Thermal Energy Management System Research Articles

Infiltration properties of n-alkanes in mesoporous biochar: The capacity of smokeless support for stability and energy storage

Biochar, also named biocarbon, is a solid particulate material produced from the thermal decomposition of biomass at moderate temperatures. It has progressively become the topic of scientific interest in energy storage and conversion applications due to its affordability, environment friendliness, and structural tunability. In this study, biochar (obtained 600 °C pyrolysis) was introduced as phase change materials (PCMs) support. Three different n-alkanes (such as dodecane, tetradecane, and octadecane) are used as PCMs. The PCMs were infiltrated in the biochar network via the vacuum impregnation method. Among the biochar/n-alkane composites, one from octadecane exhibited a high latent heat storage capacity of 91.5 kJ/kg, 15.7 % and 25.9 % higher than that of dodecane and tetradecane-based composites, respectively. The molecular length of the PCMs and intermolecular interaction between the functional groups play an imperative role. The infiltration ratio of PCM in the biochar reached 50.1 % with improved thermal stability and chemical compatibility. This is attributed to the favorable morphological and structural properties (e.g., large BET surface area and mesopore structure) of the biochar that resides the n-alkanes found in the nanosized chain length. Hence, this report will lay a foundation for the application of biochars in thermal energy management systems.

Microstructural and thermal response evolution of metallic form-stable phase change materials produced from ball-milled powders

Phase change materials (PCMs) can store and release the latent heat associated with a phase transition, so they can be applied in thermal energy management and storage systems. Among them, form-stable (FS) PCMs can consist of two immiscible phases: an active phase, which undergoes the solid–liquid transition, and a matrix, which provides the structural properties and prevents leakage of the active phase when it is liquid. This experimental study focused on the characterization of a metallic FS-PCMs based on an Al–Sn alloy, obtained by powder metallurgy from ball-milled powders, compacted at room temperature and sintered at 200, 250 and 500 °C. The main properties that characterize PCMs are the temperature range over which transition occurs and the associated enthalpy, i.e. the stored energy. Differential scanning calorimetry (DSC) is one of the more suitable characterization techniques to evaluate these properties and so the thermal response of PCMs. To check thermal response and its stability, DSC tests including several thermal cycles were conducted. DSC analyses were performed also before and after several thermal cycles simulating possible operative conditions. Moreover, microstructural analysis, through scanning electron microscopy and X-ray diffraction, allowed to relate the thermal response variations to microstructural and mechanical changes.

Phase change materials stabilized by porous metal supramolecular gels: Gelation effect on loading capacity and thermal performance

Shape-stability, PCM loading capacity, and energy storage performance of organic phase change materials (PCMs) are crucial in broad applications of thermal energy storage and management. In this study, a facile strategy was followed to design 3D-porous metal supramolecular gels as supporting materials. The phase change composites were prepared by solution impregnation of polyethylene glycol. The porous supporting material exhibited large specific surface area, high total pore volume, and micro/mesopore characteristics. In addition, the influence of gel concentration on PCM encapsulation and thermal properties of composite materials were investigated in which increasing the concentration result in a decrease in energy storage capacity and loading ratio. The as-prepared phase change composites revealed a high PCM loading capacity up to 90 wt% and energy storage capability reaches 100%. Factors such as pore characteristics and gel concentration played a central role in the thermal properties of composite PCMs. Further, the phase change composites showed high durability after 100 heating/cooling cycles without a significant shift in latent heat and phase transition temperatures. This investigation provides an insight into making a facile synthesis of gel-based composite PCMs and possible thermal energy management systems.

