Mahmoud Hammad

Characteristics of solar water pumping in Jordan

Remote underground water wells were investigated and 13 such wells were chosen for this study. Photovoltaic (PV) generators were used to power pumping the water up to the surface tanks to be used. A design method was established and illustrated depending on a pumping factor (Fp) which is a function of the solar characteristics. A laboratory solar water pumping unit was constructed and year round results were analyzed. Monthly Fp values were calculated by the experimental results.

Performance of a solar LiBr-water absorption refrigeration system

This paper describes the performance of a nonstorage, continuous, solar operated absorption refrigeration cycle. The solar collectors and the refrigeration experimental unit are manufactured locally. The results presented in this paper are based on the operation of the unit when there was enough solar energy to power its generator. This amounted to 4–5 h per day during the months of August and September in Amman, Jordan. These results include the variation of both the generator and evaporator temperatures during the test periods, the performance of the unit as a function of these temperatures and available solar intensity, and the ideal performance of the unit based on the measured temperatures. The maximum ideal coefficient of performance was determined as being equal to 1.6, while the peak actual coefficient of performance was determined to be equal to 0.55. These values are very close to published values.

Construction and operation of a demonstration biogas plant, problems and prospects

Abstract This paper discusses the design, construction and operation of a low-cost, small, farm-scale digester in which cattle wastes were used. The biogas produced contained about 65% CH 4 by volume. Production quantities and qualities were measured for a period of more than six months, both in summer and in winter. Biogas as used in two different systems: an instant, gas water-heater used to generate hot water for farm use, and a modified piston engine driving an electrical generator of one phase, 1 kW output, fuelled directly by the gas. Operation of both systems was satisfactory. The unit is being used to demonstrate the technology for potential users (mostly farm owners).

Fluidized bed combustion unit for oil shale

Abstract A fluidized bed combustion unit has been designed, constructed and installed to study the fluidized bed combustion of oil shale. It is a steel column of 18 cm inside diameter and 130 cm height fitted with a perforated plate air distributor of 611 holes, each 1 mm in diameter. Direct observation was possible by a 30 cm long sight piece. Fluidization experiments were conducted on an oil shale test sample extracted from the El-Lajjun deposit. The pressure drop across the bed was plotted against the superficial velocity for different sized particles, and the minimum fluidizing velocity for each size was obtained. The results show good agreement with calculated values from the Ergun equation. Fast and safe ignition of oil shale was initiated with kerosene, and temperatures ranging from 500–1000°C were obtained.

Experimental study of the performance of a solar collector cooled by heat pipes

This paper describes the performance of a flat-plate solar collector cooled by a set of heat pipes designed and manufactured locally to work at low-temperature conditions equal to that of the flat plate solar collectors. Efficiencies and quantities of energy transferred to a water storage tank were calculated and found to be comparable to those obtained using a water-cooled solar collector. The efficiency of such a collector depends on time of day, solar intensity, ambient temperature and flat-plate mean temperature. Efficiency was studied as a dependent variable on the mentioned parameters and analysed in different figures, then compared with the commonly used water-cooled collector.

Experimental study of the performance of a solar thermal-photovoltaic integrated system

In this work a self-contained solar heating forced water cooling unit was selected and assembled. It consists of three flat-plate solar collectors, each of area 1.2 m2, a.d.c. pump, a photovoltaic module and a storage tank. The electrical power produced by the photovoltaic module operates the d.c. pump, which circulates the cooling water through the solar collectors to transfer the heat to the storage tank. The electrical voltage and current, the water rate of flow, and water temperature at inlet and outlet of the collector were all measured. Solar irradiation, wind speed and ambient temperature were also measured. Daily distribution of electrical current, water mass rate of flow, module efficiency and collector efficiency were plotted in figures. Module efficiency, pump efficiency and collector efficiency were taken as dependent variables, while the solar irradiation, ambient temperature and time were the independent variables. Optimum values were graphically indicated and related to each other in a clear discussion. An economic study and comparison of three different systems were carried out: a common thermosyphon system; an a.c. pump circulating system; and this system, which is a d.c. pump circulating system. Results revealed that collector efficiency reached a daily average value of 47% due to d.c. pump installation powered by photovoltaic electric output.

Performance study of a domestic refrigerator powered by a photovoltaic generator

A small refrigerator (110 W) operated by a photovoltaic generator was used in this study. The performance of the refrigerator was exhibited in several figs where the power (P, in W), the capacity (cap, in W) and the coefficient of performance (COP) were treated as the dependent parameters. The evaporating temperature (Te, in °C) and the condensing temperature (Tc, °C) were used as the independent parameters. Experimental results showed that solar energy system using deep discharge batteries with inverter is an attractive substitute for the mains power; the performance curves indicated an acceptable performance of the unit. Daily energy consumption by this refrigerator reaches about 0.5 kW h/day. For a building of 50 offices a 25 kW h/day can be extracted from such systems. This will reduce CO2 emission of around 15 kg/day (5.5 tons per year).

Dimensional analysis and empirical correlations for heat transfer and pressure drop in condensation and evaporation processes of flow inside micropipes: case study with carbon dioxide (CO2)

In this paper, the experimental results of the convection heat transfer coefficient and pressure drop values during condensation and evaporation of CO2 were obtained at different operating conditions for flow inside micropipes. Reynolds number (ReD) ranged between 2000 and 15000. The dimensional analysis technique was utilized to develop correlations for Nusselt numbers and pressure drops. A comparison between experimental and correlated results was carried out. The results showed that for the condensation process, the bias errors were 5.25% and 0.4% for pressure drops and Nusselt number respectively. Consequently, Average Standard Deviation (ASD) values reached 17.94% and 4.62% for both respectively. On the other hand, for the evaporation process, the Nusselt number error was 3.8% with an ASD of 4.14%. The correlations presented in the present work can be used in calculating pressure drops and heat transfer coefficients for phase change flows in mini and micro tubes. It helps to enhance design calculations of heat exchangers, condensers and evaporators

Energy performance of plastic pipes

This paper studies the power needed to circulate heating water in building networks using different plastic pipes manufactured in Jordan. A suitable set up was designed and built for this purpose; the study included the effect of the rate of flow and the water temperature. On the basis of the results of pressure drop the pipes were divided as high quality and average quality pipes, prediction formulae for the friction factor of these two classes were derived, experimental results were compared with those predicted by the formulae and with additional published results. The effect of the pipe pressure drop on the pumps annual power consumption was illustrated using an actual application example.

Analysis of Polychlorinated Biphenyl Wastes Incineration in Rotary Kilns: Model Development and Validation

Polychlorinated Biphenyls (PCBs) are among hazardous wastes that must be incinerated for environmental and health protection. A dynamic model is introduced for the incineration of Polychlorinated Biphenyls (PCBs) in a rotary kiln. The model accounts for variations in composition and process conditions. The effects of excess air and the number of chlorine atoms in the structure of the PCBs are included in the incineration process. A MATLAB code was developed to solve the set of stiff nonlinear equations of PCBs incineration. The proposed incineration model was found to be in good agreement with the experimental data reported in the literature under ordinary feeding conditions for chlorinated compounds.