Innovative energy and mass balance of a continuous evaporating crystallizer

2019 ◽  
pp. 646-654
Author(s):  
Jan Iciek ◽  
Kornel Hulak ◽  
Radosław Gruska

The article presents the mass and energy balances of the sucrose crystallization process in a continuous evaporating crystallizer. The developed algorithm allows to assess the working conditions of the continuous evaporating crystallizers and the technological and energy parameters. The energy balance algorithm takes into account the heat released during the crystallization of sucrose, which was analyzed in this study, heat losses to the environment and heat losses due the vapor used for inert gas removal.

1978 ◽  
Vol 20 (82) ◽  
pp. 67-84 ◽  
Author(s):  
P.W. Anderton ◽  
T.J. Chinn

AbstractMass, water, and energy balances were measured lit the Ivory Glacier, South Island, New Zealand from 1969 to 1975 as part of an I.H.D. programme of representative basin studies. Ivory Glacier is a small cirque glacier within the high-precipitation maritime environment of Westland and was chosen initially for convenience of study rather than representativeness. Mass-balance investigations included a detailed study of the sampling efficiency of a pole network. Annual mass balance was consistently negative during the study period. The run-off pattern was dominated by rain. The estimated annual mean precipitation is 9630 mm for 1971-75. Snow represents about 25% of annual precipitation. Melt contributed 21% of run-off including 9% contributed by melt of perennial snow and ice. The relative contributions of different fluxes to the energy balance during summer are: net radiation 52%, sensible heat 29%, and latent heat 17%. Heat content of precipitation contributes significantly to the energy balance during individual rain-storms and is probably significant during periods of high precipitation in spring and autumn. Climatic characteristics and behaviour of Ivory Glacier appear to follow regional trends in the Southern Alps and the glacier is considered to be reasonably representative.


2009 ◽  
Author(s):  
A. Gentile ◽  
L. Pierce ◽  
G. Ciraolo ◽  
G. Zhang ◽  
G. La Loggia ◽  
...  

2019 ◽  
Vol 120 ◽  
pp. 144-155 ◽  
Author(s):  
Andrea Maria Rizzo ◽  
Marco Pettorali ◽  
Renato Nistri ◽  
David Chiaramonti

2017 ◽  
Vol 11 (6) ◽  
pp. 2799-2813 ◽  
Author(s):  
Colin R. Meyer ◽  
Ian J. Hewitt

Abstract. Meltwater is produced on the surface of glaciers and ice sheets when the seasonal energy forcing warms the snow to its melting temperature. This meltwater percolates into the snow and subsequently runs off laterally in streams, is stored as liquid water, or refreezes, thus warming the subsurface through the release of latent heat. We present a continuum model for the percolation process that includes heat conduction, meltwater percolation and refreezing, as well as mechanical compaction. The model is forced by surface mass and energy balances, and the percolation process is described using Darcy's law, allowing for both partially and fully saturated pore space. Water is allowed to run off from the surface if the snow is fully saturated. The model outputs include the temperature, density, and water-content profiles and the surface runoff and water storage. We compare the propagation of freezing fronts that occur in the model to observations from the Greenland Ice Sheet. We show that the model applies to both accumulation and ablation areas and allows for a transition between the two as the surface energy forcing varies. The largest average firn temperatures occur at intermediate values of the surface forcing when perennial water storage is predicted.


2008 ◽  
Vol 12 (4) ◽  
pp. 75-88 ◽  
Author(s):  
Nenad Ferdelji ◽  
Antun Galovic ◽  
Zvonimir Guzovic

Limitations of traditional first-law analysis, based upon thermodynamic performance of process unit coupled with mass and energy balances, are not a serious limitation when dealing with familiar systems. However, when dealing with more uncongenial, complex ones, it provides incomplete insight for such evaluation. These limitations came from the fact that first-law analysis does not indicate the sources or magnitudes of entropy production, which is, by the second law, essential criterion for scaling losses. An evaluation of plant performance will usually require a comparison of the thermodynamic performance of process units with available data from existing plants. Therefore, exergy analysis is more than useful, providing information about magnitudes of losses and their distribution throughout the system as well. Such analysis is very thankful at the level of process units but applied on higher system levels e.g. the comparison of overall plant performance (total system) or the performance of subsystems, represents the valuable method for indicating where research resources can be directed to best advantage.


2016 ◽  
Vol 20 (3) ◽  
pp. 827-830
Author(s):  
Lijuan Wang ◽  
Yuhui Di ◽  
Hui Yin ◽  
Yanfeng Liu ◽  
Jiaping Liu

The objectives of the paper are to analyze human convection, radiation, evaporation, respiration, conduction, and diffusion heat losses when the operative temperature increases from 26-34.4?C and then decreases from 34.4-26?C with a ratio of 1.4?C per 5 minutes. A energy balance model is used for sedentary subject. The results show that during temperature rising, all the heat losses are linear functions of temperature, while during temperature dropping, the convection, diffusion, and respiration heat losses are quadratic functions of temperature. The results are useful for thermal comfort evaluation and heating, ventilation, and air conditioning design.


2019 ◽  
Vol 10 (4) ◽  
pp. 627-647 ◽  
Author(s):  
Izabela Jonek-Kowalska

Research background: Energy policy is closely linked to economic development. Therefore, its optimization is an important issue especially in the contemporary European environmental conditions.  EU regulations enforce a reduction of carbon dioxide emissions and the abandonment of non-renewable energy resources. Instead, they promote renewable energy sources. In this way, new legal and environmental circumstances are becoming the main reason for the transformation of energy balances, which is a real economic and technological challenge. This transformation requires a strategic and effective approach, especially in those countries which until now have used mainly hard coal in the energy sector. Purpose of the article: According to above justification, the main purpose of the article is to identify the strategies for the transformation of energy balances that were implemented in the years 1990–2017 by chosen European countries and Turkey. Methods: The study period covers the years 1990–2017, and the subject of the research at first applies to all European countries, and then to 7 countries selected due to their high share of bituminous coal in energy balance in the first year of the analysis, treated as the initial point of transformation (1990). As a result of this selection, 6 EU members and Turkey with the largest share of coal in energy production in the year 1990 are examined. Particularly, an analysis of the trends in their energy balances in the years 1990–2017 is conducted. The research uses data on non-renewable energy consumption and renewable energy resources and the total energy consumption. The research methodology includes: analysis of the structure and dynamics, evaluation of trends and comparative analysis and presentation of development strategies. At the end of the article, a comparative analysis is carried out, the economic consequences of identified changes are assessed, and recommendations are formulated aimed at optimizing the structure of the energy balance in the future. Findings & Value added: Generally, there are four theoretical and empirical patterns of transformation strategies of energy balances with dominant coal consumption: 1) using other non-renewable energy resources; 2) replacing non-renewable energy resources with renewable ones; 3) using nuclear energy instead of coal; 4) increasing coal consumption as available and efficient energy resource. It was found that the examined countries implement mainly the strategy in which the decreasing share of coal is made up for by an increasing share of gas. Additionally, we can observe an increase in the share of nuclear energy in France, the Czech Republic and the United Kingdom. In Spain and Germany, despite the use of nuclear power plants for the production of energy, the share of nuclear energy in the energy balances has systematically decreased in time. In all analyzed countries, we can also observe an increasing share of renewable sources in energy balances, however, this growth is very slow.


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