Indicators of specific heat capacity of various types of bricks

When selecting a suitable material for a particular type of construction work, special attention should be paid to its technical characteristics. This also applies to the specific heat capacity of brick, on which the house’s need for subsequent thermal insulation and additional wall decoration largely depends.

Characteristics of brick that affect its use:

• Specific heat. A value that determines the amount of thermal energy required to heat 1 kg by 1 degree.
• Thermal conductivity. A very important characteristic for brick products, which allows you to determine the amount of heat transferred from the room to the street.
• The level of heat transfer of a brick wall is directly affected by the characteristics of the material used for its construction. In cases where we are talking about multi-layer masonry, it will be necessary to take into account the thermal conductivity of each layer separately.

Density and specific heat capacity of brick

Brick is a popular building material in the construction of buildings and structures.
Many people only distinguish between red and white brick, but its types are much more diverse. They differ both in appearance (shape, color, size) and in properties such as density and heat capacity. Traditionally, a distinction is made between ceramic and sand-lime bricks, which have different manufacturing technologies. It is important to know that the density of the brick, its specific heat capacity and the thermal conductivity of each type of brick can vary significantly. Ceramic brick is made from clay with various additives and fired. The specific heat capacity of ceramic brick is 700...900 J/(kg deg) . The average density of ceramic bricks is 1400 kg/m3. The advantages of this type are: smooth surface, frost and water resistance, as well as resistance to high temperatures. The density of ceramic brick is determined by its porosity and can range from 700 to 2100 kg/m3. The higher the porosity, the lower the density of the brick.

Sand-lime brick has the following varieties: solid, hollow and porous; it has several standard sizes: single, one-and-a-half and double. The average density of sand-lime brick is 1600 kg/m3. The advantages of sand-lime brick are excellent soundproofing. Even if you lay a thin layer of such material, the sound insulation properties will remain at the proper level. The specific heat capacity of sand-lime brick ranges from 750 to 850 J/(kg deg) .

The density values ​​of various types of bricks and their specific (mass) heat capacity at various temperatures are presented in the table:

Table of density and specific heat capacity of bricks

It is necessary to note another popular type of brick – facing brick. He is not afraid of either moisture or cold. The specific heat capacity of the facing brick is 880 J/(kg deg) . The facing brick has shades from bright yellow to fiery red. This material can be used for finishing and facing work. The density of this type of brick is 1800 kg/m3.

It is worth noting a separate class of bricks - refractory bricks. This class includes dinas, carborundum, magnesite and fireclay bricks. Refractory bricks are quite heavy - the density of bricks of this class can reach 2700 kg/m3.

Carborundum brick has the lowest heat capacity at high temperatures - it is 779 J/(kg deg) at a temperature of 1000°C. Masonry made from such bricks warms up much faster than fireclay bricks, but retains heat less well.

Refractory bricks are used in the construction of furnaces with operating temperatures up to 1500°C. The specific heat capacity of refractory bricks depends significantly on temperature. For example, the specific heat capacity of fireclay bricks is 833 J/(kg deg) at 100°C and 1251 J/(kg deg) at 1500°C.

1. Franchuk A. U. Tables of thermal technical indicators of building materials, M.: Research Institute of Construction Physics, 1969 - 142 p.
2. Tables of physical quantities. Directory. Ed. acad. I. K. Kikoina. M.: Atomizdat, 1976. - 1008 p. construction physics, 1969 - 142 p.
3. Kazantsev E.I. Industrial furnaces. Reference manual for calculations and design.
4. Mikheev M. A., Mikheeva I. M. Fundamentals of heat transfer.

Facing

Separately, it is worth mentioning the facing brick, which with equal success resists both water and increased temperature. The specific heat capacity of this material is at the level of 0.88 kJ/(kg K), with a density of up to 2700 kg/m3. Facing bricks are available for sale in a wide variety of shades. They are suitable for both cladding and laying.

