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The network method has been applied to a five-layer wall with thermal conductivities and heat-transfer coefficients varying with temperature. The following boundary conditions have been assumed on the exterior: (i) periodic incident radiative heat flux; (ii) natural convection of the surrounding air, the temperature of which varies periodically; and (iii) thermal radiation to a background sink.
Finite-time thermodynamics is used to study a compressor-driven, metal-hydride slurry air conditioner. Such a regenerative heat exchanger, the system has the potential to achieve high cooling power and efficiency. Important parameters such as the total heat conductance between reactors and reservoirs, pressure ratio of the compressor, mass ratio of slurry to hydrogen, compressor efficiency, heat...
We estimate energy consumption for domestic cooking and biogas energy resources for 21 clusters of households in a village. Data were analyzed on a cluster basis, with investments shared. Under the present conditions, biogas technology would not be economically viable. Economic analysis involving viability tools including additional benefits of biogas technology indicate that creating a market...
We examine the energy-consumption pattern of a village in Bangladesh where 100% of the households used biomass as cooking fuel and kerosene for lighting. The per capita biomass-energy consumption was 6.15 GJ/person/year with 1.72 GJ/household/year for lighting. The use of cooking fuel is influenced by the combined effects of population and total land area of the clusters. Population was found as...
An assessment is presented of the impact on system load shape of the application of cool-storage air-conditioning in the commercial sector of Thailand. A computer tool for least-cost planning is used to formulate an alternative power-development plan. Features of the resultant plan include an 8% reduction in the required capacity addition compared to a reference plan.
Test results from a demonstration of fuel-cell (FC) energy recovery and control of landfill gas emissions are presented. The project addressed two major issues: (i) the design, construction, and testing of a landfill-gas cleanup system; and (ii) a field test of a commercial phosphoric acid fuel cell (PAFC) power plant operating on the cleaned landfill gas. A summary of test results on the cleanup...
Numerical simulations of gas-solid flows, heat transfer and gas-particle combustion have been conducted for a three-dimensional, W-shaped boiler furnace. The gas-particle flow, distributions of temperature and concentrations of gaseous constituents, distributions of the rates of heat release, burnout rates of coal particles, and formations of volatiles and CO have been predicted.
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 circumsolar (α = 25°) and point-source versions of the simplified Perez model were developed to estimate irradiances on inclined planes from values for horizontal planes through the determination of sets of empirical coefficients. This model has been evaluated by us at Madrid. Mean hourly values of irradiances on vertical surfaces facing north, east, south and west were used. A modification...
An experimental technique has been developed to delineate the different hydrodynamic regimes of a gas-solid fluidized bed, each regime signifying a characteristic type of fluidization. The technique involves the measurement and statistical analysis of temperature-history records of an element of the heat-transfer surface immersed in a fluidized bed in which different regimes are brought about by...
To support their technology, factories use heat and power. Inputs may be produced internally or purchased in the market. To produce inputs internally, factories use the TPC, i.e. an energy system consisting of a steam boiler and a purely condensing turbine. Factories may also use an energy system consisting of a steam boiler and a turbine with steam extraction (TSE). Using a steady-state, bottom-up...
PR Spring bitumen was hydrotreated in a fixed-bed reactor over a commercial Mo/alumina hydrodemetallation (HDM) catalyst. Hydrodenitrogenation (HDN), hydrodesulfurization (HDS), hydrodemetallation, Conradson carbon residue (CCR) reduction, and residuum conversion were studied as a function of process operating conditions (T = 625-685 K, WHSV = 0.26-1.55 h -1 and reactor pressure = 11...
The apparent thermal capacitance of a building is obtained by adding the distributed specific heats of all building elements. It differs considerably from the effective thermal capacitance, which is calculated in the present study by forcing the solution of a lumped-system differential equation to follow the experimentally validated, finite-difference solution of a rigorous set of coupled differential...
A new system has been developed for clean and highly efficient utilization of coal. The coal is first gasified and the fuel gas is then used for industrial purposes in town gas or as a fuel for gas turbines. The char residue from the gasifier is burned in a circulating fluidized-bed combustor to generate steam for power generation, process heating, refrigeration, air conditioning, etc. The ash...
Impingement of producer gas obtained from rice-busk gasification onto a water surface has been found to be very effective in removing tar and ash from the gas. Correlations to estimate tar- and dust-removal efficiencies have been developed. An advantage of impingement is that the hot gas jet is cooled. Here, we describe experiments to study heat transfer when heated ambient air impinges on the...
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