scholarly journals Modelling Lake Titicaca's daily and monthly evaporation

2019 ◽  
Vol 23 (2) ◽  
pp. 657-668 ◽  
Author(s):  
Ramiro Pillco Zolá ◽  
Lars Bengtsson ◽  
Ronny Berndtsson ◽  
Belen Martí-Cardona ◽  
Frederic Satgé ◽  
...  
Keyword(s):  
Water Resource ◽  
Heat Balance ◽  
Resource Planning ◽  
Mountain Range ◽  
Lake Titicaca ◽  
Upper Limit ◽  
Lake Evaporation ◽  
Annual Evaporation ◽  
The Impact ◽  
The Heat Balance

Abstract. Lake Titicaca is a crucial water resource in the central part of the Andean mountain range, and it is one of the lakes most affected by climate warming. Since surface evaporation explains most of the lake's water losses, reliable estimates are paramount to the prediction of global warming impacts on Lake Titicaca and to the region's water resource planning and adaptation to climate change. Evaporation estimates were done in the past at monthly time steps and using the four methods as follows: water balance, heat balance, and the mass transfer and Penman's equations. The obtained annual evaporation values showed significant dispersion. This study used new, daily frequency hydro-meteorological measurements. Evaporation losses were calculated following the mentioned methods using both daily records and their monthly averages to assess the impact of higher temporal resolution data in the evaporation estimates. Changes in the lake heat storage needed for the heat balance method were estimated based on the morning water surface temperature, because convection during nights results in a well-mixed top layer every morning over a constant temperature depth. We found that the most reliable method for determining the annual lake evaporation was the heat balance approach, although the Penman equation allows for an easier implementation based on generally available meteorological parameters. The mean annual lake evaporation was found to be 1700 mm year−1. This value is considered an upper limit of the annual evaporation, since the main study period was abnormally warm. The obtained upper limit lowers by 200 mm year−1, the highest evaporation estimation obtained previously, thus reducing the uncertainty in the actual value. Regarding the evaporation estimates using daily and monthly averages, these resulted in minor differences for all methodologies.

scholarly journals Summer Heat and Ice Balances on Hodges Glacier, South Georgia, Falkland Islands Dependencies

1982 ◽  
Vol 28 (99) ◽  
pp. 221-238 ◽  
Author(s):  
I. G. G. Hogg ◽  
J. G. Paren ◽  
R. J. Timmis
Keyword(s):  
Latent Heat ◽  
Heat Balance ◽  
Significant Contribution ◽  
Heat Fluxes ◽  
Falkland Islands ◽  
Mountain Range ◽  
Ablation Zone ◽  
Net Radiation ◽  
Summer Heat ◽  
The Heat Balance

AbstractThe heat and ice balances of a temperate sub-Antarctic cirque glacier were measured through the 1973–74 melt season at an altitude midway between the climatic firn limit and the snout. The melt calculated from mean daily measurements at a single level of net radiation, wind-speed, temperature, and humidity agreed with that observed at nearby budget stakes. In the central ablation zone, radiation provided (54 ± 6)% and sensible fluxes (46 ± 6)% of the heat income through the summer, which was exceptionally warm and sunny. Latent-heat fluxes made no significant contribution to the heat balance. The calculation by Smith (1960) that the radiative, sensible, and latent heat fluxes contribute about equally to ablation in this zone has not been substantiated by measurement. The measured partition of the glacier’s heat balance suggested that maritime influences on its regime are mitigated by its position in the lee of a major mountain range.

scholarly journals The Interactive Impact of Building Diversity on the Thermal Balance and Micro-Climate Change under the Influence of Rapid Urbanization

2019 ◽  
Vol 11 (6) ◽  
pp. 1662 ◽  
Author(s):  
Mehdi Makvandi ◽  
Baofeng Li ◽  
Mohamed Elsadek ◽  
Zeinab Khodabakhshi ◽  
Mohsen Ahmadi
Keyword(s):  
Air Temperature ◽  
Heat Balance ◽  
Thermal Balance ◽  
Heat Island ◽  
Rapid Urbanization ◽  
Air Movement ◽  
Water Surfaces ◽  
Urban Heat ◽  
The Impact ◽  
The Heat Balance

