Process Heat Production Research Articles

5-HT Receptors and Temperature Homeostasis.

The present review summarizes the data concerning the influence of serotonin (5-HT) receptors on body temperature in warm-blooded animals and on processes associated with its maintenance. This review includes the most important part of investigations from the first studies to the latest ones. The established results on the pharmacological activation of 5-HT1A, 5-HT3, 5-HT7 and 5-HT2 receptor types are discussed. Such activation of the first 3 type of receptors causes a decrease in body temperature, whereas the 5-HT2 activation causes its increase. Physiological mechanisms leading to changes in body temperature as a result of 5-HT receptors’ activation are discussed. In case of 5-HT1A receptor, they include an inhibition of shivering and non-shivering thermogenesis, as well simultaneous increase of peripheral blood flow, i.e., the processes of heat production and heat loss. The physiological processes mediated by 5-HT2 receptor are opposite to those of the 5-HT1A receptor. Mechanisms of 5-HT3 and 5-HT7 receptor participation in these processes are yet to be studied in more detail. Some facts indicating that in natural conditions, without pharmacological impact, these 5-HT receptors are important links in the system of temperature homeostasis, are also discussed.

Calorific Value and Ash Content of Extracted Birch Bark

Wood bark is one of the main residues in the forest industry worldwide. Currently, the bark is used to produce process heat and energy. A major amount of this is mainly used in power and heating plants. Due to the fact that the demand for heating energy is seasonal, the storage of bark is necessary. The storage process of bark and therefore related problems (like biomass loss, increase of ash content etc.) were discussed in previous studies. Different approaches to increase the economic and ecologic value of wood bark through gaining extractives from the bark were investigated in order to revalue this by-product as well. This study shows the change in calorific value and ash content of birch bark based on results of ultrasound-assisted extraction (UAE). Regarding the energy content (gross calorific value), a comparison was made that showed that due to the extraction process, the energy content of the birch bark is decreased. The extraction yield of the methanol extracts results as 17.74%. The total phenolic content (TPC) of this extract was 447.75 mg GAE/g of oven-dried bark extracts. The amount of ash increased by 23.74% after the extraction. The gross calorific value of the birch bark decreased by 6.98%. The calculated energy content decreased from 2.48 MWh/m3 before extraction to 1.61 MWh/m3 after extraction, which is a loss of 35.08%. The obtained results show that through the extraction of birch bark via ultrasound-assisted extraction, valuable substances can be produced. At the same time, the ash content of extracted birch bark increased whereas the energy content decreased.

Influence of Lubricant Supply on Thermal and Efficient Performances of a Gear Reducer for Electric Vehicles

Abstract The amount of lubricating oil in a gear reducer greatly influences components’ temperature and efficiency of the reducer. A thermal network simulation model of a gear reducer for electric vehicles based on amesim software was built for thermal and efficiency analysis of the reducer, where heat production and transfer processes of each component in the reducer are considered. Moreover, secondary development submodels were developed to calculate the convection coefficients in real time based on different lubricating oil temperatures and working conditions. Next, the experiments were conducted to verify the developed model regarding transmission efficiency and lubricating oil equilibrium temperature in the reducer. The deviation between the numerical and experimental results is less than 5%, which indicates high accuracy of the developed thermal network model. Thereafter, efficiency and heat balance simulation tests under different working conditions were performed to determine an optimal lubricating oil supply, which is 14 mm gear-oil-immersion oil supply in this study. Finally, a comparison between the reducer with the optimal oil supply and that with normally used 22 mm gear-oil-immersion supply in the NEDC cycles in low temperature was done. The reducer with the optimal oil supply shows 1.032% energy saving. The method presented in this article provides a good guide to design and optimization of the gear reducer for electrical vehicles.

