scholarly journals On the admissibility of replacing the heat conduction equation of a pipe wall by the heat balance equation in investigating transients in heat exchangers

1970 ◽  
Vol 19 (6) ◽  
pp. 1555-1561
Author(s):  
V. V. Krasheninnikov
Keyword(s):  
Heat Conduction ◽  
Balance Equation ◽  
Heat Balance ◽  
Heat Exchangers ◽  
Heat Conduction Equation ◽  
Pipe Wall ◽  
Heat Balance Equation ◽  
Conduction Equation ◽  
The Heat Balance

scholarly journals The heat loss calculating methods of external walls in the buildings reconstruction

2018 ◽  
Vol 230 ◽  
pp. 02038 ◽  
Author(s):  
Varvara Vinnichenko ◽  
Azat Gabitov ◽  
Aleksandr Salov ◽  
Askar Gaisin ◽  
Dmitriy Kuznetsov
Keyword(s):  
Finite Element ◽  
Heat Conduction ◽  
Heat Loss ◽  
Balance Equation ◽  
Heat Balance ◽  
Operating Experience ◽  
Energy Performance ◽  
Heat Balance Equation ◽  
The Heat Balance ◽  
Window Frames

Heat loss analysis in cladding of brick buildings under reconstruction is presented. Thermograms obtained under thermovision inspection and window systems operating experience in conditions of the Republic of Bashkortostan are thoroughly studied. Live issue of increasing buildings energy performance in public utilities sector may largely be solved by replacement of existing window units made of wood to new PVC profile windows equipped with multi-glazed glass units both in brick and frame-panel old buildings. Significant heat loss occurs in junctions between the window frames and the wall in jamb areas. Therefore for the heat conduction matrix for the finite element is used the heat balance equation. Use of the software application to choose certain measures to eliminate the thermal bridges enables to get the thermotechnical calculations in the junction between the window and the exterior wall in the form of temperature fields. Practical recommendations for arrangement of heat insulation in junctions between the window frames and the wall to eliminate actual defects and for normal room conditions are made under examinations. To get the heat conduction matrix for the finite element we will use the heat balance equation.

Study on the Flashover Criteria for Compartmental Fires

1997 ◽  
Vol 15 (2) ◽  
pp. 95-107 ◽  
Author(s):  
W.K. Chow
Keyword(s):  
Balance Equation ◽  
Heat Balance ◽  
Lower Layer ◽  
Heat Balance Equation ◽  
Zone Model ◽  
Heat Temperature ◽  
Fire Environment ◽  
Smoke Layer ◽  
Mass Flow Rates ◽  
The Heat Balance

Criteria on the possibility of having flashover in a compartment fire were reviewed. The heat balance equation in the compartment was studied. The zone model CFAST 2.0 was applied to study the fire environment in a small compartment with a door of different area. Important parameters including the average upper and lower layer temperature, the smoke layer interface height, and the mass flow rates for intake air and outgoing smoke were calculated. Those pre dicted results were substituted back to the heat balance equation for determining the possibility of having flashover. The analysis shows that it is possible to deter mine the likelihood for flashover by using a well-validated zone model. From the heat-temperature curves derived, effect of the sprinkler can also be studied.

A Computer Model of Glaze Accretion on Wires

1996 ◽  
Vol 118 (2) ◽  
pp. 148-157 ◽  
Author(s):  
G. Draganoiu ◽  
L. Lamarche ◽  
P. McComber
Keyword(s):  
Computer Model ◽  
Balance Equation ◽  
Heat Balance ◽  
Control Volume ◽  
Water Flux ◽  
Heat Balance Equation ◽  
Ice Accretion ◽  
Surface Geometry ◽  
Related Field ◽  
The Heat Balance

