Amount Of Thermal Energy Research Articles

Environmental Sustainability of Heat Produced by Poplar Short-Rotation Coppice (SRC) Woody Biomass

As demonstrated for some time, the reduction of greenhouse gases in the atmosphere can also take place using agroforestry biomass. Short-rotation coppice (SRC) is one of the sources of woody biomass production. In our work, the supply of woody biomass was considered by examining four different cutting shifts (2, 3, 4 and 5 years) and, for each, the Global Warming Potential (GWP) was evaluated according to the IPCC 2007 method. Regarding the rotation cycle, four biomass collection systems characterized by different levels of mechanization were analyzed and compared. In this study, it was assumed that the biomass produced by the SRC plantations was burned in a 350 kWt biomass power plant to heat a public building. The environmental impact generated by the production of 1 GJ of thermal energy was assessed for each of the forest plants examined, considering the entire life cycle, from the field phase to the energy production. The results were compared with those obtained to produce the same amount of thermal energy from a diesel boiler. Comparing the two systems analyzed, it was shown that the production and use of wood biomass to obtain thermal energy can lead to a reduction in the Global Warming Potential of over 70% compared to the use of fossil fuel.

Study Assesses Potential of Renewable Energy in Power Sector

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 21348, “The Color of Energy: The Competition To Be the Energy of the Future,” by Hon Chung Lau, National University of Singapore, prepared for the 2021 International Petroleum Technology Conference, held virtually 23 March–1 April. The paper has not been peer reviewed. Copyright 2021 International Petroleum Technology Conference. Reproduced by permission. The author of the complete paper, for the purposes of this study, characterizes energies as brown, blue, or green. Brown energies are carbon dioxide (CO2)-emitting fossil fuels, such as gas, oil, or coal. Blue energies use carbon capture and storage (CCUS) technologies to remove the emitted CO2 from brown energies. Green energies are zero- or low-CO2-emitting renewable energies. By analyzing the CO2 intensity and levelized cost of energy of energy carriers of different colors, the author shows that renewable energies are best used in replacing fossil fuels in the power sector, where they have the greatest effect in reducing CO2 emission. Overview By 2017, only 11% of the world’s final consumption came from renewable energies, 85% came from fossil fuel, and 4% came from nuclear energy. Energy consumption can be divided into three sectors: power, transport, and thermal. At the time of writing, 26.4% of global power (electricity) consumption comes from renewable energies. In this sphere, renewable energies are making the most significant contribution in reducing CO2 emission. Forty-one percent of CO2 emission comes from electricity and heat, 21% from transport, and 21% from industry. Consequently, the key to global decarbonization is to decarbonize these three sectors. Green Energy Is Preferred Green energies consist of six major types: solar photovoltaic, solar thermal, wind, hydroelectricity, geothermal, and biomass. If 1 kWh of electricity generated by renewable energy (with the exception of biomass) is used to replace 1 kWh of electricity generated by fossil fuel, the net CO2 savings will amount to 0.8, 0.6, and 0.4 kg for replacing coal, oil, and natural gas, respectively. However, if 1 kWh of renewable electricity is used to generate green hydrogen (H2), which is then used for heat generation in industry, it will yield roughly 0.8 kWh of thermal energy, which replaces the same amount of thermal energy by natural gas. This amounts to a CO2 savings of only 0.16 kg CO2/kWh. Consequently, renewable power has the highest CO2 savings effect if it is used to replace fossil fuel for power generation rather than to replace fossil fuel for heat generation. Decarbonizing the Power Sector The power sector is easiest to decarbonize. The three methods foreseen to decarbonize the power sector are nuclear power, blue electricity generated by fossil-fuel power plants equipped with CCUS, and green electricity produced by renewables. The use of nuclear power plants is a country-specific issue. The dual challenge of nuclear plant safety and nuclear waste storage is a key sustainability issue. Recently, interest has been renewed in the idea of increasing investment in nuclear energy for decarbonizing the power sector. It is noteworthy that the countries for whom more than a quarter of their power generation is provided by nuclear energy are all in Europe.