Data driven model for heat load prediction in buildings connected to District Heating by using smart heat meters

An accurate characterization and prediction of heat loads in buildings connected to a District Heating (DH) network is crucial for the effective operation of these systems. The high variability of the heat production process of DH networks with low supply temperatures and derived from the incorporation of different heat sources increases the need for heat demand prediction models. This paper presents a novel data-driven model for the characterization and prediction of heating demand in buildings connected to a DH network.This model is built on the so-called Q-algorithm and fed with real data from 42 smart energy meters located in 42 buildings connected to the DH in Tartu (Estonia). These meters deliver heat consumption data with a 1-h frequency. Heat load profiles are analysed, and a model based on supervised clustering methods in combination with multiple variable regression is proposed. The model makes use of four climatic variables, including outdoor ambient temperature, global solar radiation and wind speed and direction, combined with time factors and data from smart meters. The model is designed for deployment over large sets of the building stock, and thus aims to forecast heat load regardless of the construction characteristics or final use of the building. The low computational cost required by this algorithm enables its integration into machines with no special requirements due to the equations governing the model.The data-driven model is evaluated both statistically and from an engineering or energetic point of view. R2 values from 0.70 to 0.99 are obtained for daily data resolution and R2 values up to 0.95 for hourly data resolution. Hourly results are very promising for more than 90% of the buildings under study.

Potential Early Markets for Fusion Energy

We examine potential early markets for fusion energy and their projected cost targets, based on analysis and synthesis of many relevant, recent studies and reports. Seeking to provide guidance to ambitious fusion developers aspiring to enable commercial deployment before 2040, we examine cost requirements for fusion-generated electricity, process heat, and hydrogen production based on today’s market prices but with various adjustments relating to possible scenarios in 2035, such as “business-as-usual,” high renewables penetration, and carbon pricing up to 100 $/ $$\hbox {tCO}_2$$ . Key findings are that fusion developers should consider focusing initially on high-priced global electricity markets and consider including integrated thermal storage, depending on techno-economic factors, in order to maximize revenue and compete in markets with high renewables penetration. Process heat and hydrogen production will be tough early markets for fusion, but may open up to fusion as markets evolve and if fusion’s levelized cost of electricity falls below 50 $/ $$\hbox {MWh}_{\mathrm {e}}$$ . Finally, we discuss potential ways for a fusion plant to increase revenue via cogeneration (e.g., desalination, direct air capture, or district heating) and to lower capital costs (e.g., by minimizing construction times and interest or by retrofitting coal plants).

PREDICTION OF THERMAL ERRORS IN MACHINE TOOLS THROUGH DECOUPLED SIMULATIONS USING GENETIC ALGORITHM AND ARTIFICIAL NEURAL NETWORKS

Thermal errors are one of the major contributors towards positioning discrepancies in machine tools in precision machining. Along with friction and waste heat generated from production processes and internal heat sources, environmental influences around the machine tool create considerable thermal gradients followed by non-linear structural deformations. Efficient quantification of these three contributing sources of thermal errors are required in order to formulate a reliable thermal-error compensation system. The creation of all possible thermal configurations, which a machine tool could be subjected to, is experimentally infeasible and requires complex and time-consuming coupled flow and thermo-structural simulations. This paper presents a new approach in thermal error prediction by using CFD and finite element (FE) simulations to train a three-level interconnected neural network system. The first level essentially decouples flow simulations from thermo-structural simulations using optimal FE node points found using a Genetic Algorithm (GA), which significantly reduces the required training data. The boundary convection data obtained from this level is used in the second level to predict possible thermal configurations of the machine tool, after careful consideration of parameters related to internal heat sources and production processes. The third level maps these thermal configurations onto displacements on the machine tool.

