Choice of sink for air conditioning systems. Part 2

The technical superiority of water-cooled air conditioning systems for different applications in terms of overall power rating have been established by the authors in an earlier publication. This paper deals with the generalized approach for evaluating the techno-economic choice of sink for an air conditioning system. A single parameter of unit cooling cost in fils/kWh_c (100 fils = 1 Kuwaiti dinar = US$3.25), combining the system's technical performance and economic aspects, is an effective cost-benefit criterion for making the choice for the type of sink. The results of an analysis, applied to example case studies in Kuwait, favour the water-cooled system for both the direct expansion (mostly used in the residential sector) and the chilled water (commonly used for non-residential applications) air conditioning systems.     

Formation of dialyzable iron during in-vitro digestion and extraction of mycoprotein

Mycoprotein is the biomass of the fungus Fusarium venenatum. The ability of mycoprotein to enhance production of dialyzable iron following in-vitro digestion or extraction was studied, with the aim of identifying the components responsible. Digested mycoprotein, extracted mycoprotein and digested chicken breast muscle all produced about ten times as much dialyzable iron as the control. All of the dialyzable iron from mycoprotein was ferric. Essentially all the dialyzable iron passed through a 1 kDa molecular weight cut-off membrane. Iron binding components were extracted from mycoprotein using weak acid but not water. Extraction of mycoprotein produced both dialyzable and non-dialyzable components, which bound ferric iron. Analysis of the digests and the dialyzable fraction of acid extraction showed that they contained siderophores, which contributed to the formation of dialyzable iron.     

Influence of shear in the crystallization of polyethylene in the presence of SWCNTs

It is well accepted that due to epitaxy matching, carbon nanotubes are good nucleating agent for linear polyethylene. We demonstrate that not only in the quiescent conditions but also at the relatively low shear rates the presence of single-walled carbon nanotube (SWCNT) accelerates the crystallization kinetics of polyethylene (PE). The influence of SWCNTs on the crystallization kinetics in the quiescent condition is followed with the help of rheological and differential scanning calorimetry studies. The influence of flow on the stretch of the polymer chain is probed using time-resolved small-angle X-ray scattering (SAXS) and is verified with the Deborah number. SAXS data indicates that the strong shearing conditions (shear rate > 50/s for 1 s) are requisite to form shish-kebab structure in the neat polymer. However, for the low shear (shear rate < 50/s for 1 s), the shish-kebab structure that arises due to chain orientation is enhanced in the presence of SWCNTs. The development of oriented structures in SWCNT/PE composites and their absence in the neat polymer under low shear rate indicates that the presence of SWCNTs plays a significant role in the chain orientation. Overall, the results manifest the influence of SWCNTs on chain relaxation of the polymer.     

Incineration of diesel particulate matter using induction heating technique

Incineration of diesel particulate matter for the regeneration of a mesh-type particulate-filter is achieved using induction heating technique. Heating of the diesel particulates deposited on the mesh-type particulate-filter at around 600 °C is investigated. In the case of the particulate filter, stainless-steel mesh-type filters are considered and the influence on filtering efficiency, the engine performance due to back-pressure generation is studied. Theoretical estimation shows that induction heating approach for the regeneration via exhaust gas heating requires high power (>3 kW). On the other hand, regeneration of mesh-type particulate-filter using induction heating technique requires a low input power of around 0.5 kW in the off-line condition. The proposed mesh-type particulate-filter allowed a filtration efficiency of around 30–40% at lower engine speeds and part loads. Particulate combustion through induction heating at static condition is studied and power required for mesh-type filter and sintered metal filter regeneration during engine operation is estimated theoretically.     

Development of Fe‐, Sb‐, Bi‐ and Al‐impregnated silica catalysts using rice husk silica as a support for Friedel–Crafts benzylation of arenes

The milling by‐product of rice, rice husk, constitutes a major waste of the agricultural industry. It is mainly used as a fuel additive for various purposes, leaving behind residual ash which is rich in silica (Biogenic silica). In the present project, rice husk silica was impregnated with Fe³⁺, Sb³⁺, Bi³⁺ and Al³⁺ from both their aqueous and organic solutions. The resultant catalysts were activated at 120 °C and 550 °C and used for the Friedel–Crafts benzylation of benzene using benzyl chloride. Copyright © 2003 Society of Chemical Industry     

