer slower Q-learning controller which can tackle effects of larger time constants. Therewith, further improvement of comfort can be achieved.

Increase CO2 recycling of Escherichia coli containing CBB genes by enhancing solubility of multiple expressed proteins from an operon through temperature reduction.

One of the current promising solutions to address problems of CO2 emissions is the development of biological carbon fixation strategies. This strategy leads to higher chemical biosynthetic productivity through improved biological CO2 fixation. In a previous study, we introduced the Calvin-Benson Bassham (CBB) genes of the photosynthetic bacterium Cereibacter sphaeroides into Escherichia coli to develop a strain capable of endogenous CO2 recycling by heterologous expression of the CBB genes. However, the heterologous expression of recombinant proteins in E. coli is often hampered by inclusion bodies (IB), which are protein aggregates. Various factors contribute to IB formation, including host cell metabolism, protein synthesis, transformation machinery, and target protein properties. In this study, we investigated the influence of environmental conditions, particularly culture temperature, on IB formation and CO2 recycling in the CBB strain. As a result, by reducing the culture temperature from 37°C to 30°C, a significant suppression of IB formation was achieved, resulting in a remarkable decrease in CO2 release by approximately 5.76 times. In addition, interestingly, an enhancement in the accumulation of pyruvate by approximately 2.3 times was observed at the same time. These results demonstrate the simultaneous improvements in CO2 recycling and the synthesis of organic acids achieved through temperature control. Based on the findings of this study, we believe that temperature control would be a promising approach to increasing chemical biosynthetic productivity as well as biological CO2 fixation activity in integrated autotrophic biorefinery strategies. IMPORTANCE In a previous study, we successfully engineered Escherichia coli capable of endogenous CO2 recycling through the heterologous expression of the Calvin-Benson Bassham genes. Establishing an efficient gene expression environment for recombinant strains is crucial, on par with the importance of metabolic engineering design. Therefore, the primary objective of this study was to further mitigate greenhouse gas emissions by investigating the effects of culture temperature on the formation of inclusion bodies (IB) and CO2 fixation activity in the engineered bacterial strain. The findings demonstrate that lowering the culture temperature effectively suppresses IB formation, enhances CO2 recycling, and concurrently increases the accumulation of organic acids. This temperature control approach, without adding or modifying compounds, is both convenient and efficient for enhancing CO2 recycling. As such, additional optimization of various environmental parameters holds promise for further enhancing the performance of recombinant strains efficiently.

Topology optimization of thermally activated building system in high-rise building

The building sector accounts for nearly 1/3 of global energy end-use and associated carbon emissions. Fulfilling buildings' thermal demand in an efficient way is critical for decarbonizing the building sector. Therefore, this paper introduces the thermally activated building system (TABS) as an energy retrofit solution. A TABS floor-by-floor return water temperature control approach is proposed to reduce buildings' energy use and carbon emissions. The approach includes the topology optimization of TABS and flow control. The bypass pipe connections of the TABS to each floor, namely, the floor-by-floor pipe network topology, have been optimized by using genetic algorithms to achieve the lowest total cost. A case study of a high-rise building located in Beijing demonstrates that the proposed approach can improve the system's energy efficiency compared to the conventional TABS without optimization. The reduction of energy cost can be up to 11.21% with a 13.53% annual emission reduction. In general, the proposed TABS floor-by-floor return water temperature control approach can significantly improve the building efficiency comprehensively, therefore can be considered as a promising energy retrofit solution for the decarbonization of high-rise buildings.

An adaptive indoor temperature control approach simultaneously improving thermal comfort and task performance

Air conditioning and mechanical ventilation systems help maintain the thermal comfort (TC) of occupants in a workplace. Indoor temperature determination that only aims to improve TC causes difficulty in fulfilling the occupant's task performance (TP). It is crucial to find an appropriate indoor temperature range that simultaneously accommodates occupants' TC and TP. In this study, we propose an adaptive temperature control approach that simultaneously improves the occupant's TC and TP. The relationship among the dissatisfaction rate, predictive mean vote, and indoor temperature was established and quantified. An investigation in a human-robot collaboration scenario was conducted by using the proposed approach. The preferable temperature range under various combinations of TC and TP is recommended. The proposed algorithm successfully achieves a significant energy-saving of 9.98% within the desired temperature range. By reducing the preferred upper limit of the temperature range by 3 °C compared to current standards, the algorithm further reduces energy consumption. To validate the effectiveness of the proposed model, we developed empirical formulas that establish the relationship between thermal comfort, task performance, and temperature, enabling the identification of optimal indoor temperature settings. Additionally, our model effectively captures the complex trade-offs and complementary nature between thermal comfort and task performance with respect to indoor temperature. Overall, this approach offers a solution for setting indoor temperatures in the workplace.