Thermoelectric generators

As the world is changing and developing with every passing day, the requirements of power are also increasing. There is a shift in utilizing the electrical energy as much as possible and for this reason, many countries have already made policies for completely ruling out the machines which don’t run on electricity. Apart from electricity, there are other forms of energy that can be used to convert that form into a more desirable form. For example, in a plant where the smoke comes out of the chimneys or in a car, the smoke carries a large amount of thermal energy with it. This energy is nothing but a waste and reduction in the efficiency of the systems. If somehow, this energy could be recovered, the efficiency can be increased. Thermoelectric generators serve for this purpose. Thermos electric generators get the heat and using the principle of heat conduction and p and n type materials, the heat can be directly converted into the electricity. There are many materials available in the market for p and n type but in our case, we chose silicon germanium which is also one of the most commonly used. First of all, a single module of thermoelectric generator will be made using p and n type material, as well as using conductive material and some ceramic substance. Then, the entire assembly will be made and this assembly will be exported to Ansys where custom materials will be added and applied on to the geometry. After performing analysis on full model, a comparative study will be presented in which the effect of material of conductive plate on to the voltage difference will be studied

Deterioration of heat transfer in turbulent channel flows due to nanoparticles

Custom-designed nanoparticles offer the possibility of influencing the thermo-physical properties of heat carriers, such as water and transformer oil. The present study aims to clarify to what extent such nanofluids may improve convective heat transfer under turbulent flow conditions. The applied assessment methodology is based on wall-resolving large eddy simulations and analytical considerations, exemplified by diamond-water nanofluids of different particle concentrations. It is observed that a change in heat transfer due to nanoparticles is affected by two competing mechanisms. On the one hand, the modified thermo-physical properties of the suspension obviously favor heat transfer. On the other hand, an addition of particles drastically dampens turbulence which causes the opposite effect. At fixed energy input by the pump, the second effect usually dominates, so that the performance of the nanofluid deteriorates compared to the carrier fluid without particles. In other words, increasing the turbulence intensity of the carrier fluid is more efficient to transfer a certain amount of thermal energy than using nanofluids. However, if a specific turbulence level shall not be exceeded in a technical system, nanoparticles can help to further improve convective heat transfer.

Heat Recovery from Wastewater—A Review of Available Resource

The EU Directive 2018/2001 recognized wastewater as a renewable heat source. Wastewater from domestic, industrial and commercial developments maintains considerable amounts of thermal energy after discharging into the sewer system. It is possible to recover this heat by using technologies like heat exchangers and heat pumps; and to reuse it to satisfy heating demands. This paper presents a review of the literature on wastewater heat recovery (WWHR) and its potential at different scales within the sewer system, including the component level, building level, sewer pipe network level, and wastewater treatment plant (WWTP) level. A systematic review is provided of the benefits and challenges of WWHR across each of these levels taking into consideration technical, economic and environmental aspects. This study analyzes important attributes of WWHR such as temperature and flow dynamics of the sewer system, impacts of WWHR on the environment, and legal regulations involved. Existing gaps in the WWHR field are also identified. It is concluded that WWHR has a significant potential to supply clean energy at a scale ranging from buildings to large communities and districts. Further attention to WWHR is needed from the research community, policymakers and other stakeholders to realize the full potential of this valuable renewable heat source.

Efficiency Evaluation of Solar Concentrator without Tracking System Type of Compound Parabolic Concentrator (CPC)

