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Radiant systems are being increasingly used for space heating and cooling of buildings. The contemporary research of radiant systems addresses mainly floor and ceiling structures. Research regarding the possibilities of their incorporation in wall structures is lacking, despite their potential advantages. This study addresses a radiant wall system manufactured according to a patent. The patented design involves panels that consist of pipes arranged in milled channels in thermal insulation. The potential advantage of this system is the fact that the thermally active panels can be attached to the facades of existing buildings as a part of their retrofit. Thereby, only minor interventions on the interior side of the retrofitted buildings are needed. To test and improve the design of the wall system, laboratory measurements and computer simulations were performed on a wall fragment for its operation under summer conditions. The results indicate a significant potential for improvement of the patented design by addressing the imperfections in the contact between pipe and wall. Inserting a metal fin between pipe and wall enhanced the cool distribution within the wall fragment considerably. From the three materials of the metal fin considered, using copper led to highest values of the cooling output, followed by aluminium. For these two metals the effect of increasing the thickness of the fin on the cooling output was small. On the contrary, the fin made of steel was the least efficient in terms of cool distribution. In this case the cooling output was most sensitive to the thickness of the fin.

In the following years and decades the increase in cooling capacity will put tremendous pressure on the energy infrastructure and severely increase the environmental impacts. In a moderate climate and well thermally insulated buildings like, e.g., in Europe, installation of low-exergy radiant systems could help alleviate these negative effects. Wall systems may be especially suitable for installation in existing buildings, however, their possible applications in buildings retrofit have not been fully explored. We therefore investigate the possible applications of wall cooling in existing buildings by numerical simulations of two-dimension heat flow through a wall fragment. Three wall systems are proposed and compared in terms of thermal response and heat transfer. The effect of various parameters is investigated to facilitate the design of the wall systems.

The analyzed topic belongs to the field of design and operation of HVAC systems, focusing mainly on mixing chambers. The paper deals with problems of condensation and freezing of water vapour on walls of mixing chambers in a special case, when the partial pressure of the final resulting state of the mixture of warm moist air and colder air is located above the saturation limit. Experimental in situ methods and computer computational fluid dynamics (CFD) modelling method were used for processing. The main contribution of this work is the finding that partial condensation and freezing of water vapour may occur in local parts of the mixing chamber. It causes problems in terms of hygienic safety and service life of these devices. In particular it has been found that condensation and freezing of water vapour may occur even if relative humidity of the resulting mixture is about 70 %., The analyzed topic belongs to the field of design and operation of HVAC systems, focusing mainly on mixing chambers. The paper deals with problems of condensation and freezing of water vapour on walls of mixing chambers in a special case, when the partial pressure of the final resulting state of the mixture of warm moist air and colder air is located above the saturation limit. Experimental in situ methods and computer computational fluid dynamics (CFD) modelling method were used for processing. The main contribution of this work is the finding that partial condensation and freezing of water vapour may occur in local parts of the mixing chamber. It causes problems in terms of hygienic safety and service life of these devices. In particular it has been found that condensation and freezing of water vapour may occur even if relative humidity of the resulting mixture is about 70 %.

In water distribution systems can be found particles of rust and other mechanical contaminants. The particles are deposited in locations where the low velocity of water flow. Where a can cause the pitting corrosion. Is a concern in the systems made of galvanized steel pipes. The contribution deals with CFD (Computational Fluid Dynamics) simulations of water flow and particles deposition in water distribution system. CFD Simulations were compared with the corrosive deposits in real pipeline. Corrosion is a spontaneous process of destruction of metal material due to electrochemical reactions of metal with the aggressive surrounding. Electrochemical corrosion is caused by the thermodynamic instability of metal and therefore can not be completely suppress, it can only influence the speed of corrosion. The requirement is to keep metal properties during the whole its lifetime. Requested service lifetime the water pipe according to EN 806-2 is 50 years., V rozvodech vody lze nalézt částice rzi a jiné mechanické nečistoty. Tyto částice se ukládájí v místech, kde jsou nízké rychlosti proudění vody. Tam mohou působit řadu let. Toto se týká vodovodních systémů z pozinkovaných ocelových trubek. Příspěvek se zabývá CFD (Computational Fluid Dynamics) simulací proudění vody a ukládání částic v systému rozvodu vody. CFD simulace byly porovnány s ložisky koroze v reálném potrubí. Koroze je spontánní proces destrukce kovových materiálů v důsledku elektrochemické reakce kovu s agresivním prostředí. Elektrochemické koroze je způsobena nestabilitou termodynamické kovu, a proto nemůže být zcela eliminována, lze jen ovlivnit rychlost koroze. Je požadováno aby kovové materiály potrubí uchovaly své vlastnosti po celou dobu jeho životnosti. Požadovaná životnost vodovodního potrubí v souladu s EN 806-2 je 50 let.