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Dissolution of CO 2 droplets in the ocean has been studied. Owing to hydrogen bonding and supersaturation with CO 2 , seawater at the surface of the CO 2 droplets becomes highly structured. Since this quasi-crystalline structure is similar to that of hydrate crystal elements, hydrate formation on the droplets will not cause a dramatic decrease in the dissolution rate as reported...
To evaluate optimal management strategies which reduce fossil-fuel carbon emissions, an idealized gross returns objective function was developed for the production of irrigated maize with the inclusion of a disincentive carbon-taxing term. The gross returns objective function is multivariant and optimized through a gradient search procedure. Carbon emissions emanating from maize production stem...
The technical feasibility of oxygen-enriched combustion (OEC) to enhance the performance of SMR was investigated. For a small-capacity unit, membrane separation is an appropriate air-enrichment technique. Four production scenarios were considered for the retrofit of an existing hydrogen-production unit. The scenarios were compared, using the new intrinsic energy efficiency coefficient. The exergy...
We present the results of a comparative study on thermally stratified tanks for hot storage. A two-dimensional model is employed. A numerical solution was obtained using the control-volume technique due to Patankar. The two-dimensional model was simplified for the pure conduction case. Results from the two models were compared with each other and with available numerical and experimental results.
The applicability of exergy in the methodology of environmental life-cycle assessment (LCA) is discussed. Exergy consumption (or entropy production) may be used as a measure of resource depletion and competition when performing the impact assessment of an LCA. Exergies of several metal ores and other natural resources are calculated using system boundaries compatible with LCA, i.e. the inflow is...
The thermodynamic efficiencies of selected HFCs (hydrofluorocarbons) have been investigated for applications in binary geothermal conversion systems. Following examination of thermodynamic cycles, interactions with sensible heat sources were considered. For every working fluid, there is a temperature range for optimal use. Each fluid is best applied with a heat source at a temperature somewhat above...
The collector efficiencies of solar air heaters can be improved by operating several subcollectors in series in place of a single collector with the same total area. The improvement increases with increasing insolation and a decrease in flow rate or collector aspect ratio. The subcollector area for maximum efficiency is unity.
The Dutch electricity sector has traditionally been dominated by the public sector. Although this organisational structure resulted in a reliable and low-priced system, it is said not to be completely stable and efficient. National and international developments stimulate the introduction of a liberalised system. In this article, we present the model NEDMOD which is used to estimate possible welfare...
The following reaction has been investigated over various metal oxides for the purpose of utilizing solar or nuclear heat as an energy source: (2 + x) CH 4 + xH 2 O→C 2 H 4 + xCO + (3x + 2)H 2 . Oxides of Zn, Mn, Co, Ni, Mg and Fe were used at 900°C. The greatest activity for C 2 H 4 formation was observed with Fe 3 O 4 (magnetite);...
A computer analysis has been developed for studying the energy and exergy performance of an indirect-injection, naturally-aspirated diesel engine operating under transient load or speed conditions and covering the operating profile of both industrial and automotive engines. The model is validated at steady-state operation and incorporates many novel features for simulating the transient response...
The optimal heating-system-retrofit strategy for existing buildings differs due to varying prices of energy, building and installation features, climate conditions, etc. We have examined a test building situated in Linkoping, Sweden. By using the OPERA model, we were able to arrive at the optimal retrofit strategy, which includes a ground-coupled heat pump using electricity to run the compressor...
Abductive network machine learning is proposed as an alternative to the conventional multiple regression analysis method for modelling and forecasting monthly electric energy consumption. The AIM (abductory induction mechanism) is used to model the domestic consumption in the eastern province of Saudi Arabia in terms of key weather parameters and demographic and economy indicators. Models are synthesized...
The performance of a thermoelectric device used as a heat pump or refrigerator is mainly affected by the Peltier, Fourier, Joule and Thomson effects. The differential equations governing the temperature field inside the device operated between two heat reservoirs are established by using nonequilibrium thermodynamics. New expressions are derived for the COP and the rate of heat pumping. Effects...
We present a new concept of modelling energy-using behaviour of residential customers by the use of linguistic variables and a fuzzy logic approach. Trapezoidal- and delta-shaped fuzzy filters were applied to transfer uncertainties of customer declarations expressed in linguistic variables into parameters of structural models. This approach involves individual treatment of each customer. In surveys...
The dynamic energy optimization model deeco is a tool for analyzing competition and synergy between different technologies of the rational use of energy and for utilizing renewable energies. For given time series of the fluctuating heat and electricity demand, deeco calculates the optimal combination of energy-conversion technologies while taking into account local parameters like ambient temperature...
CO 2 is a significant greenhouse gas. CO 2 emissions result mainly from energy consumption, which is closely related to the rate of economic development, efficiency of energy use and the structure of the energy-supply system. We estimate CO 2 emissions in Shanghai for 1990 and 2010 and compare our results for Shanghai with those of other regions in the world. There exists...
We present the development of structural models for energy consumption in the residential sector. Customers were segmented into four main categories with six sub-groups within each category. A survey of over 100 customers provided data on the 17 appliances considered, which are grouped into three main categories. The models provide energy-use patterns for each category of customers for selected...
Biomass accounts for 17% of the total Swedish energy supply. The potential increase in annual domestic biomass production is considerable. The costs and primary energy use required for producing one unit of electricity and one unit of heat, as well as the CO 2 emissions involved, were analysed for different biomass- and fossil-fuel-based systems. Supply systems based on cogeneration plants...
We present projections of rural energy supply and demand and assess the contributions to global warming. The output of a dynamic system model is used in the LEAP model and overall energy balances are then compiled using a bottom-up approach. Biomass fuels constitute the major energy sources for rural people. A major share of the fuel is consumed for cooking using traditional stoves which have an...
A methodology has been developed for assessing the sensitivity of electricity and natural gas consumption to climate at regional scales. The approach involves a multiple-regression analysis of historical energy and climate data, and has been applied to eight of the most energy-intensive states, representing 42% of the total annual energy consumption in the United States. Statistical models were...
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