A novel enhancement of shape/thermal stability and energy-storage capacity of phase change materials through the formation of composites with 3D porous (3,6)-connected metal–organic framework

Leakage at temperatures above the melting point and thermal-transport performance are prime factors for the effective application of phase change materials (PCMs). In this study, a shape-stabilized composite PCM based on a three-dimensional (3D) porous (3,6)-connected metal–organic framework (MOF) and polyethylene glycol (PEG) was designed. The (3,6)-connected Zn2+ MOF gel was used as a porous supporting material, whereas PEG was employed as an energy-storage material. The PCM, which was impregnated by a capillary force and anchored by a weak hydrogen-bonding interaction between hydroxyl and amine groups, was stabilized by the supporting material. The 3D and two-fold interpenetrated structure of the MOF provided continuous heat-transfer paths in the composite PCM. The resulting composite material exhibited a high transition enthalpy (159.8 kJ/kg) with an encapsulation efficiency and impregnation ratio of 93.4% and 92.2%, respectively. The large interior surface accessibility of the MOF played a vital role in enhancing the thermal properties of the as-synthesized composite PCM. Additionally, the composite PCM exhibited excellent thermal stability and reliability even after 100 thermal cycles. Therefore, the composite PCM is a promising candidate for thermal-energy management systems owing to its high latent heat, suitable phase-change temperature, good chemical compatibility, reduced extent of supercooling, and high thermal stability.

Analysis and use of building heating and thermal energy management system

To explore the role and influence of thermal energy management system on building heating, by building a thermal energy management system based on the Internet of Things, the situation of heating system and building heating is analyzed, the heat utilization rate of building heating, the stability of heating temperature, the change of heating energy consumption are mainly studied, and the energy consumption of building and the comprehensive effect of thermal energy management system and residents? satisfaction are analyzed. The research results show that through the role of the Internet of Things thermal energy management system, the heat utilization rate of heating buildings has increased from about 65% to about 80%, about 15%. The fluctuation of heating water temperature is reduced from 12?C before the system is adopted to 4 ?C, which improves significantly. The coal consumption per hour of heating system is reduced from 63 kg/h to 50 kg/h, and the coal saving is about 15%. This not only saves resources but also reduces environmental pollution. The heat management system based on the Internet of Things has significantly improved the heating system and building heating. Through the application of thermal energy management system, not only the heat utilization rate is increased, but also the consumption of resources is reduced and the environment is protected. Meanwhile, it solves the problem of building heating and the maximization of efficiency in the operation of heating companies. The research on building heating and thermal energy management system has a positive effect on the follow-up research.

Analysis and application of building heating and thermal energy management system

Objective: Through the analysis and application of building heating and thermal energy management system, this paper proposes a new thermal energy control strategy to improve the automation level of building heating optimization. Method: This study analyzes the principle of indoor heat balance in buildings. Aiming at the different heating needs of different buildings, a new control strategy is proposed by combining neural network models and fuzzy control theory. Finally, this strategy is applied to the actual building heating, and the practical application value of the strategy proposed by this study is verified through experiments. Result: In the heating stage, after applying the control strategy, the maximum relative error of the temperature is 0.047, and the average error is 0.013. In the antifreeze stage, the maximum error is 0.143 and the average error is 0.09. After the implementation of the control strategy, the temperature fluctuations in the room change little and remain almost between 19 ?C and 21 ?C. Buildings consume less heat with the highest energy saving rate of 14.37% and the average energy saving rate of 9.23%. Conclusion: The control strategy proposed in this study can adjust the indoor temperature according to the actual situation and achieve the purpose of reasonable heat use. Moreover, it has certain energy-saving effects and can be applied to building heating.

Sewage treatment degradation thermal energy management system of sewage treatment plant

