摘要:

AbstractThe effect of the inlet and outlet diffuser design on the performance of thermal stratification in a vertical water tank is investigated experimentally. Two sets of diffusers are used in the experiments, which are conducted with a moving thermocline (both up and down) for different flow rates. The results indicate that the preservation of the initial thermocline is excellent when using a settling mesh. It is also shown that the extraction efficiency of the tank is higher at low flow rates during charging, whereas it is lower at low flow rates during discharging.

ISSN:0363-907X    

DOI:10.1002/er.4440150702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA 1700 m2solar pond was constructed in the desert of Kuwait where severe weather conditions prevail in all seasons. The paper describes in detail a diffuser design for the gradient establishment, gradient stability, and thermal performance of the pond. The main problem encountered in operating the pond was mixing between the upper zone and the gradient zone, even when the wind speed was as low as 5 m/s. No mixing between the gradient and the lower connective zone was observed. The wind effect was severe in causing mixing even when the upper convective zone increased to 0.90 m.

ISSN:0363-907X    

DOI:10.1002/er.4440150703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractHeat pumps have been known for a long time, but, until the energy crisis of 1973, there were only a few studies covering them. Since that time, in addition to alternative energy sources, scientists and engineers have started studying heat pumps more earnestly. There are several kinds of heat pump and utilizations of them, but the most common one is the vapour‐compression heat pump. In recent years researchers have started to study metal hydride heat pumps.The paper considers the metal hydride bed, its thermodynamics, and its utilization as a heat pump. It is also compared with conventional heat pumps. The results indicate that the metal hydride heat pump has several advantages, and its utilization in the industrial, commercial and residential fields is foresee

ISSN:0363-907X    

DOI:10.1002/er.4440150704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper investigates the impact of the imposition of a broadly based energy tax on the US economy in general and the agricultural sectors in particular. The analytical approach used in the analysis consisted of a general equilibrium model composed of 12 producing sectors, 13 consuming sectors, six household categories, classified by income, and the government. The effects of a 10 cents per million Btu tax on energy on prices and quantities are examined. The results are revealing. For example, a 10 cents per million Btu tax on energy imposed at the point of production would result in lower output by the producing sectors (by about $9.154 billion), an increase in the consumption of goods and services (by about $20.292 billion), and a reduction in welfare (by about $4.30 billion). The government would realize an increase in revenue of about $6.356 billion. If the Btu tax were imposed at the point of consumption, there would be lower output by the producing sectors (by about $5.88 billion), an expansion in the consumption of goods and services (by about $19.830 billion), and a reduction in welfare (by about $7.066 billion). The government would realize an increase in revenue of $6.688 billion. The agricultural sectors would be minimally impacted. For example, if a 10 cents per million Btu tax were imposed at the point of production, output in the program crops sector would rise (by $8.3 million), output in the livestock sector would decline (by $83 million), output in the all‐other‐agriculture‐commodities sector would be reduced (by $118 million), and output in the forestry sector would rise (by $34.7 million). If the Btu tax were imposed at the point of consumption, output in the program crops sector would fall (by $38 million), output in the livestock sector would decline (by $42 million), output in the all other agriculture commodities sector would be reduced (by $94 million), and output in the forestry sector would rise (by $221 mil

ISSN:0363-907X    

DOI:10.1002/er.4440150705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe heat transfer and pressure drop characteristics of the flow in convergent and divergent ducts of rectangular crosssection are obtained through the simulation of the flow by a three‐dimensional parabolic model. The results show that in both convergent and divergent flows heat transfer decreases and pressure drop increases sharply near the entrance region of the ducts. Generally, the Nusselt number increases with increasing convergent/divergent angle, aspect ratio, or Reynolds number, and the pressure drop increases with increasing convergent/divergent angle or decreasing aspect ratio or Reynolds number in both flows. However, an increasing convergent/divergent angle may also result in a lower pressure drop owing to the recovery of static pressure from dynamic pressure. Furthermore, the pressure drop in a divergent flow is generally lower than that in a convergent flow except in the entrance region. For divergent flows with high divergent angle or high Reynolds number, flow separation may occu

ISSN:0363-907X    

DOI:10.1002/er.4440150706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe behaviour of an updraft moving bed gasifier of diameter 76 mm and height 787 mm, with rice husk as a fuel, has been studied. The gasification rate of the rice husk was varied in the range of 3.5–12.5 × 10−3kg/m2s. The air velocity was varied in the range of 0.07–0.11 m/s. The producer gas obtained from the gasifier has a calorific value in the range of 3712–4464 kJ/m3. A set of theoretical kinetic equations on the assumption of nonequilibrium conditions has been developed and solved numerically. The simulated temperature profile and outlet gas composition have been compared with those obtained from experimental runs. This model, which is developed from a mechanistic approach, can appreciably explain the behaviour of the present system within the range of variables

ISSN:0363-907X    

DOI:10.1002/er.4440150707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA mathematical model of the combustion of a droplet surrounded by hot gas with a uniform free stream motion is made from the numerical solution of conservation equations of heat, mass and momentum in both the carrier and the droplet phases. The gas‐phase chemical reaction between the fuel vapour and the oxidizer is assumed to be single‐step and irreversible. The phenomenon of ignition is recognised by the sudden rise of temperature in the temperature/time histories at different locations in the carrier phase. To ascertain the process irreversibilities, the instantaneous rate of entropy production and its variation with time have been determined from the simultaneous numerical solution of the entropy conservation equations for both the gas and liquid phases. The relative influences of pertinent input parameters, namely the initial Reynolds number Rei, the ratio of the free stream to initial temperatureT∞and the ambient pressure on (i) the local and average Nusselt numbers, (ii) the life histories of burning fuel drops, and (iii) the entropy generation rate in the process of droplet combustion have been establ

ISSN:0363-907X    

DOI:10.1002/er.4440150708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440150709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440150701

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY