The paper deals with issues related to the energy efficiency of buildings as an object basis for district heating.

In this paper the analysis of gas-turbine and gas-piston power plants widely employed for electricity, heat cold production is given. Currently a wide range gas turbines are produced worldwide with 200−300 MW in simple cycle (efficiency 35−40 %) up to 600 combined 60 % over). The micro-turbine class low-power (10−400 kW) having efficiency 15−19 25−28 cycle. If necessary, they unite into clusters. electrical from few kW 20 MW, form modular stations block electricity production. near future...

The article summarizes the results of studies tribotechnical properties detonation coatings based on magnesium orthosilicate under conditions constant load in sliding velocity field. structural and phase composition was studied using modern physical analysis methods. developed have high stable antifriction entire load-velocity range tests. It is emphasized that result friction additive effect both carbide graphite film dispersed surface oxide structures, synthesis which provides modification...

The article presents the results of a series experimental studies thermophysical properties polymer micro- and nanocomposites when using methods for obtaining them based on mixing components in dry form or melt. study was performed composites polyamide 6 filling it with carbon nanotubes, copper aluminum microparticles. During studies, mass fraction filler varied from 0.3 to 10 %, temperature — 320 525 K. data effects composite materials their heat conductivity, specific capacity density. It...

A set of experimental studies has been carried out to establish the effect mixing time components nanocomposite materials on their thermal conductivity, specific heat, and density. The physical properties polypropylene-carbon nanotube composites were be studied. During experiments, duration in melt polymer varied from 5 52 minutes, mass fraction filler ‒ range 0.3...10 %, temperature – 290 K 475 K. It was found that an increase could lead a significant (more than 70 times) conductivity. is...

This paper reports a study into features of the formation structures permanent butt joints plates with thickness 1.5 mm made from high-strength aluminum alloy 7075 Al-Zn-Mg-Cu system. Welding by melting these was performed using three techniques: laser, microplasma, and hybrid laser-microplasma. To implement latter two, compressed arc on multipolar asymmetric current used. The purpose research to establish tendency characteristic defects possibility their elimination. It has been determined...

Considered indicators of reducing harmful emissions into the environment by gas-fired water-heating and steam boilers municipal heat-power engineering, which are equipped with heat-recovery systems boiler exhaust-gases. The results studies on relative decrease nitrogen oxides other substances generated during fuel combustion in when used for complex plants heating heat-network water a chemical water-purification system plant, as well humidifying air presented. It is shown that use such...

ThE EnVIronMEnTAl rElIABIlITy of GAS-fIrED BoIlEr unITSBy APPlyInG MoDErn hEAT-rECoVEry

This paper reports the experimental study carried out to establish dependence of thermal conductivity polypropylene-based nanocomposites filled with carbon nanotubes on main parameter temperature regime their manufacturing ‒ level overheating a polymer melt relative its melting point. The has been conducted for that were manufactured by applying method based mixing components in special disk extruder. During composite process, varied from 10 75 K, mass share filler ranging 0.3 10.0 %. It is...

The results of studies on improving the environmental characteristics boiler plants municipal heat-power engineering in application technologies for deep recovery heat from exhaust-gases gas-fired boilers are presented. data reduction environment by reducing amount and temperature harmful emissions resulting fuel combustion given. given equipped with complex heat-recovery systems characterized cooling below dew point water vapor contained them. It is shown that decrease due to a consumption...

The paper presents results of a study on flow and temperature fields in bare tubes cooled with SuperCritical Water (SCW). This is based Computational Fluid Dynamics (CFD) simulation the FLUENT code for upward flows vertical heated length 4 m an inner diameter 10 mm. Operating conditions were: Mass flux – G ≈ 500 1000 kg/m2s; heat q = 189 826 kW/m2; inlet coolant Tin 320–360°C. CFD predictions were compared experimental data this study. All three heat-transfer regimes: 1) normal transfer; 2)...

The results of investigating the influence fillers different nature on thermal conductivity polymer composites are widely presented in modern scientific works many authors. However, there has been little analysis obtained data within existing percolation models conductivity. Using mathematical simulation allows to improve methods manufacturing and manage properties a wide range.The paper presents experimental numerical studies poly(methyl methacrylate) containing aerosil, carbon nanotubes,...

This paper deals with CFD predictions for flow and heat transfer in supercritical water a bare tube. Studies were performed using the software FLUENT upward flows vertical tubes heated length of 4 m an inner diameter 10 mm at high values mass flux (G > 1000 kg/m2s). Turbulence models verification data given physical conditions are presented. Besides testing different turbulence that presented modern catalog these is carried out. Namely, related to following three groups: High–Reynolds...

This paper reports a series of experimental studies to establish regularities the integrated effect exerted on specific heat capacity polymer nanocomposites by such factors as temperature regime their production, value mass fraction filler, and composite material. The were conducted for based polypropylene filled with carbon nanotubes. When obtaining composites, method mixing components in melt was used. During studies, varied from 295 455 K, filler ‒ 0.3 10 %. basic parameter technological...

We have examined, for the plate heater included in a heat recovery system of boiler plant, influence its thermophysical parameters on losses exergetic power under different operational modes heating boiler. A procedure calculation given unit is based an integrated approach that combines methods with thermodynamics irreversible processes. mathematical model includes differential equation exergy balance and thermal conductivity air boundary conditions third kind. The has been solved jointly...

This paper reports a study into the regularities of interphase interaction, features in formation intermetallic phases (IMPs), and defects when surfacing steel on titanium four ways: P-MAG, CMT, plasma by an indirect arc with conductive wire, PAW. A general tendency has been established IMP occurrence all considered methods. It was determined that technique involving wire is less critical as regards formation. That makes it possible to obtain layer minimum thickness (25...54 μm) combination...

Виконано розрахункові дослідження щодо відвернення конденсатоутворення в газовідвідних трактах котельних установок під час використання методів: часткового байпасування відхідних газів повз теплоутилізатор, підмішування до димових після теплоутилізатора нагрітого повітря, підсушування цих шляхом їхнього нагрівання у поверхневих теплообмінниках та методу теплоізоляції труб. Наведено принципові схеми разі застосування систем теплоутилізації з використанням вказаних методів захисту трактів....

The object of this study is structural formation during the surfacing steel (iron) on titanium with plasma-sprayed coatings to obtain a butt connection titanium-steel bimetallic plates. task be solved was devise technology for applying barrier layer between and defect-free joint edges sheets carbon steel, clad titanium, under conditions arc or plasma titanium. application carried out by spraying wire iron powder. In case, coating thickness 150...750 μm applied Grade2 which 1–2 mm thick...

The application of the heat recovery- system with combined use recycled municipal boiler plants is substantiated.
 thermal characteristics and levels increase in efficiency a rational ratio areas exchange surfaces water- air-heating equipment this for different regions Ukraine are determined.

The work is devoted to increase of thermal and ecological efficiency water-heating gas-fired boilers municipal heat-power engineering. To improve efficiency, heat-recovery technologies are used in which deep cooling the exhaust-gases from with realization condensation mode heat recovery equipment ensured. implement this regime throughout heating period, it advisable use complex systems several transfer agents heated sufficiently different potentials. enhance environmental effect when using...