Heat transfer calculation through a wall
(without interior heat sources)

Calculation of an amount of heat transmitted through the homogeneous wall, depending on a difference of temperatures of its surfaces

Applet for build-up of system of nomograhic charts for calculation of an amount of heat transmitted through a wall [J/s]
Applet for build-up of system of nomograhic charts for calculation of an amount of heat transmitted through a wall [cal/s]

The thermal stream transmitted through a wall, pays off by formula

q = l · F · (T₂ - T₁) / d, [1]

where

l – thermal conductivity of a material of a wall, W/(m·К);

F – wall surface area, m²;

T₂ - T₁ – difference of temperatures of surfaces of a wall, ^oС;

d – thickness of a wall, m.

Heat transfer (in the general case) - the transfer of heat from more heated bodies to less heated ones

Heat transfer can be carried out by convection, heat conduction or radiation (radiation)

Heat transfer - heat exchange between media through a wall separating them from a homogeneous material due to the thermal conductivity of the wall material

Thermal conductivity - the transfer of heat from one part of the body to another (heat transfer through a layer of homogeneous material), i.e. is the ability of a body to conduct heat

Thermal conductivity coefficient - the amount of heat [J] transferred per unit time [s] through a unit area [m²] of a homogeneous material per unit length [m].

The circuit design of nomographs is presented in drawing 1.

Drawing 1. The circuit design of system of nomographs for graphic-analytical calculation of heat transfer through the wall

After applet start an auxiliary window will have the following appearance (drawing 2).

Drawing 2. An additional window of an applet on build-up of system of nomographs for graphic-analytical calculation of heat transfer through the wall

In an auxiliary window the circuit design of disposing of nomographs is already shown, but she demands recurring feeding into, therefore on each small square which is marking out a nomograph "is clicked" by the right key of the mouse and the left key "clicked"on that place where there should be a colour flag indicator (a place of disposing of meaning of parametre Z of a nomograph). It is possible choose any other location of variable parametre Z. After recurring appointment of the circuit design of nomographs "is clicked" by the left key of the mouse on sign "[-]", had in left overhead to the angle of the circuit design of nomographs. It will change the aspect on "[+]". It means, that the circuit design of nomographs is fixed. .

Drawing 3. An additional window of an applet on build-up of system of nomographs with the tuned circuit design of nomographs

After attaching of the circuit design of nomographs, "is in succession clicked" on everyone sign, marking out a nomograph, and it is pushed three buttons "In the working memory" ("В ОЗУ"), "Substitution ID" ("Подстановка ИД"), "the Total formula" ("Итоговая формула") for entering of all parametres of a nomograph into an on-line storage and design formula formation.

We transfer to the basic window and we induct meanings of steps on axes "X" and "Y". We push the button "to Build on ID" ("Построить по ИД").

Drawing 4. The basic window of an applet for build-up of system of nomographs for graphic-analytical calculation of heat transfer through the wall

More detailed instruction on operation with an applet.

Topic of the section: calculation of heat flux through a flat homogeneous wall.

graphic-analytical systems The contact information. E-mail: nomogramka@gmail.com

Heat transfer calculation through a wall (without interior heat sources)

Calculation of an amount of heat transmitted through the homogeneous wall, depending on a difference of temperatures of its surfaces

Heat transfer calculation through a wall
(without interior heat sources)