A Predictive Reinforcement Learning Approach for Temperature Control in Buildings

This paper discusses the adoption of a special Reinforcement Learning approach, namely the Actor-Critic (AC) one, to the temperature control of medium-size buildings. In particular, the approach here proposed is a predictive AC, in the sense that the AC algorithm is coupled not directly with the plant to be controlled, but with a predictor, thus enforcing a predictive behavior of the decision-making part of the AC. The reward function is defined on a prediction horizon, with 3 different formulas, as well as 3 different ways to compute the control action based on the predicted behavior. A real test case is considered and a comparison with a nonlinear MPC previously developed is given. Results are definitely encouraging in that predictive AC control reaches a similar performance as nonlinear MPC, without the need of realtime optimization.

The Impact of the Temperature Control Strategy in Steady-State Virtual Vacuum Simulation on the Spontaneous Evaporation Rate and Corresponding Evaporation Coefficient

In the present paper, we propose a novel simulation approach that allows one to capture the steady-state evaporation into virtual vacuum state by maintaining a constant number of atoms within the liquid phase during the simulations. The proposed method was used to perform virtual vacuum simulations of argon at a temperature of 90 K in order to study the effects of the chosen simulation temperature control approach on the system’s temperature profiles, spontaneous evaporation rates, and the energetic characteristics of the evaporating atoms. The results show that the expected non-uniform temperature profile across the liquid phase can be flattened out by dividing the liquid phase into separately thermostated bins. However, the desired liquid surface temperature can be achieved only when the thermostat region boundary is placed outside the liquid phase. The obtained relationship between the surface temperature and the spontaneous evaporation rate show that the spontaneous evaporation rate and corresponding evaporation coefficient evaluation may change up to 21% when the surface temperature changes in a narrow temperature interval of 2.45 K. Furthermore, the results demonstrate that the thermostat region boundary position has no impact on the energetic characteristics of the evaporating argon atoms, even when the boundary is placed outside the liquid phase.

Toward Sustainable Gentle Awakenings and Sleep Inertia Mitigation: A Low-Cost IoT-Based Adaptable Lighting and Temperature Control Approach

In this paper, our design aims to assist in sleep inertia reduction and avoid the startle response and irritation caused by alarm-made unpleasant wakeup stimuli. Thus, we propose an approach that employs a soft and alerting sunrise simulation, conditionally utilizes natural light, and appropriately lowers the bedroom temperature for awakening a sleeper tenderly and gradually to gain full alertness. This approach is inspired by known scientific implications confirming the effectiveness of lights and temperatures on wakefulness. In this regard, we present an economical do-it-yourself digital tech-assisted system for bedroom lighting and temperature control. The system design is based on the smartphone and Internet of Things (IoT) technology. We develop the hardware and software in the system for implementing three IoT-based control tasks. One is the tuning of artificial light brightness using the pulse width modulation technique. Another is the opening of the window curtain using stepper motor control and light detection. The other is the activation of the air-conditioning setting using an infrared remote control and temperature detection. We construct a testbed for conducting experiments. Experimental results demonstrate that the proposed system can execute task requirements satisfactorily. The proposed system is promising for achieving our goal. It embodies features of sustainability.

Temperature control of vibrating heat-generating hardware using spray evaporative cooling in the nucleate boiling region

A temperature control approach using evaporative spray cooling of vibrating surfaces in the nucleate boiling region is proposed and verified experimentally. This is relevant to temperature control of heat-generating automotive vehicle components. By exploiting an experimentally calibrated dynamic correlation model to represent evaporative spray cooling of a flat test-piece, a PID controller has been adopted with emphasis focused on the choice of gain parameters to ensure both stability of temperature control, and favourable responses in terms of relevant performance measures. Optimum linearisation of the correlation model has been achieved by solving an appropriate Wiener-Hopf equation, mainly to undertake a practical stability assessment of the closed-loop temperature control system. To verify the predicted control system performance, experimental measurements have been obtained from an instrumented, and spray-evaporatively-cooled, flat test-piece exposed to displacement vibration from a shaker. Experimental testing, appropriate to automotive vehicle component applications, includes large-amplitude, low frequency vibration at 12 mm and 1.9 Hz, and low amplitude, high-frequency vibration at 0.02 mm and 400 Hz. To assess the effects of different PID controller gains on the thermal performance of the thermal management system, a coefficient of performance (COP) is used, defined as the ratio of heat power removal to the required pumping power. To achieve a reduction in the settling time, and an increase in the rise time of stable control, a PID controller with a negative proportional gain showed most promising results. A 10.5% increase in COP was achieved in comparison to a PID controller with positive gains. This information is useful for the design and optimization of thermal management systems using evaporative spray cooling.