It is useful to analyze any optical system theoretically before proceeding with its design in order to ensure the effectiveness of the design through computer simulations that are important and useful in designs for the ability to predict the performance of solar concentrator under any conditions. For this design, non-sequential ray tracing mode wasused in the Zimax program with a light source that simulated solar radiation. The purpose of the design of a compound parabolic concentrator (CPC) is to take advantage of the solar radiation that falls on it without the need for an efficiently tracked system within certain limits of the angle of solar radiation fall known as the acceptance angle. That is, obtaining the largest possible number of rays received inside the CPC through reflections in the inner walls of it, which give a large amount of thermal energy to the surface of the recipient, which in turn gets this energy to be used to create electrical energy. The efficiency of receiving reflected solar radiation in this type of concentrator is great compared to other solar concentrators.
 Simulated design of solar reflector concentrator has been presented. The concentrator is a type of compound parabolic concentrator (CPC) involved of internal reflector surface (Hollow and within Poly methyl methacrylate (PMMA) polymer material) without tracking system. CPC has the property to overcome problems result from variation of incidence angle of the sun during daytime. Because the tracking system expensive and has technical problems. The efficiency of CPC has been obtained by using Zemax optical design program, for different designs has concentration ratio(c=1,2,3,4,5). That is, the ratio of the output aperture to the input aperture. Taking into account the angle of acceptance that plays a major role in the form of design and its efficiency the results are shown when designing the model with radial aperture of (50mm) and length of (500mm).The design of concentrations ratio is depends on the acceptance angle.
 c=5 at normal incident angle (ÆŸ=0). And it is almost similar if the material is used PMMA within CPC, and degradation of efficiency with increasing the incidence angle.

The dependence of the coefficient of efficiency (CE) of the heating installation "EFI" upon the initial temperature of the heat-carrying agent

The purpose of the study is to determine the increase in the efficiency of the electrophysical ionization device on a scientific basis, which produces thermal energy based on the regularity of the electrophysical ionization process. This research article discusses the dependence of the amount of thermal energy obtained in the device of electrophysical ionization on temperature. It is noted that if in the case of the traditional method of heating the substance used in the heating industry, the relative heat capacity of the substance is important, then when heated by an unconventional method, in other words, the temperature of the substance is important in the electrophysical ionization device. This indicator, determined on the basis of the experiment, emphasizes the need to apply depending on the correct choice of the physical parameters of the substance the electrophysical ionization method for the efficient production of thermal energy in the heating industry from the heat-carrying substance. Although the heating of water is mainly carried out using various well-known traditional and non-traditional methods, the natural law of heating water is unique. This law notes the dependence of the magnitude of changes in the internal energy of water in a certain volume of heated water and on the speed of movement of this mass. Considering from the point of view of the regularity of the above direction, it is noted that in order to compare the water heated by the traditional method, appropriate calculations have been made.

Phase change materials and their use for energy accumulation

Problems with overheating and unstable temperature of industrial equipment are the reasons for generating significant costs that for companies. Solving the problems related to heat removal is a challenge in modern industry. Phase change materials are the solution to these challenges (PCM). These substances can accumulate and release large amounts of thermal energy during the phase change transition. The value of the phase transition enthalpy determines the energy storage capacity. The paper presents the results of phase transitions of selected materials. The measurements were carried out on a stand for testing phase change materials. The laboratory stand made it possible to determine the thermodynamic parameters of the phase transition. The substances analysed are kinds of paraffin of different chemical composition. Due to the diversity of substances, it is possible to analyse the influence of the chemical composition on possible uses in industrial applications for energy storage.

Advantages and disadvantages of mechanical manure dewatering

The article provides an analysis of the performed experiments on mechanical dewatering of manure by a press and a centrifuge. It was determined that 2.5-3.5 tons of liquid can be removed from 10 tons of manure with 70% moisture. It is known that the mechanical method of removing moisture from manure saves a significant amount of thermal energy in comparison with the thermal method, which is moisture evaporation. However, along with water, nutrients dissolved in it, especially nitrogen, are removed from the manure. The subsequent use of nitrogen-depleted manure as fuel is beneficial because less nitrogen oxide is released into the atmosphere. Moreover, when coal is added to the manure, it is possible to intensify this process. Up to 44% of nitrogen, up to 41% of phosphorus and up to 35% of potassium pass into the liquid fraction. Such liquid can be used for foliar feeding of plants with a close arrangement of sowing crops. When using manure as a fertilizer, it is more expedient not to use mechanical dewatering, but to perform thermal drying with simultaneous disinfection from pathogenic microflora and weed seeds. To exclude formation of manure lumps with an outside crust and some droppings that didn’t undergo disinfection, it must be pre-mixed with dry droppings or sawdust.

