Energy saving in an air conditioning system using modified HVAC unit as an energy reducer

Nowadays, global warming, environment pollution, and limitations in energy resources have appeared as a serious global crisis. Therefore, energy efficiency and energy conservation are necessary in all energy-consuming devices, such as heating, ventilating, and air conditioning (HVAC) systems. The aims of this project are to evaluate the performance and energy conservation of a conventional air conditioning system and also compare its performance with the proposed HVAC system, which consists of a heat recovery unit to reduce the initial capital cost and electricity consumption of the system. Through hour-by-hour simulations, the annual energy consumptions of these two systems have to be calculated and analysed. A CO₂-based demand controlled ventilation strategy offers a great opportunity to reduce additional energy consumption in the above HVAC systems, while providing the required ventilation.     

Computational investigation of flow parameters and efficiency of single and double inlet cyclone separators

Cyclone separators are one of the device used in power plant for long time; so many developments have been made in geometry, orientation and entry angle. In the present work an attempt is made with replacement of single inlet with double inlet. Computational analysis is done with Fluent 6.3.26 with Gambit 2.4.6 mesh generation using Cooper meshing facility. Eulerian–Lagrangian approach is adopted in the simulation with air as a working fluid and assumed to have continuous properties (Continuum). The collection efficiency of single and double inlet separator is studied using Lapple model, and it is found that there is an increase of 13.2% in collection efficiency for cyclone separator with double inlet. It is also found that higher inlet velocities are possible with double inlet separator without wall erosion when compared to single inlet separator.     

Superhydrophobic surfaces: a review on fundamentals,applications, and challenges

Superhydrophobicity is the tendency of a surface to repel water drops. A surface is qualified as a superhydrophobic surface only if the surface possesses a high apparent contact angle (>150°), low contact angle hysteresis (<10°), low sliding angle (<5°) and high stability of Cassie model state. Efforts have been made to mimic the superhydrophobicity found in nature (for example, lotus leaf), so that artificial superhydrophobic surfaces could be prepared for a variety of applications. Due to their versatile use in many applications, such as water-resistant surfaces, antifogging surfaces, anti-icing surfaces, anticorrosion surfaces etc., many methods have been developed to fabricate them. In this article, the fundamental principles of superhydrophobicity, some of the recent works in the preparation of superhydrophobic surfaces, their potential applications, and the challenges confronted in their new applications are reviewed and discussed.     

Characterisation of zein–oleic acid films and applications in fruit coating

Pure zein films are known to be very hydrophobic, but are inappropriate for edible coating applications because of their brittle nature. In an attempt to improve the flexibility of these coatings, the influence of low concentrations of oleic acid (OA) as a plasticiser on mechanical, topographical and wetting properties of zein thin films was evaluated. Films were first obtained by casting from aqueous ethanol solutions with 4.0% in mass of zein and additions of 0%; 0.25%; 0.50%; and 1.0% (w/w) of OA. The results indicate an improvement in mechanical properties with increasing plasticiser leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with minor influence on tensile strength. All plasticised zein films have similar initial contact angle (approximately 69°) with a time‐dependent receding drop behaviour. An increase in plasticiser concentration increases film’s affinity towards water. As measured by atomic force microscopy, a consistent linear relation (R² = 0.991) was estimated between film composition and surface adhesion and consequently on the hydrophilicity. Surface topography also varied with plasticiser addition, becoming smoother as the OA concentration increases. When tested as an edible coating on pears (Pyrus communis L.), a formulation with 0.25% wt of plasticiser achieved the best results in preserving the pear mass as measured during the evaluated storage time (12 days) at room temperature. A 0.5% concentration of plasticiser had no influence and higher amounts resulted in a reduction in fruit protection.     

Network infrastructure design with a multilevel algorithm

This paper presents a novel algorithm to deal with the network design problem, which optimizes the network levels considering their interdependency. The idea is to design a low cost and optimized network providing the number and the geographic location of devices as well as the links among them for each network level, while taking into account the existing dependency among them. In addition, a new database composed of real and georeferenced data is created and make available for the research community. This database contains three datasets that represent distinct projects related to geographic regions of the city of Curitiba (Brazil). The experimental results show that the proposed algorithm provides a significant cost reduction in the network design. The savings of this proposal go from 1% to 40% (depending on the network size, number of levels and demand nodes), making it attractive for companies that spend a considerable amount of resources in network projects and deployment.     

Backup compass mechanisms in pigeon orientation with the sun in the zenith

The sun is known to guide homing pigeons as a priority cue. The literature indicates that under total overcast conditions pigeons rely on a backup mechanism akin to the magnetic inclination compass for which there is much laboratory evidence in migratory birds. Total overcast conditions are not favorable for orientation research in the State of S?o Paulo, Brazil. The orientation of homing pigeons raised near the tropic of Capricorn was therefore observed around the time of the December solstice, when the sun culminated directly overhead, with a consequent interruption of the sun compass for a short time every day. In these experiments, carried out between 1981 and 1993, local geomagnetic field inclination was -25 degrees to -29 degrees 30', so that a functioning magnetic inclination compass should have been available to the birds. Whereas the birds released with sun to zenith angles between 10 degrees and 30 degrees were well oriented, both in the morning (99 vanishing bearings) and in the afternoon (143 vanishing bearings), those released with the sun less than 5 degrees away from the zenith showed random orientation (105 vanishing bearings), with no evidence of an alternative magnetic compass mechanism.