Objective: The paper is to study the sewage treatment degradation thermal energy management system of a sewage treatment plant, to achieve the energy saving and emission reduction. Methods: This paper studies the electron equivalent reaction of biochemical reaction of organic matter. Under the environmental conditions of biochemical degradation of sewage, biochemical oxygen demand (BOD5) is used to indicate the amount of heat generated by the degradation of organic matter in sewage. The paper designs a management system based on sewage heat recovery, and uses it to carry out heat recovery of sewage. Also, the energy-saving benefits produced by the heat management system are studied. Results: The sewage heat recovery system is more energy-efficient than the common air-conditioning supply system. In the use of sewage heat management system for one year, it achieves energy saving of 30.4% better than that of ordinary air-conditioning systems. The system for one year saves electric energy of 2145464 kWh, which is equivalent to saving 2511994?104 kJ primary energy. This system saves 858.2 tons per year of standard coal, reduces CO2 emissions by 2789.1 tons per year, reduces SO2 emissions by 19.61 tons per year, reduces NO2 emissions by 7.12 tons per year, reduces ash emissions by 135.19 tons per year, and saves tap water replenishment 40243 tons per year. Conclusion: The sewage thermal energy management system can utilize the thermal energy in the sewage, thereby using the sewage as a new clean energy. It can effectively improve China?s current energy shortage and make a substantial contribution China?s energy saving and emission reduction goals.

Investigation of the Dielectric and Thermal Properties of Non-Edible Cottonseed Oil by Infusing h-BN Nanoparticles

Vegetable oils have emerged as insulating fluids in transformer applications and as a prominent and effective alternative for traditional dielectric fluids. However, most of vegetable oils are edible causing their application on a large scale to be limited. In the present work, a novel non-edible vegetable oil is developed as an insulating fluid. The developed oil is oxidation-inhibited cottonseed oil (CSO) based nanofluids. Tertiary butylhydroquinone was used as antioxidant. The concept of nanofluids was used to overcome the limited dielectric and thermal properties of cottonseed oil. Hexagonal Boron Nitride (h-BN) nanoparticles at low weight fractions (0.01 - 0.1 wt%) were proposed as nanofillers to achieve adequate dielectric strength and improved thermal conductivity. Stability of prepared CSO based nanofluids was analyzed using Ultraviolet-visible (UV-Vis) spectroscopy. Then, the prepared nanofluids were tested for dielectric and thermal properties under a temperature range between 45 °C and 90 °C. The dielectric properties include breakdown strengths under AC and lightning impulse voltages, dielectric constant, dissipation factor, and resistivity, while thermal properties include thermal conductivity and thermogram analysis. The dielectric and thermal properties were significantly improved in CSO based nanofluids. The creation of electric double layer at nanoparticle/oil interface and the lattice vibration of nanoparticles were used to clarify the obtained results. The proposed CSO based h-BN nanofluids open up a great opportunity in both natural ester insulating fluid applications and thermal energy management systems.

Simulation and operation control strategy of ground source thermal energy management system by cold and heat auxiliary technology

To explore the performance of the ground source thermal energy management system under the cold and heat sources, based on the cold and heat auxiliary technology, a ground source thermal energy composite management system is constructed and simulated. The constructed ground source heat pump-refrigeration unit-hybrid heating management system of urban heating networks, as well as the simple system, are analyzed and investigated in terms of power consumption and underground temperature control. The research results show that the constructed ground source heat pump-refrigeration unit-hybrid heating management system of the urban heating network has lower power and energy consumption than a simple system during the same period, which meets the economic requirements and guarantees the system with relatively low energy consumption. For underground temperature control, the constructed system is more stable than a simple system without excessive temperature fluctuations. The operation control strategy of the constructed system is mainly for chiller units, heat pump units, cooling towers, source side, and side circulation water pump modules. In summary, the constructed ground source heat pump-refrigeration unit-hybrid heating management system of an urban heating network based on the ground source heat pump meets the requirements for energy consumption and temperature control and can operate the control strategy normally. The results are significant for subsequent researches on the ground source thermal energy management system based on cold and heat auxiliary technology.