Generalized Filter Topology Using Grounded Components and Single Novel Active Element

This paper introduces a new active element combining the useful features of differential voltage, dual-X and first generation current conveyors. The new proposed active element is further utilized to introduce a new generalized filter topology employing grounded components only. The proposed single active element-based topology benefits from first-order and second-order filter realization by appropriate impedance specialization. The circuit topology with single current input provides two output currents and voltages in each case. A thorough study of proposed active element along with extensive simulations is carried out to validate the filter topology. A detailed non-ideal study is also given. To further support the usefulness of filter topology, higher-order filters are also realized. The new active element and the new filter structure provide advancement to the existing knowledge; with the scope of active element being further exploited for analog signal processing applications in general. The proposed differential voltage dual-X first generation current conveyor (DV-DXCCI) and its filtering applications are simulated using TSMC 0.25  \(\upmu \) m technology.     

Techno-economic performance analysis of solar cooling systems

Vapour absorption cooling systems, powered by solar thermal energy, are now commercially manufactured in sizes ranging from 1.5 to over 20 RT (one refrigeration ton = 3.51 kW of cooling). The needed thermal energy at appropriate temperature potential can either be provided by solar thermal collectors or else from a solar pond. The paper gives the assessment criteria and results for technical and economic evaluation of the performance of absorption chiller using a solar pond. These results, based on Kuwait's environmental data and costs, have been compared with three alternate cooling systems, namely:

• 1 Solar thermal collector absorption cooling system.
• 2 Solar photovoltaic cooling system.
• 3 Standard vapour compression cooling system.

The criteria, used for performance evaluation of the solar cooling systems on a technical basis, consists of assessing the extent to which such systems can make a positive contribution in a conserving fossil fuel. This is done by first estimating the total electrical energy needed by the standard system (defined in para. 3 above) to produce one unit of cooling output. Solar cooling systems are then analysed and compared with a standard system to establish their electrical energy saving or generation capability, after accounting for the parasitic electrical energy used in pump/fan motors and equivalent energy needed for the production of soft water (used-up in the cooling tower) from seawater desalination. The economic analysis considers the cost and life of subsystems and that of the electrical and water desalination plants to arrive at the unit cooling cost. The unit cooling is defined as the ratio of amortized capital investments plus operation and maintenance costs over the year and the total yearly cooling production by the system. The results show that the solar pond absorption cooling system is the closest competitor to the conventional cooling system.     

Enhanced biosynthesis of extracellular matrix proteins and TGF-beta 1 by polyinosinic-polycytidylic acid during cutaneous wound healing in vivo

OBJECTIVES: We sought to determine the utility of left ventricular expansion velocities in differentiating constrictive pericarditis from restrictive cardiomyopathy. BACKGROUND: Several studies have shown that left ventricular diastolic expansion is influenced by the elastic recoil forces of the myocardium. These forces are affected by intrinsic myocardial disease but should be preserved when diastole is impaired as a result of extrinsic causes. METHODS: Using Doppler tissue imaging, we measured peak early velocity of longitudinal axis expansion (Ea) in 8 patients with constrictive pericarditis, 7 patients with restriction and 15 normal volunteers. Transmitral early (E) and late (A) Doppler flow velocities, left ventricular systolic and diastolic volumes, ejection fraction and mitral annular M-mode displacement were also compared between the groups. RESULTS: The Ea value was significantly higher in normal subjects (14.5 +/- 4.7 cm/s [mean +/- SD]) and in patients with constriction (14.8 +/- 4.8 cm/s) than in those with restriction (5.1 +/- 1.4 cm/s, p < 0.001 constriction vs. restriction). There was weak correlation between Ea and the extent of annular displacement (r = 0.55, p = 0.004) and the E/A ratio (r = 0.44, p = 0.03). There was no correlation between Ea and E (r = 0.33, p = 0.07) or ejection fraction (r = 0.21, p = 0.26). By multivariate analysis, Ea was the best variable for differentiating constriction from restriction. CONCLUSIONS: Our study indicates that longitudinal axis expansion velocities are markedly reduced in patients with restrictive cardiomyopathy. The poor correlation found with transvalvular flow velocities suggests that Ea may be relatively preload independent. The measurement of longitudinal axis expansion velocities provides a clinically useful distinction between constrictive pericarditis and restrictive cardiomyopathy and may prove to be valuable in the study of diastolic function.