Numerous cities face the serious problems of rapid urbanization and climate change, especially in recent years. Among all cities, Wuhan is one of the most affected by these changes, accompanied by the transformation of water surfaces into urban lands and the decline of natural ventilation. This study investigated the impact of surface urban heat island enlargement (SUHI) and block morphology changes in heat balance. Accordingly, the interactive impact of building diversity with major building forms (low-rise, mid-rise, and high-rise) on thermal balance and microclimate changes under the influence of urban land expansion at the residential block scale was studied. To investigate the heat balance changes by air temperature intensification and air movement reduction, a long-term and field observational analysis (1980–2018) coupled with computational fluid dynamic simulation (CFD) was used to evaluate the impact of building diversity on thermal balance. Outcomes show that urban heat island intensity (UHII) increased by 2 ℃ when water surfaces in urban areas decreased; consequently, there was a deterioration in the air movement to alleviate UHII. Thus, the air movement declined substantially with UHII and SUHI enlargement, which, through increased urban surfaces and roughness length, will become worse by 2020. Furthermore, the decline in air movement caused by the transformation of urban water bodies cannot contribute to the heat balance unless reinforced by the morphology of the urban blocks. In the design of inner-city blocks, morphological indicators have a significant impact on microclimate and heat balance, where increasing building density and plot ratio will increase UHII, and increasing water surfaces will result in an increase in urban ventilation. Lastly, a substantial correlation between air temperature and relative humidity was found, which, together with the block indicators, can help control the air temperature and adjust the urban microclimate.

The impact of water resource planning on water issues in Beijing, China

Water Policy ◽  
2014 ◽  
Vol 17 (4) ◽  
pp. 612-629 ◽  
Author(s):  
Wei Fu ◽  
Dihua Li
Keyword(s):  
Water Supply ◽  
Water Resource ◽  
Water Conservation ◽  
Water System ◽  
Resource Planning ◽  
Water Diversion ◽  
Systematic Analysis ◽  
Water Resource Planning ◽  
The Impact ◽  
Water Issues

Water has become a critically important resource in Beijing. In this study, a systematic analysis of changes in conditions related to water resources in Beijing since 1949 was performed. These include changes in water quantity and quality, water disasters, as well as an analysis of the evolution of water resource planning in Beijing over this period of time. Also, past approaches to urbanization have been looked at to see whether they exacerbated Beijing's water issues. The aggravating water issues were found to be associated with water resource planning in five ways. Water supply and flood protection projects have failed to control the complex water system and have exacerbated water shortages. Excessive project-oriented water diversion efforts and a lack of resource-oriented water conservation have allowed aquatic environments to deteriorate. Water supply planning has been based on demand that has intensified a lowering of the groundwater table. Improper measures that allowed wastewater to be used for irrigation of agricultural soils have aggravated water pollution. In general, water resource planning has not necessarily been conducive to solving water problems; it has even exacerbated Beijing's water crisis. The results and recommendations of this study may serve as a reference for future water resource planning in Beijing.

Analysis of the Impact of Boiler Slag’s Physical Sensible Heat Recovery on the Thermal Economy of Thermal Power Plant

2012 ◽  
Vol 608-609 ◽  
pp. 1298-1301
Author(s):  
Yong Li ◽  
Shi Ming Xu ◽  
Sheng Wen Huang ◽  
Wu Yi Du
Keyword(s):  
Power Plant ◽  
Heat Balance ◽  
Heat Recovery ◽  
Power Plants ◽  
Thermal Power ◽  
Sensible Heat ◽  
Whole Plant ◽  
Before And After ◽  
The Impact ◽  
The Heat Balance

Based on the situation that the transformations of the technology which is used to reclaim the physical sensible heat of the boiler slag in some industrial captive power plants, it has been used the heat balance method and the equivalent heat drop method to calculate and analyze the thermal economic indicators before and after the transformations of the unit, and then reveal the mechanism of the impact of the boiler slag’s physical sensible heat on the thermal economy of the whole plant.

