Advice 1: How to calculate the thermal conductivity

The thermal conductivity represents the ability of a material to conduct heat. Conductivity is accomplished by thermal transfer of kinetic energy between particles inside of the material, and in contact with others. Calculation of thermal conductivity is widely used in construction for the development of special materials, protecting the house from the cold.
How to calculate the thermal conductivity
Instruction
1
Determination of the thermal conductivity of materials is carried out using a conductivity coefficient which is a measure of the ability to transmit heat flow. The lower the value of this index, the higher the insulating properties of the material. In this case the conductivity does not depend on density.
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The numerical value of the conductivity is equal to the amount of thermal energy that passes through a section of material with a thickness of 1 m and 1 sq m over 1 second. The temperature difference on opposite surfaces is taken equal to 1 Kelvin. The amount of heat is the energy that gains or loses material by heat transfer.
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The formula of heat conduction as follows:Q = λ*(dT/dx)*S*dτ, where:Q – thermal conductivity;λ – thermal conductivity coefficient;(dT/dx) is the temperature gradient;S is the cross-sectional area.
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When calculating the thermal conductivity of construction structures divided into components and summed their conductivity. This allows to determine the measure of the ability of the house construction (walls, roofs, Windows, etc.), cutting off the heat flow. In fact, the thermal conductivity of the building structure is a combined thermal conductivity of its material, including air gaps and a film of the outside air.
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Based on the value of the thermal conductivity of the structure is determined by the amount of heat loss through it. This value is obtained by multiplying the thermal conductivity on the calculated time period, the total area of the surface as well as on the temperature difference between the outer and inner surfaces of the structure. For example, for walls of 10 square m with a conductivity of 0.67 at temperature difference of 13°, the heat loss in 5 hours will be 0,67*5*10*13 = of 435.5 j*m.
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The thermal conductivity coefficients of different materials are contained in the table of thermal conductivity, for example, for vacuum it is equal to 0, and for silver, one of the most teploprovodny materials, 430 W/(m*K).
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During the construction together with the thermal conductivity of the materials should take into account the phenomenon of convection, which is observed in materials in liquid and gaseous state. This is especially true in the development of system of water heating and aeration. To reduce heat loss in these cases establish cross dividers made of felt, wool and other insulation materials.

Advice 2 : How to calculate the volume of the heating system

With the installation of heating devices in homes, industrial and office buildings often need to know the amount of system heating. Well, when such data are provided by the customer, but it happens not always. There are methods of assessing total system and its individual components, depending on capacity.
How to calculate the volume of the heating system
Instruction
1
To calculate the volume of the heat carrier in the heating system when it replacement or reconstruction special use design tables available in reference editions. So, one section of the aluminium radiator has a volume of 0.45 liters of coolant, the section of the new iron battery – 1 L., section of old cast-iron batteries – 1.7-liter one meter pipe with a diameter of 15 mm – 0,177 l of coolant, and if used, the pipe diameter, e.g. 32 mm, the volume is 0.8 l and so on.
2
One of the most common occasions when you want to find out the amount of system of heating – the installation of the expansion tank and feed pumps. Total volume system heating at the same calculate by adding the volumes of the boiler, heating devices (radiators) and piping part of the system by the formula:V = (VS x E) / d, where V is the volume of the expansion vessel; VS is the total volume of the system (boiler, radiators, pipes, heat exchangers etc); E - the coefficient of expansion of the liquid ( % ); d - efficiency of the expansion tank.
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The calculations consider such factors as the expansion of the fluid. For water systems, heating it is approximately 4%. In the case of use in the system of ethylene glycol expansion coefficient of approximately 4.4 percent.
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For less accurate calculating system of heating , use a formula based on power: 1 kW = 15 HP For such approximate calculations require knowledge of the power system of heating, the need for details to calculate the size of pipes, radiators, the boiler and other elements of the system disappears. Example: if the heating power for a residential building is 50 kW, the total volume system heating VS is computed as:VS = 15 x 50 = 750 L.
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When conducting calculations keep in mind that in the case of use in the system of heating and new modern radiators and pipes, the volume of the system would be less. Detailed information can be found in the technical documentation of the hardware manufacturer.

