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An analysis of a drier with passive drying-air temperature control for use on farms is presented. The experimental solar drier with a grain capacity of 90 kg has an initial capital cost of @$601. Semi-skilled artisans can build the drier at half the price if one used local materials. The cost of sun drying, including a 25% grain loss, is @$0.11/kg. With delivery of useful energy at @$0.06/kWh,...
In the development of new tariffs, customer diversity should be taken into account to achieve more efficient demand-side management goals. This means that customers' reactions to rate changes need to be analysed at an individual customer level. We use daily consumption pattern (DCP) models for the analysis of rate effects. The DCP is assumed to consist of the daily rhythm of consumption, the effects...
We describe the measured air-conditioning and thermal performance of a typical Thai single-family residence. Although the measurements represent a single case study, it is the first time that an analysis has been performed on a Thai house with typical modern construction. In such buildings, the lack of building thermal insulation, the utilization of non-ducted air-conditioning equipment and the...
A 2 kW concentrating solar furnace was used to study the thermal decomposition of TiO 2 at temperatures of 2300-2800 K in an Ar atmosphere at 1 bar. The condensed products may be described as TiO x ; the minimum values of x that we obtained experimentally were 1.91, 1.86, and 1.83 for temperatures of 2300, 2500, and 2700 K, respectively. The final products, after the temperature...
An endothermic chemical system composed of pulverized metal oxide and carbon has been investigated with a view to utilizing waste heat and carbonaceous compounds effectively. Oxides of Cu and Mn and also MMn 2 O 4 (M = Li or Mg) were used. In an N 2 -gas stream, the metal oxide was reduced by reaction with carbon which was concurrently oxidized to generate CO and CO 2...
The choice of energy carriers by households depends mainly on their economic status. The role of the environment in which they operate is equally significant. The energy-ladder concept is used in this study to describe the way in which households climb the ladder with increase in economic status. A multilogit model has been developed to study the effects of different factors on the selection of...
We present a preliminary analysis of a geoengineering option based on the intentional increase of ocean alkalinity to enhance marine storage of atmospheric CO 2 . Like all geoengineering techniques to limit climate change, with today's limited understanding of the climate system, this approach must be regarded as a potential strategic option that requires ongoing assessment to establish its...
We present the findings of a literature survey on decision analysis in energy and environmental modeling. Surveyed studies are classified according to the decision analysis technique used and by application area. It has been found that decision making under uncertainty is the most important application technique and energy planning and policy analysis is the most common application area. The results...
A study has been carried out on heat recovery from air that ventilates a hot tool in a tool shop. The recovered heat is used to preheat air for space heating of this tool shop. Software has been used to analyze the heat-recovery efficiency and thermal comfort (TC) when the size and temperature of the hot tool are varied. An increase in hot tool size of 10% yields an energy loss of up to 2% and...
This paper deals with energy end-use models for pulp, paper, and paperboard mills. The models are consistent with data published in the U.S. Department of Energy's 1991 Manufacturing Energy Consumption Survey (MECS). A graphical framework for depicting these energy flows is presented. Development of these models is a key step in creating energy process-step models for pulp, paper, and paperboard...
Flames over a wood element in quiescent air may be classified as (a) near-extinction, (b) stable-smokeless, and (c) smoky. The direct connection of these forms of flames with the surface gas flux (SGF) emitted from a pyrolyzing solid was investigated. Measurements were made on flames of wood pyrolysis gas issuing out of an 8.5-mm tube. For comparison, the same device and an 8.5-mm wick were used...
We show that an absorption-refrigeration system affected by the irreversibility of finite-rate heat transfer may be modelled as a combined cycle, which consists of an endoreversible heat engine and an endoreversible refrigerator. Finite-time thermodynamics of endoreversible heat engines and refrigerators is used to optimize the primary performance parameters such as the coefficient of performance,...
The optimization problem of a combined refrigeration cycle formed by two endoreversible Carnot refrigeration cycles in series without intermediate reservoirs has been studied using finite-time thermodynamics. The fundamental relation between cooling quantity and coefficient of performance (COP) of the combined cycle is derived for a general physical model of a combined cycle. Relations are derived...
The effects of feed rate of waste tires (0.21-0.52 kg/h), oxygen concentration (0-11%), pyrolysis temperature (700-880°C), and fluidizing gas velocity (1.5-3.0 u mf ) on product (gas, oil, char) yield, composition, energy recovery, and heating value of the product gas have been determined in a fluidized-bed reactor (0.076 m i.d. 1.2 m-high). The product yield, composition and heating...
We use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space heating by using the heat contents of some of the refuse hot-air flows (RAF). Several RAFs are often available with different flow rates and temperatures. A proper scenario for use of their heat contents is essential for efficient management of the energy system. Using a steady-state, bottom-up approach,...
Results are presented of a theoretical study to assess the viability of using water-in-oil emulsions for power-station boilers to reduce pollutant emissions, deposit buildup on heat-transfer surfaces and excess-air-requirements while improving boiler efficiency. The variables studied include the water concentration (0-10%) and percentage of maximum output (40-100%). SO x and NO x ...
We have investigated analytically the performance of the thermally driven, advanced three-stage adsorption chiller utilizing low-grade waste heat of 50°C and lower temperatures as the driving heat source, in combination with a heat sink (cooling water) of 30°C. The closed cycle chiller for use in air-conditioning utilizes the silica-gel-water adsorption system. A cycle-simulation program was constructed...
The proliferation of nonlinear loads has raised new concerns about the power quality in commercial buildings. Higher cost of repair, and the reduction in average life of equipment, both on the supply and demand sides, as a result of poor power quality cannot be overlooked or ignored. As lighting loads are the largest fraction of the load in most commercial buildings, a small increase in their harmonic...
The effects of various fin shapes on solar collector efficiency and material cost have been investigated. A heat-transfer analysis for fins used in an aluminium flat-plate solar collector has been performed. Heat fluxes were considered for only one side of the fins. Fin and/or collector efficiencies vs fin-tip heat-loss parameter and fin length were calculated. An economic evaluation is given.
This paper deals with policies to meet increasing demand for electricity in Turkey and elsewhere. Environmental problems created by exploitation of domestic resources should not be ignored. We comment on adverse effects of large-scale hydroelectric projects in India and Canada. We argue in favor of small-scale dams for sustainable development.
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