Ultrathin liquid thermal insulation Bronya and its modifications
THE HEAT-PROTECTIVE COATING "Bronya" IS A QUALITATIVELY NEW LEVEL OF SAFETY OF OBJECTS OF THE THERMAL POWER COMPLEX
Such a heat-protective coating (based on similar principles) was originally developed on the instructions of NASA. In the future, it was possible to "land" and adapt it for the tasks of thermal protection and energy saving of objects on Earth, and then to establish industrial production in the USA. At the end of the 90s, ultrathin heat insulators of foreign production appeared in Russia, then domestic materials appeared, including superior in characteristics. The result: the system of heat-protective coatings for civil purposes, in the construction industry, industry, and the energy complex has been enriched with a product with exceptional physical properties. Since the materials offered are mainly produced abroad, they have a high cost, which limits the possibility of their mass use in construction, energy, housing, etc. In turn, domestic analogues often leave much to be desired, and with their "quality" or an overly high mark–up for "know-how", they cause the end user to be negative and biased towards liquid ceramic thermal insulation materials. Liquid composite thermal insulation material Bronya and its modifications is the first product developed in Russia using original technology, made from high-quality imported components and has no analogues in terms of price-quality ratio. The production of Bronya is fully certified, which guarantees consistently high quality of the product. We are proud of the quality of the Bronya. Pride in our product is formed from positive ratings and thanks from our customers. Our clients appreciate the impeccable declared and guaranteed functionality of the material and turn to us again and again.
Volgograd Innovative Resource Center LLC is the only company in Russia that not only produces a "copied" American thermal insulation design, but also made ultrathin thermal insulation more technically advanced and more affordable. Constantly developing new exclusive modifications, we expand the range of tasks to be solved, increase the economic profitability of the use of ultrathin thermal insulation. Our company has a full range of certificates for Bronya thermal insulation, allowing it to be used both on residential, public and industrial buildings and structures, and on pipelines and equipment with a working surface temperature from -70 ° C to +260 ° C. Coatings have the following combination of properties: lightness with high strength, elasticity, excellent adhesion to metal, concrete, brick, wood, plastic. Plus durability and environmental cleanliness (the heated coating does not emit harmful compounds into the atmosphere of the room). According to the results of artificial aging in the climatic chambers of heat and cold - "After 30 years of artificial aging, no visible changes and deviations from the parameters of TU were DETECTED." This allows us to guarantee the performance of the coating from the manufacturer - 15 years outside and 30 years indoors!
In other words, I did and forgot for a long time!
In a thick fluid composition of synthetic rubber and acrylic polymers, there are evacuated (rarefied gas) glass microspheres and silicone microspheres filled with air (Fig. 1). After application to the protected surface, during the evaporation of water and subsequent polymerization of the coating, cocoons of evacuated microspheres are formed around silicone microspheres.
Fig. 1.Schematic representation of the thermal protective coating Bronya.
Silicone and vacuumed ceramic microspheres structured in this way create an elastic power frame of the coating, which has a high thermal resistance. The polymer, relying on this elastic frame, forms a longitudinally layered structure in the form of films separated by the thinnest air gaps. As a result, an elastic multi-layer labyrinth heat-reflecting coating is formed that does not allow droplet moisture to pass through, blocking all heat transfer mechanisms. Bronya coating is a qualitative breakthrough of modern science in construction and industrial practice. Our coating has proven itself especially visibly and noticeably in the heat power industry. It is known that in a room where people work, according to safety regulations, pipelines and shut-off valves must be insulated so that the temperature on the insulation surface does not exceed +45 ° C. However! All these insulated pipelines pose an even greater hidden danger. The fact is that, depending on weather conditions, the rules of operation of the heating unit are constantly changing. And with the change of modes, the equipment is constantly exposed to a variety of thermal and hydrodynamic shocks. And, as a result, it periodically fails. Often, alas, in crash mode. It is impossible to discern a developing fistula under isolation, respectively, and to eliminate it in time in the usual preventive mode. When a leak occurred, several tens of meters of insulation on the working equipment were cut urgently, sometimes to determine the cause of the damage. A sense of danger and expectation of an accident is a constant psychophysical state of the personnel of old boiler houses and thermal units. The use of ultrathin thermal insulation Bronya has qualitatively transformed boiler rooms and heating units. The coating is equally suitable for both hot and cold surfaces. It became possible to apply thermal insulation in the most inaccessible places. The coating is applied to the operating equipment of cold water and hot at t up to +150 °C. Prevents the formation and development of corrosion, which prolongs the service life of the metal. It became possible to isolate all pipelines and shut-off valves totally. Allows you to determine the place of damage to the pipe in a matter of minutes. Everything is in plain sight. Any drop of leaked fuel, water or a trickle of steam is immediately visible. The thickness of the coating is only ~ 1 ÷ 4.5 mm, depending on the temperature of the pipe - the necessary thermal insulation (water, steam). In rooms where ultra-thin thermal insulation Bronya is used, it is light and cozy, comfortable temperature and humidity. Energy consumption for ventilation is sharply reduced. Additional areas appear. Repair of equipment and pipelines is significantly facilitated. Expanded preventive capabilities have reduced the accident rate to almost zero.