Density of ceramic brick

Brick is a wall building material made in the form of a parallelepiped.
The products in question have many useful characteristics, they are highly durable and perfectly withstand adverse weather conditions. The main indicators of any wall material are density, thermal conductivity and ability to absorb moisture. In our article we will get acquainted with such a characteristic of ceramic brick as density, because the thermal conductivity coefficient of the walls being built will depend on this indicator (the higher the density, the better the heat will pass through the structure of the material). Ceramic bricks are made from clay of a special composition. After the raw material is formed, it is sent to tunnel kilns for firing. According to the requirements of building codes, the maximum density of ceramic bricks of a monolithic structure is 2000 kg/m 3. If we take material with voids, the volume of which can reach up to 40%, then the density of such products will be slightly lower, in the range of 1000-1400 kg/m3. As you can see, solid products have a much higher density than hollow ones, so they are used for laying the main walls of a building and columns, and slotted analogues are recommended for installing load-bearing walls of one-story buildings or laying interior or inter-apartment partitions.

A single ceramic brick with standard dimensions of 25×12×6.5 centimeters has a density of within 1600 kilograms. It should be noted that the type of brick in question is divided into several subtypes:

• ordinary clay brick is most often used for laying main walls and partitions; it can also be used to lay columns or pillars;
• high-strength ceramic bricks are used by builders in particularly critical places;
• facing – material for finishing load-bearing walls of buildings, framing window and door openings, decorating external walls and erecting arches.

After we have become familiar with the main types of ceramic bricks, we can summarize that when choosing any wall material, you need to understand for what work each product is suitable, and knowing the density of ceramic bricks, measured in kg/m 3, allows you to calculate the wall load on foundation. With the correct calculation of the foundation, you don’t have to worry about the durability of the house.

Refractory

Fireproof blocks can be divided into several types:

Types of refractory bricks

• carborundum;
• magnesite;
• dinas;
• fireclay.

Fire-resistant products are used to build high-temperature furnaces. Their density is 2700 kg/m

3

. The heat capacity of each type depends on the manufacturing conditions. Thus, the heat capacity index of carborundum brick at a temperature of 1000

O

C is 780 J. Fireclay brick at a temperature of 100

O

C has an index of 840 J, and at 1500

O

This parameter will increase to 1.25 kJ.

Brick Density

• What does the density of a brick depend on?
• Density of ceramic brick
• Density of sand-lime brick
• Density of solid brick
• Density of hollow bricks

An important characteristic when building houses is the density of the brick. It can be called a variable value only because the surface of this material is hygroscopic, therefore, when calculating the mass of a brick building, dry mass + 10% is taken into account.

Modern brick cannot be compared with pre-revolutionary models for one simple reason. Previously, they did not skimp on firing and clay, compacting the mixture as much as possible. Those who have ever drilled into an old brick wall know how tightly it grips the drill. There were also no standards for brick, so this material weighed, on average, 1.5-1.8 times more for the same volume. This can be considered an indicator of quality, but at the same time the load on the foundation increased significantly. There were no thermal calculations, so the thickness of the walls in such buildings and structures often reached up to 1 meter. From the point of view of a modern market economy, such an expense is completely unreasonable, especially considering that modern walls are insulated, and houses are heated using completely different methods.

What does the density of a brick depend on?

There are several universal reasons that affect the density of high-quality brick, regardless of its type:

1. Fracture . This is a natural property of clay. However, now there are polymer mixtures that do not crack, so the density will be much higher.
2. Humidity . Although we have already mentioned it above, it is worth telling about it in more detail. The brick picks up the bulk of moisture directly during laying. It absorbs a certain amount of moisture, which is then balanced depending on weather conditions. This indicator also depends on the so-called vapor permeability. If the brick does not retain moisture, it will allow air to pass through well. Typically, material that accumulates moisture is used for the construction of basement walls and sewer lines.
3. A type of clay or any other material . Sand from two different deposits with the same volume has a different mass. The same thing is observed for clay. Silicate sand for white bricks also has different densities. Despite compaction, the properties of the material or mixture play a role.

Influence of temperature conditions

The quality is greatly influenced by temperature. Thus, with an average density of the material, the heat capacity may differ depending on the ambient temperature.

Table comparing the thermal conductivity of logs with brickwork

From the above it follows that it is necessary to select building materials based on its characteristics and further scope of its application. This way it will be possible to build a room that will meet the necessary requirements.

Density, mass and other technical parameters of bricks

When carrying out masonry work, it is important to know how much a brick weighs and what its density and structure are. These parameters directly affect the strength and insulation qualities, which in turn are taken into account when calculating the loads and thermal resistance of the structures being built. The average values ​​for each type are standard, but the exact value depends on the manufacturer and is indicated in the product certificate.

