scholarly journals Development of a Double Skin Facade System Applied in a Virtual Occupied Chamber

Inventions ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 17
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Hazim Awbi
Keyword(s):  
Solar Radiation ◽  
Indoor Air Quality ◽  
Integral Equations ◽  
Indoor Air ◽  
Mass Concentration ◽  
Airflow Rate ◽  
Venetian Blinds ◽  
Double Skin ◽  
Linear Integral ◽  
Linear Integral Equations

In this study a system constituted by seven double skin facades (DSF), three equipped with venetian blinds and four not equipped with venetian blinds, applied in a virtual chamber, is developed. The project will be carried out in winter conditions, using a numerical model, in transient conditions, and based on energy and mass balance linear integral equations. The energy balance linear integral equations are used to calculate the air temperature inside the DSF and the virtual chamber, the temperature on the venetian blind, the temperature on the inner and outer glass, and the temperature distribution in the surrounding structure of the DSF and virtual chamber. These equations consider the convection, conduction, and radiation phenomena. The heat transfer by convection is calculated by natural, forced, and mixed convection, with dimensionless coefficients. In the radiative exchanges, the incident solar radiation, the absorbed solar radiation, and the transmitted solar radiation are considered. The mass balance linear integral equations are used to calculate the water mass concentration and the contaminants mass concentration. These equations consider the convection and the diffusion phenomena. In this numerical work seven cases studies and three occupation levels are simulated. In each case the influence of the ventilation airflow and the occupation level is analyzed. The total number of thermal and indoor air quality uncomfortable hours are used to evaluate the DSF performance. In accordance with the obtained results, in general, the indoor air quality is acceptable; however, when the number of occupants in the virtual chamber increases, the Predicted Mean Vote index value increases. When the airflow rate increases the total of Uncomfortable Hours decreases and, after a certain value of the airflow rate, it increases. The airflow rate associated with the minimum value of total Uncomfortable Hours increases when the number of occupants increases. The energy production decreases when the airflow increases and the production of energy is higher in DSF with venetian blinds system than in DSF without venetian blinds system.

Application of solar radiation to the ventilation of an experimental chamber through a set of dual skin facades

2020 ◽  
pp. 25-35
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Mª Manuela Lúcio ◽  
Mª Inês Conceição ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Integral Equations ◽  
Indoor Air ◽  
Carbon Dioxide Concentration ◽  
Integral Model ◽  
Experimental Chamber ◽  
Airflow Rate ◽  
Numerical Work

The aim of this numerical work is to evaluate the influence of a set of three Dual Skin Façades (DSF) on the thermal comfort and air quality inside a virtual occupied experimental chamber under various airflow rates. Each DSF is constituted by two transparent glasses and an adjustable venetian blind located in the air channel existing between the two surfaces. A system of energy balance integral equations is used to estimate the air temperature inside the virtual chamber and DSF and the temperature in the different elements of the virtual chamber and a system of mass balance integral equations is used to estimate the contaminants inside the virtual chamber and the DSF. The uncomfortable hours integral model is used to evaluate the total number of uncomfortable hours due to warm and cold indoor conditions and also due to indoor air quality conditions. The acceptable levels of indoor thermal comfort, evaluated by the Predicted Mean Vote index, must be within category C of ISO 7730 standard. The acceptable levels of indoor air quality, evaluated by the carbon dioxide concentration, must be below the limit of 1800 mg/m3 proposed by the ASHRAE 62.1 standard. Three airflow rates were chosen: 0.0389 m3/s, 0.0778 m3/s and 0.1167 m3/s. The airflow that guarantees, at the same time, the best indoor air quality and thermal comfort levels is obtained through the minimization of the total number of uncomfortable hours. As best option, it was obtained the airflow rate of 0.1167 m3/s.

