Heat Disposal Research Articles

Enhancing Cu2+ removal efficiency in a hybrid electrodeposition system based on vertically placed thermally regenerative batteries using gradient porous electrodes

Thermally regenerative batteries (TRB) can combine with an electrodeposition cell (EC) to develop a hybrid system (TRB-EC) for low-grade waste heat disposal and Cu2+ recovery from wastewater. To improve the Cu2+ removal efficiency in EC, a vertically placed reactor and gradient porous electrodes are proposed to remiss ammonia crossover and enhance power generation in TRB. The vertically placed reactor effectively reduced the NH3 concentration difference on the both side of anion exchange membrane, inhibiting NH3 transmembrane transport. Moreover, the gradient porous anode is used to adjust the physical and chemical distribution in anode chamber. The results indicate that the maximum power density of 14.6 W/m−2 is obtained in a TRB employing the gradient porous electrodes (the pore order is large-middle-small scale), which is 22 % better than that of electrodes with uniform-size pores. Through the strategy of flow catholyte, the maximum power density can be further increased to 19.4 W/m−2 and the cathodic coulombic efficiency is improved to 92.7 %. Due to above optimal design, the Cu2+ removal efficiency of the hybrid system can reach an impressive value of 98.4 % (87.7 % in TRBs and 10.7 % in EC), showing a promising method of heat waste and Cu2+ disposal.

Energy saving when using equipment for the disposal of low-potential waste heat

The article discusses the problem of energy saving in the context of comparing different types of heat exchangers for the utilization of high-potential waste heat. The advantages and disadvantages of various regenerative ventilation schemes are analyzed and the most efficient heat exchangers are proposed for use in various fields. These include various types of regenerative heat exchangers. The factors influencing reliability and creation of optimal operating modes with high energy savings are considered. Recommendations for the use of enthalpy heat exchangers with the required technical characteristics are given. Various types of nozzles are shown to ensure better efficiency. The advantages and disadvantages of regenerative heat exchangers with an intermediate carrier and techniques for reducing the cost of manufacturing such structures are considered. The areas of application of small-sized plate heat exchangers are given. The principle of operation of heat exchangers on heat pipes (HHP) and their technical characteristics are considered. A compactness criterion has been introduced, which allows comparing different types of heat exchangers. The instantaneous boiling apparatus for the utilization of low-potential internal (by-product) energy resources (IER) and possible applications are considered in detail. In all cases of using the considered schemes, the prospects for their development in industry are noted.

Analysis of Vaporizer Effect for Accelerated Heat Dissipation of Car Air Conditioner (AC)- An Experimental Study on Gas-Fueled Cars

It is a concrete effort today in realizing the concept of Low-Cost Green Car (LCGC) through the conversion of oil-fueled cars to the form of fuel gas. In the system (fuel system) gas car there is a vaporizer unit that functions to change the liquid phase to the gas phase while stabilizing it at a working pressure of ± 1.5-2 bar, thus the work of the vaporizer unit requires heat. On the other hand, the car’s AC system will dissipate heat through the condenser, where the performance of the cooling system will be better by accelerating the heat disposal in the condenser. This research aims to build an energy conservation system between the AC and Vaporizer systems using an efficient control valve model with the concept of rotation. With the application of this rotational valve system, it is expected that the control of hot fluid to the vaporizer is faster and faster. The results of data analysis showed enthalpy (h) refrigerant changes before and after the expansion valve/capillary pipe, down at 240 kJ/kg. COP increased slightly with efficiency figures rising by 0.03.