Weight of different types

Density is divided into true and average, the first is determined empirically and is not important for consumers. The second indicator characterizes the ratio of the mass of one product to its volume and depends on the raw material, the proportion of voids and cracks and porosity. Both quantities are measured in kg/m3. The average density and weight of one brick will differ between different brands; the minimum is observed in warm, highly efficient ceramics, and the maximum in silicate and hyper-pressed artificial stone.

Elements made from clay with subsequent firing are divided into solid and hollow; the second group can have both through holes of various shapes and hidden voids and pores. The standard-approved density of solid red brick reaches 2000 kg/m3, but the range for most manufacturers varies between 1600-1900. External walls need additional insulation. The weight of solid blocks in 1NF format reaches 3.45-3.8 kg.

Hollow types have a density from 1200 to 1500 kg/m3, taking into account the proportion of cracks up to 37%; standard 1NF is no more than 2.9 kg. The specific gravity of some brands reaches 1700, but this is an exception. The average density of lightweight ceramic stone (porous, thermally efficient) is 1100-1150 kg/m3, advanced manufacturers have lowered this figure to 800.

Frost resistance

Frost resistance is determined by freezing and thawing cycles. This parameter is important when choosing the type of brick for laying load-bearing walls. The brand depends on the number of cycles and is indicated on the products. The highest frost resistance is found in facing and red bricks, which can withstand temperatures down to -50 degrees Celsius and below. If you use sand-lime brick, its properties are worse, so the masonry will have to be done in two layers. Silicate is also not suitable for foundation construction.

In winter weather conditions, heat in the house is maintained by the heating boiler of the heating system. But in order to prevent heat dissipation, you need walls, floors and ceilings made of appropriate material that maintains the set temperature well. The type of brickwork plays an important role during construction. The material should be selected taking into account all parameters and weather conditions.

In the next video you will find an overview of the thermal conductivity of ShB 8 brick.

Studying the density of bricks

The consumer characteristics of the resulting building depend on the properties of bricks such as moisture resistance, fire resistance, frost resistance, porosity of the shard, weight, as well as the maximum load-bearing load and color. It is based on the desired qualities of the future home that the material for construction is selected. But there is one quality that is always taken into account when buying bricks - density.

Brick density is a parameter that directly affects the thermal and sound insulation of buildings and the overall weight of the structure. The density coefficient is calculated as the ratio of the mass of a brick body to its volume. Moreover, the volume takes into account the overall dimensions, including technical voids. Thus, the lighter the brick, the lower its density, with the same dimensions.

They reduce the density of bricks due to voids with air. This can happen in two ways - by increasing the porosity of the shard with the help of special foaming additives, as well as by creating visually observable technical voids inside the block (most often from the bed side).

What does brick density affect?

Qualities such as the weight and density of a material directly determine the possibilities of its use in construction:

By choosing bricks with less density, they have the opportunity to build warmer houses, since the air filling the voids is the best thermal insulation; When buying bricks with a higher density (and fewer voids), they make a choice in favor of the strength and durability of structures.

The most popular in domestic latitudes, ceramic bricks are produced solid (solid) and hollow (with special technical voids), as well as with normal or increased porosity of the shard (porous). Thus, even a solid “inside” can give a brick the properties of a hollow one, being, in fact, an intermediate option.

What are hollow bricks?

Depending on the production technology, brick voids can have different shapes (round, slot-shaped, rectangular), different quantities and sizes, different locations (through, closed on one side), and differ in the direction of the holes. In addition, both the ordinary and facing blocks are made hollow.

Advantages of hollow and porous bricks:

• Lighter and warmer brick allows you to build less thick walls;
• The number of pores and voids directly affects sound insulation parameters;
• Hollow brick is warmer than solid brick, since heat transfer is possible only through a dense texture;
• Often the lower cost, compared to solid brick, allows for significant savings on the estimate.

Among the disadvantages, it is worth mentioning that hollow brick with horizontal holes cannot serve as a material for load-bearing walls, since its strength is not capable of withstanding long-term heavy loads. The moisture absorption of hollow blocks is also higher, which can seriously worsen the climate in the house without additional hydro- and vapor barrier.

Solid brick, what are you?

Solid brick is made from baked clay without foaming additives and the formation of technological voids. This feature makes it more durable and wear-resistant. Solid brick can also be ordinary, facing and even kiln refractory.