Thermal production and heat cost analysis of the potential of solar concentrators for industrial process applications: A case study in six sites in Morocco

Industrial Process Heat (IPH) represents a promising sector of application for solar concentration technologies – the Linear Fresnel Reflectors (LFR) as an alternative to the conventional source of thermal energy. Morocco is endowed with an abundant solar resource as other countries in the MENA region, with high level of DNI available over the year especially in the southeast, mid-south, and the south (Moroccan Sahara Desert). The main objective of this work is to assess the potential of solar thermal production of industrial process heat considering six different sites in Morocco. The evaluation has been done with respect to the Levelized Cost of Heat (LCoH), representing the whole production cost structure. This study includes as well a comparison of the same application in Stellenbosch (South Africa) and Andasol (Spain). The results show that the annual thermal production is 7.2 GWh-th/year in Zagora, 6.4 GWh-th/year in Missour, and around 6.3 GWh-th/year in Ben-Guerir and Erfoud. As expected, the Moroccan sites show, in general, higher thermal energy production with +1.4 GWh-th/year in Zagora compared to the Andasol site, and +2.9 GWh-th/year compared to Stellenbosch. The cheapest LCoH has been found to be 2.47 c$/kWh-th in Zagora, whereas it was 4.02 c$/kWh-th in Stellenbosch and 3.04 c$/kWh-th in Andasol, with a difference of +62.75% and +23.1% respectively.

Passive and Walk-Away Safe Small and Microreactors for Electricity Generation and Production of Process Heat for Industrial Uses

Abstract This paper presents the passive design and safety features as well as the biological dose estimates for end-of-life handling of postoperation for the walk-away safe, scalable liquid metal-cooled small modular (SLIMM) and very-small, long-life, modular (VSLLIM) small and microreactor with high-assay low enrichment uranium (HALEU). These passive operation sodium cooled, fast-neutron spectrum reactors have recently been developed at the University of New Mexico's Institute for Space and Nuclear Power studies. The SLIMM-small modular reactor could generate 100–10 MWth continuously, 24/7 without refueling for 6.3–68 full power years (FPYs), respectively, while the VSLLIM microreactor could generate 10–1.0 MWth without refueling for 5.8–92 FPYs, respectively. These reactors would be factory constructed, assembled, and sealed and then transported to designated sites by rail, a truck, or a barge. At the site, these reactors would be installed below ground, to protect against impact by an airplane or a missile, and mounted on seismic isolation bearings, to resist earthquakes. The SLIMM and VSLLIM reactors could provide for both electricity generation and process heat and the electrical plants can easily be connected to a central or distributed grid with renewable energy sources. The integrated VSLLIM reactor and other plant components for electricity generation and/or process heat production could all be deployed on a single railroad car, a barge, or an 18-wheeler truck, to small and remote communities, and advance bases or outposts.

The effects of L-shaped heat source in a quarter-tube enclosure filled with MHD nanofluid on heat transfer and irreversibilities, using LBM: numerical data, optimization using neural network algorithm (ANN)

In this paper, the process of natural convection heat transfer (NCHT) and production of entropy (POF) in a portion of a tube has been modeled two-dimensionally. The examined problem is a quarter-tubular enclosure (quarter of a tube) which is filled with water-alumina nanofluid and subjected to a magnetic field (MF) of strength B0 at angle ω relative to horizon. Lattice Boltzmann Method (LBM) is used to simulate this problem. The ranges of parameters used in this investigation are: 0 < ω < 90, 0 < Ha < 60, and 0.1 < L, H < 0.5, and the obtained results include the Nusselt number (Nu), generated entropy, and Bejan number (Be). The results of thermal and dynamic analyses indicate that by growing the Hartmann number (Ha), the NCHT and POF values go up and the Bediminishes. Heat transfer is also improved by increasing the length of the enclosure’s hot walls. The highest amount of heat transfer occurs at the MF angle of 60º, and it is 10.3% greater than the amount of heat transfer occurring at horizontal MF. Finally, an artificial neural network was used to simulate the cavity performance based on these parameters. An optimization is performed on the parameters of heat source length and Ha. The optimization is aimed at finding suitable parameter values that lead to the highest heat transfer rate and lowest POF. A table listing a number of optimal points has been presented at the end of the paper. The optimization results indicate a desirability of about 0.56, which is achieved under the best conditions at defined parameter ranges. In this case, the values of Nu and POF are 7.26 and 3.54, respectively. The optimal state occurs at the non-dimensional hot wall length of about 0.5 and Ha of 37.7.

