Investigation of Titanium Oxide Coating on Copper Heat Exchanger Surface for the Inhibition of Calcium Carbonate Scaling

Based on the Weather Research and Forecasting model and the Models-3 community multi-scale air quality model (WRF-CMAQ), this study analyzes the impacts of meteorological conditions and changes in air pollutant emissions on the heavy air pollution episode occurred over North China around the 2020 Spring Festival (January to Februray 2020). Regional reductions in air pollutant emissions required to eliminate the PM2.5 heavy pollution episode are also quantified. Our results found that meteorological conditions for the Beijing-Tianjin-Hebei and surrounding “2+26” cities are the worst during the heavy pollution episode around the 2020 Spring Festival as compared with two other typical heavy pollution episodes that occurred after 2015. However, because of the substantial reductions in air pollutant emissions in the “2+26” cities in recent years, and the 32% extra reduction in emissions during January to February 2020 compared with the baseline emission levels of the autumn and winter of 2019 to 2020, the maximum PM2.5 level during this heavy pollution episode around the 2020 Spring Festival was much lower than that in the other two typical episodes. Yet, these emission reductions are still not enough to eliminate regional heavy pollution episodes. Compared with the actual emission levels during January to February 2020, a 20% extra reduction in air pollutant emissions in the “2+26” cities (or a 45% extra reduction compared with baseline emission levels of the autumn and winter of 2019 to 2020) could help to generally eliminate regionwide severe pollution episodes, and avoid heavy pollution episodes that last three or more consecutive days in Beijing; a 40% extra reduction in emissions (or a 60% extra reduction compared with baseline emission levels of the autumn and winter of 2019 to 2020) could help to generally eliminate regionwide and continuous heavy pollution episodes. Our analysis finds that during the clean period after the heavy pollution episode around the 2020 Spring Festival, the regionwide heavy pollution episode would only occur with at least a 10-fold increase in air pollutant emissions.

In China, as the major source of energy consumption and air pollutant emissions, the power industry is not only the principal force that bears the responsibility of national emission reduction targets but also a breakthrough that reflects the effectiveness of emission reduction. In this study, based on the integrated MARKAL-EFOM system (TIMES) model and scenario analysis method, a bottom-up energy system optimization model for the power industry was established, and four scenarios with different constraints were set up to predict and analyze the power demand and the energy consumption structure. Emission characteristics, emission reduction characteristics, and emission reduction cost of sulfur dioxide (SO2), nitrogen oxide (NOX), particulate matter 2.5 (PM2.5), and mercury (Hg) were quantitatively studied. Finally, for the environmentally friendly development and optimal adjustment of power production systems in China, the control path in the power industry that is conducive to the emission reduction of air pollutants was obtained, which is of great significance for the ultimate realization of climate friendliness. The results demonstrate that from 2020 to 2050, the power demand of the terminal departments will increase, with the composition significantly changed. The focus of power demand will change from industry to the service industry gradually. If no additional targeted emission reduction or adjustment policies are added in the power industry, the primary energy and air pollutant emissions will increase significantly, putting great pressure on resources and the environment. For the emission reduction of air pollutants, the promotion effect of emission reduction measures, such as the implementation and promotion of non-fossil fuels, is restricted. The power industry can introduce and maximize the best available technologies while optimizing the structure of energy consumption to realize efficient emission reduction of air pollutants and energy conservation. In 2030, emissions will reach peak values with reasonable emission reduction cost. This has the additional effect of abating energy consumption and preventing deterioration of the ecological environment, which is of profound significance for the ultimate realization of climate friendliness.