Comparison with other materials

Among the materials that can compete with brick, there are both natural and traditional ones - wood and concrete, and modern synthetic ones - penoplex and aerated concrete.

Wooden buildings have long been erected in northern and other areas characterized by low winter temperatures, and this is not without reason. The specific heat capacity of wood is significantly lower than that of brick. Houses in this area are built from solid oak, coniferous trees, and chipboard is also used.

If wood is cut across the grain, the thermal conductivity coefficient of the material does not exceed 0.25 W/M*K. Chipboard also has a low rate - 0.15. And the most optimal coefficient for construction is wood cut along the grain - no more than 0.11. It is obvious that in houses made of such wood excellent heat retention is achieved.

The table clearly demonstrates the spread in the thermal conductivity coefficient of brick (expressed in W/M*K):

• clinker – up to 0.9;
• silicate - up to 0.8 (with voids and cracks - 0.5-0.65);
• ceramic – from 0.45 to 0.75;
• slot ceramics – 0.3-0.4;
• porous – 0.22;
• warm ceramics and blocks – 0.12-0.2.

At the same time, only warm ceramics and porous bricks, which are also expensive and fragile, can compete with wood in terms of heat retention in the house. However, brickwork is used more often in the construction of walls, and not only because of the high cost of solid wood. Wooden walls are afraid of precipitation and fade in the sun. Wood also does not like chemical influences; moreover, wood can rot and dry out, and mold forms on it. Therefore, this material requires special processing before construction begins.

In addition, fire can very quickly destroy a wooden structure, since wood burns well. In contrast, most types of brick are quite resistant to fire, especially fireclay brick.

As for other modern materials, foam block and aerated concrete are usually chosen for comparison with brick. Foam blocks are concrete with pores, which includes water and cement, a foaming composition and hardeners, as well as plasticizers and other components. The composite does not absorb moisture, is highly frost-resistant, and retains heat. It is used in the construction of low (two to three floors) private buildings. Thermal conductivity is 0.2-0.3 W/M*K.

Brick density - tables, calculation formula, description and examples

Brick has been one of the main materials in construction for many hundreds of years.

Therefore, the density of the brick plays a critical role, knowing the value of which you can understand the thermal conductivity and volumetric weight, as well as the weight of the sample per unit volume.

Sand-lime brick

This type of building material is made from sand and lime in a ratio of 1/9. Having a very low cost, this brick is one of the most affordable on the market.

Another advantage is the wide color palette in which sand-lime brick is produced.

However, it has high thermal conductivity and heavy weight, which is why it is not used in the construction of load-bearing walls, partitions and fireplaces due to the deformation of this building material under the influence of high temperatures. Sand-lime brick is divided into two types: hollow and solid, and has a density from 1100 to 1950 kg/m3.

Ceramic brick

Solid ceramic brick is used to build many objects - load-bearing, internal and external walls, as well as columns and arches. Its hollow counterpart is used to build lightweight structures and fill frames.

The density for the first option is at least 2000 kg/m3, and for the second – from 1100 to 1400 kg/m3.

Solid brick

Also widely known as “construction” or “ordinary”. It is used to build literally all structures, be they pillars, load-bearing systems, arches, etc. due to its high strength and cold resistance, although walls built using this building material require additional insulation.

Its approximate concentration is 1900 kg/m3. There is a red solid brick that we can often see as the main building material for the external walls of houses, window frames and basements.

Withstands such loads due to its very high strength - 2100 kg/m3.

Hollow brick

It has internal voids from 13% to 50% of the volume and has a porous structure, as a result of which it is quite fragile and light. It has excellent noise and heat insulation and is perfect for interior walls and partitions, as well as as a filler for frames.

The density of this brick ranges from 1000 to 1450 kg/m3.

Clinker brick

It is made from red clay, dried and fired at extremely high temperatures, which gives the building material a high density - 2100 kg/m3 - and increased wear resistance.

However, the disadvantage of this brick is its high price, which is justified by labor-intensive production.

The second disadvantage is increased thermal conductivity. It is often used in the construction of roads, for cladding facades and basement floors of residential buildings.

Fireclay brick

Probably one of the most expensive building materials on this market. The high price is justified by fire resistance, which allows it to withstand temperatures up to +1600°C, being a leader in this area.

