CEMENT INDUSTRY PREFERENCES FOR CAPTIVE POWER PLANTS IN PERSPECTIVE OF CURRENT ENERGY CRISES OF PAKISTAN

In the current wake of energy deficiency, senior management of Pakistan Cement Industry is forced to look for non-conventional sources for electricity generation. Comparative study of captive power plant (CPP) options may help the top management in decision making and highlight the industry preferences for installation of new CPPs. This paper presents an Analytical Hierarchy Process (AHP) based multidimensional approach to select the CPP’s for cement industry and to prioritize the factors affecting this selection. The CPP’s shortlisted for this analysis include; Coal Fired CPP (CF-CPP), Refused Derived Fuel CPP (RDF-CPP) and Waste Heat Recovery CPP (WHR-CPP). The AHP routines are modelled in respective software. Data specific models are solved using the data collected from top management of different cement plants in Pakistan. The quantitative data for alternative power plants with respect to each criterion has been collected from different data bases. AHP results show that Pakistan cement industry has a strong demand for non-conventional CPP’s and the top management is giving high priority to factors like ‘Automation’ and ‘Performance’ while installing the CPP’s. Management is not much sensitive about the associated initial costs. The paper concludes with a ranking list in which WHR-CPP is at the top while RDF-CPP and CF-CPP are at the second and third place respectively. The results may help the policy makers of international CPP manufacturing firms and national cement industries in their future strategic decisions

Effect of Heat Sink Configuration on the COP of Thermoelectric Vaccine Refrigerator

Polio vaccines are significantly sensitive to temperature and environment. During polio vaccination campaigns in far off villages of Pakistan, it is one of the biggest challenges to store and transport the vaccine without affecting its quality. Various refrigeration techniques are used to keep the vaccine below ambient temperature. The energy consumption of conventional refrigeration systems is too high and the refrigerants having CFCs are hazardous to environment, contributing to global warming by depleting ozone layer. These are also slightly difficult to be developed into a lightweight and portable solar devices used outside.  Solar Powered Thermoelectric Refrigerator (SPTR) is a distinct type of refrigeration system which runs on solar energy rather than that of conventional source of electrical energy, based upon the peltier effect to create hot and cold sides. The current research work was carried out at the Mechanical Engineering Department, U.E.T. Lahore (KSK Campus). The experimental results indicated the unit is capable to maintain a temperature of 6 0C at an ambient temperature below that of 50 0C. The maximum coefficient of performance was recorded as 0.78. Special configuration of heat sink was used to get maximum heat dissipation with minimum cost. An optimal value of solar irradiance let the cooling rate and coefficient of performance to attain maximum value. The designed SPTR would be of a great potential for cold storage in the areas where electricity supply is absent. It has the advantages of being small, lightweight, low running cost, noiseless, portable, reliable, and also low initial cost in mass production. &nbsp

Comparative Study of Dissimilar Weldings of AA6061 and AA2024 Aluminum Alloys by FSW and GTAW

In this research weldability of AA6061 and AA2024 aluminum alloys by GTAW and FSW was studied. Friction Stir Welding (FSW) and Gas Tungsten Arc Welding (GTAWA) of AA6061 and AA2024 aluminum alloys were carried out with sheet thickness for both alloys was 3 mm. The process parameters used for FSW were 950 rpm tool rotational speed with feeding rate of 50 mm/min. Gas Tungsten Arc Welding of AA6061and AA2024 aluminum alloys was carried out using ER5356 filler rod to avoid the hot cracking and liquidation in the weld. Comparative study of the joint strength and the microstructure examination showed that the heat affected zone in AA6061 has minimum hardness and strength due to the formation of dark bands of Al-Mg2Si eutectic. The joint failure occurred in heat affected zone for both FSW and GTAW welded samples. Results showed that by using Titanium in the filler rod as an alloying addition solve the problem of hot and liquidation cracking and also it refine the grain structure of the weldments. Results also showed that AA6061 and AA2024 aluminum alloys are weldable by GTAW welding using ER5356 filler metal and 80 % more joint strength than that of the FSW welded joint can be achieved

Evaluation of LC Resonant Pressure Sensor for Smart Stent Application

This paper aims to project the design and evaluation of inductor capacitor (LC) pressure sensor for smart stent application. The sensor was fabricated through ultraviolet (UV) patterning process using SU-8 polymer material because of its biocompatibility and suitability to fabricate small patterns. In the second phase of the research illustrates the measurement of pressure difference of blood and wireless monitoring inside the coronary artery having a stent implant equipped with LC resonant pressure sensor. This rectangular shaped pressure sensor (with and area of 4 x 4 mm2), consists of an inductive coil and a capacitive plate, which exactly matches with the radio frequency-identification (RFID) design. The LC pressure sensor circuit is able to communicate with external antenna by matching the resonance frequency of both circuits. The fabricated sensor has 1.3 pF capacitance, 100 nH inductance with the resonance frequency about 440 MHz. The fabricated sensor is placed in a small vacuum chamber and the chamber pressure is controlled by using a syringe pump. The change of 100 MHz in the resonance frequency is observed in a pressure range of 0 to 16 kPa. Through a series of experimental analysis, it has been perceived that the discussed sensor can effectively measure pressure difference inside the vacuum and the change in resonance frequency can be further detected by using wireless equipment. The sensor can be widely used in the applications to effectively monitor the pressure difference of blood inside the human coronary artery

Enhanced efficiency of GaAs-GaxAl1-xAs laser with /4 antireflections coating of TiO2 thin films: an Optical Engineering

Titanium dioxide (TiO2) dielectric material was deposited as ~l/4 antireflections (AR) coating on one facet of GaAs-GaxAl1-xAs double heterostructure (DH) laser. Single layer ~ l/4 AR coating was achieved by successive deposition of TiO2 thin films in vacuum in small steps by thermal evaporation technique, while measuring the threshold current after each coating outside the vacuum. Threshold current, reflectivity and far-field patterns of laser show the significant influence of AR coatings on light output characteristics. Internal loss parameter a and the gain coefficient b for the DH laser were determined from threshold current under the case temperature of the laser