Investigation of heat-transfer and fluid dynamic of nanofluids used in heating building

This paper proposes an approach to investigating numerically the behavior of pressure drop and heat transfer flowing through a pipe under constant wall heat flux for copper (II) oxide (CuO), aluminum oxide (Al2O3) and silicon dioxide (SiO2) nanofluids. This approach consists of (a) using the industrial computational fluid dynamics code Ansys CFX 15 for all the simulations reported in this paper, (b) validating the numerical results for the flow of water by comparing the Nusselt number and friction factor in a circular tube used in heating buildings in cold regions and (c) evaluating the use of the three nanofluids in heating buildings. An excellent concordance is obtained with the water- and nanofluid-associated theoretical–empirical heat transfer and pressure drop correlations. Numerical results showed that the use of nanofluids in heating buildings is more efficient. From the thermal condition, the aluminum oxide nanofluid is more effective than the copper (II) oxide and silicon dioxide nanofluids, and the performance index of the aluminum oxide nanofluid is also higher compared with those of copper (II) oxide and silicon dioxide nanofluids. The analysis shows that using nanofluids in heat exchangers could reduce volumetric and mass flow rates. Nanofluids require smaller heating systems, which are able to distribute the same quantity of thermal energy using base fluids. This will also reduce environmental pollutants because smaller heating units use less power.

Energetics of X-Class Flares at the Minima of 22, 23, and 24 Solar Cycles

Quite often powerful flares occur during a decrease of solar activity. In this work, we make an attempt to consider X-class flares at the minima of solar activity cycles as a separate group of events. Out of nine X-class flares we selected three such events that occurred at the minima of solar cycles 22–24: SOL1996-07-09T-09:09 (X2.6), SOL2006-12-13T-10:26 (X3.4), and SOL2017-09-06T-11:53 (X9.3); they were well observed by various instruments. All three selected flares are characterized by significant gamma-ray emission, which indicates ion acceleration during the impulsive phase. For the selected events, we estimated the energetics and distribution of the released free energy of the magnetic field between different flare components, including thermal energy and the energy of accelerated electrons and ions. No preferred energy-release channels have been identified for the considered flares at the solar activity minima. It turned out that the amount of magnetic free energy is several times higher than the amount of thermal energy and the energy of accelerated electrons and ions; the possible causes of this imbalance are discussed.

Forecasting Wastewater Temperature Based on Artificial Neural Network (ANN) Technique and Monte Carlo Sensitivity Analysis

Wastewater contains considerable amounts of thermal energy. Heat recovery from wastewater in buildings could supply cities with an additional source of renewable energy. However, variations in wastewater temperature influence the performance of the wastewater treatment plant. Thus, the treatment is negatively affected by heat recovery upstream of the plant. Therefore, it is necessary to develop more accurate models of the wastewater temperature variations. In this work, a computational model based on artificial neural network (ANN) is proposed to calculate wastewater treatment plant influent temperature concerning ambient temperature, building effluent temperature and flowrate, stormwater flowrate, infiltration flowrate, the hour of day, and the day of year. Historical data related to the Stockholm wastewater system are implemented in MATLAB software to drive the model. The comparison of calculated and observed data indicated a negligible error. The main advantage of this ANN model is that it only uses historical data commonly recorded, without any requirements of field measurements for intricate heat transfer models. Moreover, Monte Carlo sensitivity analysis determined the most influential parameters during different seasons of the year. Finally, it was shown that installing heat exchangers in 40% of buildings would reduce 203 GWh year−1 heat loss in the sewage network. However, heat demand in WWTP would be increased by 0.71 GWh year−1, and the district heating company would recover 176 GWh year−1 less heat from treated water.

Understanding pore formation and the effect on mechanical properties of High Speed Sintered polyamide-12 parts: A focus on energy input

High Speed Sintering is a novel powder-bed fusion Additive Manufacturing technique that uses an infrared lamp to provide intensive thermal energy to sinter polymer powders. The amount of thermal energy is critical to particle coalescence related defects such as porosity. This study investigates the effect of energy input on porosity and the resulting mechanical properties of polyamide-12 parts. Samples were produced at different lamp speeds, generating varying amount of energy input from a low to a high level. They were then scanned using X-ray Computed Tomography technique, following which they were subject to tensile testing. A strong correlation between energy input, porosity and mechanical properties was found, whereby pore formation was fundamentally caused by insufficient energy input. A greater amount of energy input resulted in a reduced porosity level, which in turn led to improved mechanical properties. The porosity, ultimate tensile strength and elongation achieved were 0.58%, 42.4 MPa and 10.0%, respectively, by using the standard parameters. Further increasing the energy input resulted in the lowest porosity of 0.14% and the highest ultimate tensile strength and elongation of 44.4 MPa and 13.5%, respectively. Pore morphology, volume, number density and spatial distribution were investigated, which were found to be closely linked with energy input and mechanical properties.