Air pollutant emissions from coal-fired power plants in China over the past two decades

AimSeveral papers have analysed the clinical benefits and safety of Virtual Fracture Clinics (VFCs). A significant increase in the use of Trauma and Orthopaedic (T&O) VFCs was seen during the COVID-19 pandemic. This study aims to investigate the social impact of VFCs on the travel burden and travel costs of T&O patients, as well as the potential environmental benefits in relation to fuel consumption and travel-related pollutant emissions.MethodAll patients referred for T&O VFC review from March 2020 to June 2020 were retrospectively analysed. The travel burden and environmental impacts of hypothetical face-to-face consultations were compared with these VFC reviews. The primary outcomes measured were patient travel time saved, patient travel distance saved, patient cost savings and reduction in air-pollutant emissions.ResultsOver a four-month period, 1359 VFC consultations were conducted. The average travel distance saved by VFC review was 88.6 kilometres (range 3.3-615), with an average of 73 minutes (range 9-390) of travel-time saved. Patients consumed, on average, 8.2 litres (range 0.3-57.8) less fuel and saved an average of €11.02 (range 0.41-76.59). The average reduction in air-pollutant vehicle emissions, including carbon dioxide, carbon monoxide, nitric oxides and volatile organic compounds was 20.3 kilograms (range 0.8-140.8), 517.3 grams (g) (range 19.3-3592.3), 38.1g (range 1.4-264.8) and 56.9g (range 2.1-395.2), respectively.ConclusionsVFCs reduce patient travel distance, travel time and travel costs. In addition, VFCs confer significant environmental benefits through reduced fuel consumption and reduction of harmful environmental emissions.

Performance analysis of different U-shaped heat exchangers in parabolic trough solar collector for air heating applications

An overview will be given about investigations on heat and mass transfer in narrow channels and narrow cavities, from work carried out in the last years up to the current status of research of some relevant scientific groups in Europe. The major topics of this report are evaporation heat transfer and the flow boiling pressure drop in narrow channels; microscale heat and mass transfer phenomena in pool boiling from enhanced evaporator tubes with sub-surface channels are also addressed. In the last years a challenging topic has been the enhancement of the efficiency of heat exchangers by employing micro-structured heat transfer surfaces. The need for smaller heat exchangers with higher heat transfer rates and/or smaller thermal approaches is caused by the ongoing miniaturisation of mechanical and electronic components, leading to higher heat fluxes which can damage or even destroy the components. On the other hand, enhanced heat transfer in big equipment, e.g. heat exchangers for the petrochemical and chemical industries, can lead to significant materials and energy savings and thus reduce environmental pollution. Therefore the European Union, European industries and national organisations have supported various projects to develop and to investigate a new generation of heat transfer surfaces, to better understand the related heat transfer phenomena and to model the heat transfer from these micro heat exchanger elements. There is a very extensive research in this scientific field, comprising both flow boiling and pool boiling. The present paper deals with heat transfer in narrow channels and/or cavities and with the flow boiling pressure drop occurring during heat and mass transfer in narrow channels. Investigations of major European institutions, carried out in the past and at the moment will be presented as a contribution to the overview on the current state-of-the-art in Europe, without claim of completeness. Some recent results on microscale pool boiling and flow boiling obtained in our institute will also be presented (Shuai et al., 2002; Kulenovic et al., 2002; Chen et al., 2002a, b).

Low-carbon transport policy measures will contribute to greenhouse gas emission reductions, as well as improvements in air quality via air pollutant emission reductions. Here, we developed a regional transport energy model by integrating a transport demand model and an energy system model to explore the associated air pollutant emission reductions achieved by low-carbon transport initiatives when projecting a path towards carbon neutrality. Several scenarios were created to identify the effectiveness and feasibility of low-carbon strategies using the Avoid–Shift–Improve (A-S-I) framework including “Technology”, “Regulation”, “Information”, and “Economy” instruments. Significant reductions in air pollutant emissions alongside transport decarbonization in China could be realized by implementing policy measures to establish effective transport demand management, a modal shift in transport use, and technological improvements. In particular, the “Improve” strategy was more effective in delivering significant reductions in air pollutant emissions than were the “Avoid” and “Shift” strategies, but the policy effects of each A-S-I pillar varied greatly for different pollutants and across different regions. An air pollution reduction strategy for the transport sector should be designed in an integrated manner based on a series of different strategies and tools.

