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Zh. Ay menów HEUOTECHNICAL SYSTEMS AND PROSPECTS OF THEIR USE FOR HEAT TREATMENT OF SLAG-AUCAU

CONCRETE

Journal oflndustriol Technology and Engineering, 2012, 2(2): 45 - 48

positive experience on the practical use of solar water heating Systems in heat supply. These are the countries with favorable climatic conditions: the USA, Japan, France, and the UK [5]. Analysis, conducted in Japan, about savings of energy, consumed by the heat treatment of reinforced concrete products, has shown elear preference for solar energy of radiation. In the manufacture of curing chambers of reinforced concrete products from transparent materiał in summer the temperaturę rises due to the sun in 5 hours by 19 °C.

These shorteomings, typical for the sun sensitive coatings, were eliminated in the structural components of the solar installation-collectors of solar energy (CSE), designed to convert solar energy into thermal energy. The latter, in its tum, heats the air or liquid thermal carrier. On a sunny day, the capacity of the fiat CSE is 70-100 liters of hot water per 1 m³ of the area of the latter. Annual savings of heat production from the use of solar collectors are 100-170 kg of equivalent fuel.

Similar helio systems with transitory heat carrier in the technology of production of reinforced concrete structures and concrete were designed in the Central Research Institute of Transport Construction [6]. In the presented helio unit the oil, which circulates in the heating elements of the system-registers, is the transitory heat carrier. The use of helio systems with transitory heat carrier is possible all year round. However, these heat systems have some drawbacks:

-    Low value of efficiency factor of helio systems within limits of 0.2 - 0.3;

-    Absence of data on the influence of special features of this type of heat treatment of products on their physical - mechanical properties.

The so-called batch technology of production of precast units, at which the products of thickness up to 150 mm are warehoused in a batch with simultaneous covering them with translucent cloth with smali gaps between the boards, is known. During the light day the products are heated, forming a heat accumulator. To preserve the heat the batches of products are also covered on the top by heat-insulating coating that allows gaining extra strength up to 10 % R28-

To the simplest devices, that do not require Capital investments for their production, one should refer conventional concrete work forms, equipped with translucent rejecters of mass production. In this case, the curing concrete, as a piąte of unlimited thickness, undergoes unilateral thermal effect with formation of

elio-technical system of fiat -piąte collector

type, in which concrete in the heat-insulanc" form work is the heat receiver, and the silicate plastic sheet or film materials are aggregates of the translucent grating. The inerease oi translucent plates number with one air gap between them inereases the temperaturę in the concrete by 1 - 2 °C at the environmem temperaturę of 40 - 45 °C.

However, the thermal resistance to the air gap    negatively affects at low outside

temperatures. At environmental air temperaturę above 16 °C the translucent coating is madę as a single layer one, at the temperaturę rangę from plus 10 to minus 10 ⁰ C -as a double-layer one with the air gap between the two translucent coatings in the rangę of 20-50 mm. The effectiveness of employment of concrete work forms is provided by the tightness of their connection [7].

From thermo-physical and technological point of view the scheme of helio-chamber is effective when inside the volume, formed by heat- insulated walls and bottom, as well as by the translucent lid, a hermetically closed Container of heat sensitive materiał (steel) is placed.

Between the gratings and the Container an air gap is anticipated. Heat-insulated walls and bottom are covered with heat-reflective screens of metallized film of PTFE-OA type. Two types of helio-chambers are accepted: with heat-insulated walls and bottom or only with heat-insulated bottom [8].

Helio-chambers with heat-insulated walls and bottom have respectively one, two and three-layer translucent coatings of polymcric film with transparency coefficient of 0.86. Grating of helio-chambers with heat-insulated bottom is perfomied as one- and two-layered. The intemal volume of both types of helio chambers is the same. The impact of the number of gratings on the temperaturę conditions of both helio chambers has been checked up. The maximum temperaturę was obtained at a dual-layer translucent grating. From thermal physical point of view the two-layer light coating of walls and bottom is optimal.

In the above mentioned unit the temperaturę regime is determined mainly by the presence of heat sensitive materiał in the chamber volume. Absorbing the solar energy, metal heats up and becomes a generator of thermal energy: the solar energy in the unit converts into thermal one. At the presence of heat sensitive materiał the temperaturę of the air reaches 80 °C or higher in the unit. Temperaturę inerement compared to environment temperaturę under adequate conditions of carrying out experiment is morę than 50 °C. The