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The level and structure of rural energy consumption have been changing greatly in the developed region of China, where the economy is growing rapidly. The growth of rural industry is giving rise to a substantial increase in energy demand. The availability of reliable and secure energy supplies is one of the factors which limits the rate of sustained economic growth. Energy conservation is an important...
The work presented in this paper demonstrates that different subgroups in the population described by various economic and demographic characteristics have different levels of greenhouse gas emissions from personal automotive transportation. Further these characteristics may be assigned a rank or importance in terms of association with emissions levels. And once socioeconomic characteristics of...
We examine load-frequency control of isolated WDMHPS provided with conventional proportional-plus-integral controllers. The parameters of the controller are optimised for system performance with step or realistic disturbances using an integral-square-error (ISE) criterion. Non-optimum gain settings may result if only step changes are assumed in input wind power or in load. The controller works...
Exergy optimization has been carried out for an endoreversible cogeneration cycle using finite-time thermodynamics. The optimum values of the design parameters of the cogeneration cycle at maximum exergy output were determined. Our model is more general than the endoreversible power cycle found in the literature. The effects of design parameters on exergetic performance are investigated and the...
A considerable amount of exergy is contained in the liquid slag tapped from blast furnaces. Relatively new processes for heat recovery from these slags are described in this paper. The slags yield a useful, dry granulated product with a glass content that depends on the process employed. Exergy in liquid and solid slags can be exploited to produce both steam and heated air. The steam may be used...
The power generated by a wind turbine depends on both the design characteristics of the turbine and the properties of the wind resource. These parameters determine the capacity factor (ratio of average power output to rated power of the turbine). Since detailed information on the wind-speed frequency is often lacking, the shape factor (k) of the Weibull distribution is taken to be equal to 2, which...
Low-level thermal energy is upgraded by using the reversible reactions of 2-propanol dehydrogenation and acetone hydrogenation. A new design criterion for optimal operation is proposed using modeling and numerical simulation. Optimal values have been obtained for the reflux ratio and the number of trays of the distillation column for given operating conditions. Simulation results show that the enthalpy...
This article deals with some methodologies for economic and technical evaluations of cogeneration projects proposed by several authors. A discussion on design philosophy applied to thermal power plants leads to the decision problem of a conflicting, multiobjective formulation that includes the most important parameters. This model is formulated to help decision makers and designers in choosing compromise...
We have used a thermoelectric cooler and a coldness-recovery device (CRD) for summer air conditioning of a train carriage. The coldness-recovery device is a countercurrent heat exchanger. This air-conditioning system is described in terms of a heat-exchanger network for which we have developed computer software (GOLAM2-R). We have simulated six different control scenarios for the energy system...
The technique of energetic optimization is employed to investigate the optimal performance of a corrugated, collector-driven, irreversible Carnot heat engine and an absorption refrigerator. A minimum operating parameter and a relation between the maximum overall efficiencies are obtained for the systems under consideration.
A transient mathematical model is presented for a box-type solar cooker with a one-step outer reflector hinged at the top of the cooker. It is based on analytical solution of the energy-balance equations using Cramer's rule for different elements of the cooker. The various heat-transfer coefficients are assumed to be temperature dependent. To validate the model, the temperature distribution obtained...
The mixing behavior of light paper pellets in a sand fluidized bed is investigated for varying proportions of paper pellets (0-20 mass%) over a range of superficial air velocities (0-1.5 m/s) at ambient conditions. It is found that a fluidization number greater than 2 is essential to achieve good mixing as long as the proportion of paper pellets in the bed is up to about 10 mass%. For 20 mass% of...
Electricity authorities in the UAE have not been successful in developing reliable and accurate models of system peak load. In this study, we develop a time-series-based decision-support system that integrates data management, model base management, simulation, graphic display, and statistical analysis to provide near-optimal forecasting models. The model base includes a variety of time-series techniques,...
The heat-integrated distillation column (HiDiC) provides one of the most effective applications of heat-pump technologies to industrial processes. It reinforces a separation process and yields larger energy savings than other methods such as overhead-to-reboiler heat pumps, which involve moving heat between the hottest and coldest points in the distillation column. A simulation study of this column...
Previous efforts in rural energy modelling have been reviewed and critically examined. A system-dynamics model of an integrated energy system for farming in Bangladesh has been developed based on Huq's revised model. The model considers energy use in various forms, including food production and consumption. The physical quality of life is also discussed. The model incorporates existing feedback...
A criterion, based on optimization principles, for determining the SAT setpoint in VAV systems is presented. It is generally accepted that conventional SAT reset controls (SATRC), bounded by either space humidity or ductwork size, will save cooling and/or heating energy. However, the ventilation consequences and penalty resulting from increased fan power have generally been overlooked. Ventilation...
The top heat-loss factor (U t ) of a box-type solar cooker varies with plate temperature, wind heat-transfer coefficient and ambient temperature. A method for correlating U t with these variables is presented for a cooker with double glazing. A set of equations is developed for correlating data obtained in indoor experiments at different plate temperatures and wind speeds.
Planning over the intermediate and long terms for the operation of solar energy systems must be based on the use of measured data and performance models of system components. We present a dynamic model for predicting the thermal performance of a low-temperature solar power plant. We analyse the optimal control regime for energy management. Validation of the model was performed on a large solar...
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