International Energy Agency The International Energy Agency (IEA) was established in 1974 within ... more International Energy Agency The International Energy Agency (IEA) was established in 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. A basic aim of the IEA is to ...
This paper is divided into two parts; the first describes a CFD analysis of a gland packing labyr... more This paper is divided into two parts; the first describes a CFD analysis of a gland packing labyrinth seals in 20 MW steam turbine in LNG plant using ANSYS CFX code as an isothermal simulation in fluid domain. The results of two turbulence models k-ε and k-ω SST are compared and validated against experimental data. It is shown that the labyrinth seal leakage is proportional to the clearance cube so any variation in clearance can have a significant impact on the steam leakage. This clearance between the shaft and the labyrinth seal vary as a function of operating temperature due to the different rates of thermal expansion of the materials for these two components. Likewise the fluid temperature has a direct effect on fluid dynamic behavior. For that; the second part of the paper investigates the effect of fluid thermal conditions of the labyrinth seal via the heat transfer and Nusselt number variation in the stator and the rotor, for different cases of inlet temperature (400 °C, 200 ...
Calculation of heat losses of buildings according to European standard EN ISO 10211 and Czech sta... more Calculation of heat losses of buildings according to European standard EN ISO 10211 and Czech standard ČSN 73 0540 is simplified to one-dimensional time-steady heat conduction through the building construction in direction of the largest temperature gradient. This simplification of the calculation is incorrect in case of complex geometry. Calculation according to norm takes into account this inaccuracy and uses Linear Thermal Transmittance Ψ [W/(m·K)] in 2D geometry or Point Thermal Transmittance χ [W/(m2·K)] in the 3D geometry as a calculation correction. This contribution is focused on detailed calculation of linear thermal transmittance in case of contact external peripheral wall and plastic window frame. Results of two-dimensional transient numerical simulation show unsteady linear thermal transmittance in time and dependence on solar radiation. All of these variable boundary conditions can be easily simulated in the software CalA as well as complex geometry.
The topic of this publication is numerical modelling of a radiant component in indoor climates, w... more The topic of this publication is numerical modelling of a radiant component in indoor climates, which is the fundamental parameter for designing heat-radiating panels. The radiant component has a significant impact not only on the thermal comfort, but mainly on the human health. When designing the heat-radiating panels, the numerical modelling enables optimizing of this radiant component in the living/working area in order to reduce utmost, so called, radiation shadows. These radiation shadows cause strong variability in the radiant component of thermal comfort in living or working areas as well as the undesired thermal asymmetry as perceived by human body. The result of this publication is an algorithm defining the mean radiant temperature in 3D geometry combined with one-dimensional transient heat transfer in building constructions. The algorithm for this calculation process in 2D geometry has been developed in our own software RadiA using Surface To Surface and Ray Tracing radiat...
Velké průmyslové objekty jsou velmi efektivně vytápěny sálavými otopnými panely. Návrh těchto sál... more Velké průmyslové objekty jsou velmi efektivně vytápěny sálavými otopnými panely. Návrh těchto sálavých otopných panelů je nutné provést tak, aby v pobytové zóně osob bylo dosaženo co největší tepelné pohody. Příspěvek se zabývá popisem a ověřením nového výpočetního softwaru RadiA určeného pro modelování časově neustáleného vývoje sálavé složky ve vnitřním klimatu budov ověřeného experimentálním měřením v reálném provozu.
ABSTRAKT Příspěvek spadá do oblasti modelování a simulace sdílení tepla vedením v netekoucích lát... more ABSTRAKT Příspěvek spadá do oblasti modelování a simulace sdílení tepla vedením v netekoucích látkách. Tepelně technické vlastnosti materiálů jsou obecně závislé na mnoha faktorech, přičemž významná je jejich závislost na teplotě. Modelování dvourozměrného vedení tepla se v tomto případě stává úlohou nelineární. Cílem tohoto příspěvku je na konkrétním příkladu parovodu prezentovat vliv nelineárního součinitele tepelné vodivosti na výsledné teplotní pole a tepelné toky. Tento vliv nelineárního součinitele tepelné vodivosti na měrnou tepelnou ztrátu parovodu může být až 14 % jak ukazují výsledky. Klíčová slova: numerická simulace; vedení tepla; nelineární součinitel tepelné vodivosti; vlastní software CalA
Numerical simulations and experiments were performed for a thermally active wall with pipes arran... more Numerical simulations and experiments were performed for a thermally active wall with pipes arranged in milled channels in the thermal insulation. The advantage of this system is its suitability for installation in both new and existing buildings in the form of precast heat insulation panels attached to their facades.The study shows that by active control of the supply water temperature, it is possible to alternate the wall´s function between space heating and a thermal barrier. The wall system has the potential to significantly reduce heat loss when used as a thermal barrier. When operated as space heating, embedding the pipes in thermal insulation reduced the heating capacity by 50% as compared to systems with pipes arranged in a concrete core and by 63% for pipes arranged in a layer underneath the surface. It is crucial that pipes arranged in channels are embedded in a thermally conductive material. Failing to do so can substantially diminish the heating capacity due to the imper...