Distributionally robust optimization for dispatching the integrated operation of rural multi-energy system and waste disposal facilities under uncertainties

With the increasing global attention to environmental protection and sustainable development, governments around the world attach great importance to the low-carbon reform of rural energy and waste management. The interaction between waste-to-energy technology (W2E) and rural multi-energy system has emerged as one of the important issues that must be considered. Based on this, this paper combines two W2E technologies, biomass biogas power generation and garbage incineration power generation, with photovoltaic and energy storage systems. A distributionally robust optimization (DRO) model for the waste-disposal-facilities-involved rural multi-energy system (W-RMES) is proposed. An ambiguity set of the photovoltaic output probability distribution is constructed by the Wasserstein metric. The minimum operation cost of W-RMES is solved under the condition that the prediction error of photovoltaic output obeys the worst probability distribution of the ambiguity set. Finally, through simulation verification, the rational utilization of waste can effectively realize the coordination and optimization between the waste disposal and multi-energy supply of electricity, heat, and biogas. Compared with the conventional rural energy system, W-RMES is more economical and eco-friendlier, which is reflected in the reduction of operation cost by >14.87 %, the removal of flue gas production by >12.89 % and the improvement of waste disposal capacity by >21.77 %. Besides, the model also realizes systemic coordination of robustness and economic efficiency.

Improving the efficiency of energy saving through the use of thermal energy

The article analyzes the problem of energy saving in the context of organizational and technical measures. One of the energy saving factors is the use of waste heat of various potential. The advantages of using waste heat in the energy sector and the scope of their application are considered. Power plants for waste processing and their parameters are described. Examples of the creation of special energy devices for the chemical industry are given. The connection of internal (by-product) energy resources (IER) with technologies using melting furnaces is noted. The boundaries of the use of heat recovery boilers (HRB) in various industries are determined. The schemes of HRB application at the wastewater disposal site with quantitative and qualitative characteristics are given. A method for improving economizers using bimetallic pipes and heat exchangers is given. The use of batteries in the disposal and consumption of waste heat is justified. The ways of increasing the efficiency of compressed air systems and the features of using arc steelmaking furnaces to reduce energy consumption are considered. The comparison of local heat supply schemes with regenerative ones is carried out and the prospects for the development of these schemes are noted.

Antimony Nanoparticles Encapsulated in Self-Supported Organic Carbon with a Polymer Network for High-Performance Lithium-Ion Batteries Anode.

Antimony (Sb) demonstrates ascendant reactive activation with lithium ions thanks to its distinctive puckered layer structure. Compared with graphite, Sb can reach a considerable theoretical specific capacity of 660 mAh g−1 by constituting Li3Sb safer reaction potential. Hereupon, with a self-supported organic carbon as a three-dimensional polymer network structure, Sb/carbon (3DPNS-Sb/C) composites were produced through a hydrothermal reaction channel followed by a heat disposal operation. The unique structure shows uniformitarian Sb nanoparticles wrapped in a self-supported organic carbon, alleviating the volume extension of innermost Sb alloying, and conducive to the integrality of the construction. When used as anodes for lithium-ion batteries (LIBs), 3DPNS-Sb/C exhibits a high invertible specific capacity of 511.5 mAh g−1 at a current density of 0.5 A g−1 after 100 cycles and a remarkable rate property of 289.5 mAh g−1 at a current density of 10 A g−1. As anodes, LIBs demonstrate exceptional electrochemical performance.

Use of energy-efficient systems for ensuring the microclimate of the premises

The article considers the use of the WLHP system, which is an alternative to already existing heating systems. It allows you to streamline engineering networks and implement energy-saving measures in the heat consumption sector. The advantages of the system are noted and the use of a heat pump in the system is recommended for the disposal of excess heat in the premises in order to reduce heat consumption. Measures related to energy-efficient technologies in Poland, Germany, and Sweden, including the use of heat pumps, were considered. The information regarding of the measurements СОР of energy-saving equipment implemented in Ukraine, in accordance with current standards, with the aim of improving the quality characteristics of the equipment present in the WLHP system, was introduced. The advantages of such a solution in comparison with traditional systems for ensuring the microclimate of premises are noted.

Closing repository void spaces using bentonite: does heat make a difference?

