Numerical study of the air distribution in the Crew Quarters on board of the International Space Station

The current concept of Crew Quarters on board of the International Space Station has several issues according to the crew member’s feedback. Major issues concern noise levels, the accumulation of CO2 and the quality of the air distribution. Our study targets the airflow distribution, to diagnose this issue, we realise a series of numerical simulations (CFD) based on a real scale replica of the Crew Quarters. Simulations were set with a zero-gravity mode and with the theoretical air parameters inside the SSI. The geometry includes a thermal manikin having the neutral posture of a body in the absence of gravity. Numerical simulations were run for the three different air flow rates provided by the current ventilation system. Results have shown that the air distribution inside the Crew Quarter is insufficient for low airflow rates but becomes acceptable for the higher airflow rate, however the higher airflow rate can potentially produce draught discomfort

The stability of the radiative regime in Bucharest during 2017-2018

The paper presents an analysis of the solar irradiation and the stability of the solar radiative regime, available for Bucharest and the southern area of Romania. The study is based on meteorological data measured at 3.6 seconds, on several consecutive days of each season, in the years 2017 and 2018. Data acquisition was performed at Technical University of Civil Engineering Bucharest. The daily mean values for sunshine number and sunshine stability number are computed and analysed. The analyses carried out in this research are useful for applications of solar energy and conversion to thermal energy in hot air solar collectors to estimate the temperature variation at the collector air outlet as well as for photovoltaic panels to estimate the resulting electrical energy

Experimental and numerical study of the air distribution inside a car cabin

The main declared goal of all car manufacturers is to ensure high comfort inside the cabin and to reduce the fossil fuel. It is well-known that the time spent by the people indoor has raised in the last decade. The distance between the home and the workplace increased due to diversity of activities and hence job diversity. The thermal comfort during the travel must to be ensured to reduce the occupant’s thermal stress. The present study is investigating a comparison between the measured data and the numerical simulation results in the case when the ventilation system is functioning. It was evaluated the effect of the boundary conditions air flow and air velocity distribution in a passenger compartment in two cases: first is the general used constant inlet flow and the second is a new approach of importing the measured data obtained during the experimental measurement session as a boundary condition.CFD simulations were made taking as input the measured data obtained during experimental session. We have observed differences between initial simulation results and the measured data, therefore, for more accurate results, a new approach is needed, to impose as boundary conditions the measured data

Numerical Model Development of the Air Temperature Variation in a Room Set on Fire for Different Ventilation Scenarios

Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements’ dimensions, burner heat release rate variation) were imposed to the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model. Besides the air temperature, at this point, other essential parameters were determined in the entire experimental space: indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. We found that if the ventilation rate increases, the indoor temperatures in that specific point decrease, and the sprinkler is activated later or, in some cases, it might never be activated. However, this conclusion is not valid for the entire analyzed space, as the ventilation system alongside the natural air movement imposes specific air speed and specific temperature distribution inside the analyzed space

Fire modeling in a nonventilated corridor

The main objective of this study was to determine the effect of fire in a nonventilated corridor. A real-scale model of a corridor has been modeled in Fire Dynamics Simulator(F.D.S.) in order to determine the evolution of indoor temperatures, the visibility and the oxygen quantities during a fire. The start time of a sprinkler has also been determined. The use of sprinklers in buildings has become a necessity and a requirement imposed by technical norms. The provision of this type of installation has become a common feature in buildings with a high fire risk, with two main effects: fire extinction and protection of structural and partition elements from high temperatures[1

Numerical study of the air distribution in the Crew Quarters on board of the International Space Station

International audienc

Experimental and numerical study of the air distribution inside a car cabin

International audienc

The stability of the radiative regime in Bucharest during 2017-2018

The paper presents an analysis of the solar irradiation and the stability of the solar radiative regime, available for Bucharest and the southern area of Romania. The study is based on meteorological data measured at 3.6 seconds, on several consecutive days of each season, in the years 2017 and 2018. Data acquisition was performed at Technical University of Civil Engineering Bucharest. The daily mean values for sunshine number and sunshine stability number are computed and analysed. The analyses carried out in this research are useful for applications of solar energy and conversion to thermal energy in hot air solar collectors to estimate the temperature variation at the collector air outlet as well as for photovoltaic panels to estimate the resulting electrical energy

The Direct Effect of Enriching the Gaseous Combustible with 23% Hydrogen in Condensing Boilers’ Operation

Following the international trend of using hydrogen as combustible in many industry branches, this paper investigates the impact of mixing methane gas with 23% hydrogen (G222) on condensing boilers’ operation. After modeling and testing several boilers with heat exchange surface different designs, the authors gathered enough information to introduce a new concept, namely High-Performance Condensing Boiler (HPCB). All the boilers that fit into this approach have the same operational parameters at nominal heat load, including the CO2 concentrations in flue gases. After testing a flattened pipes condensing boiler, a CO2 emission reduction coefficient of 1.1 was determined when converting from methane gas to G222 as combustible. Thus, by inserting into the national grid a G222 mixture, an important reduction in greenhouse gases can be achieved. For a 28 kW condensing boiler, the annual reduction in CO2 emissions averages 1.26 tons, value which was experimentally obtained and is consistent with the theoretical evaluation

Numerical model of a solar ventilated facade element: experimental validation, final parameters and results

The present paper analyses the airflow through the lobed orifices of a transpired solar collector which acts as a solar ventilated facade element through numerical simulation. This study is part of a complex research project which analyses the implementation of phase changing materials within air solar collectors. We decided to study an elementary part of the collectors' absorbent plate with four equivalent orifices in order to obtain the velocity and temperature field at the outlet of the computing domain since the numerical simulation of the entire solar collector (more than 5000 orifices) is not feasible due to the big amount of computational resources and time needed. This paper presents the experimental validation of the numerical model, its final parameters and preliminary results. The numerical simulation was conducted using Ansys Fluent CFD software and the results were processed via Tecplot. The boundary conditions imposed were emphasised and k-ε RNG turbulence model was used according to the literature. After comparing the velocity profiles and temperature fields obtained with both experimental and numerical approaches we concluded that the numerical model reproduces real flow phenomena within acceptable limits. The numerical model thus obtained will be used in further studies in order to optimise the collectors' geometry and characteristics by means of parametrical analyses