Adaptive Thermal Comfort of an Office for Energy Consumption-Famagusta Case

The aim of this study was to determine how much thermal comfort can be obtained through heat/energy transfers between the office/external air and the transparent/opaque surfaces of an office by combining different transparent and opaque wall surface ratios with different window opening percentages using dynamic thermal simulations. It found that the optimum window-to-wall ratio (WWR) for energy conservation is 40%, with a 20% window opening ratio. The 80% and 90% thermal comfort ranges of the adaptive thermal comfort methodology are found in May, October, September, and the yearly average, while June and August are only in the range of 80% acceptability. The office constantly loses heat through air flow with any glass size on its external facade and any window opening ratio. Moreover, all sizes of opaque and transparent internal surfaces transferred heat from outside by conduction, while the opaque wall similarly always transferred energy to heat up the office air internally and outside air externally through convection. The external glass also heats the office air by convection, except in the months of January, November, and December.

Effect of the opening and location ratio on the performance of an H-Darrieus VAWT

Vertical axis wind turbines such as Darrieus turbines are a very interesting category of low wind speed domestic wind turbines. Further research work is needed to enhance their efficiency to fulfill the higher demand in small applications for power generation. The main objective of this work is to find a Darrieus turbine design to boost the starting capacity of the turbine through an opening located at the lower surface of the airfoil. We carried out a thorough CFD (Computational Fluid Dynamics) investigation to determine the impact of the opening position on the Darrieus rotor's output. This new type of airfoil uses a standard NACA 0015 profile and a profile with an opening on the lower surface of the profile. Different sizes of the opening in a symmetrical profile are evaluated through the CFD method to predict the Cp and CT of this H-Darrieus turbine design. Five sections were designed to describe the research of this new H-Darrieus rotor. Generally speaking, the results showed that the Cp decreases with the opening ratio, the desirable rotors with the lower surface opening ratio are 0.12 to 0.36 considering this with the low CpLP.

Experimental and theoretical study on the internal pressure induced by the transient local failure of low-rise building roofs

A case study on the internal pressure induced by a local failure on the vulnerable gable roof of a low-rise building was extensively conducted experimentally and numerically. Five roof opening configurations were tested in the wind tunnel under three different boundary layer conditions, based on 1:40 scaled models. The effects of opening shape, opening position, opening ratio, building internal volume, and wind speed on peak transient and steady-state internal pressures were studied. The study results indicate that the peak transient and steady-state internal pressures and the corresponding transient overshoot ratio all increase with an increasing opening ratio. The peak steady-state internal pressure is little affected by the approaching wind speed; while the peak transient internal pressure coefficient shows a significant linear relationship with the wind speed. The coupling effect of vortex shedding and Helmholtz resonance in double building volume compensation situation may cause larger fluctuating internal pressure. Both the vortex shedding and Helmholtz resonance reduce the internal pressure coherence to some extent. The agreement between the numerical and experimental results is much better for the mean internal pressure than that for fluctuating internal pressure or peak internal pressure.

Parametric Study on Buckling Behavior of Aluminum Alloy Thin-Walled Lipped Channel Beam with Perforations Subjected to Combined Loading

The objective of the research presented in this paper is to investigate the buckling behavior of a perforated thin-walled lipped channel beam subjected to combined load. A nonlinear finite element method was used to analyze the buckling behavior of the beam. Experimental tests were made to validate the finite element simulation. Three factors with three levels for each factor were chosen to examine their influence on the buckling behavior of the beam and these factors are: the shape of holes, opening ratio and the spacing ratio of. The finite elements outcome was analyzed by using Taguchi method to identify the best set of three-parameter combinations for optimum critical buckling load. The analysis of variance technique (ANOVA) was implemented to determine the contribution of each parameter on buckling strength. Results showed that the mode of buckling failure of the perforated beam is lateral-torsional buckling and the hexagonal hole shape, =1.7 and = 1.3 were the best combination of parameters that gives the best buckling strength. The results also showed that the shape of holes is the most influential on buckling behavior of the perforated beam for this case of loading.