Bentonites are commonly proposed for use in the geological disposal of high heat generating radioactive wastes. Repository designs include bentonite as a buffer to occupy the void space around the waste canisters because of the favourable properties it can exhibit that enhance the isolation and containment functionality of the repository. Many repository concepts introduce small voids within the bentonite because the buffer is incorporated as individual bricks stacked around the waste canisters. These voids must be closed to prevent the persistence of high permeability pathways for fluids. As bentonite hydrates, it expands and can exert a considerable swelling pressure on the surrounding host rock. The bentonite also expands to fill the engineering cavities inherently present in the repository, but the non-uniform development of total stress and pore pressure could cause persistent material heterogeneities to occur. This is likely to be exacerbated by the thermal gradients existing between the hot waste and the temperature of the surrounding host rock in the early stages of repository post-closure. Whilst this is an area of ongoing research, the final extent of bentonite homogenisation within the repository and for how long property variations persist, is not well understood.In this study, four tests were conducted on pre-compacted, sodium-activated MX80 bentonite samples placed next to a water-filled engineering void, to examine the effect of elevated temperature on the development of swelling and swelling pressure as a function of sample size. The sample lengths were chosen to give small bentonite-to-void ratios, and to represent extremities of behaviour, such that an acceptable upper limit of void size might be established. The results demonstrated that even under extreme bentonite-to-void ratios, the bentonite was able to swell and completely fill the void space, exerting a small but measurable swelling pressure. Under the conditions of this study, the results have shown larger end-of-test swelling pressures and higher final dry densities along their entire length than shown in equivalent tests conducted at ambient temperature. In addition, the elevated temperature tests showed a rapid initial increase and then decrease in swelling pressure at the start of testing, approaching an asymptote in swelling pressure more quickly, whilst uptaking less water than in the ambient temperature case. This implied that heating the bentonite reduced the test duration by about 60%, which is most likely explained by a reduction in the viscosity of the test permeant at higher temperatures.

Application of Finnish energy saving and emission reduction technology in glass industry

Finland has formed a unique energy saving and emission reduction concept in the process of realizing the leap from agriculture to industrialization, which has been shown in the utilization of raw materials, optimizing fuel structure, recovering waste heat and waste disposal. These concepts and aspects have been widely used in the glass industry, from the early glass technology reform to the present stage of technological innovation for the development of Finnish glass industry to provide an important guarantee. Finland experience provides experience and reference for the development of glass industry in China, which has important strategic significance in the increasingly severe environment of energy crisis.

Pore pressure response to disposal of heat generating radioactive waste in a low permeability host rock

Low permeability rocks provide an attractive option for disposal of radioactive waste because transport of radionuclides will be diffusion dominated and hence slow. However, heat generated by the waste will cause an increase in the pore pressure which may become high enough to damage the rock creating higher permeability areas and faster radionuclide transport paths. It is therefore important to understand the magnitude of pore pressure changes caused by the heating effect of the waste, to develop confidence that the rock will maintain its low permeability.This paper considers coupled Thermal-Hydraulic-Mechanical (THM) modelling of two experiments at the Meuse/Haute-Marne URL: the TED experiment at 1/5th scale and the ALC experiment at full repository scale. Modelling these experiments has enabled testing of understanding of key processes and parameterisation through a blind prediction of the results of the ALC experiment based on modelling of the TED experiment. Calibration of models to both experimental data sets has improved understanding of the importance of processes and parameters in determining pore pressures.The modelling captures the key features of the experiment, demonstrating that the physical processes are well represented in the model whilst spatial variability of physical properties can lead to significant uncertainties in pore pressure estimates. The work demonstrates the benefits of conducting experiments at full-scale, ideally located close to the repository site, and of building a good understanding of the spatial variability of the host rock properties.

