Calculation of heat transfer of the radiator section. Technical characteristics of cast iron radiators. Choosing a radiator: a comparison of existing options
Aluminum sectional radiators
In Russian conditions, where winter lasts about six months, and sometimes even more, sufficient room temperature is a prerequisite for comfort. Well-known cast-iron radiators cope with this task well. Their history began from time immemorial - as soon as it became possible to heat dwellings by means of steam or hot water. However, they appearance has long ceased to satisfy consumers, and more presentable novelties appeared on the market. For example, the heat transfer of which is no worse than that of cast iron.
Spontaneous work is also possible at any time, since infrared system heating moves quickly. However, for small spaces, the device is heavily dependent on power and we quickly get too warm. Individuality and flexibility are the key factors here. The high quality and efficient working model can ideally be used as transitional and additional heating as well as full heating. In addition, you can use infrared heating to dry the building.
However, you should not use this infrared heating in rooms with more than 17 m² as full heating, as the possibilities are not enough. With its 800W, the device is extremely efficient, especially in large rooms and areas. Because he plays full force. Especially when drying a construction site, the device quickly convinces in drying and can be used perfectly for drying large surfaces. In addition, the device with its 24 kg is not exactly light.
Types of heating devices
The essence of any heating system is to create a comfortable temperature for a person in the room. It fluctuates between 18-22 degrees above zero. Pipes and heating appliances, heating up hot water, give off heat to the surrounding space. In this case, a significant role is played by the material from which the radiators are made, as well as their design and type of heating system.
Therefore, you should always be in the apartment of this infrared heating in a fixed location. It is almost universal, which has been designed for multifunctional use. Basically, you can use this infrared body well in rooms up to 12 square meters. If this value is significantly exceeded, the device will lose its effectiveness. According to test reports and experience reports, the device also convinces in rooms that are no more than 12.5 square meters.
How to save on heating
You can use heating both in individual living rooms and in the garage, basement or garden house, for example on ceilings or walls. Thanks to the thermocrystal coating and modern technology high energy efficiency is guaranteed. Since the white panel can be covered by you, decorative positioning is possible at any time, such as in the living room.
She may be:
- centralized
- autonomous
Depending on the scheme, heating is divided into:
- dependent
- independent
Another type of separation of heating systems is according to the coolant circulation method:
- natural
- forced
In terms of material, there are several types of radiators:
In small rooms, infrared heating of magma shows its full potential. Whether it is the reduction of thermal radiation, the reflection of infrared heat, or the dissipation of an electric bridge, the model benefits here because of its method of construction and good technology. However, in the case of rooms of 15 square meters, the power is no longer sufficient to achieve the full heating effect. Here it can be used as an additional source of heat. The low weight of four kilograms and convenient handling make the device extremely mobile.
- cast iron
- steel
- aluminum
- copper
- bimetallic
- convector type
A little more
District heating implies that heat is supplied to houses through pipes from a boiler house located at some distance from the heat supply facilities.
Heat dissipation of batteries from different materials
Therefore, changing places of application is never associated with effort. A total of 500W provides good performance, especially in rooms up to 12.5 square meters. Also, you can use infrared emitter in this area is excellent for selective heating. Thanks to the radiator expansion options, you can also heat large areas or clearly large rooms, greatly increasing the flexibility of use.
Brief description of systems and equipment and notes for use
Since the device is extremely light at 7kg, transport, positioning and/or repositioning is not a problem. To start the fuel system to feed the engines, set the fuel pump fuse switch to the Automatic Pump Changeover position. The "pump no. 2 running" light comes on. Pump No. 1 must be turned on by pressing the "Pump No. 1 On" button. The illuminated field "pump No. 1" is highlighted. In the event of a failure of pump No. 1 during flight, the illuminated field "pump No. 1" lights up and the light field "pump No. 2" lights up.
With autonomous, or "local" heating, the heat source - the heating boiler - is located directly in the house, and from it hot water is distributed through pipes to radiators. The dependent scheme is that hot water with a temperature of about +150 degrees in the control unit is diluted cold water up to + 90 + 100 degrees, after which it enters the pipes and radiators.
Pressing the "Pump #1 On" button causes that pump to turn on again. The motor lubrication system is self-contained and is used to lubricate and dissipate heat from all bearings and motor drives. The main gearbox has its own lubrication system.
The helicopter is equipped with a grease level alarm in the grease reservoir. When the lubricant level drops in a liter container, the alarm level is indicated. When the block goes further down to liters, the stage is activated. When the lubrication level rises, the alarm turns on. When the lubrication level rises above 1, the control lamp goes out.
In an independent circuit, hot water is directed to the water heater. Here she is thanks to her high temperature serves as a source of heat for water circulating through pipes and radiators. At the same time, hot water with a temperature of +150 degrees does not come into contact with colder water, which is used for space heating and has an indicator of +90 + 100 degrees.
With continuous illumination of the control lamp, minimum oil 1 and lubrication level 1 in the engine lubrication tank, the engine lamp also signals with continuous lights. The spaces of the left and right engine and final drive are separated from each other by a refractory titanium sheet.
The fire extinguishing system consists of. The fuse switches and the changeover switch must be turned on before starting the motors. When a fire breaks out in a room, the fire alarm goes off. On the equipment panel and on the control panel of the fire extinguishing system in the corresponding room, the illuminated “fire” and the illuminated field light up. With a signal, the corresponding valve in the valve opens and the fire extinguishing container opens automatically. The light fields "1, container open" and "valve open" light up on the control panel.
Natural circulation is based on the different densities of cold and hot water. As a result, cold water entering the heating boiler pushes out warmer water. And thanks to the given slope of the pipes, the latter is distributed by gravity through the pipeline and heating devices. Forced or artificial circulation is carried out using pumping equipment.
The extinguishing agent flows through the pipe to the hearth. If the fire is extinguished, the light field "Fire" and the illuminated area for the corresponding room are lit. If the fire with the first container automatically opened has not been extinguished, the helicopter operator must press the button for the second row of the container and, if necessary, the button for the third row of the container.
These containers are opened and the illuminated fields "Container string addressed" or "Container with container addresses" light up. If the valve and the first row of containers do not open automatically in the event of a fire, the helicopter operator must press the button for the corresponding room in which the fire occurred, and then press the button for the second and, if necessary, the third row of containers.
Types of heating devices
According to their design, radiators can be:
- ribbed
- panel
- in the form of round tubes
- sectional
- tubular
Cast iron heating appliances
Cast iron radiator (battery)
Cabin ventilation and heating and loading area
The compressed air system is used to actuate the brakes and load the weapon, and to remove and expand the external load device. On the ground, it is filled with compressed air surfaces. On the Mi-2 helicopter, the front left cockpit window is electrically heated.
Heating and ventilation system
The heating and ventilation system maintains a certain temperature in the helicopter cabin. A fan driven by an electric motor, two radiators, two pipes from compressors with valves, an inlet pipe that is controlled from the cabin, a suction pipe in the cabin that is covered with sheet metal, Pedals, fiber optic cable. The following steps are required for summer commissioning.
Until recently, traditional cast iron sectional radiators were practically the only devices for space heating. Now there are products made of bimetal, steel and aluminum. Each of them has its own advantages and disadvantages. Despite the fact that aluminum radiators give off heat quite well, cast iron ones still surpass them in several ways.
- Close the hot air valves.
- Close the suction line in the cab with a rubber cap.
- Remove the rubber cap from the suction line in the cab.
- Open the hot air valve.
Their main advantage is high resistance to corrosion due to the wall thickness. And hence the weight. The anti-corrosion properties of cast iron are due to the fact that the gray cast iron used in these products consists of iron and carbon, which is resistant to oxidation processes and electrochemical reactions.
Water in the heating system contains oxygen and some chemical additives in the form of alkalis - to eliminate the risk of scale formation inside pipes and radiators. Cast iron is resistant to both oxygen and alkaline environments, which cannot be said about aluminum.
Supply of on-board network for stationary engines
The electrical equipment installed on the helicopter provides. Supply of all electrical and radio equipment of the helicopter, drive and remote control for various controls of the helicopter and engines. To power electrical equipment, the "Battery" switch must be installed on the upper center console, and the "Battery" switch must be set to "On".
Two control voltage regulators are located behind the dashboard. They serve to maintain and regulate voltage. electrical system at different speeds and loads, as well as the parallel operation of two generators. All circuits of the electrical system are protected against overload and short circuit.
To the virtues cast iron radiators should include:
- durability
- strength
- high cross section
- high heat transfer
- the ability to withstand high coolant pressure, reaching up to 18 atmospheres
Fuses are used for most of the loads installed on the helicopter. They are designed for a specific load and cannot be replaced by others. To obtain control pressure on the joystick in different phases of flight, there are trimmers for manual control.
Types of heating devices
The disk consists of three layers. A third layer of molten metal is bonded between the two outer layers, which consist of unsplit drawn glass. At both sides. Electrodes for supplying current. The rail heating is switched on by means of a fuse on the right cab control panel.
Excellent radiators
The durability of cast iron products is time-tested. Until now, in many apartments you can see these devices, which have been serving for many decades without any leaks. If this happens, then they have nothing to do with the cast iron itself. The reason is usually a poor connection of individual sections or a poor-quality connection. steel pipes. But there have never been cases of destruction of the cast iron itself.
To start the wiper, turn on the fuse on the right panel and the wiper switch on the dashboard. After switching off, the wiper return switch must be switched to the “return” position.
Use in switch position. . Landing and swinging headlight are enabled using the "control" and "light" fuses on the left control panel and the "headlight" switch. Incoming lights are made with a switch on the shutter lever.
The load indicator is turned on with a switch on the left control panel. The position lamps are turned on with a switch on the control panel and switched to a "bright" or "dark" position with a switch on the instrument panel in the lower left corner.
The large cross-sectional cross-section of cast-iron radiators provides excellent throughput for many years. If deposits form on the inner walls, they do not interfere with the flow of the coolant, therefore they do not play a significant role in the pressure drop in the network.
The heat transfer of cast iron is somewhat lower compared to bimetallic products, but heated cast iron cools more slowly than steel or aluminum. A large battery retains heat in the house longer in the event of an emergency shutdown of heat supply. And the ability to arrange a radiator with any number of sections is a real chance to achieve the desired temperature in any room.
The rim of the cockpit and the loading area are illuminated with white lamps. The lighting is turned on with a fuse on the left control panel and two "helicopter cockpit guide" and "charging space" switches on the middle control panel.
Devices, remotes and control panels are illuminated in red. The brightness of red light lamps can be controlled using rheostats. Radio equipment is supplied constant voltage 28.5±1V from the electrical system of the vehicle. The circuits are protected against overload and short circuit.
Important! The advantages of cast iron radiators include the fact that they give off heat in the form of low-frequency radiation, which is more familiar to the human body.
A significant disadvantage of cast iron appliances is their unsightly appearance and heavy weight. However, in recent times products with improved design appeared, although their cost is not affordable for every consumer. The development of technology has made it possible to produce cast iron products with less weight and volume of sections. They are characterized by less thermal inertia, and thermostats can be used with them.
Aluminum radiators
aluminum radiator
Considering various types of radiators, we do not touch on copper ones, since they are practically not used due to the high cost and complexity of installation. Therefore, the question of which radiator is better - aluminum or copper - can be considered resolved. At the same time, both metals are not recommended for use in centralized heating systems, since additives in the coolant quickly disable both aluminum and copper devices.
They can only be used where there is constant control over the composition of the coolant, or in autonomous systems private houses.
The advantage of aluminum products is their attractive appearance, similar to bimetallic ones. High heat dissipation such devices due to the large number of ribs. Their total area, together with the flat parts, is sometimes 0.5 sq.m. At the same time, 50% of the heat enters the room in the form of radiation, and another 50% - as a result of convection of warm air. And thermal heads for temperature control can reduce the loss of thermal energy by 20-30%.
At aluminum radiators There are other positives as well:
- low cost
- great heat dissipation
- good permeability of intercollector pipes
- light weight
- ability to withstand pressure up to 18 atmospheres
The design of aluminum radiators is represented by smooth panels interconnected by many ribs. The distance between the panels can be different, so you can always choose an option that fits into the interior and the size of the room. Each section has an upper and lower collector, which allows you to remove accumulated air. Of the products on the market, they are in great demand today, harmoniously fitting into any interior.
Note! If there is no coolant in the heating system, it is recommended to turn off the radiator using stop valves to avoid corrosion. After turning off, it is imperative to open the air vent valve.
Bimetal radiators
Bimetal radiators
These devices are also sectional type heating appliances. They combine the positive properties of steel and aluminum:
- durability
- strength
- excellent heat dissipation
- resistance to aggressive coolant medium
- modern design
But besides this, bimetallic radiators are distinguished by increased resistance to corrosion due to the fact that aluminum does not come into contact with water. And they are able to withstand high pressure in the system. The strength and reliability of bimetallic products is associated with the use of paronite gaskets in their manufacture. They are also used in industrial pipelines.
A small cross section of the channels through which the coolant circulates makes it possible to reduce its volume, which positively affects the operation of thermostats. At the same time, the design of bimetallic radiators is simple in execution and does not contain cavities where air could accumulate.
Accessories for radiators
On the modern market there are products of many manufacturers. At the same time, in some models, the material is not of the highest quality. Or their design does not suit your taste. However, such radiators cost less than their counterparts with higher qualities.
The solution to the question of how to choose bimetallic radiators depends on:
- financial condition of the consumer
- design features of the product
- appearance
Leading positions in the market are occupied by manufacturers from Russia and Italy, among which there is also the inventor of bimetallic radiators - Sira. There is no fundamental difference between the presented models. Only steel radiators RIFAR MONOLIT and PILIGRIM stand out. The former are able to withstand pressure up to 100 atmospheres, which does not happen at all in everyday life. And the second ones have a copper core that is not subject to corrosion, especially in autonomous heating systems.
The difference can still be observed in the center-to-center distances varying from 300 to 800 mm. There are models in which the connection to the pipes occurs through the lower pipe, which is widely used in autonomous heating systems. There are also manufacturers who custom-made rounded radiators. As for the design, the products differ in color, so you can choose exactly the option that best suits your interior.
Steel heating appliances
Steel tubular radiators
Steel radiators can be made in the form of registers from round pipes or in panel design.
Panel products have gained great popularity due to their qualities:
- low cost per kilowatt hour, which indicates efficiency
- good design
- variety of sizes
- high heat transfer
These devices are made in the form of two plates with recesses, which are collectors and connecting channels. The presence of ribs between the plates increases the convection heating effect.
Convector radiators
Convector type radiator
In the past, convector batteries looked like metal pipe on which it was mounted great amount thin steel plates. The room was heated by warm air circulating between these plates. Now there are convector devices of other types. These are floor and skirting boards, built directly into the floor structure and heating the lower layers of air in the room.
Most often they are used in public buildings or where it is impossible to fix wall appliances, for example, with glass walls up to the floor.
Conclusion
Despite the huge variety of heating appliances of domestic and foreign production, made of different materials, deserve the most trust. They have favorable technical characteristics and reasonable cost. Their use in heating systems of private country houses is especially important.
The main purpose of a heating radiator is to maximize the heating of a room. Calculation of heat transfer of a radiator of heating batteries - necessary condition determining the effectiveness of the device. Each device model has its own heat transfer parameters depending on various factors (location features, connection type, etc.). Heat dissipation ( thermal power, radiator power) is the amount of thermal energy transferred by the device over a certain period of time. The unit of measure for heat transfer is Watt. Sometimes the calculation can be done in calories per hour (1 W = 859.8 cal / h). The heat of the heating device is produced as a result of the processes:
- Heat transfer.
- Convection.
- Emissions (radiation).
The percentage of all types of heat transfer for each model for heating is different.
Heating radiators: essence and features of heat transfer characteristics
Radiators are usually called devices in which heat transfer by direct radiation is at least 25%. But today there are devices that fully work on the convector principle. They are very simple yet reliable. The small size of the convectors makes it possible not to limit yourself when arranging a room. And the cost of convectors is relatively inexpensive. But the disadvantage of convectors is the low level of heat transfer and the convection heating method, and not the radiator one. This creates a strong air circulation in the room and a draft is obtained.
The table shows the values of the heat transfer coefficient.
To choose a device for heating a house or apartment, you need to rely on accurate calculations of the required power. Of course, it is very difficult to take into account all the factors. There are several methods for calculating the required heat transfer of heating devices. The essence of the simplest method is based on the number of windows and walls. If there is one outer wall and one window on it, then a power rate of 1 kW is calculated for every 10 sq.m. area. Another method is more complex, but thanks to it you can get a more accurate indicator of the required power. Calculation formula: S x h x41 (S is the area of the room, h is the height of the ceilings, 41 is the indicator of the minimum power per 1 cubic meter of the room).
Choosing a radiator: a comparison of existing options
The heat transfer of heating radiators from different materials is different. In search of a suitable option for heating a room, you need to compare different models, because devices that are often similar in shape and volume differ in power. The heat transfer from the surface of cast iron radiators is relatively small, since the thermal conductivity of cast iron is quite low. A big plus of cast iron radiators is a fairly large internal clearance, which increases their performance. But still, these batteries have more disadvantages than advantages.