The experimental study of thermal energy recovery from shower greywater

ABSTRACT Long-term savings can be achieved by small household improvements to deal with the increasing energy costs that are important to all of us. Hot shower greywater is discharged to the environment with a significant amount of thermal energy. In this study, unlike the studies in the field, the recoverability potential of the shower greywater thermal energy was experimentally studied and compared by the horizontal and vertical connection of the helical coil and brazed plate heat exchangers to a unit shower cabin. The shower water heating energy consumption of thermosiphon can be reduced by approximately 16.13% and 24.69% by mounting the helical coil heat exchanger horizontally and vertically. The saving rates reach 20.62% and 27.34% for brazed plate heat exchanger, too. It could be assessed that annual energy saving can be a minimum of 247.1 kWh and a maximum of 418.7 kWh for an average family of four people. The economic size of the saving was determined between $25.2 to $42.7, annually. The installation cost of a heat exchanger for a shower cabin is $87 and it was determined that the payback period could be 2 years. The reduction of carbon dioxide emission by the possible saving of energy is an estimated minimum of 203.85 kg/year. The study aims to contribute to the creation of literature for academic studies and design processes, as well as awareness for practitioners and investors.

MODELING AND OPTIMIZATION OF THIN-FILM SOLAR THERMOELECTRIC COOLING DEVICES

We present a mathematical model for a thin-film solar thermoelectric cooling and power generation depending on current flow at the interface between two different materials. Based on the direction of the current flow, an amount of thermal energy is absorbed or dissipated to offset the disparity in thermal energy between the two key materials. The reliability of thermoelectric energy transfer is obtained in terms of the power generation mode by applying two boundary clauses, one is the external heat input and the other is the temperature at the superior surface. Accordingly, to achieve an efficient and steady-state thermophotovoltaic process due to a thin-film solar cell system, a better understating of the solar energy conversion is needed. The calculated results owing to the process of solar cell conversion provide important intrinsic reliability for thin-film solar cells. with this approach, we address and analyze several modules composed of multiple n-type and ptype thermoelectric heterostructure that connected electrically in series and thermally in parallel.

Experimental Investigation on Fuel Coolant Interaction Using Simulant Ceramic Melts in Water: Insights and Conclusions

Steam explosion is one of the crucial and poorly understood phenomena which may occur during severe accident scenario and may lead to containment failure. In spite of several experimental and analytical studies, the root cause of steam explosion has not been understood. Recent claims in the literature suggest that the presence of fine fragmentation during steam explosion causes its occurrence. In order to investigate this and understand the root cause of steam explosion, series of experiments were performed with 50 g to 2500 g of CaO-B2O3, a corium simulant in 4.5 litre of water. It was observed that steam explosion may occur even in the absence of fine fragments, which is contrary to the claims in the literature. To investigate further, conversion efficiency analysis was performed. This suggested that the amount of thermal energy converted to mechanical energy is more important deciding factor in explaining the occurrence of steam explosion. The present study discusses the importance of conversion efficiency in deciding steam explosion and also gives a new perspective to look at steam explosion phenomenology.

Modeling and Simulation of Phase Change Materials: Application to Building with Low Energy Consumption

The use of phase change materials must allow storage / destocking of energy from solar or internal gains. The applications in the case of light constructions will lead to an improvement in the thermal comfort of users and a reduction in energy consumption. The use of phase change materials (PCMs) in the energy-saving walls themselves makes it possible to substitute sensible heat storage for latent heat storage which requires a much lower volume and mass for the same amount of thermal energy. The objective of this work is the study of heat transfer by conduction during a phase change, and aims on the one hand to model and simulate the phase change behavior and on the other hand to approach the mechanism of heat exchange at the solid-liquid interface. The results obtained in 2D show the temporal evolution of the temperature, the position and the speed of the solid-liquid interface.