Development of experimental designs of the integrated heater for the disposal of low-potential waste heat of ventilation emissions

The aim of the study is to develop an experimental design of a complex air heater, conduct and analysis of the experiments, as well as to determine the main characteristics of the thermo-electric generator during the utilization of low-potential heat-La exhaust gases. The experimental setup consists of two units – thermoelectric generator operating on the principle of cross-heat exchanger heat exchange for heat recovery with parallel warmed of the supply air, which is supplied in the form of a mixture in the burner boiler unit and adsorber unit, filled blast furnace slag for the purification of waste gases from nitrogen oxides, c and carbon.

Effect of porous insertion on convective energy transport in a chamber filled with a temperature-dependent viscosity liquid in the presence of a heat source term

Development of electronic devices demands to create an effective cooling system using optimal working liquid and porous insertions near the heat-generating elements. Such features allow intensifying the heat disposal from the heated element area. In this study, the unsteady convection of a variable viscosity liquid within a chamber having a heat-generating element under the impact of porous insertion is investigated. A porous layer surrounds the energy source located on the lower surface. The horizontal and vertical walls are thermally insulated, kept at constant cooling temperatures, respectively. Partial differential equations written in non-dimensional non-primitive variables with appropriate additional conditions are worked out by the finite difference method. The governing characteristics are the non-dimensional medium permeability, volumetric heat flux, variable viscosity and thickness of the porous insertion. The influence of these properties on local and mean fields’ characteristics for the energy transport and flow structures are studied in details. The calculations demonstrate that the inclusion of a porous insertion and the variation of its properties lead to more essential cooling of the heater.

Using lakes and rivers for extraction and disposal of heat: Estimate of regional potentials

There is increasing interest in using waterbodies as renewable energy sources to heat and cool buildings and infrastructure. Here, we estimate the potentials for heat extraction and disposal for the main lakes and rivers of Switzerland based on acceptable temperature changes in the waterbodies, and compare them to regional demands. In most cases, the potentials considerably exceed the demand, and minor impacts on the thermal regime of the waterbodies are expected. There are, however, critical situations: rivers crossing densely-populated areas, where demand often exceeds the potential, and heat disposal in summer into lowland rivers and shallow lakes, where temperatures may exceed ecological criteria. To assess the impacts of a realistic thermal use, we model the temperature effects in two lakes: Upper Lake Constance, a large lake with relatively low population density, and Lower Lake Zurich, a smaller lake with high regional demand. The estimated mean temperature alterations are −0.05 to +0.02 °C for Lake Constance, and −0.60 to +0.22 °C for Lake Zurich. Based on the model results, we discuss the effects of operating parameters on the efficiency and impacts of thermal use. Our analysis demonstrates that waterbodies provide real alternatives for heat/cold production in many regions of the world.

Numerical Analysis of the Thermal Interaction of Cell Phone Radiation with Human Eye Tissues

Introduction: The present study aimed to present a numerical analysis of the penetration depth, specific absorption rate (SAR), and temperature rise in various eye tissues with varying distance between radiation source and exposed human eye tissues (i.e., cornea, posterior chamber, anterior chamber, lens, sclera, vitreous humor, and iris) at frequencies of 900 and1800 MHz. Materials and Methods: A theoretical model was proposed based on the tissue dielectric and thermal properties, Maxwell equations, Joules law of heating, and microscopic form of Ohm's law to find the realistic situation of the cell phone radiation interaction with various human eye tissues. Results: According to the results, the anterior chamber had the highest temperature rise, compared to the vitreous, sclera, lens, cornea, and posterior chamber. By assuming the distance of 5 cm and exposure time of 30 min, the maximum rise in temperature for the anterior chamber was estimated to be 1.2°C and 2.2°C for 900 and 1,800 MHz frequencies, respectively. Conclusion: As the findings indicated, the anterior chamber had the maximum rise in temperature, compared to other investigated tissues. This could be due to the disposal of excess heat by the perfusion of the blood in the vitreous, posterior chamber, sclera, and lens tissues and the cooling effects produced due to convection/conduction in the cornea tissue. However, the anterior chamber tissue had no such mechanism for heat disposal.