Performance investigation of a passive battery thermal management system applied with phase change material

Lithium-ion batteries will produce a lot of heat during working, which can increase the temperature and temperature difference in the battery module, and seriously impair the capacity, life, and safety of the batteries. Therefore, an effective thermal management system should be implemented to control the temperature of the batteries, while reducing the energy consumption and cost of the system as much as possible. In this paper, a passive, low-cost battery thermal management system consisting of pouch lithium-ion cells and phase change material units is designed. Based on the heat production process of the battery and heat transfer theory of the phase change material, a numerical model is built and the performance of the thermal management system is analyzed. It is found that the phase change material units can effectively decrease the maximum temperature and the maximum temperature difference on the cell at the end of discharge, and thus have good heat storage capability and temperature equalization capability. After insulating heat dissipation from the surfaces of the phase change material units, a temperature retaining function can also be achieved. The effects of the design parameters of the phase change material unit on its thermal management performance are further investigated, including the thermal conductivity, viscosity, and latent heat of the phase change material, the thickness of the phase change material unit, and the thermal conductivity of the unit shell. It could provide theoretical references and technical means for the design and implementation of passive, low-cost battery thermal management systems applied with phase change materials.

Operational and economic analysis of a Velox-type combined heat &amp; power plant with a throttle valve

For many years, the Department of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a small-capacity (about 500 kWe) steam-gas power plant. Based on many years of experience in operation of this power plant utilizing the Velox-type gas-steam system, an idea arose to modify this type of thermal power cycle to create a combined heat and power (CHP) plant of small capacity, dedicated for distributed heat and power production or production process steam with high temperature. Previous thermodynamic and economic analysis of that type of low-power CHP plant confirmed many advantages of using this type of solution in low-power engineering. The new idea is to add a throttle valve between the economizer and the evaporator for the reference cycle of the gas-steam Velox-type CHP plant. It was further assumed that water would partially be vaporized on the valve. This paper presents a thermodynamic and economic analysis of this type of a system with an added throttle valve. Downstream the valve, the evaporated water fraction is fed directly into the steam superheater. It is determined how such a retrofit affects the system thermodynamic and economic characteristics. The system is modelled in the EBSILON® Professional 14 software.

Overview of Biomass Conversion to Electricity and Hydrogen and Recent Developments in Low-Temperature Electrochemical Approaches

Biomass is plant or animal material that stores both chemical and solar energies, and that is widely used for heat production and various industrial processes. Biomass contains a large amount of the element hydrogen, so it is an excellent source for hydrogen production. Therefore, biomass is a sustainable source for electricity or hydrogen production. Although biomass power plants and reforming plants have been commercialized, it remains a difficult challenge to develop more effective and economic technologies to further improve the conversion efficiency and reduce the environmental impacts in the conversion process. The use of biomass-based flow fuel cell technology to directly convert biomass to electricity and the use of electrolysis technology to convert biomass into hydrogen at a low temperature are two new research areas that have recently attracted interest. This paper first briefly introduces traditional technologies related to the conversion of biomass to electricity and hydrogen, and then reviews the new developments in flow biomass fuel cells (FBFCs) and biomass electrolysis for hydrogen production (BEHP) in detail. Further challenges in these areas are discussed.

Energy Recovery from Olive Pomace by Hydrothermal Carbonization on Hypothetical Industrial Scale: a LCA Perspective

