Вирішено актуальну задачу підвищення ефективності повітророзподілу взаємодією зустрічних неспіввісних струмин для забез-печення нормативних параметрів повітря у приміщеннях. Показано, що для досягнення максимальної ефективності повітророзподі-лу необхідно подавати повітря струминами, що інтенсивно затухають ще до входу в робо-чу зону. Показано економічну ефективність використання повітророзподільника порівня-но з альтернативними варіантами, наведе-но питомі показники ефективності повітро-розподілу Ключові слова: повітророзподіл, зустрічні неспіввісні плоскі струмини, швидкість, над-лишкова температура, змінний режим Решена актуальная задача повышения эффективности воздухораспределения вза-имодействием встречных несоосных струй для обеспечения нормируемых параметров воздуха в производственных помещениях. Показано, что для достижения максималь-ной эффективности воздухораспределения необходимо подавать воздух струями, интен-сивно затухающими еще до входа в рабочую зону. Показана экономическая эффектив-ность использования воздухораспределителя в сравнении с альтернативными варианта-ми, приведены удельные показатели эффек-тивности воздухораспределения Ключевые слова: воздухораспределение, встречные несоосные плоские струи, ско-рость, избыточная температура, перемен-ный режим UDC 697.922.565; 697.921.47
The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Сalculations of the equation by using one-parameter model of turbulence SpalartAllmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it's possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.
The developed two-level air-jet screen of an industrial bath is experimentally investigated. The principle of its operation is the supply of air by a shielding jet at the upper level and the suction of polluted air at the lower level symmetrically from opposite sides. At this stage of experimental research, the velocity fields and the nature of the interaction of inflow jets and suction flares have been studied. When determining the geometric dimensions of the air-jet screen structure, the location of key components and system elements, it is important to know, ensure and not exceed the allowable values of air flow velocity above the surface of the liquid mirror. During the observations of the aerodynamic properties of two-level air-jet screens, questions arose about the need to use flat rotational flows and control the velocity field in their interaction. Minimization of the interaction of inflow jets and flares of suction is the basis of the concept of designing a sсreen of this type. The shielding conditions have been experimentally confirmed due to the stabilization of the velocity field above the bath surface. The corresponding dependencies of change of formation of the protective air screen from the basic parameters as that a ratio of velocity "inflow-removal" and geometrical characteristics of a design are defined. For the developed air-jet screen of galvanic baths experimentally determined conditions of effective shielding are as follows: the ratio of the width of the slot for ejection of air from the working area to the width of the gas-tight wall is 0.75, and the ratio of screening jet velocity to air removal rate is within 0.3-2.45. This achieves a capture efficiency of up to 90 %. The expediency of arranging an ejection slot under the air supply slot to increase the flow rate and range of the jet has been confirmed.
The scheme of air exchange organization using air supply above a working zone by convex wall jets that interact with each other has been substantiated. This scheme is advisable in cases where it is impossible to supply air directly to the working zone. It provides optimal microclimate parameters with minimal recirculation of polluted air from the upper zone. Simulation of the air exchange organization in an exhibition hall in International Exhibition Centre in Kyiv with ventilation at a constant air volume (CAV) has been performed. The floor area is 5258 m2, the height is 19 m, the minimum outdoor air flow is 21.667 m3/s (78000 m3/h). The current design scheme of air exchange organization is zonal. General air exchange is 43.3333 m3/s (156000 m3/h). Recirculation is accepted 50 %. The air flow supplied in the upper and middle zones is, respectively, 22.5 m3/s (81000 m3/h) and 20.833 m3/s (75000 m3/h). Inlet air has temperature 291.65 K (18.5 °C). It is supplied downward by twisted jets. There are 65 Trox VDL-AHLD-E3/800/0/0/0/RAL 9010 air diffusers with a diameter of 800 mm. The proposed scheme is single-zonal using 24 diffusers PES-D-8-10/15-0,9 4 m above the floor and air removal from the upper zone. This scheme allows halving the air exchange to the minimum outdoor air without recirculation. The air temperature should be decreased by 3.3 K to 288.35 K (15.2 °С). The number of air-conditioners is decreased twice. The calculated consumption of cold decreased by 65.58 W/m2 or 29 %, the calculated consumption of heat for the second heating – by 7.17 W/m2 or 18 %. Saving of capital investments in prices of February 2020 is 792.16 UAH/m2 or 55 %, and decrease of operating costs for the cooling period is 6.61 UAH/m2 or 15 %. Thus, the system is economically beneficial from the beginning of its installation. In the future, its operation will be simulated in a mode with a variable flow rate.
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