Impacts of using lakes and rivers for extraction and disposal of heat

The extraction and disposal of heat from lakes and rivers is a large yet scarcely exploited source of renewable energy, which can partly replace fossil fuel heating and electrical cooling systems. Its use is expected to increase in the near future, which brings attention to the impacts of discharging thermally altered water into aquatic systems. Our review indicates that thermal discharge affects physical and ecological processes, with impacts recorded at all levels of biological organization. Many in situ studies found local effects of thermal discharge (such as attraction or avoidance of mobile organisms), while impacts at the scale of the whole water body were rarely detected. In complex systems, diffuse impacts of thermal discharge are difficult to disentangle from natural variability or other anthropogenic influences. Discharge of warm water in summer is likely to be most critical, especially in the context of climate change. Under this scenario, water temperatures may reach maxima that negatively affect some species. Given the diversity and complexity of the impacts of thermal pollution on aquatic systems, careful planning and judicious management is required when using lakes and rivers for extraction and disposal of heat. We discuss the drivers that influence the severity of potential impacts of such thermal use, and the options available to avoid or mitigate these impacts (such as adapting the operating conditions).This article is categorized under: Science of Water > Water Quality Water and Life > Stresses and Pressures on Ecosystems Engineering Water > Sustainable Engineering of Water

Theoretical analysis of suitable fluids for high temperature heat pumps up to 125 °C heat delivery

Industrial processes with applications such as pasteurization, drying and distillation have heat demand at a temperature between 100–125 °C. Industries with large amounts of waste heat and cooling demand will benefit from the development of high temperature heat pumps (HTHPs) which can replace conventional heating and waste heat disposal systems. This potentially saves both investment and operational cost of a boiler and a cooling tower with a single more efficient and less complex energy system. At the same time, the environmental footprint is reduced. The working fluids for these high temperature heat pumps using the vapour compression technology are often constrained by their high compressor suction and discharge temperature as well as the safety and environmental impact of the fluids. Within these limits, this paper conducts a theoretical analysis to evaluate available and potential fluids with thermodynamic properties that are applicable for HTHPs. The evaluations show that certain hydrocarbons and halocarbons are the most promising fluid candidates for waste heat upgrade from low temperatures to high temperatures, up to 125 °C.

INCREASE IN CHELYABINSK HEATING SYSTEM EFFICIENCY BY UTILIZATION OF LOW-GRADE WASTE HEAT

We consider the possibility of improving the heat supply system in Chelyabinsk through the introduction of heat pump technology for the disposal of low-grade waste heat. The paper analyzes the problems of the heat supply system in Russia. The majority of consumers in large cities of the central Russia are supplied with heat energy through the centralized heat supply system. This approach is largely outdated and inapplicable to the modern energy system. We propose the method for increasing the efficiency of centralized heating using heat pumps. This paper makes the evaluation of the effectiveness of the use of this method, namely performs a calculation study, the final result of which is estimation of efficiency of low-grade waste heat utilization in the Chelyabinsk heat supply system. For this purpose, we have previously analyzed the sources of information on the ways of utilization of waste thermal energy, the principles of the heat pumps operation, and the classification of urban sources of waste heat. The first stage of this study is the development of a calculation technique that makes it possible to estimate at varying initial parameters of the heat supply system objects. The developed technique allows estimating the efficiency of using heat pumps for each category of municipal sources of waste heat energy: energy (CHP, boilers, heating networks) and non-energy (residential, public and production facilities) ones. The second stage is the application of this technique to Chelyabinsk. As a starting point for this stage, we take the data which characterize the climatic features, energy parameters of the sources of centralized heating supply, as well as data on the population, economy and industrial facilities in Chelyabinsk. The result of the study is the numerical value of the efficiency of waste heat utilization in Chelyabinsk.