IntroductionIn recent years, with the intensification of climate change, reducing greenhouse gas emissions has become a necessary measure to address climate change. The carbon trading policy, as an effective policy to promote carbon reduction, has been accepted and implemented by many countries.MethodThis study employs the twofold difference approach and synthetic control method to evaluate the impact of carbon trading policies on air pollutant emissions.ResultResults showed that implementing carbon trading could lead to an average reduction of 54.13 million tonnes of CO2 annually, alongside decreases of 176.1 thousand tonnes of SO2 and 112.5 thousand tonnes of NOx. Among the six pilot regions—Hubei, Guangdong, Shanghai, Beijing, Tianjin, and Chongqing—Hubei exhibited the most significant CO2 reduction, approximately 66.25 million tonnes. Hubei and Beijing also showed notable synergistic effects for SO2 reduction. The synergistic emission reduction effect of NOx was more evident in Chongqing, Shanghai, and Hubei.DiscussionThese findings highlighted the effectiveness of carbon trading in mitigating CO2 and related air pollutants. To enhance and optimize the carbon trading market, the study recommends increasing the clean energy share in the energy mix, improving market management systems, enforcing reasonable penalties for defaults, and developing tailored carbon trading mechanisms for different industries.

Plasma hydrophilic surface treatment for dehumidifying heat exchangers

This paper describes heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a fin-tube heat exchanger. The experiments in which the moist air was passed into the heat exchanger coated with sorption material were conducted under various conditions of air flow rate (0.5–1.0 m/s) and the temperature of brine (14–20°C) that was the heat transfer fluid to cool the air flow in the dehumidifying process. It is found that the sorption rate of vapor is affected by the air flow rate and the brine temperature. Meanwhile, the attempt of clarifying the sorption mechanism is also conducted. Finally the average mass transfer coefficient of the organic sorbent coated on heat transfer surface of a fin-tube heat exchanger is non-dimensionalzed as a function of Reynolds number and non-dimensional temperature, and it is found that the effect of non-dimensional temperature on them is larger than Reynolds number .

Heat exchangers of various types (gas-gas, gas-liquid, liquid-liquid) are widely used in power plants of thermal power plants and nuclear power plants. Like any technical system, the heat exchange apparatus is estimated by the main quality indicator-energy efficiency. At present, most of the studies devoted to this issue are related to the determination of the intensification of the heat transfer process and the determination of the energy efficiency of convective heating surfaces. At the same time, both at the design stage, and especially for the functioning heat exchanger, it is required to determine its energy efficiency (further energy efficiency), which usually decreases with time. It is necessary to distinguish between the energy efficiency of the heat exchanger as a whole, in which the heat transfer occurs in the case of two-sided flow around the heat exchange surface and the energy efficiency of the surface on each side. (In the case of a heat exchanger with one-sided flow around the heat transfer surface, these concepts are often assumed to be identical, which is far from always correct). At the same time, after increasing the energy efficiency of the heat exchanger, due to the justified introduction of design changes, it is necessary to carry out a technical and economic calculation showing the means and time spent on the modernization of the apparatus. In the present paper, the existing design methods for increasing energy efficiency in low-pressure heaters of the PN-1100-25-6-1 type are considered and one of the promising ones is selected. The technical and economic calculation of this heater has been completed

Significant reduction in air pollutant emissions from household cooking stoves by replacing raw solid fuels with their carbonized products

This study evaluated the effect of the size and layout of adiabatic patch surfaces on heat exchange surfaces to improve the efficiency of heat and mass transfer and their exchange within a certain duct length, considering three factors: (1) the length of the heat exchange surfaces, (2) the location and layout of the adiabatic surfaces, and (3) the number of local adiabatic surfaces. Based on computational fluid dynamics (CFD), a simple numerical simulation model was developed to analyze the heat and mass transfer coefficients. The results provide dimensionless parameters at the heat exchange surface with the partitioning (patch) effect for various conditions in terms of the size, location/layout, and number of local adiabatic surfaces. Finally, the heat exchange efficiency, determined according to the locally installed adiabatic patch surface conditions, was examined, with a focus on the design of the joint component for a compact heat exchange element.

