Thermal insulation of surfaces, walls and floors

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Thermal insulation of surfaces, walls and floors

Сообщение merehan1 » 08 сен 2020, 03:47

Heat Insulation:
Thermal insulation is the use of materials that have properties that help limit the leakage and transfer of heat from outside the building to inside it in the summer, and from inside to outside in the winter.

1- Heat that penetrates walls, ceilings, and floors.

2- Heat that penetrates windows, doors, and other openings.

3- Heat that is transferred through the ventilation holes.

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Thermal Transfer Coefficient
And expresses the time rate of passage of the thermal current in watts (watt, w) through the structural elements inside and outside the building, and symbolizes. It has a U and the unit of measure is: Watt / m2 ° C.

The value of the thermal transfer coefficient is necessary to know the efficiency of the heat insulator, so that the lower the value of the thermal transfer coefficient, the greater the insulation capacity.

Coefficient of thermal conductivity
It is the amount of heat that passes through a unit of area for a structural element by a temperature difference factor of one Celsius, and its unit of measure is: Watt / m. O °.

Heat transfer methods:
Heat is transferred through materials by means of physical transmission, which are conduction, convection, and radiation that can be defined as follows:

A) Delivery
It is the transfer of heat through the particles of a hotter (hotter) solid object to its cooler (less hot) particles and contact with the hot particles in it.

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B) Pregnancy
It is the transfer of heat in liquids as well as in moving gases. It occurs as a result of the movement of hot particles of a liquid or gas. This movement forms convective currents that in turn work to balance the temperature of the liquid or gas. In gas such as air, the heat transfer is carried out in the air surrounding the heat source, so the air molecules in contact with the heat source rise up due to their expansion and light weight, and they are replaced by particles of cold air that is also heated up to the top, transferring the heat through its particles.

C) radiation
and he. The conversion of thermal energy in an object into radiant heat energy (energy that radiates to the outside) and its transfer to another body. He, in turn, converts it into heat energy. Thermal rays are electromagnetic waves that are similar to light waves and differ from them in wavelength and are called ultraviolet rays, and thus they need a material medium through which they travel and thus the transfer of thermal energy occurs radiatively, even in a vacuum.

Benefits of thermal insulation
1- Rationalizing electrical energy consumption during cooling and heating operations, by up to 30-40%.

2- Protecting the structural elements of the building and preserving furniture from temperature changes

3- Raise the level of comfort and health safety for the building's occupants

4- Reducing the costs of purchasing air conditioning and heating equipment by reducing its capacity

5- Reducing environmental pollution, heat emissions and noise

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Criteria for choosing suitable thermal insulation materials:

1- The insulating material should have a low thermal conductivity coefficient.

2- It must be of a high degree in its resistance to water and water vapor

3- To be of a high degree in its resistance to thermal radiation.

4- To be of a high degree in its resistance to the stresses resulting from the large differences in temperature that lead to mutual and continuous expansion and contraction. Which causes the loss of some important properties of the thermal insulation material.

5- It must have good mechanical properties, such as a high compressive strength coefficient and a coefficient of resistance to fracture.

6- To be fire resistant.

7- It should not result in harm, health, and be resistant to bacteria and mold and not subject to the growth of insects in it.

8- It should be dimensionally stable in the long term, with little ability to expand or contract under the influence of surrounding weather and climatic factors.

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9- To be resistant to chemical reactions and changes.

10- To be easy to install.

11- It must be in conformity with the Jordanian standard specifications.

2- Mechanical properties of thermal insulation materials:
Among the most important mechanical properties of thermal insulation materials that must be known and determine whether or not a material can be used in a specific application are properties such as: pressure resistance, bending resistance, shear resistance. The compressive strength property is one of the most important mechanical properties required for insulating materials and indicates the strength that the material can withstand when it is subjected to a specific compressive force or weights. This property is measured in terms of mass divided by area (kg / m2) or kilopascal

3- Physical Characteristics:
The most important ones are density, dimensional stability, thermal expansion, elasticity, slack resistance, water absorption property, water vapor permeability and capillary rise.
The property of water absorption and water vapor permeability is one of the most important physical properties that affect the resistance of the thermal conductivity of the insulating materials, the coefficient of thermal conductivity of water is very high and therefore the absorption of the thermal insulation material of water or moisture leads to a significant increase in the value of the thermal conductivity coefficient of the insulating material, and this is proportional. With the amount of water or moisture that is inside the material, which consequently the material loses its thermal insulation ability significantly. Therefore, the higher the moisture (water) in the insulation material, the more heat it conducts, and thus its heat insulation property decreases.

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4 - Burning Characteristics:
Knowing the combustibility and the ability of the insulating material to resist fire helps in determining the risk that may arise when it is burned. Knowing the characteristics related to the behavior of insulating materials during fire, especially those that are combustible, helps in taking appropriate measures to prevent the potential danger from them. Among the most important values ​​that can be determined in this field are the rate of combustion, the rate of spread of flame on surfaces, the rate of fire spread, the intensity of smoke, and the toxicity of the materials resulting from combustion.

5 - health and safety features:
Some insulating materials have certain properties, some of which may endanger a person, whether at the time of storage, during transportation or installation, or during the period of use. Some of them have caused permanent or temporary impairments in the human body, such as wounds, blisters, poisoning, lung infections, or allergies to the skin and eyes. It necessitates the importance of knowing the chemical composition of the insulating material, in addition to its other physical properties in terms of its flammability, sublimation and other characteristics mentioned in paragraph 3-4 (combustion properties).

6 - Acoustic Characteristics:
Some heat-insulating materials are also used to fulfill sound insulation requirements such as dispersing or absorbing vibration. Therefore, knowing the properties associated with this aspect may achieve two goals in one way as a result of using these materials, namely thermal insulation and sound insulation.
In addition to the above properties, there are other properties that may be necessary when choosing the appropriate insulating material, such as knowledge of density, ability to resist shrinkage, possibility of use for several times, ease of use and maintenance, regularity of dimensions and resistance to chemical reactions, available sizes and thicknesses, in addition to the economic factor that plays an important role in The use of these insulating materials as well as the life span of the insulation material compared to the level of insulation quality provided by that material.

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