Theoretical and experimental analysis of thermal energy management system of air source self-powered electric gas generator

In order to solve the problem that the auxiliary equipment of electric gas turbine can operate only by relying on external power, and realize the purpose that auxiliary equipment of electric gas turbine can operate independently without the external power grid, in this research, a management system of air source self-powered electric gas generator is proposed. Firstly, the process of the thermal energy management system of the air source self-powered electric gas generator is introduced, and the thermodynamic theory of the thermal energy management system of the air source self-powered electric gas generator is analyzed. Then, the experimental conditions of air source self-powered electric gas generator are introduced. Finally, the results of variable speed and terminal variable flow in heating condition and terminal variable flow in cooling condition of the thermal energy management system of air source self-powered electric gas generator are analyzed. The results show that whether the thermal energy management system of air source self-powered electric gas generator studied in this research is in heating or cooling conditions, both the output power of the engine and the power of the compressor increase with the increase of the rotating speed. It can be concluded from the variable flow results in heating conditions that the smaller the end flow is, the smaller the output power of the engine will be. In this way, the loss of heat transfer efficiency of the plate can be reduced as much as possible, and the users? demand for heat can be met.

Study on energy efficiency evaluation and influencing factors of ground source thermal energy management system operation

The paper combines the testing work of ground source heat pump systems, discusses the installation, use methods and test errors of various testing instruments, combines the field test experience, gives the main points of ground source heat pump energy efficiency testing, and according to the problems encountered during the test. The faults with high frequency are analyzed, and the methods of fault diagnosis and troubleshooting are given. This paper uses the ground-source heat pump experimental platform to set up multiple sets of experimental schemes to study the impact of factors such as pipe diameter, single and double U, and flow rate on system energy efficiency. At the same time, it combines engineering cases to ?large flow small temperature difference?, ?imbalance? phenomenon is analyzed, and feasible solutions and suggestions are given. By analyzing the energy efficiency and benefits of actual engineering of multiple ground source heat pump systems, the paper concludes that ground source heat pump systems have a wider application prospect in a certain area of Hubei.

Numerical and experimental study of the thermal rectification of a solid-liquid phase change thermal diode

Phase change materials (PCMs) are highly effective to enhance the sustainability of thermal energy storage, management and control systems. The quest to find other novel applications of PCMs diverts attention towards phase change thermal diodes. However particularly, solid-liquid phase change thermal diodes (SL-PCTDs) suffer from fairly low thermal rectification ratio, hampering their implementation as thermal management and temperature control units. Herein, a SL-PCTD prototype is reported that is capable to access thermal rectification ratio of 3.0, being the highest in the family of SL-PCTDs. With the help of a theoretical model, the design was optimized in terms of bi-terminal length, providing the guideline to physically fabricate and experimentally execute the SL-PCTD. Paraffin wax and calcium chloride hexahydrate have been employed to assemble phase change bi-terminals. In operation, the heat flux was manipulated within a wide temperature bias of 10–40 °C, in both the forward and reverse directions. Also, theoretical model includes the natural convection and liquid-height-dependent effective thermal conductivity of calcium chloride hexahydrate, helping to meet the prerequisites of a high-performance design.

Optimal Real-Time Residential Thermal Energy Management for Peak-Load Shifting With Experimental Verification

Controlling residential thermal loads and thermal energy storage is a viable tactic to engage end-users in demand response programs (DRPs). This paper focuses on the development of an optimal real-time thermal energy management system (TEMS) for smart homes to respond to DRP for peak-load shifting. The proposed TEMS combines two model predictive controllers to manage two thermal energy storage systems, a water storage tank (WST) and the building thermal mass, to schedule residential heat pump loads to off-peak periods. The intention is to manage the operation of a ground source heat pump (GSHP) to produce the desired amount of thermal energy by controlling the volume and temperature of the stored water in the WST while optimizing the operation of the heat distributors to control indoor temperature. The primary contributions are the development of a new control strategy for GSHPs coupled with WST based on building identification to minimize total energy consumption and cost. This paper also proposes a real-time indoor dynamic temperature set-point strategy based on real-time pricing tariffs for enhancing peak-load shifting of heat pump loads with an acceptable variation in thermal comfort. Simulation and experimental results demonstrate that the proposed TEMS has significant potential for real-time peak-load shifting.

Melamine Foam-Supported Form-Stable Phase Change Materials with Simultaneous Thermal Energy Storage and Shape Memory Properties for Thermal Management of Electronic Devices.