An Analytical and Computational Investigation of Room Heating due to Complex Geometry Heat Sources

2015 ◽  
Author(s):  
Fabian Friedrich ◽  
Philipp Epple ◽  
Michael Steber ◽  
Antonio Delgado
Keyword(s):  
Heat Balance ◽  
Complex Geometry ◽  
Electrical Energy ◽  
Compressed Air ◽  
Heat Sources ◽  
Computational Investigation ◽  
New Production ◽  
Decisive Influence ◽  
The Impact ◽  
The Heat Balance

The compressed air generated by a compressor, is one of the most expensive known energy forms. The reason therefore is that electrical energy is converted directly into heat. The dissipation of the heat has a decisive influence on the performance of a compressor. Due to lack of standards during the planning phase of new production halls the heat balance, i.e. the supply and removal of the generated heat, very often the compressor is not considered proper. Even the German Engineering Association Directive VDMA 4363 “Lüftung der Betriebsräume luftgekühlter Kompressoren” (Ventilation of Industrial Premises Air-Cooled Compressors) [4] does not answer this question. In order to close this gap the impact of the volume of the room in order to keep the compressor running at a proper temperature is investigated. The influence of the orientation and size of the hot surfaces on the room heating is analyzed in detail as well.

scholarly journals Assessing the Influence of Compounding Factors to the Water Level Variation of Erhai Lake

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 29
Author(s):  
Huaxin Wu ◽  
Shengrui Wang ◽  
Tao Wu ◽  
Bo Yao ◽  
Zhaokui Ni
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Water Resource ◽  
Lake Water ◽  
Human Activities ◽  
Resource Planning ◽  
Test Method ◽  
Erhai Lake ◽  
Water Level Changes ◽  
The Impact

Climate change and human activities cause lake water level (WL) fluctuations to exceed natural thresholds, with implications for the available water resources. Studies that explore WL change trends and the main driving forces that affect water level changes are essential for future lake water resource planning. This study uses the Mann–Kendall trend test method to explore the WL fluctuations trend and WL mutation in Erhai Lake (EL) during 1990–2019 and explore the main driving factors affecting water level changes, such as characteristic WL adjustments. We also use the principal component analysis to quantify the contribution of compound influencing factors to the water level change in different periods. The results showed that the WL rose at a rate of 47 mm/a during 1990–2019 but was influenced by the characteristic WL adjustment of EL in 2004 and the WL mutation in 2005. In 1990–2004, the WL showed a downtrend caused by the increase in water resource development and utilization intensity, and in 2005–2019, the WL showed an uptrend caused by the combined decrease in evaporation, outflow, and the increase in water supply for water conservancy projects. Additionally, the largest contributions of outflow to WL change were 19.34% and 21.61% in 1990–2019 and 1990–2004, respectively, while the largest contribution of cultivated area to WL change was 20.48% in 2005–2019, and it is worth noting that the largest contribution of climate change to WL change was 40.35% in 2013–2019. In the future, under the increase in outflow and evaporation and the interception of inflow, the WL will decline (Hurst exponent = 0.048). Therefore, planning for the protection and management of lakes should consider the impact of human activities, while also paying attention to the influence of climate change.

scholarly journals Summer Heat and Ice Balances on Hodges Glacier, South Georgia, Falkland Islands Dependencies

1982 ◽  
Vol 28 (99) ◽  
pp. 221-238 ◽  
Author(s):  
I. G. G. Hogg ◽  
J. G. Paren ◽  
R. J. Timmis
Keyword(s):  
Latent Heat ◽  
Heat Balance ◽  
Significant Contribution ◽  
Heat Fluxes ◽  
Falkland Islands ◽  
Mountain Range ◽  
Ablation Zone ◽  
Net Radiation ◽  
Summer Heat ◽  
The Heat Balance

AbstractThe heat and ice balances of a temperate sub-Antarctic cirque glacier were measured through the 1973–74 melt season at an altitude midway between the climatic firn limit and the snout. The melt calculated from mean daily measurements at a single level of net radiation, wind-speed, temperature, and humidity agreed with that observed at nearby budget stakes. In the central ablation zone, radiation provided (54 ± 6)% and sensible fluxes (46 ± 6)% of the heat income through the summer, which was exceptionally warm and sunny. Latent-heat fluxes made no significant contribution to the heat balance. The calculation by Smith (1960) that the radiative, sensible, and latent heat fluxes contribute about equally to ablation in this zone has not been substantiated by measurement. The measured partition of the glacier’s heat balance suggested that maritime influences on its regime are mitigated by its position in the lee of a major mountain range.

