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The influence of climatic variables on variations in residential electricity consumption (rec) in Hong Kong for the period 1980-1994 has been investigated. The association between a potential weather stress index, clo, and rec was also examined. Utilizing monthly data and stepwise multiple regression analyses, it was found that the vapor pressure was not significantly related to rec while cloud...
Long term global energy scenarios are needed for long term policy on energy and climate change. IIASA-World Energy Council (WEC) energy scenarios up to 2100 are evaluated here to show that they satisfy economic and environmental criteria and take into account resource and market penetration constraints. They are contrasted with the IPCC scenarios of 1992 which are too simplistic to use to the analysis...
Calculating energy savings and emission-reduction potentials for municipal energy systems requires computer models with high spatial and temporal disaggregation. Consequently, the computational effort necessary to run such models is considerable. For the optimization models eco, ecco-solar and deeco, this problem has so far been solved by assuming that the time intervals considered are independent...
We present the applicable exergy analysis and estimate irreversible losses that are generated during operation of a hybrid air-conditioning cycle with emphasis on a partly closed solar regenerator that is used to regenerate weak desiccant. The desiccant mass-flow rate has been chosen as the fundamental parameter for analysing the system. We find an optimum mass-flow rate for minimum irreversibility,...
The effect of collector aspect ratio on the collector efficiency of baffled solar air heaters has been investigated theoretically. With constant collector area, the collector efficiency increases when the collector aspect ratio increases. This is the same results as those obtained in the previous work for flat-plate solar air heaters without fins and baffles. Although the collector efficiency of...
Using household-survey data in a village of West Bengal, we justify investments in solar lanterns. A government distribution program alone cannot sustain this activity. Willingness to pay by households for the new technology determines success of the program.
Hot-water consumption for apartments in the developed and developing communities of Johannesburg has been determined by measurements over a period of one year. The results of the average consumption per person per day are presented for the different months of a year. Also given are, hourly hot-water consumption per person per day for summer weekdays, summer weekends, winter weekdays and winter weekends.
A method for identifying and characterizing technologies that can improve the energy efficiency in the long term is described and applied to the paper and board industry. Current paper-making processes require 3-9 GJ heat per tonne of paper, mainly for the removal of water that is added initially to the fibers, and 1.3-2.9 GJ electricity/tonne. The selection of technologies is based on the results...
The problem of heat conduction in a multi-layer, two-dimensional, orthotropic cylinder subject to asymmetric and periodic temperature distribution on the outer wall is solved analytically. Dimensional analysis of the problem shows that heat conduction through the cylinder is a function of the Biot number (Bi) and the following four non-dimensional parameters in each layer: frequency ratio (α ...
We propose a simple method for estimating the likely energy savings in electric lighting due to daylighting and the possible cooling penalty. Fractions of the working year and cooling season when daylighting alone is adequate to provide the indoor design illuminance are presented for on-off and top-up controls. Based on the simple average daylight factor method, energy savings in electric lighting...
The problem of mean thermal radiation transfer in a fluctuating, statistically uniform medium, with spatial temperature distribution given by a generalized telegraphic process, is solved. The solution is based on the use of the Laplace transformation and replacement of an original temperature-fluctuation distribution function by another one, which practically does not distort average terms in the...
Aluminium manufacturing is highly energy-intensive and a large contributor of CO 2 . The emissions per tonne of aluminium manufacturing in India have been estimated. Demand for aluminium and associated CO 2 emissions have been projected for the industry as a whole for the years 2001/02 and 2006/07. The reduction potential in CO 2 emissions through energy-conservation measures...
We use a decomposition model to analyze changes Of CO 2 emission intensity in the developed countries for 1980-94. During this period, emission intensifies decreased by 33.26% from 788.7 u (1 u = 1 kg Of CO 2 /1000 US$ at 1990 prices) in 1980 to 591.9 u in 1994. The rate of decrease in CO 2 emission intensifies has decelerated; the decrease during the first 7-year period...
This study was undertaken to compare the economic viability in Johannesburg, R.S.A., of vertical ground-source and air-source systems. Capital costs and optimum borehole length of the ground system were determined. Monthly heating and cooling capacities, and COPs were evaluated to determine running costs. Payback periods, net present values and internal rates of return were computed. The vertical...
Environmental issues relating to air transport are analyzed. An inventory calculation system for air traffic is developed to determine annual fuel consumption and emissions. It uses airline data on routes, hours of flights, density of traffic, fleet mix, and ratings of engine manufacturers. It was applied to an airline company in Greece. Yearly environmental loads have been calculated and show...
Separate models correlating natural gas (NG) consumption to climate have been developed for the residential and commercial sectors of the 50 U.S. states. The models relate a population-weighted average temperature to state per capita NG consumption on a monthly basis. The majority of the models have Pearson correlation coefficients greater than 0.90 supporting the use of temperature as the sole...
The comminution process has exceedingly low efficiency because it is highly irreversible. An outline of energy analysis for comminution is presented. The application refers to an ore-processing plant, which consists of a series of crushers feeding a traditional ball mill that delivers products to a downstream metallurgical process. For optimization, the design characteristics are fixed, i.e. decision...
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