Treatment of Spent Nuclear Fuel for Separation, Immobilization and Disposal of Heat Generating High Level Fission Products, Caesium and Strontium

Separation of heat generating, high level fission product caesium and strontium from spent nuclear fuel boosts the capacity of waste repositories by as much as fifty times. For efficient use of already scarce repositories, separation of such fission products is mandatory. Separations of caesium and strontium using Chlorinated Cobalt Dicarbollide (CCD), PEG (Polyethylene Glycol), UNEX process and by Calixarenes or Fission Product Extraction Process (FPEX) were discussed. The UNEX method was then proposed as the most feasible method option. Following separation, nuclear waste immobilization techniques for such high-level fission product were discussed. The techniques included usage of concrete, glass and synthetic rock. Among them synthetic rock was identified as the most suitable one for immobilization of high-level nuclear waste. Finally, a safe disposal system with necessary required geology was shown for safe disposal of the waste.Journal of Chemical Engineering, Vol. 30, No. 1, 2017: 37-42

Analysis of heatline based visualization for thermal management during mixed convection of hot/cold fluids within entrapped triangular cavities

Abstract A comprehensive investigation has been carried out to analyze the fluid and heat flow during mixed convection in entrapped triangular cavities for heat disposal (case 1: hot inclined and cold horizontal wall) and heat recovery (case 2: cold inclined and hot horizontal walls) to/from the industrial fluids via heatline approach. Galerkin finite element method is employed to solve the governing equations and the results are illustrated for various Grashof numbers (103 ≤ Gr ≤ 105), Prandtl numbers ( P r = 0.026 and 7.2) and Reynolds numbers (1 ≤ Re ≤ 100). At R e = 1 , the symmetric fluid circulation cells occur whereas, the asymmetric fluid circulation cells occur at Re ≥ 10 and G r = 10 5 in both the cases and both Pr. The conduction dominant heat transfer is observed at P r = 0.026 and G r = 10 5 involving all Re. In contrast to P r = 0.026 , the heat flow field is highly influenced by the fluid flow field at P r = 7.2 for all Re and G r = 10 5 . In the upper cavity, the average Nusselt number of the top wall ( N u t ¯ ) is higher at Re → 0, G r = 10 5 for the case 1, and at R e = 100 , G r = 10 3 for the case 2 involving P r = 7.2 . In the lower cavity, the average Nusselt number of the bottom wall ( N u b ¯ ) is higher at R e = 100 , G r = 10 3 for the case 1, and at Re → 0, G r = 10 5 for the case 2 involving P r = 7.2 .

Improving the energy efficiency of NPP

The objective of the present study is the analysis and assessment of potential ways for enhancing the energy efficiency of nuclear power generation.Currently used and promising advanced thermodynamic cycles of nuclear power plants in power generation are examined. Ways for enhancing parameters of working agents in the NPP steam-turbine plants are suggested. Thermodynamic assessment was made of enhancement of thermal efficiency of NPP equipped with fast reactors due to the increase of coolant temperature at the reactor core outlet and, correspondingly, the increase of temperature and pressure of steam generated by steam generator. Analysis of efficiency of utilization of waste low-potential heat at the NPP using heat pumps was performed.Contemporary level of development of machine building industry for power generation, development of high-efficiency high-temperature gas turbines and steam compressors allow addressing the possibility to achieve high conjugated parameters of steam at NPPs equipped with conventional light-water reactors without exceeding the permissible conditions for operation of reactor cores with fuel cladding made of zirconium alloys.Application of heat pumps within the cooling circuit of the main condenser of steam-turbine power plant for the purpose of enhancement of financial indicators is not justifiable. As it was demonstrated by estimation calculations, the use of heat pumps within the main condenser loop is promising only for reducing heat discharged by NPPs in the environment. Utilization using heat pumps of low-potential heat removed by equipment cooling systems is the efficient way to improve NPP efficiency. Non-productive extraction of steam from the thermal cycle of the power unit is reduced in this case which results in the additional power generation as well as reduces heat disposal in the environment.