International Energy Agency The International Energy Agency (IEA) was established in 1974 within ... more International Energy Agency The International Energy Agency (IEA) was established in 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. A basic aim of the IEA is to ...
This paper is divided into two parts; the first describes a CFD analysis of a gland packing labyr... more This paper is divided into two parts; the first describes a CFD analysis of a gland packing labyrinth seals in 20 MW steam turbine in LNG plant using ANSYS CFX code as an isothermal simulation in fluid domain. The results of two turbulence models k-ε and k-ω SST are compared and validated against experimental data. It is shown that the labyrinth seal leakage is proportional to the clearance cube so any variation in clearance can have a significant impact on the steam leakage. This clearance between the shaft and the labyrinth seal vary as a function of operating temperature due to the different rates of thermal expansion of the materials for these two components. Likewise the fluid temperature has a direct effect on fluid dynamic behavior. For that; the second part of the paper investigates the effect of fluid thermal conditions of the labyrinth seal via the heat transfer and Nusselt number variation in the stator and the rotor, for different cases of inlet temperature (400 °C, 200 ...
Calculation of heat losses of buildings according to European standard EN ISO 10211 and Czech sta... more Calculation of heat losses of buildings according to European standard EN ISO 10211 and Czech standard ČSN 73 0540 is simplified to one-dimensional time-steady heat conduction through the building construction in direction of the largest temperature gradient. This simplification of the calculation is incorrect in case of complex geometry. Calculation according to norm takes into account this inaccuracy and uses Linear Thermal Transmittance Ψ [W/(m·K)] in 2D geometry or Point Thermal Transmittance χ [W/(m2·K)] in the 3D geometry as a calculation correction. This contribution is focused on detailed calculation of linear thermal transmittance in case of contact external peripheral wall and plastic window frame. Results of two-dimensional transient numerical simulation show unsteady linear thermal transmittance in time and dependence on solar radiation. All of these variable boundary conditions can be easily simulated in the software CalA as well as complex geometry.
The topic of this publication is numerical modelling of a radiant component in indoor climates, w... more The topic of this publication is numerical modelling of a radiant component in indoor climates, which is the fundamental parameter for designing heat-radiating panels. The radiant component has a significant impact not only on the thermal comfort, but mainly on the human health. When designing the heat-radiating panels, the numerical modelling enables optimizing of this radiant component in the living/working area in order to reduce utmost, so called, radiation shadows. These radiation shadows cause strong variability in the radiant component of thermal comfort in living or working areas as well as the undesired thermal asymmetry as perceived by human body. The result of this publication is an algorithm defining the mean radiant temperature in 3D geometry combined with one-dimensional transient heat transfer in building constructions. The algorithm for this calculation process in 2D geometry has been developed in our own software RadiA using Surface To Surface and Ray Tracing radiat...
Velké průmyslové objekty jsou velmi efektivně vytápěny sálavými otopnými panely. Návrh těchto sál... more Velké průmyslové objekty jsou velmi efektivně vytápěny sálavými otopnými panely. Návrh těchto sálavých otopných panelů je nutné provést tak, aby v pobytové zóně osob bylo dosaženo co největší tepelné pohody. Příspěvek se zabývá popisem a ověřením nového výpočetního softwaru RadiA určeného pro modelování časově neustáleného vývoje sálavé složky ve vnitřním klimatu budov ověřeného experimentálním měřením v reálném provozu.
ABSTRAKT Příspěvek spadá do oblasti modelování a simulace sdílení tepla vedením v netekoucích lát... more ABSTRAKT Příspěvek spadá do oblasti modelování a simulace sdílení tepla vedením v netekoucích látkách. Tepelně technické vlastnosti materiálů jsou obecně závislé na mnoha faktorech, přičemž významná je jejich závislost na teplotě. Modelování dvourozměrného vedení tepla se v tomto případě stává úlohou nelineární. Cílem tohoto příspěvku je na konkrétním příkladu parovodu prezentovat vliv nelineárního součinitele tepelné vodivosti na výsledné teplotní pole a tepelné toky. Tento vliv nelineárního součinitele tepelné vodivosti na měrnou tepelnou ztrátu parovodu může být až 14 % jak ukazují výsledky. Klíčová slova: numerická simulace; vedení tepla; nelineární součinitel tepelné vodivosti; vlastní software CalA
Numerical simulations and experiments were performed for a thermally active wall with pipes arran... more Numerical simulations and experiments were performed for a thermally active wall with pipes arranged in milled channels in the thermal insulation. The advantage of this system is its suitability for installation in both new and existing buildings in the form of precast heat insulation panels attached to their facades.The study shows that by active control of the supply water temperature, it is possible to alternate the wall´s function between space heating and a thermal barrier. The wall system has the potential to significantly reduce heat loss when used as a thermal barrier. When operated as space heating, embedding the pipes in thermal insulation reduced the heating capacity by 50% as compared to systems with pipes arranged in a concrete core and by 63% for pipes arranged in a layer underneath the surface. It is crucial that pipes arranged in channels are embedded in a thermally conductive material. Failing to do so can substantially diminish the heating capacity due to the imper...
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