An innovative approach for temperature control of massive concrete structures at early ages based on post-cooling: Proof of concept

This study proposes a new methodology for the embedment of flexible PVC hoses (with the shape/geometry of the intended cooling pipes) that allows their removal a few hours after casting (i.e. after setting), while allowing that water is pumped through the circular cavity afterward (through a flexible/impermeable sleeve placed to shield the exposed concrete cavity). The PVC hoses are initially filled with oil under pressure, which are deflated a few hours after casting (particularly after setting is identified), and removed without relevant constraints due to their reduction in diameter inherent to deflation. All components and materials embedded into concrete (hose, sleeve) are fully recoverable after the end of the temperature control period, avoiding the loss of materials, with important financial and sustainability gains. This paper intends to show the proof-of-concept carried out in laboratory context conditions, highlighting the features that led to the selection and phasing procedure of the solution proposed.

Feedback-feedforward fuzzy logic approach for temperature control in bioethanol vacuum distiller

<span>Energy conservation and diversification are becoming a major research issue. Awareness of the limited sources of energy from fossil fuels encourages research on renewable energy. Bioethanol is a promising fuel substitute for gasoline. Bioethanol processing includes sugar extraction, fermentation, distillation, and absorption. Temperature and pressure controls are essential in bioethanol processing. This paper presents a feedback-feedforward fuzzy logic approach for temperature control in a bioethanol vacuum distiller. In this study, vacuum pressure is employed as feedforward inputs for a fuzzy logic controller. The feedforward input directly modifies the main controller, i.e., fuzzy logic controller, through fuzzy rules. The controller is implemented using Arduino Mega 2560 microcontroller. The results show that the proposed feedback-feedforward fuzzy logic controller could successfully maintain the temperature at the desired setpoint value with small steady-state error (3.85%) and relatively shorter settling time compared to classical PID controller and fuzzy logic controller.</span>

A precision temperature control approach for piezoelectric jet dispenser

Jet dispenser is widely used in LED (light emitting diode), microelectronic and optoelectronic packaging field. Temperature fluctuation of adhesives is a significant factor which affects the consistency of jet dispenser. As the working condition of jet dispenser is variable, the traditional PID temperature control method cannot meet requirements of high precision dispensing. A new temperature control system is designed for a proposed jet dispenser. Fuzzy PID temperature control approach is applied in the system. Temperature fluctuation is decreased from ±3.2 to ±1.1 °C with the new system. The jetting performance will be improved with the temperature control approach.

Actual Temperature Evolution of Thick Raft Concrete Foundations and Cracking Risk Analysis

Heat of the hydration-induced temperature evolution of a 3.30 m thick raft concrete foundation for wind turbines at the early ages was monitored in situ through a temperature sensor testing system. The temperature variation patterns and risk of cracking were studied. Finite element analysis (FEA) conducted on the temperature fields determined the lower thickness threshold requiring temperature control. A comprehensive temperature control approach suitable for thick raft foundations was proposed based on a practical engineering project. Temperature monitoring and analysis results showed that the early temperature field evolution featured two characteristic phases: heat accumulation and heat release. A remarkable temperature gradient was observed along the vertical direction of the foundation. The maximum temperature difference between the concrete core and the top surface was approximately 35°C, indicating a risk of cracking. The accuracy of the FEA was ensured by adopting the concrete heat generation rate obtained from the adiabatic temperature rise test. A further FEA performed on foundations with various thicknesses demonstrated that a thicker foundation corresponded to a higher vertical temperature gradient. Moreover, a raft thickness larger than 2.50 m corresponded to a maximum temperature difference between the concrete core and the surface higher than 25°C, above which cracking prevention measures should be taken. Field test results proved the applicability of a suite of temperature feedback regulation measures proposed herein, including layered pouring, thermal insulation, and in situ real-time temperature monitoring, to thick raft mass concrete structures with relatively small volumes. Good control of temperature difference was achieved using this approach.