It is made mainly in trapezoidal, conical and arched shapes in yellow and bright red colors. Density ranges from 1700 to 1900 kg/cm3.

Facing brick

It has a fairly narrow application due to its smooth and “glossy” surface and is used for laying external walls that require a special plane.

It is produced in a variety of colors, which are achieved by selecting different clay masses, fired at different temperatures and time spent in firing. Like other clay-based building materials, facing bricks have increased thermal insulation properties and are practically not subject to corrosion.

The density of this brick is measured in the range from 1300 to 1450 kg/m3.

Characteristics affecting quality

The following product properties must be taken into account:

• thermal conductivity is the ability to transfer heat received from indoor air to the outside;
• heat capacity - the amount of heat that allows heating one kilogram of building material by one degree Celsius;
• density - determined by the presence of internal pores.

Below is a description of the different types of products.

Types of bricks

Brick weight

The most popular on construction sites is ceramic ordinary solid single brick 250 (mm) long, 120 (mm) wide, 65 (mm) high, its weight ranges from 3.3 to 3.6 (kg).

Brick weight and density:

Many resources on the Internet have replicated weight tables that provide accurate data on the mass of bricks, but the table data is incorrect, since the mass parameter depends solely on the class coefficient of the average density of the product.

Because this coefficient can vary greatly among different products and manufacturers; the mass of the finished brick is a floating value.

When making calculations, it is advisable to check this coefficient with manufacturers, and then, using the formula: m=l*b*h*p, calculate the required value, where:

• l – product length;
• b – width;
• h – thickness (height);
• p — Average density, kg/m3.

Important: all the data presented below refer to average typical brick options, and give only an approximate idea of ​​the mass with an error of up to 15%.

Dependence on temperature of use

The technical performance of bricks is greatly influenced by temperature conditions:

• Trepelny . At temperatures from -20 to + 20, the density varies within 700-1300 kg/m3. The heat capacity indicator is at a stable level of 0.712 kJ/(kg K).
• Silicate . A similar temperature regime of -20 - +20 degrees and a density from 1000 to 2200 kg/m3 provides the possibility of different specific heat capacities of 0.754-0.837 kJ/(kg K).
• Adobe . When the temperature is identical to the previous type, it demonstrates a stable heat capacity of 0.753 kJ/(kg K).
• Red . Can be used at temperatures of 0-100 degrees. Its density can vary from 1600-2070 kg/m3, and its heat capacity can range from 0.849 to 0.872 kJ/(kg K).
• Yellow . Temperature fluctuations from -20 to +20 degrees and a stable density of 1817 kg/m3 gives the same stable heat capacity of 0.728 kJ/(kg K).
• Construction . At a temperature of +20 degrees and a density of 800-1500 kg/m3, the heat capacity is at the level of 0.8 kJ/(kg K).
• Facing . The same temperature regime of +20, with a material density of 1800 kg/m3, determines the heat capacity of 0.88 kJ/(kg K).
• Dinas . Operation at elevated temperatures from +20 to +1500 and density 1500-1900 kg/m3 implies a consistent increase in heat capacity from 0.842 to 1.243 kJ/(kg K).
• Carborundum . As it heats from +20 to +100 degrees, a material with a density of 1000-1300 kg/m3 gradually increases its heat capacity from 0.7 to 0.841 kJ/(kg K). However, if the heating of the carborundum brick is continued further, its heat capacity begins to decrease. At a temperature of +1000 degrees it will be equal to 0.779 kJ/(kg K).
• Magnesite . A material with a density of 2700 kg/m3 with an increase in temperature from +100 to +1500 degrees gradually increases its heat capacity of 0.93-1.239 kJ/(kg K).
• Chromite . Heating a product with a density of 3050 kg/m3 from +100 to +1000 degrees provokes a gradual increase in its heat capacity from 0.712 to 0.912 kJ/(kg K).
• Chamotte . It has a density of 1850 kg/m3. When heated from +100 to +1500 degrees, the heat capacity of the material increases from 0.833 to 1.251 kJ/(kg K).

Select the bricks correctly, depending on the tasks at the construction site.

If you find an error, please select a piece of text and press Ctrl+Enter.

Content

Table I: Standard Specific Heat Capacity Values ​​Note: Specific heat capacity is shown here using temperature units in Kelvin(K).