The design of power transmission lines requires a knowledge of combined wind and ice loading and of the dynamic behavior of wires loaded with ice accretion. The calculation of the wind forces, in turn, imposes a need for a more detailed computer model for determining glaze accretion shape. For this purpose, a computer model of glaze accretion on wires, was developed. It is based on experimental results in the area of ice accretion on wires, as well as on results in the related field of the glaze ice accretion on airfoils. The model incorporates the time dependent on feedback between the growing accretion and the air stream, the variation of the heat transfer coefficient around the cylinder, and the surface runback of water. The main components of the model are the computation of the air flow field, the computation of the impingement water at the control volume level, the solving of the heat balance equation, and the computation of the accretion shape on the wire. The surface air velocity is obtained through the solution of the potential flow around the iced wire and wake, followed by the integration on the surface of the laminar boundary layer. The water flux is computed in each control Volume down to the separation point. The heat balance equation derived from the energy equation is solved to determine the freezing fraction and the resulting modified ice surface geometry.

scholarly journals Improvement of the Heat Balance Equation Accuracy, in the Case of Saturation Diving

2021 ◽  
Vol 15 (3) ◽  
pp. 318-322
Author(s):  
Anca Constantin ◽  
Tamara Stanciu
Keyword(s):  
Body Temperature ◽  
Balance Equation ◽  
Heat Balance ◽  
Good Accuracy ◽  
Absolute Humidity ◽  
The Body ◽  
Heat Balance Equation ◽  
The Absolute ◽  
The Heat Balance ◽  
Theoretical Results

The body temperature of a diver is one of the most important aspects of the concept of underwater safety and comfort. The heat balance equation previously established, was improved in this paper by introducing a linear dependence of the absolute humidity on the body temperature, as the absolute humidity influences the latent heat flux needed for the humidification of the breathing gas. The solution of the new proposed heat balance equation is a step forward in assessing the body temperature in both cases of unitary and saturation diving. The paper presents the equation and its solutions in the case of breathing either air or Heliox and compares the theoretical results with the values measured in the frame of simulated saturation diving with Heliox 5/95, in the hyperbaic laboratory. The proposed equation predicts the body temperature of the diver, at the end of a 30 minutes immersion with a good accuracy. The relative error is up to 1%.

Reducing the Risk of Fire Fighting in Harsh Climatic Conditions

2021 ◽  
pp. 69-74
Author(s):  
T.A. Kulagina ◽  
◽  
T.A. Yenutina ◽  
V.I. Tereshkov ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Balance Equation ◽  
Heat Balance ◽  
Climatic Conditions ◽  
Maximum Length ◽  
Heat Balance Equation ◽  
Ambient Temperatures ◽  
First Law Of Thermodynamics ◽  
Flow And Heat Transfer ◽  
The Heat Balance

The sustainability of the development of the northern territories of Russia from the Urals to the Pacific Ocean, where the bulk of the country natural resources is concentrated in the twenty-first century, is determined by the integrated approach to planning and managing the risks of using machines, structures and equipment, critical and hazardous industrial facilities and technological support and support at the stages of their operation. Climatic factors have a noticeable effect on increasing the risks of abnormal situations occurrence in emergency situations, for example, on the efficiency of fire departments activity in the winter period of the year and at extinguishing fires in harsh climatic conditions, when water may freeze inside the hoses and in the working chamber of the feed pump. Due to a malfunction in the fire equipment, the scale of the territory covered by the flames can significantly increase, and the extinguishing process will become more complicated. Operability of the hose lines in low temperature conditions is calculated using Methodological Recommendations for ensuring the operability of pump and hose systems of fire trucks when extinguishing fires in the conditions of extremely low temperatures, determining the maximum length of the hose line before icing begins. It is shown in the paper that the maximum length of the hose line, that is, the distance from the pump to the beginning of icing, should be calculated using the heat balance equation, which is based on two equations of the first law of thermodynamics — for flow and heat transfer. At the same time, it is required to combine thermal and hydraulic calculations. The methods are presented in the article for predicting the operability of pumps and hose lines in the conditions of extremely low ambient temperatures, used in fire truck systems for extinguishing fires, including at the energy facilities. It is shown that there are errors and shortcomings in the Methodological Recommendations for ensuring the operability of pump and hose systems of the fire trucks when extinguishing fires in the conditions of extremely low ambient temperatures, including at the energy facilities. It is also shown that the maximum length of the hole line, that is, the distance from the pump to the beginning of icing, should be calculated using the heat balance equation, which is based on two equations of the first law of thermodynamics — for flow and heat transfer.

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