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 Ablation and Heat Balance of the Yukikabe Snow Patch in the Daisetsu Mountains, Hokkaido, Japan

1984 ◽  
Vol 5 ◽  
pp. 122-126 ◽  
Author(s):  
A. Sato ◽  
S. Takahashi ◽  
R. Naruse ◽  
G. Wakahama
Keyword(s):  
Latent Heat ◽  
Air Temperature ◽  
Heat Balance ◽  
Meteorological Parameters ◽  
Heat Sources ◽  
Sensible Heat ◽  
Net Radiation ◽  
Ice Caps ◽  
Air Temperatures ◽  
The Heat Balance

A good correlation was found between the ablation of snow and degree day index (cumulative values of positive daily mean air temperature) during the summer of 1978 on the Yukikabe snow patch in the Daisetsu mountains, central Hokkaido. The volume change of the snow patch in the ablation season of any year can hence be estimated from air temperature using this relationship. Each of the heat-balance terms controlling the ablation is evaluated separately by using empirical equations and assumed values for meteorological parameters at the snow patch. Triangular diagrams are constructed in order to illustrate the relative contributions of sensible heat, latent heat, and net radiation, the main three heat sources. A higher contribution from sensible and latent heat is found for the snow patches of Japan than for many glaciers and ice caps elsewhere. This may be due to higher mid-summer air temperatures than in other glaciated parts of the world.

Research on Heat Conductivity with a Time-Varying Heat Source

2014 ◽  
Vol 698 ◽  
pp. 637-642
Author(s):  
Anton Eremin ◽  
Ekaterina Stefanyuk ◽  
Liubov Abisheva
Keyword(s):  
Heat Conduction ◽  
Heat Source ◽  
Heat Balance ◽  
Integral Method ◽  
Approximate Analytical Solution ◽  
Heat Conduction Problem ◽  
Time Varying ◽  
Heat Sources ◽  
Plate Temperature ◽  
The Heat Balance

Using additional boundary conditions in the integral method of the heat balance, an approximate analytical solution to the heat conduction problem for an endless plate with time-varying heat sources has been found. It is shown that with any heat source capacity an unlimited plate temperature increase takes place in the course of time.

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.

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.

scholarly journals Ablation and Heat Balance of the Yukikabe Snow Patch in the Daisetsu Mountains, Hokkaido, Japan

1984 ◽  
Vol 5 ◽  
pp. 122-126 ◽  
Author(s):  
A. Sato ◽  
S. Takahashi ◽  
R. Naruse ◽  
G. Wakahama
Keyword(s):  
Latent Heat ◽  
Air Temperature ◽  
Heat Balance ◽  
Meteorological Parameters ◽  
Heat Sources ◽  
Sensible Heat ◽  
Net Radiation ◽  
Ice Caps ◽  
Air Temperatures ◽  
The Heat Balance

A good correlation was found between the ablation of snow and degree day index (cumulative values of positive daily mean air temperature) during the summer of 1978 on the Yukikabe snow patch in the Daisetsu mountains, central Hokkaido. The volume change of the snow patch in the ablation season of any year can hence be estimated from air temperature using this relationship. Each of the heat-balance terms controlling the ablation is evaluated separately by using empirical equations and assumed values for meteorological parameters at the snow patch. Triangular diagrams are constructed in order to illustrate the relative contributions of sensible heat, latent heat, and net radiation, the main three heat sources. A higher contribution from sensible and latent heat is found for the snow patches of Japan than for many glaciers and ice caps elsewhere. This may be due to higher mid-summer air temperatures than in other glaciated parts of the world.

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 Calculation of material and heat balance of melting refined ferrochrome using the new complex reducing agent of aluminosilicochrome

2020 ◽  
Vol 4 (315) ◽  
pp. 57-62
Author(s):  
A. M. Baisanova ◽  
◽  
Ye.Zh. Shabanov ◽  
K. V. Grigorovich ◽  
◽  
...  
Keyword(s):  
Phase Composition ◽  
Heat Balance ◽  
Material Balance ◽  
Electricity Consumption ◽  
Electrical Energy ◽  
Reducing Agent ◽  
Low Power Consumption ◽  
Complex Alloy ◽  
Exothermic Reactions ◽  
The Heat Balance

The article presents the results of calculating the material and thermal balances of refined ferrochrome (RFeCr) smelting using a new reducing agent. According to the results of the material balance and enlarged laboratory tests, it was found that when the traditional reducing agent silicochrome (FeSiCr48) is completely replaced with a complex alloy of aluminosilicochrome (FeAlSiCr), a metal of the following chemical composition can be obtained, %: Cr 66.8-69.1; C 0.21-0.29, Si 1.91-2.02. The composition of FeAlSiCr for silicon and chromium is the same as that of FeSiCr48, but additionally contains Al. In the process of obtaining refined ferrochrome, this aluminum passed into slag and changed its phase composition. In the CaO-MgO-Al2O3-SiO2 system, the phase composition of the slag moved from the region of bicalcium silicate to the region of helenite, which allowed to obtain non-crumbling slags. In addition, due to the high activity of FeAlSiCr (where, ∑ = Si + Al ≥ 60%), the basicity of the slag was maintained at the level of CaO/SiO2 = 1.6-1.7, against to 2. Based on the results of the heat balance calculation, it was found that the use of a complex FeAlSiCr reducing agent leads to a 24% reduction in electricity consumption. The low power consumption compared to the classical technology is explained by the presence of two active elements in the FeAlSiCr, silicon and aluminum. Thus, the amount of heat introduced by exothermic reactions prevails with the heat introduced by electrical energy.

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.

THE IMPACT OF MINERAL FERTILIZERS ON THE BIOLOGICAL YIELD OF SUGAR BEET CROP (BETA VULGARIS L. VAR. SACCHARIFERA)

2018 ◽  
Vol 28 (4) ◽  
pp. 1281-1284
Author(s):  
Petar Petrov ◽  
Bojan Mitrovski
Keyword(s):  
Sugar Beet ◽  
Field Trials ◽  
Mineral Fertilizers ◽  
Qualitative Properties ◽  
New Production ◽  
Economic Significance ◽  
Random Block ◽  
Biological Yield ◽  
Sugar Beet Crop ◽  
The Impact

Due to the great economic significance of the sugar beet, the new production trends are aimed at improving the quantitative and qualitative properties and one of the basic agro technical measures that is directly dependent on the yield and quality of the turnip is the properly conducted plant nutrition. Exporting high quantities of nutrients from the soil, the sugar beet requires application of advanced agro-technology, primarily application of adequate and controlled nutrition and irrigation. Application of this measure, in combination with soil processing, has sustained influence over the following cultures in the crop rotation in terms of nutrients regiment and fight against weeds.In order to determine the effects of mineral fertilizers on sugar beet, field experiment was conducted on fluvisol soil. The experiment is set according to a random block system, following the standard methods of agricultural chemistry for conducting field trials. The experiment includes eight variants, as follows: 1. Control (non-fertilized), 2. NP, 3. NK, 4. PK, 5. NPK, 6. N2PK, 7. N2P2K, 8. N3PK.In the phase of technological maturity of sugar beet, collection of the vegetative material and measurement of the height of the biological yield of the turnips was carried out. Based on the survey results, it can be concluded that the variant N2P2K has achieved the highest yield of swollen roots, i.e. 69.330 kg/ha. The highest yield of leafy greens was achieved in the variant N3PK, i.e. 41.920 kg/ha, which indicates the fact that nitrogen has direct influence over the vegetation mass of sugar beet.

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