As mentioned above, an ordinary normal person will not get burned by contact with any surface heated to +45 ° C. Therefore, if your hand is lying on a hot surface calmly, without experiencing pain, then the temperature on the surface is no higher than +45 ° C. For traditional types of insulation used for many decades - as a rule, mineral wool and its analogues, plus a protective coating ("casing", — most often - galvanized tin or metal foil) - everything is correct. Temperature above +45°C is traumatic. Many years of experience are behind this. However, in the case of ultra-thin thermal insulation Bronya, everything is completely wrong! Devices, both contact and non-contact, show a surface temperature of +75 ÷ + 90 ° C, and the hand calmly endures, the person does not experience any uncomfortable sensations. What's the matter here? A paradox?! There is no paradox. It's just that the entire surface of the coating is strewn with semi-floating thin-walled vacuumed microspheres that protrude above the surface of the layered polymer base of the coating. The volumetric weight of the evacuated microspheres is ~ 0.1 g/cm3. As a result, the heat capacity of the surface layer (~50 microns) is ten times less than the average heat capacity of the coating itself. The hand touches just these protruding microspheres and instantly cools them due to the incomparable heat capacity of the hand and the surface layer of near-surface thin-walled microspheres (see Fig.3). The heat inflow along the thin walls of microspheres is negligible. The radiant heating of the hand from the polymer base remains. It is also very small. Firstly, because most of the surface (~70%) is shielded by microspheres, and the remaining part of the surface emits with a blackness coefficient of ~0.35, i.e. the power of the radiation flux is also weak and the hand easily copes with it.
When the hand touches the surface layer, the coating temperature almost instantly approaches the temperature of the hand, i.e. it decreases by more than 40 ° C!
Fig. 3.Illustration of the thermal paradox of the Bronya coating.
When measuring the temperature with a contact thermometer, the part of the surface closed by the thermometer sensor is shielded from convective air flows. As a result, it shows an inflated temperature in the measurement zone (see Fig. 4).
Fig. 4.Illustration of the shielding of the surface of the coating from convective air flows by the sensor of the standard contact thermometer
Another picture is observed when measuring the surface temperature with a conventional pyrometer (see Fig. 5). Here there is a temperature radiation illumination by radiation coming directly from the polymer surface. The slightest breeze changes the temperature at the surface microspheres, and the total measurement error can be tens of degrees.
Fig.5. Illustration of temperature measurement on the surface
Thus, we are faced with a systemic contradiction. The coating meets all the requirements of the most reasonable safety, but conflicts with the provisions of the SNIP regulating the permissible temperature of equipment surfaces in areas where people work. The issue of revising the current regulatory documents that would individualize the thermal insulation material Bronya among many other heat insulators and would establish special allocated norms for the permissible temperature of surfaces in working areas for it has become acute. At the same time, there is no need to replace the measuring equipment traditionally used in the certification of workplaces with another one. You just need to register that the surface temperature is +75...+90 °C of the thermal insulation coating Bronya - normally fixed, for example, by the most common contact thermometer - is safe for people to work. The coating deserves such a dedicated individual approach, because it works on physical principles that differ from the usual concepts for thermal insulation materials. The last thesis has every reason to be voiced. There are several reasons for this. The first layers of the coating (the material is applied in layers) work according to the usual rules - at first sharply and then noticeably (by tens of ° C) reduce the surface temperature of hot pipelines. The following layers (5th, 6th, 7th...and further) they no longer have any significant significance. After a thickness of 6 mm - just unjustified costs. The temperature drops by units of degrees. In other words, the heat transfer coefficient of the coating is strongly dependent on the absolute surface temperature and the temperature difference between the surface and the environment, i.e. It is a complex combination of radiation-conductive-convective heat exchange. This means that the main contribution to heat transfer is made by radiation, and heat loss due to thermal conductivity and surface-air convection) is negligible compared to the radiation component, see Fig. 6.
Fig.6.Illustration of the mechanisms of heat transfer from the surface of the Bronya insulation
In other words, the power of the heat flow from the surface to the environment due to radiant heat transfer falls as the fourth degree of temperature multiplied by the radiation coefficient e (degree of blackness). Due to the usual thermal conductivity or conductive heat exchange, the heat transfer power decreases in proportion to the temperature difference rT. Thus, with a decrease in surface temperature, radiant heat transfer decreases sharply and "catches up" with the power of conductive-convective heat transfer. The latter itself is quite small due to the near-surface microspheres. There is a kind of "temperature slippage" or significant blocking of the convective component. This happens due to a significant thickening of the boundary layer occupied by near-surface thin-walled microspheres. As a result, the temperature on the surface of the coating stops, somewhere around +50..60.. + 75 ° C (depending on the base temperatures - water, steam) and further decreases with increasing coating thickness. The surface is normally warm to the touch, but does not meet the prescribed sanitary standards. Such temperature effects are completely unusual for conventional thermal insulators. In the example with ultrathin thermal insulation, Bronya - the indicators of temperature measuring devices are higher, and heat loss is lower! An important advantage of the coating is its resistance to ultraviolet radiation, especially intense in northern latitudes. Another distinctive feature of this coating is that the fight against corrosion is now carried out completely according to an unconventional scheme: - firstly, first of all, by minimizing condensation on the surface of the protected object— - and only, secondly, by building an impervious barrier to condensed moisture to its surface. In the case of the modification "Bronya Antikor", there is also the work of the most powerful rust inhibitors in the composition of the material, which do not worsen the thermophysics of the thermal insulation coating. Any metal tank covered with an Bronya heat insulator will remain warm for a long time with sharp temperature drops. As a result, the appearance of frost and large ice on the surface is practically excluded. The falling snow is blown away, water drains, water vapors practically do not condense. The properties of the surface layer ensure faster runoff of rainwater, which further reduces heat loss. With a systemic decrease in temperature, moisture due to diffusion through the coating films and molecular pores will be pushed from the metal surface into the surrounding atmosphere (respiratory activity), as a result, the coating becomes resistant to almost any combination of thermo-moisture impacts. Thus, the Bronya heat insulator performs, first of all, the role of a heat-reflecting barrier. At the same time, the coating performs the role of a "smart" waterproofing agent, building layered protection against moisture and, above all, by minimizing moisture condensation on the surface of the protected object.
Fig. 7.Illustration of the heat (cold) reflective properties of the Bronya coating
The coating prevents capillary absorption of water into the object and thus does not supply moisture for evaporation. Sufficient openness of the membrane for vapor diffusion ensures constant drying of building materials, which increases their own thermal resistance. Heat loss is further reduced. "At stake" is the economy of brick, timber, insulation and air conditioning systems. Thermal protection Bronya is a comfortable environment at minimal cost, Thus, a whole complex of physical effects is combined in a thin membrane. Millimeter coating does today what only thick walls could do before. The coating is a balanced compromise of all the best qualities of thermal and hydro insulation. Volgograd Innovation Resource Center Russia, Volgograd
* A sample can be provided for laboratory testing. Contact us - we are ready to answer all your questions