This work aimed to analyze and compare the environmental impacts of hydrothermal carbonization (HTC) process performed on olive pomace, aimed at energy recovery. Twelve alternative pathways, considering variable process conditions in terms of temperature (260, 280 and 305 °C), heat recovery layouts and the subsequent combustion of the generated solid product, were analyzed. Results, related only to the processing phases (i.e. without including avoided effects), showed, as expected, that the final environmental performance depends on the HTC process temperature. Moreover, it was noted that the resulting impacts are from 1.4 to 2.0 lower for the layouts with heat recovery, for all the analyzed impact categories, with exception of Freshwater Toxicity. It was also reported that by substituting the fuel in marginal processes of heat production, environmental load reduction potential, regarding all impact categories, can be achieved. The highest benefits were achieved by substituting coal with HTC pellet in the heat production, followed by wood pellets and natural gas. Concerning the contribution analysis, the combustion processes of HTC and wood pellet represent the major contributions to the Climate Change and Acidification impacts, the combustion processes of HTC and wood pellet represent the major contributions, around the 95% and the 75% of the total, respectively, for the cases with the highest HTC temperature and no recovery scheme. For the Eutrophication potential, biomass production contributes significantly to the final effect. Regarding the Freshwater Ecotoxicity, the major part of the impact is coming from the HTC process and the relative liquid phase emissions assumed to be composed by phenols and furfurals released from the process. However, this part of the system needs to be further analyzed in detail.

Numerical investigations of CO2 and N2 miscible flow as the working fluid in enhanced geothermal systems

Abstract In this study, the heat extraction from geothermal reservoirs with the application of CO2 and N2 miscible flow as the novel working fluids has been investigated based on the discrete fracture network model. The miscible flow with different CO2 and N2 proportions and highly pressure and temperature dependent properties have been integrated into reservoir simulations. The heat production processes for CO2 and N2 miscible flow have been simulated with two different discrete fracture networks, which also take the thermal-hydraulic-mechanical (THM) coupling mechanisms into consideration. Based on simulation results, it is revealed that the heat extraction efficiencies show an irregular trend with the increasing proportions of N2 in the mixture. It is found that the miscible flow with two different N2 proportions (20% and 40%) can be a more efficient working fluid than the one with larger N2 proportions. Based on simulation results, cumulative heat production curves that represent ten CO2 and N2 proportions can be divided into three categories. Evaluations of relevant permeabilities and effective normal stresses at sample points were made, which contributed to the comprehensive analysis of the heat transfer processes. It is also found that there are reasonable ranges for the miscible flow with different CO2 and N2 proportions as working fluids that allows higher heat extraction efficiencies, which are validated by a series of comparisons. Thus, in order to define the humps on the heat extraction efficiency curves, a new concept of the optimized heat extraction efficiency range is proposed and validated. It is proved that fluid properties of the miscible flow with different CO2 and N2 proportions and the reservoir temperature determine the optimized heat extraction efficiency range directly. This study proposes the miscible flow of CO2 and N2 as the working fluid, which provides a new alternative for geothermal energy production.

Numerical simulation of landslide motion based on thermo-plastic mechanics

Landslides with long run-out and high velocities pose severe threat to infrastructures and lives in mountain areas. Frictional heating has long been considered a mechanism responsible for some remarkable characteristics of natural landslides such as surprisingly long travel distances and high velocities. In order to study the influence of this mechanism on the motion of such landslides, one method considering the thermo-plastic mechanics was combined with a depth-averaged model for simulating the long run-out motion of landslides in the condition of deformation. The effects of several key parameters on thermo-plastic mechanics were discussed by several numerical tests through the processes of landslide motion, heat production and diffusion, pore-fluid pressure generation and dissipation, and thermo-plastic collapse of the soil skeleton at the shear zone. Then the effectiveness of the model was verified by comparing the numerical results with the field investigation of Sanxicun landslides.

Optimization of heat production processes in the biofuel vortex combustion systems

Optimization of heat production processes in the biofuel vortex combustion systems

Comparison of multi-field coupling numerical simulation in hot dry rock thermal exploitation of enhanced geothermal systems