Advice 3 : How to calculate the thickness of insulation

During the construction of the building, be sure to remember about the thermal insulation. Areas where building regulations on insulation are violated, is called cold bridges. Usually they are from the higher temperatures (indoors) appear wet, or the point of "dew" that brings the formation of mildew and mold. Improper insulation of their homes will bring about depletion of the family budget.
How to calculate the thickness of insulation
Instruction
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Determine the construction of the outer walls. It depends on the following factors: climatic, economic, structural features of the object and others. Determine the surface finishing of external walls (internal and external). Diagram of interior and exterior decoration depends on the solution of the exterior and interior of the structure. This automatically adds several layers to the thickness of the wall of the house.
2
Calculate the heat-transfer resistance of the selected wall (Rпр.) This value can be found by the formula, it is necessary to know the material from which made the wall and its thickness: Rпр.=(1/α (V))+R1+R2+R3+(1/α (n)), where R1, R2, R3 – resistance of heat transfer of each layer of the wall, α – the heat transfer coefficient of the inner surface of the wall, α(n) is the heat transfer coefficient of the outer surface of the wall.
3
Calculate the minimum allowable values of thermal resistance of (Rmin) for the climate zone where the building is carried out according to the formula R=δ/λ, δ – thickness of the layer of material in meters, λ is the thermal conductivity of material (W/m*K). The thermal conductivity can be seen on the packaging material, or define a special table thermal conductivity material, for example, for polystyrene PSB-s 15, density 15 kg/m3 , it is equal to 0,043 W/m mineral wool with a density of 200 kg/m3, and 0.08 W/m.
Thermal conductivity – the ability of a material to exchange heat with the environment. The higher the conductivity, the material is colder. The higher the thermal conductivity of concrete, metal, marble, low - air. Thus, materials which are based on air, for example, polystyrene are extremely warm. 40mm foam = 1m of brickwork. The coefficient has a constant value for each climate zone, it can be found in the directory DBN V. 2.6-31:2006 (Thermal insulation of buildings).
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Compare Rmin with Rпр. find the difference Δ R. If the result of the calculation of Rmin< or = Rпр., the wall insulation is not necessary because existing regulatory layers provide insulation. When Rmin>Rпр., then determine the difference, subtract the larger value from a smaller ΔR= Rmin- Rпр.
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Find the thickness of insulation according to ΔR. The insulation should provide the missing heat-transfer resistance. Choosing the insulation material, be aware of the following its characteristics, such as coefficient of thermal conductivity, coefficient of water absorption, density, Flammability class. The coefficient of water absorption - the ability of a material to keep the absorbed water. The smaller its value is of greater interest in this material as insulation. Used in the construction of materials with a high coefficient of water absorption, for example, glass wool or mineral wool. Additionally, in this case, a vapor - and waterproofing. To do this, so as not to allow material to get wet. If this happens, the conductivity strongly increases, for example, mineral wool twice.
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Also important is the Flammability and density of insulation. The latter characterizes the load on the supporting structures. Building materials are divided into non-combustible and combustible, which are divided into 4 groups: low-flammable (G1); ameranouche (G2); normalnaya (G3); zelenogorye (G4). The denser the material, the less flammable the cost is higher. After choosing the material, calculate by the formula the thickness of the insulation: ΔR= δ/λ, where δ= λ/ΔR, δ is the required thickness of the selected insulation, expressed in metres.

Advice 4 : How to calculate cubic meter of wood

In everyday life and technology wood called the internal part of the tree underneath the bark. For wood , the main and most important are the following properties: texture (figure fibers of wood), strength, hardness, deformability (the ability derivativesa), specific viscosity, thermal conductivity, sound conductivity.
How to calculate cubic meter of wood
You will need
  • To measure the cubic capacity of the lumber you will need a tape measure and a special table (which you can request from the seller, called "subatomic".
Instruction
1
Wood is a raw material for the production of more than twenty thousand products and articles. Methods of processing of wood raw material divided into three groups: mechanical, chemical-mechanical and chemical. Mechanical processing of wood is to change its shape by sawing, planing, milling, peeling,drilling, cleaving. As a result of mechanical processing receive a variety of consumer goods and industrial products. The value of various species of wood is their strength, durability and uniqueness of the figure. This wood is used to make beautiful furniture, flooring, doors, and various interior items that are considered elite, given the initial high cost and the size of the effort spent on processing it. In Russia, the most common the following species: oak, cherry, beech, pear, rosewood, mahogany, walnut, maple.
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Board — lumber thickness up to 100 mm and a width exceeding twice the thickness. Boards are made of logs or timbers. Used in construction, furniture industry, manufacturing etc. depending on propylesoste edges are of the following types of boards: edged ( skromnoi both sides), one-way cut (with the edge on one side) and edging. When the sale of the timber, of course, have to measure them. Indeed, in contrast to other types of products do not sell them either individually or by weight, and in cubic metres. Volume of sawn softwood and hardwood is defined in two ways. You need to measure par and calculate its volume, the volume is calculated by the formula V= length X(times) width X(times) the thickness. So you will get the volume of one Board, now count all the plates, multiply the volume of one Board on a number of boards and you will get the volume you imported lumber.
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Still the amount of wood you can calculate using the so-called kubaturnykh (GOST 5306-83), which is designed to calculate the amount of edging saw-timbers of coniferous and deciduous species. In subatomic (standard) a table of the volume of one meter length and table of one piece of lumber. Based on these, and determine the purchase price. For example, we need to find the volume of 70 edging boards thickness 22 mm, width 125 mm and length 4.5 m. For this table, find the thickness of sawn timber 22 mm and at the intersection of horizontal column where you specify the width of 125 mm, and vertical columns, wherein said length of 4.5 m, find the volume 0,01238 m3. Then by multiplying the volume by the number of timbers in the party will get the desired volume in m3: 0,01238 m3 X 70=0,8666 m3. For reference will answer that in four-axle gondola is about 55-60 m3 of edged softwood lumber.
Note
Recalculate your results 2 time to avoid errors. Be careful with wood, don't get yourself a splinter, it is better to use gloves.
Useful advice
Do not hurry with the payments, the seller will have to sell and you to buy!
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