Fundamental Evaluation of Thermal Switch Based on Ionic Wind

A significant amount of thermal energy (mainly under 200 °C) is wasted in the world. To utilize the waste heat, efficient heat management and thermal switching is required. The basic characteristics of a thermal switch that controls the flow of heat by switching on/off the ionic wind is discussed in this study. The study was conducted through experiments and numerical simulations. A heater made of aluminum block maintained at 100 °C was used as a heat source, and the rate of heat flow to a copper plate placed over it was measured. Ionic wind was induced by corona discharge with a needle placed on the heater. The ratio of heat transfer coefficients was obtained in the range of 3–4, with an energy efficiency of around 10. The heat flux at this condition was approximately 400 W/m2. The numerical simulations indicate that the heat transfer is enhanced by ionic winds, and the results were found to corroborate well with the experimental ones.

Wind Energy Usage for Building Heating Applying Hydraulic System

The most ordinary way to use wind energy for building heating needs is to convert mechanical wind energy into electrical energy and to use electrical energy for heating. Though there are ways to convert mechanical wind energy into thermal energy without transitional energy conversion – hydraulic systems can be implemented for this purpose. Wind rotor gives rotational motion to the pump of hydraulic system and it creates fluid circulation in the hydraulic system. A part of liquid mechanical energy due to hydraulic resistance of the system converts into the thermal energy when the liquid circulates in the close hydraulic loop and it heats up the liquid that can be used for heating purposes. Different hydraulic valves can be integrated in the hydraulic system and they can work as the load-regulating component of the system. The purpose of the study was to adjust the hydraulic load to the optimal value in order to generate a maximum amount of thermal energy. During the study, the work of a wind rotor was simulated by an electric motor, rotated at different frequencies (without feedback). The hydraulic system consisted of a gear pump, an adjustable load regulation valve, pipes, oil tank, sensors for measuring motor shaft rotational speed, oil temperature and pressure. The experiments were carried out at different electromotor speeds: 12.5, 17.5 and 22.5 Hz, and for different oil temperatures in the range of 20 to 50 °C. The relationship between the opening degree of the valve and the amount of generated thermal energy was determined. The study showed that wind energy usage can cover a significant part of the building's thermal energy needs at the same time reducing pollution and the usage of the fossil fuel for heating purposes.

Verification оf Non-Stationary Mathematical Model оf Concrete Hardening in Thermal Technological Installations

Thermo-technical installations consuming significant amounts of thermal energy are used in order to intensify precast and reinforced concrete production processes under industrial conditions. Despite significant progress in the study of concrete hardening in accelerated hydration devices, a prominent lack of reliable and cost-effective research and optimization methods of their operation is observed. The methods used in real production processes are mainly based on empirical dependences obtained for specific technological conditions. These methods can not always be applied for other modes and technologies. The present paper develops calculation methods based on fundamental laws that make it possible to obtain functions for evolution of concrete product hydration process. Methods of mathematical modeling permit to develop new ways directed on improvement of modes for heat treatment of concrete products and accelerated hydration technologies. The paper describes a mathematical model for calculating a hardening process of a concrete product that includes a transient three-dimensional heat conductivity equation, a function of internal heat release due to behavior of exothermic reactions of cement hydration and also a system of initial and boundary conditions. A numerical simulation for temperature and hydration coefficient of a concrete product having shape of a 0.1´0.1´0.1 m cube has been performed in the paper. Verification of the non-stationary mathematical model for calculating temperature fields and hydration degree while using experimental data on concrete product strength obtained under industrial conditions. Investigations on hydration degree function of time have shown that experimentally obtained values of compressive strength correlate with hydration coefficient and hydration rate functions of heat treatment time which are calculated on the basis of the proposed non-stationary mathematical model of concrete product hardening. Satisfactory agreement of experimental and calculated data confirms adequacy of the proposed non-stationary mathematical model for calculating temperature fields and hydration degree with accelerated heat treatment of concrete products.