Paraffin wax (PW) is widely used as a phase change material (PCM) in the thermal energy storage field, whereas the leakage and strong rigidity of PW have hindered its practical applications. In this work, binary melamine foam (MF)/PW blends with simultaneous thermal energy storage and shape memory properties were prepared through vacuum impregnation. Herein, PW performs as a latent heat storage material and as a switching phase for shape fixation and MF serves as a supporting material to prevent the leakage and as a permanent phase for shape recovery. Due to the light weight and super-elasticity of MF, the MF/PW PCMs possess not only good encapsulation ability and a high latent heat, but also excellent shape-fixing and recovery properties (shape-fixing and recovery ratios are about 100%). Besides, the MF/PW PCMs can be fabricated into arbitrary shapes using MF as a template, and they exhibit excellent shape memory cyclic performance and thermal reliability. A temperature-sensitive and temperature-controlled deployable panel is further established, which can be installed in the electronic device and used for temperature protection. With high thermal energy storage capability, excellent shape memory properties, shape designability, and stable cycling reliability, this multifunctional MF/PW PCM shows a promising application in thermal energy management systems.

The The Methodology of Thermal Energy Management for Nearly Zero Energy Buildings

Distributed generation causes an unbalanced power grid, which leads to a problem with unpredicted energy surplus balancing. In this vast problem, active cooperation with individual consumers on the energy market is crucial to ensure stability of the power system. Therefore, basing on analysis of power demand for the power system, the control algorithm of Thermal Energy Management System for the net Zero Energy Buildings was developed. One of the possibility of shifting peak power demand is using a building structure as a thermal energy storage. The potential of energy management was confirmed by numerical analysis of two nearly zero energy building models (a heavy and a light construction). A heavy construction building consumes less energy than a light construction but possibilities of obtaining measurable cost savings for user are higher in a case of light construction building. The objective of this study is to show that it is possible to save about 17–28% of the yearly cost of electricity by using the proposed control algorithm. On the contrary, lack of active and conscious usage will result in yearly increase of energy costs at the level of 5–8%. At the same time functioning of the HVAC system according to the proposed algorithm does not significantly effects on thermal comfort.

A novel solidification model considering undercooling effect for metal based low temperature latent thermal energy management

Abstract A numerical study of solidification process of a metal phase change material during the energy discharge stage considering non-equilibrium undercooling effect is performed for low-temperature latent thermal energy management (TEM) system. A multi-dimensional convection-diffusion algorithm for non-equilibrium solidification is proposed. In the model, the solidification interface velocity is based on undercooled kinetic solidification, which is subsequently used for solid fraction calculation using an interface tracking method. The model is validated with the benchmark experimental data. The solidification behavior obtained from the conventional and the proposed solidification models are compared. The conventional model failed to capture the solidification characteristics arising from the undercooling effects. The proposed model successfully captures various stages of solidification, namely liquid cooling, undercooling, kinetic solidification and recalescence, and solid cooling. The influence of undercooling on the coupled heat transfer and fluid flow behavior during solidification is described. An interesting flow reversal behavior is noticed at an early stage of nucleation. The energy discharged is found to be slower with the undercooling effects than that predicted by the conventional model. The results provide insights for metal based TEM system in the temperature range of 10 °C–50 °C where the energy discharged is affected due to undercooling.

A Market-Based Optimization Approach for Domestic Thermal and Electricity Energy Management System: Formulation and Assessment

The increase of domestic electrical and thermal controllable devices and the emergence of dynamic electrical pricing leads to the opportunity to integrate and optimize electrical and thermal energy at a house level using a home energy management system (HEMS) in order to minimize the energy costs. In the literature, optimization-based algorithms yielding 24-h schedules are used in spite of their growing complexity with the number of controllable devices and their sensitivity to forecast errors which leads, in most of the cases, to suboptimal schedules. To overcome this weakness, this paper introduces a domestic thermal and electrical control based on a market approach. In contrast with the optimization-based HEMS, the proposed market-based approach targets a scalable and reactive optimal control. This paper first formulates the market-based optimization problem with generality and discusses its optimality conditions with regards to the microeconomic theory. Secondly, this paper compares its optimality to an optimization-based approach and a rule-based approach under forecast errors using Monte Carlo simulations. Finally, this paper quantifies and identifies the effectiveness boundaries of the different approaches.