Numerical and Experimental Modeling of Indoor Air Quality Inside a Conditioned Space with Mechanical Ventilation and DX-Air Conditioner

2020 ◽  
Vol 38 (9A) ◽  
pp. 1257-1275
Author(s):  
Wisam M. Mareed ◽  
Hasanen M. Hussen
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Thermal Conditions ◽  
Airflow Rate ◽  
Air Conditioner ◽  
Breathing Zone ◽  
Lecture Room ◽  
Ventilation Performance

 Elevated CO2 rates in a building affect the health of the occupant. This paper deals with an experimental and numerical analysis conducted in a full-scale test room located in the Department of Mechanical Engineering at the University of Technology. The experiments and CFD were conducted for analyzing ventilation performance. It is a study on the effect of the discharge airflow rate of the ceiling type air-conditioner on ventilation performance in the lecture room with the mixing ventilation. Most obtained findings show that database and questionnaires analyzed prefer heights between 0.2 m to 1.2 m in the middle of an occupied zone and breathing zone height of between 0.75 m to 1.8 given in the literature surveyed. It is noticed the mismatch of internal conditions with thermal comfort, and indoor air quality recommended by [ASHRAE Standard 62, ANSI / ASHRAE Standard 55-2010]. CFD simulations have been carried to provide insights on the indoor air quality and comfort conditions throughout the classroom. Particle concentrations, thermal conditions, and modified ventilation system solutions are reported.

scholarly journals On Solvability Conditions for a Certain Conjugation Problem

Axioms ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 234
Author(s):  
Vladimir Vasilyev ◽  
Nikolai Eberlein
Keyword(s):  
General Solution ◽  
Differential Equations ◽  
Integral Equations ◽  
Mellin Transform ◽  
Algebraic Equations ◽  
Conjugation Problem ◽  
Solvability Conditions ◽  
Linear Algebraic Equations ◽  
Linear Integral ◽  
Linear Integral Equations

We study a certain conjugation problem for a pair of elliptic pseudo-differential equations with homogeneous symbols inside and outside of a plane sector. The solution is sought in corresponding Sobolev–Slobodetskii spaces. Using the wave factorization concept for elliptic symbols, we derive a general solution of the conjugation problem. Adding some complementary conditions, we obtain a system of linear integral equations. If the symbols are homogeneous, then we can apply the Mellin transform to such a system to reduce it to a system of linear algebraic equations with respect to unknown functions.

On the location of the Weyl circles

1981 ◽  
Vol 88 (3-4) ◽  
pp. 345-356 ◽  
Author(s):  
F. V. Atkinson
Keyword(s):  
Integral Equations ◽  
Complex Plane ◽  
Riccati Equations ◽  
Sturm Liouville ◽  
Linear Integral ◽  
Linear Integral Equations

SynopsisThe paper deals with explicit estimates concerning certain circles in the complex plane which were associated with Sturm–Liouville problems by H. Weyl. By the use of Riccati equations instead of linear integral equations, improvements are obtained for results of Everitt and Halvorsen concerning the behaviour of the Titchmarsh–Weyl m-coefficient.

Integral equations and relations for Lamé functions and ellipsoidal wave functions

1968 ◽  
Vol 64 (1) ◽  
pp. 113-126 ◽  
Author(s):  
B. D. Sleeman
Keyword(s):  
Wave Function ◽  
Green’S Function ◽  
Integral Equations ◽  
Green's Function ◽  
Function Theory ◽  
Natural Generalization ◽  
Wave Functions ◽  
Linear Integral ◽  
First Time ◽  
Linear Integral Equations

AbstractNon-linear integral equations and relations, whose nuclei in all cases is the ‘potential’ Green's function, satisfied by Lamé polynomials and Lamé functions of the second kind are discussed. For these functions certain techniques of analysis are described and these find their natural generalization in ellipsoidal wave-function theory. Here similar integral equations are constructed for ellipsoidal wave functions of the first and third kinds, the nucleus in each case now being the ‘free space’ Green's function. The presence of ellipsoidal wave functions of the second kind is noted for the first time. Certain possible generalizations of the techniques and ideas involved in this paper are also discussed.

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