The heat transfer coefficient of cast iron is much lower than that of other materials (aluminum, steel, copper, etc.). Cast iron is a brittle material, and the walls of the battery are thick enough, and this further reduces heat transfer. Under laboratory conditions, the power of one section cast iron battery at a heat carrier temperature of 90 °C is 180 watts. Heat transfer values are approximately 130-150 W per section. For example, for a room with an area of 15 meters, you need 12 cast iron sections (16 x 100 / 125 = 12). But taking into account various factors, in life this figure is much lower. With centralized heating, a significant part of the heat is lost on the way to the consumer, and the heat output of one battery can be 60-70 watts.
The figure shows a cast iron radiator.
Steel radiators are a modern alternative to cast iron radiators. This is a positive combination of sectional devices and convectors. They have a smooth, even surface, which distinguishes them from cast iron radiators. To increase the heat transfer of the device, additional sections are welded to the panels, which work as convectors. But still, the heat transfer of steel heaters is not much greater than the heat transfer of cast-iron radiators. And with a decrease in the temperature of the coolant, a device made of steel significantly reduces heat transfer. Although if you make a comparison with cast iron batteries, they are inferior in weight and have a more attractive appearance. When the water temperature in the system is 70 °C, the heat transfer indicators may give different indicators than the manufacturer's table.
Aluminum and bimetal models - a modern solution
Unlike steel and cast iron radiators, aluminum radiators have a much higher heat output - up to 200 watts. They are very popular in the West and in the USA, where people live mostly in low-rise buildings. But aluminum batteries not suitable for heating systems with high pressure. Therefore, it is preferable to install them in houses that have their own heating system. In addition, contaminants in the coolant can corrode the aluminum surface of the battery. The calculation of aluminum heating radiators is carried out in the same way as for other devices. The temperature in them often depends on the temperature of the coolant.
Aluminum heating batteries different sizes.
Today, the popularity of bimetallic radiators is growing, with which they prefer to replace old batteries. The heat transfer of bimetallic models is no less than aluminum. The heat transfer of one section of the device with a bimetal is about 170 watts. The calculation of bimetallic devices should be done with a margin, taking into account climatic and weather conditions. Therefore, the calculation of sections of bimetallic radiators should be carried out so that the power is higher than the power of the cast-iron radiators that stood here earlier.
Usually devices are bought for one or two sections more than the previous cast iron ones. If you need to make a calculation of bimetallic radiators for a new building, then you should rely on the heat transfer properties of each section. Usually 100W is taken for each section and 70-100W per square meter of the room. Keep in mind that over time, the heat transfer of heating media decreases. It is desirable that the calculation be with a margin. Precisely everything is quite difficult to calculate. It is necessary to take into account the height of the room, the thermal insulation qualities of doors and windows, the floor. After all most of heat escapes precisely because of poor thermal insulation. The cost of bimetallic radiators is higher than heaters made of other materials.
The level of heat transfer and the method of connecting the device
The heat transfer of radiators may also depend on the connection method. For efficient heat transfer, a direct one-way connection is desirable. Therefore, the calculation of power is made with a direct connection. The diagonal type of connection is used if the heating device has more than 12 sections. This greatly reduces heat loss. The most disadvantageous in terms of power is a single-pipe connection. Heat loss can reach 40%. How can you increase heat transfer by purchasing such a device?
- One of the ways is constant wet cleaning and cleaning of the heater surface. Cleaner radiator - higher heat transfer and better heating.
- Proper coloration also affects heat transfer. A very thick layer of paint reduces heat transfer.
- It will be effective to use special paints with low heat transfer resistance for pipes and devices.
It is also important to correctly install the battery. Common mistakes when installing radiators: installation very close to the floor or to the wall, covering the heaters with unnecessary decor items.
It will not be superfluous to check the inside of the radiator in order to eliminate shortcomings that may interfere with the normal movement of the coolant in the future. To reduce useless heat loss, heat-reflecting screens made of foil material are used. Heat consumption can be reduced by 5-7% by placing heat-reflecting screens behind the heating device. They isolate the walls from heating, which allows you to raise the temperature of the air in the room by one to two degrees. Heat-reflecting screens are used quite widely: in residential premises, office buildings, hospitals, schools, etc. This installation is especially effective for radiators mounted on the outer walls of the room.