온배수에너지를 활용한 IoT 기반 스마트 양식장 개발

Most power companies are wasting hot water in the sea, called the wasted warm water energy. This research attempts to develop the thermal energy management system of warm water energy that is utilized in a fish farming systems based on Internet of Things(IoT). It had developed a remote control and monitoring system of a smart fish farm by using IoT technology. In this system, we had proposed to build a smart fish farming system that has the function of sensing and monitoring by several sensors such as; oxygen, temperature, pH, and water level. It also provide a close loop water flow control in the aquarium which are controlled by microcontroller and supported by Massage Queue Telemetry Transport (MQTT) communication protocol on the mobile application or website application. The proposed system is realized the smart fish farming system based IoT using wasted warm water energy, which is very powerful to create a natural environment of fish growing condition and life cycle. This system is capable to do control and monitoring through mobile and web application. It is satisfied with the performance through the analysis of aquarium system and experiment results for the designed smart fish farming system. Moreover, this proposed system has main advantages which are minimize the human effort for the fish farming and unmaned, and it is applied to new concept smart fish farm aquarium in the near future.

Modeling electric load and water consumption impacts from an integrated thermal energy and rainwater storage system for residential buildings in Texas

The United States’ built environment is a significant direct and indirect consumer of energy and water. In Texas, and other parts of the Southern and Western US, air conditioning loads, particularly from residential buildings, contribute significantly to the peak electricity load on the grid, straining transmission. In parallel, water resources in these regions are strained by growing populations and shrinking supplies. One potential method to address both of these issues is to develop integrated thermal energy and auxiliary water (e.g. rainwater, greywater, etc.) storage and management systems that reduce peak load and freshwater consumption. This analysis focuses on a proposed integrated thermal energy and rainwater storage (ITHERST) system that is incorporated into a residential air-source chiller/heat pump with hydronic distribution. This paper describes a step-wise hourly thermodynamic model of the thermal storage system to assess on-peak performance, and a daily volume-balance model of auxiliary water collection and consumption to assess water savings potential. While the model is generalized, this analysis uses a case study of a single family home in Austin, Texas to illustrate its capabilities. The results indicate this ITHERST system could reduce on-peak air conditioning electric power demand by over 75%, with increased overall electric energy consumption of approximately 7–9%, when optimally sized. Additionally, the modeled rainwater collection reduced municipal water consumption by approximately 53–89%, depending on the system size.

Thermal transport in Si and Ge nanostructures in the 'confinement' regime.

Reducing semiconductor materials to sizes comparable to the characteristic lengths of phonons, such as the mean-free-path (MFP) and wavelength, has unveiled new physical phenomena and engineering capabilities for thermal energy management and conversion systems. These developments have been enabled by the increasing sophistication of chemical synthesis, microfabrication, and atomistic simulation techniques to understand the underlying mechanisms of phonon transport. Modifying thermal properties by scaling physical size is particularly effective for materials which have large phonon MFPs, such as crystalline Si and Ge. Through nanostructuring, materials that are traditionally good thermal conductors can become good candidates for applications requiring thermal insulation such as thermoelectrics. Precise understanding of nanoscale thermal transport in Si and Ge, the leading materials of the modern semiconductor industry, is increasingly important due to more stringent thermal conditions imposed by ever-increasing complexity and miniaturization of devices. Therefore this Minireview focuses on the recent theoretical and experimental developments related to reduced length effects on thermal transport of Si and Ge with varying size from hundreds to sub-10 nm ranges. Three thermal transport regimes - bulk-like, Casimir, and confinement - are emphasized to describe different governing mechanisms at corresponding length scales.