In order to alleviate the environmental crisis and improve energy structure, countries from all over the world have focused on the hot dry rock geothermal resources with great potential and with little pollution. The geothermal heat production from Enhanced Geothermal System (EGS) comes with complex multi-field coupling process, and it is of great significance to study the temporal and spatial evolution of geothermal reservoir. In this work, a practical numerical model is established to simulate the heat production process in EGS, and the comparison of thermal-hydraulic (TH), thermal-hydraulic-mechanical (THM) and thermal-hydraulic-mechanical-chemical (THMC) coupling in geothermal reservoir is analyzed. The results show that the stable production stage of the three cases is approximately 5 years; however, compared with TH and THMC coupling, the service-life for THM coupling decreased by 1140 days and 332 days, respectively. The mechanical enhanced effects are offset by the chemical precipitation, and the precipitation from SiO2 is much larger than the dissolution of calcite. Cited as : Chen, S., Ding, B., Gong, L., Huang, Z., Yu, B., Sun, S. Comparison of multi-field coupling numerical simulation in hot dry rock thermal exploitation of enhanced geothermal systems. Advances in Geo-Energy Research, 2019, 3(4): 396-409, doi: 10.26804/ager.2019.04.07

Characterization of cassava biomass using differential scanning calorimetry and thermogravimetry for energy purposes

Most of the agricultural industries generate daily waste, which due to toxicity or quantity deserve special attention. The cassava starch produces a significant quantity of residues, which must be rationally used for minimizing the environmental impact of the agricultural activities. The present study aims to enhance the use of this solid residue. We analyzed the cassava bagasse by means of the following techniques: thermogravimetric analysis (TG) and differential scanning calorimeters (DSC). It was addressed the effects of operational conditions (final temperature, heating rate, atmosphere, air flow and size of particles). The cassava bagasse samples collected in a cooperative production facility in Paraty-RJ were characterized using TGA/DSC in order to describe the thermal behavior of these residues. The DOE methodology proposed by Taguchi was used to analyze and cover a broader range of operational parameters. The most influential variables were identified for the process of heat production using DOE technique. These variables provide the best combination for heat flux with residence time of 30 min, air flow of 50 mL min−1, particle size sieved to 0.42–0.71 mm and heating rate of 25 °C min−1. The main parameters related with the thermal decomposition, effective activation energy and decomposition mechanism were newly determined using thermal techniques analysis methods (TGA/DSC) for the cassava residue.

Techno-Economic Optimization of Electricity and Heat Production in a Gas-Fired Combined Heat and Power Plant With a Heat Accumulator

Abstract At present, power systems based on gas turbines are mainly used for electricity and heat generation. Gas turbines are used in industrial and institutional applications due to high-temperature exhaust, which can be used for heating, drying, or process steam production. The combined cycle gas turbine plants are a mature technology with high reliability and offering rapid response to changing demand for electricity and heat. The combination of a gas turbine with a heat recovery system and a heat accumulator makes the combined heat and power (CHP) plant a flexible unit. The paper presents the optimization tool for the planning process of electricity and heat production in the gas-fired CHP plant with a heat accumulator. The detailed mathematical model of the analyzed cogeneration plant was developed with the EBSILON®Professional and verified based on the results from on-site tests and warranty measurements. The implemented optimization algorithm is used to maximize the profits of the CHP plant operation. The presented solution is based on an evolutionary algorithm. The optimization algorithm is applied to the production determination for the day-ahead planning horizon, with 1-h time step. The obtained results show that the developed optimization model is a reliable and efficient tool for production planning in a CHP plant with gas turbines. The comparative exergy analysis for different technologies of heat recovery from gas turbine exhaust gases was performed to evaluate the quality of the energy conversion process in the CHP plant.

Filtration and heat processes in lateral extrusion of plastically compressible materials

We consider the process of heat production and transfer in the lateral extrusion of plastically compressible material. Heating of the material occurs due to friction and due to energy dissipation during the irreversible deformation process. We assume that the material obeys to Green’s elliptical yield condition and to the normality rule. We also consider the fluid filtration process in the pores of the material. It is assumed that the movement of the fluid is caused by change in density of the material during deformation. In the present paper we obtain exact solutions of the equations determining the mechanical behavior of the material at a steady flow in the case of small change in density. The approximate analytical solutions of the heat transfer problem and filtration problem in uncoupled formulation are also obtained.