scholarly journals Modeling Lake Titicaca Daily and Monthly Evaporation

2018 ◽  
Author(s):  
Ramiro Pillco Zolá ◽  
Lars Bengtsson ◽  
Ronny Berndtsson ◽  
Belen Martí-Cardona ◽  
Frederic Satgé ◽  
...  
Keyword(s):  
Heat Balance ◽  
Heat Storage ◽  
Time Step ◽  
Lake Titicaca ◽  
Daily Data ◽  
Water Ecosystem ◽  
Daily Time Step ◽  
Lake Evaporation ◽  
Meteorological Observations ◽  
Transfer Method

Abstract. Lake Titicaca is an important water ecosystem of South America. Due to uncertainties in estimating the evaporation losses from the lake, surface water storage calculations are uncertain. In this paper, we try to improve evaporation loss estimations by comparing different methods to calculate daily and monthly evaporation from Lake Titicaca. These were: water balance, heat balance, mass transfer method, and the Penman equation. The evaporation was computed at daily time step and compared with estimated evaporation using mean monthly meteorological observations. We found that the most reliable method of determining the annual lake evaporation is using the heat balance approach. To estimate the monthly lake evaporation using heat balance, the heat storage changes must be known in advance. Since convection from the surface layer is intense during nights resulting in a well-mixed top layer every morning, it is possible to determine the change of heat storage from the measured morning surface temperature. The mean annual lake evaporation was found to be 1700 mm. Monthly evaporation computed using daily data and monthly means resulted in minor differences.

Gasification of Biomass: The Consequences of Equilibrium

2003 ◽  
Author(s):  
S. A. Scott ◽  
A. T. Harris ◽  
J. S. Dennis ◽  
A. N. Hayhurst ◽  
J. F. Davidson
Keyword(s):  
Free Energy ◽  
Heat Balance ◽  
Alternative Fuels ◽  
Calorific Value ◽  
Process Variables ◽  
Heating Value ◽  
Thermodynamic Limits ◽  
The Impact ◽  
The Heat Balance ◽  
Insight Into

A model minimising Gibbs Free Energy is used to examine the thermodynamic limits of performance of a gasifier for biomass and other alternative fuels. The minimisation of free energy is highly flexible in that it allows a large number of species to be examined. Such an equilibrium model gives insight into the differences in the behaviour of coal and biomass in gasifiers. Biomass differs from coal in terms of heating value, ash, volatile and carbon contents and the amount of elemental oxygen. The model has been used to explore, entirely from a thermodynamic viewpoint: (i) the off-gas compositions, (ii) the impact of process variables on the heat balance and when gasification is complete, (iii) the effect of different gasification agents on process performance and (iv) optimisation of the calorific value of the hot and cold gas produced. Dried sewage sludge was used as a typical biomass fuel for these simulations. For biomass fuels with a low calorific value, it is shown that co-gasification with a support-fuel of higher calorific value, for example coal, is more practicable than gasification of the biomass alone.

Analysis of electro- and thermophysical processes occurring during electrocontact baking of flour products.

2020 ◽  
Vol 29 (11) ◽  
pp. 50-55
Author(s):  
V.I. Maklyukov ◽  
◽  
E.O. Gerasimova ◽  
N. V. Labutina ◽  
E.N. Rogozkin ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Theoretical Calculation ◽  
Heat Balance ◽  
Electric Contact ◽  
Wheat Dough ◽  
Baking Process ◽  
Free Moisture ◽  
Contact Heating ◽  
The Heat Balance

The article considers the results of research conducted during electric contact heating of rye-wheat dough pieces. It is established that the electrical conductivity of the crumb dough does not depend on the total humidity of the material, but mainly on the amount of free moisture. Using the current and temperature graphs, you can imagine how free moisture changes during the baking process and the influence of the thermophysical and colloidal process on the change in the value of free moisture. Experimentally determined the amount of heat that is spent on baking 1 kg of bread. The accuracy of the theoretical calculation of this parameter in the heat balance of the baking chamber is confirmed.

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