Silicate

Sand-lime brick is in high demand in construction; its popularity is due to its strength, availability and low cost. The specific heat capacity is 0.75 - 0.85 kJ, and its density is from 1000 to 2200 kg/m3.

The product has good sound insulation properties. A wall made of silicate product will insulate the structure from the penetration of various types of noise. It is most often used for the construction of partitions. The product is widely used as an intermediate layer in masonry, acting as a sound insulator.

Brick oven

Brick oven

- a stove made of ceramic bricks.

Content

• 1 Foundation
• 2 Materials of manufacture
• 3 Classification 3.1 By type of fuel chamber 3.1.1 For firewood
• 3.1.2 For coal

Foundation [edit | edit code]

Furnaces weighing 750 kg or more are installed on a separate foundation or base [1] [2]. With less weight, installation on the ceiling is allowed, provided that it has sufficient load-bearing capacity.

Manufacturing materials [edit | edit code]

The main type of brick is solid ceramic brick with standard dimensions in Russia of 250x120x65 mm. Brick grade not lower than M100 [3] [4], density more than 1600 kg/m 3 [5] (weight of one brick more than 3.12 kg). For fuel chambers and initial chimney paths exposed to high temperatures of the order of 1600–1850 °C, refractory fireclay bricks with dimensions of 250 × 123 × 65 or 230 × 112 × 65 mm are used [6] .

Solution

• Clay - used for laying the stove and pipes up to the roof level.
• Limestone - foundation in dry soil [3].
• Cement - foundation in wet soil [3], pipe above roof level [7][4].
• Lime-cement - part of the pipe running in the attic [7][4].

For laying refractory bricks, refractory clay with sand is used, for refractory bricks, refractory clay with fireclay powder is used [4] [3].

Stove appliances are mainly made of cast iron. List of devices:

• Grate or a set of single grates.
• Firebox door.
• Blower or ash pan door.
• Cleaning doors - close the openings for cleaning the oven channels.
• View door.
• View - a double lid (pancake and lid) with a frame for opening and closing the smoke channel. Located behind the view door.
• The valve is a plate in a frame for opening and closing the smoke channel.
• A stove with burners (with closable holes) or without them (solid).
• A damper for closing the mouth of a Russian stove.

Classification [edit | edit code ]

By type of fuel chamber [edit | edit code]

Each type of fuel corresponds to a certain shape of the fuel chamber. Under

(lower platform) of the chamber can be blind (for example, like a Russian stove) or grate. Under the grates there is a blower (ash pan) chamber.

The minimum thickness of the outer walls of the firebox is half a brick; for stoves with a power of more than 3489 W it ranges from 3/4 to a whole brick, depending on the heat transfer of the stove [8].

Height of the fuel layer and firebox [9]

For firewood [edit | edit code]

Wood produces a high flame, since most of it, before burning, goes into a gaseous state (sublimation process) [10]. To ensure the most complete combustion, the heating

stoves must have sufficient free space above the firewood layer (indicated in the table).
The maximum height from the grate to the firebox overlap is 1 m [8]. The height of the stove firebox with the hob
is in the range of 280–420 mm (4–6 rows of masonry [11]), which is due to the need for flame contact with the cast iron stove. Minimum length 35 cm [12] .

It is recommended to line the firebox of wood stoves with a power of more than 3000 W with refractory bricks [12].

For coal[edit | edit code]

For the combustion of brown and hard coal, the presence of a grate is mandatory. The coal firebox is lined [13]. The walls of the firebox for anthracite are completely lined with refractory bricks [14].

For brown coal or dry sod peat

For peat with high humidity. The arrow shows the exit of steam through the steam outlet slot

Trumpet [edit | edit code]

Brick pipe by location:

• Mounted - installed on the roof of a thick-walled furnace [15].
• Root - free-standing on its own foundation.
• Wall - the smoke channel is located in the brick wall of the building.

• Fluffing, cutting - thickening of the pipe wall at the point where it passes through the ceiling. Fire protection element.
• Otter is a thickening of the wall hanging over the roof. Closes the gap between the pipe and the roof from precipitation.
• The cap is the thickening of the wall at the very top of the pipe.

Pipe channel dimensions, not less than [16]:

• 140x140 mm - for furnaces with power up to 3500 W.
• 140×200 mm - 3500-5200 W.
• 140×270 mm - 5200-7000 W.

