Utilization of waste materials and industrial by-products is a sustainable solution to environmental and ecological problems. Use of such materials makes their reutilization in cement, concrete and other construction materials, and also reduces the cost of cement and concrete manufacturing. Other indirect benefits include reduction in landfill cost, energy saving and reduction in solid waste. Electronic waste (e-waste) consists of discarded refrigerators, radios, TVs, Air conditioners, Mobile phones, computers and several other electronic gadgets that have reached their end of life or become obsolete. Efforts are being made in the construction industry to use nonbiodegradable components of e-waste as a partial replacement of the coarse or fine aggregates in concrete. This study focuses on the utilization of e-waste plastic particles in concrete and tests the feasibility of utilizing shredded e-plastic particles as partial replacement of coarse aggregate. It was observed that when e-plastic alone was used, there was a decrease in strength but when 10% fly ash was added results comparable to control specimen were obtained. It is thereby suggested that utilization of this e-waste in concrete will reduce the requirement for conventional coarse aggregates thereby resulting in conservation of natural resources.

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This research is a continuation of our previous work [19], in which, I’ve investigated many control techniques for the multi-input multi-output (MIMO) control systems for air conditioners. In the present work, I’ve suggested another control technique which exhibited better performance in the cases where permanent disturbances are present. I’ve applied the technique to a model room that simulates a computer room and is conditioned by a simple, less expensive, and energy-saver HVAC system. The two control inputs are; the opening angle of a fresh air gate and the steam flow rate from a humidifier. The two controlled outputs are the temperature and humidity. The control technique and the in-door conditions are simulated using a written program that works along with a commercial code. The sampling interval for each controlled variable is modified to allow more accuracy for measured data. When applying accidental and permanent disturbances in both controlled variables, the suggested technique exhibited accepted performance. The controlled variables that are affected with permanent disturbances achieved their set-point values after longer time intervals than those of the cases where only accidental disturbances are present. Two comparisons were made between the controlled and uncontrolled system by operating the system for a certain period, and fixing the fresh air opening at 25% and 50% of the full opening area. The consumed energy in the two cases was compared with that of the case when applying the control technique for the same period. An energy-saving of about 15.3% was recorded in the first case and about 37.6% for the second case. The present technique is a case-independent and may be applied to any MIMO control system with little modifications.

During a pool boiling process, the bubble distribution plays an essential role in the heat transfer enhancement. In the present work, a controllable test rig was prepared to investigate the heat flux and superheat temperature in a nucleate pool boiling process. Aqueous solutions of three surfactants were tested on three heated tubes that are made of brass, aluminum, and stainless steel with almost the same surface roughness. The investigated surfactants are; TRITON X-100, SLES, and SDS, each one was tested at concentrations; 0, 100, 400, 700, 1000, 1300, 1600 and 1900 ppm. For each case, the measured superheat temperatures and their corresponding heat fluxes and physical properties of the surfactant solution are fed into suitable relations. Consequently, correlations could be deduced to relate the heat flux to the bubble distribution, the superheat temperature and the concentration of different surfactant solutions. The results showed that, for all cases, the density of bubble distribution increased with the superheat temperature, the heat flux, and the surfactant concentration. For TRITON-X, the bubble distribution increased considerably with the surfactant concentration until the range of values between 400 and 700 ppm, and beyond this range, this rate of increase started to decay.

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