Extracorporeal magnetic thermotherapy materials for self-controlled temperature through phase transition

Temperature regulation of magnetic thermotherapy used for the treatment of diseases needs to be precise and accurately controllable. Substantial efforts have been focused recently on manipulating the parameters of alternating magnetic field (AMF) and developing nanoparticles with low Curie temperatures for a desired thermotherapy temperature. Herein, a simple and effective approach for temperature control in magnetic thermotherapy through phase transition is reported. In general, extracorporeal magnetic thermotherapy materials are synthesized by introducing superparamagnetic nanoparticles in a phase change material with high phase transition enthalpy in the thermotherapy temperature range of 41 °C–47 °C. Given the magnetothermal effect of superparamagnetic nanoparticles and temperature control characteristics by phase transition of a phase change material, the temperature of the material in AMF can be self-regulated in the thermotherapy range. Moreover, the materials exhibit excellent thermal stability, form-stable properties, and outstanding reproducibility in temperature control for repeated use. This novel strategy may open a promising avenue for the study of temperature self-controlled thermotherapy.

Heavy duty gas turbine monitoring based on adaptive neuro-fuzzy inference system: speed and exhaust temperature control

Gas turbines are currently a popular power generation technology in countries with access to natural gas resources. However they are very complex systems the operation of which at peak performance is challenging. This paper proposes the use of a hybrid approach based on an Adaptive Neuro-Fuzzy Inference System (ANFIS) for the control of the speed and the exhaust temperature of a gas turbine. The main aim is to maintain turbine operation at optimum performance. The results obtained, based on the use of the Rowen model, clearly show the effectiveness of the proposed hybrid speed/exhaust temperature control approach for the gas turbine.

Reconfigurable water-substrate based antennas with temperature control

We report an unexplored reconfigurable antenna development technique utilizing the concept of temperature variable electromagnetic properties of water. By applying this physical phenomena, we present highly efficient water-substrate based antennas whose operating frequencies can be continuously tuned. While taking the advantage of cost-effectiveness of liquid water, this dynamic tuning technique also alleviates the roadblocks to widespread use of reconfigurable liquid-based antennas for VHF and UHF bands. The dynamic reconfigurability is controlled merely via external thermal stimulus and does not require any physical change of the resonating structure. We demonstrate dynamic control of omnidirectional and directional antennas covering more than 14 and 12% fractional bandwidths accordingly, with more than 85% radiation efficiency. Our temperature control approach paves the intriguing way of exploring dynamic reconfigurability of water-based compact electromagnetic devices for non-static, in-motion and low-cost real-world applications.

A new temperature treatment method of near-space crew capsule using phase change material

Environment control system of the near-space capsule is of great importance to maintain a comfortable environment and working conditions for crew members as well as onboard equipments. Temperature, as the most important parameter, is controlled by the phase change cool storage device in crew capsule. To improve the design of environment control system, a numerical study of the thermal environment within a crew capsule suspending in the stratosphere was conducted in this article. The main structure and thermodynamic parameters of the phase change cool storage device were calculated. The numerical results showed that the air temperature distribution of the crew capsule was reasonably good with a variation range between 21°C∼27°C. To test the effect of this new method, a simulative capsule was set up to address an experimental study. The experimental results showed that, the indoor temperature rise was effectively suppressed under the temperature treatment compared to none—temperature treatment. This research demonstrated an improved temperature control approach using phase change material, and the research findings can contribute toward an improved environmental control system design for near-space crew capsules.

Research on Temperature Control System of Cable Harness Based on Symbolic Control Method

The cable must be tested in cyclic heating condition for a long-time period according to the national standard before the delivery. By cyclic heating test, the actual current-carrying capacity of the cable is determined. In this paper, the cable cyclic heating system and temperature control technology is studied. In regard to the relation between heating temperature in working condition and ampacity of large-lag cable core, symbolic method-based temperature control approach is designed, which realizes the adaptive temperature control process of long-time constant lag system and meets the demand of cable temperature control in the field environment test.

Tunable bandgap in hybrid perovskite CH3NH3Pb(Br3−yXy) single crystals and photodetector applications

We report the synthesis of CH3NH3Pb(Br3−yXy) (X=Cl and I) single crystals via a stepwise temperature control approach. High-quality CH3NH3Pb(Br3−yXy) crystals with a tunable bandgap from 1.92eV to 2.53eV have been prepared successfully in this way. And further experiments revealed the influence of halogen content and preparation temperature on the structural and optical properties of these crystals. It is observed that chlorine can lower the critical nucleation energy, which results in crystallizing at lower temperature with the chlorine content increasing, while the nucleation energy increases slowly with increasing iodine content. Moreover, in contrast to Frank–van der Merwe growth with low heating rate, high heating rate leads to a mass of small size single crystals and Stranski-Krastanov growth. The single crystals with tunable band gap and impressive characteristics enable us to fabricate high performance photodetectors for different wavelengths.