Selection of a heating stove [edit | edit code]

Heat loss in the room [edit | edit code]

The required power of a heating stove is determined by the heat loss of the room, which depends on many factors: climatic conditions, area and height of the room, the number of external walls, the type of building materials and the degree of insulation of the house. The average hourly heat output of the furnace should be equal to the heat loss of the heated room [18] (±15% [19]).

Approximately calculated using the formula [19]:

• Q = 125 ⋅ f ⋅ k - for corner rooms, Q = 125 ⋅ k
  - for corner rooms less than 10 m 2.
• Q = 80 ⋅ f ⋅ k - for non-corner rooms, Q = 80 ⋅ k
  - for non-corner rooms less than 10 m 2, where Q is the heat loss of the room (W), 125 and 80 are empirical coefficients, f is the floor area (m 2) , k - heat transfer coefficient of external walls (W/m2).

Rnosl. = δ/λ - heat transfer resistance of walls made of one material or a separate layer of material in walls made of several materials, where δ is the thickness of the material layer (m), λ is the thermal conductivity coefficient of the material

[21] (W/[m °C]).
R verbose = R1 + R2 + … + 0.155
+
0.058
is the heat transfer resistance of walls made of several materials, where R1 and R2 are the heat transfer resistance of individual layers of materials, 0.155 [22] is the heat transfer resistance at the inner surface of the walls (Rв), 0.058 [23] is the resistance heat transfer at the outer surface of the walls (Rн) [24].

For rooms with a height of 2.5-3 m, the obtained Q value is increased by 10%. For rooms with two external corners, the Q value is also increased by 10%.

The formulas are calculated for an external temperature of −30 °C. For other temperatures, correction factors are used:

• 1.35 - at a temperature of −35 °C and below.
• 0.85 - from −10 to −20 °C.
• 0.75 - above −10 °C.

Heat transfer of the furnace [edit | edit code]

The maximum power of a batch furnace develops when firing twice a day. For example, the heat transfer of one square meter of the active surface (mirror) of an open-standing (distance to the walls of the room is at least 130 mm) thick-walled wood-burning stove, with single and double firing, is 330 and 550 W, respectively. To find out the required mirror area of ​​an open-standing stove with a double firebox, it is necessary to divide the heat loss of the room by 550 W/m2 [25]. For southern regions, with outside temperatures of +5 °C and above, a single combustion is recommended [26].

The mirror area of ​​an existing furnace is equal to the product of its perimeter and active height. The active height of the furnace is approximately equal to its height from the floor level minus 300 mm [25]. The area of ​​the upper plane of the ceiling is taken into account if the height of the furnace does not exceed 2.1 m, and a correction factor of 0.5 is introduced for the ceiling [19] [25].

Types of Heat Transfer

• Heat transfer is the physical process of transferring thermal energy from a more heated body to a less heated one.

Everything here is quite simple, there are only three of them: thermal conductivity, convection and radiation.

Thermal conductivity

That type of heat transfer that can be characterized as the ability of bodies to conduct energy from a more heated body to a less heated one.

It's about transferring heat through contact. Admit it, have you ever warmed yourself near a radiator? If you sat close to it, then you warmed up due to thermal conductivity. Cuddling a cat who has a hot belly is also effective.

Sometimes we go a little overboard with the possibilities of this effect when we lie down on the hot sand at the beach. There is an effect, but not a very pleasant one. Well, an ice heating pad on your forehead has the opposite effect - your forehead transfers heat to the heating pad.

Convection

When we talked about thermal conductivity, we used a battery as an example. Conduction is when we get heat by touching a battery. But all the things in the room do not touch the radiator, and the room is heated. This is where convection comes in .

The fact is that cold air is heavier than hot air (cold air is simply denser). When the battery heats a certain volume of air, it immediately rises to the top, passes along the ceiling, has time to cool down and go back down to the battery, where it heats up again. Thus, the entire room is heated evenly, because increasingly hot currents replace increasingly colder ones.

Radiation

We already mentioned the beach, but we were talking only about the hot sand. But the heat from the sun is radiation . In this case, heat is transferred through waves.

Both ways. The heat that we feel directly from the fireplace (when your face is hot, if you are located too close to the fireplace) is radiation . But heating the room as a whole is convection .