Preface. Introduction to Heat Transfer Enhancement - Preview of Contributions S. Kakac. The Imperative to Enhance Heat Transfer A.E. Bergles. Sustainability Criteria for Heat Exchanger Design N.H. Afgan, M.G. Calvalho. Extended Surface Heat Transfer in Heat Exchangers and Performance Measurements P.J. Heggs. Microfin Tube Technology - The Effects of Spiral Angle on Evaporative Heat Transfer Enhancement S.-Y. Oh, A.E. Bergles. Heat Transfer Enhancement by Wing-Type Longitudinal Vortex Generators and their Application to Finned Oval Tube Heat Exchanger Elements M. Fiebig, Y. Chen. Effect of Fin Heat Conduction on the Performance of Punched Winglets in Finned Oval Tubes Y. Chen, M. Fiebig. Heat Transfer and Fluid Flow in Rib-Roughened Rectangular Ducts B. Sunden. On the Airside Performance of Fin-and-Tube Heat Exchangers C.-C. Wang. Optimum Design of Air-Cooled Fin-and-Tube Heat Exchangers: Accounting for the Effect of Complex Circuiting C.-C. Wang. Flow and Heat Transfer Mechanisms in Plate-and-Frame Heat Exchangers B. Sunden. Heat Transfer Enhancement in a Plate Heat Exchanger with Rib-Roughened Surfaces R. Tauscher, F. Mayinger. Heat Transfer Augmentation in Channels with Porous Copper Inserts T.M. Kuzay, J.T. Collins. Boiling on Structured Surfaces R.L. Webb, L.-H. Chien. Heat Exchangers for Thermoacoustic Refrigerators: Heat Transfer Measurements in Oscillatory Flow C. Herman, M. Wetzel. A Study on the High Performance Ceramic Heat Exchanger for Ultra High Temperatures M. Kumada. Boiling and Evaporation of Falling Film on Horizontal Tubes and its Enhancement on Grooved Tubes Y. Fujita. Numerical and Experimental Investigation of Enhancement of Turbulent Flow Heat Transfer in Tubes by Means of Truncated Hollow Cone Inserts T.Ayhan, et al. Modern Advances in Optical Measuring Techniques -- Tools to Support Energy Conservation F. Mayinger. Enhancement of Combined Heat and Mass Transfer in Rotary Exchangers U. Dinglreiter, F. Mayinger. Advances in Understanding of Flame Acceleration for the Improving of the Combustion Efficiency C. Gerlach, et al. Heat and Mass Transfer with Drying of Water-Based Varnishes J. Mintzlaff, F. Mayinger. Energy Conversion in a Hydrogen Fueled Diesel Engine: Optimization of the Mixture Formation and Combustion P. Prechtl, et al. Enhancement of Heat Transfer with Horizontal Promoters S.U. Onbs oglu, A.N. Egrican. The Effect of Augmented Surfaces on Two-Phase Flow Instabilities S. Kakac. Flow Boiling inside Microfin Tubes: Recent Results and Design Methods J.R. Thome. Flow Boiling of Refrigerant-Oil Mixtures in Plain and Enhanced Tubes J.R. Thome. Influence of Confinement on FC-72 Pool Boiling from a Finned Surface M. Misale, et al. Prediction of Condensation and Evaporation in Micro-Fin and Micro-Channel Tubes R.L. Webb. Performance Enhancement of Heat Exchangers for Semiconductor-Chip Manufacturing Wen-Jei Yang, S. Torii. Evaporation and Condensation Heat Transfer Enhancement for Alternative Refrigerants used in Air-Conditioning Machines T. Ebisu. Development of New Concept Air-Cooled Heat Exchanger for Energy Conservation of Air-Conditioning Machine T. Ebisu. Multi-Hole Cooling Effectiveness on Combustion Chamber Walls B. Leger, P. Andre. Experimental Studies on Influence of Process Variables to the Exergy Losses at the Double Tube Heat Exchangers A. Can, et al. Enhancement of Direct-Contact Heat Transfer in Concentric Annuli T.A. Ozbelge, M.K. Shahidi. U

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