Energy in Agriculture最新文献

This paper develops a thermal analysis of greenhouse performance using a single energy balance equation based on solar efficiency factor, overall energy loss coefficient, including the effect of thermal inertia by means of a third parameter.

The characteristic parameters are extracted from experimental data obtained on two types of greenhouse using linear regression analysis. Although very simplified, this thermal model explains about 80% of the variability of collected solar energy in a greenhouse.

Anaerobic digestion of screened dairy manure in anaerobic rotating biological contact reactors at 35°C was investigated. Reactors using discs made of cedar wood and acrylic plastic were used. The reactor with cedar wood discs had a shorter start-up period than one utilizing acrylic plastic discs. Within an operational period of 3 months, the highest methane production rate of 1.67 l CH₄ l⁻¹day⁻¹ was obtained at 1 day hydraulic retention time for the reactor with wood media. Anaerobic rotating biological reactors using plastic media gave the highest methane production rate of 1.89 l CH₄ l⁻¹day⁻¹ at 1 day hydraulic retention time after an operational period of 10 months. The results have demonstrated that anaerobic bacteria readily adhere to and develop into a bacterial film on rotating discs made of cedar.

The design details and performance of a low-cost solar dryer which can be used for dehydrating 10–15 kg fruit and vegetables are described in this paper. Field tests indicated that by the use of a solar dryer, the drying time for chillies can be reduced to nearly half of that by the open drying method.

Upgrading of aqueous alcohol to anhydrous ethanol may be accomplished using a packed bed adsorption process, in which cracked grain corn is the adsorbent. A 0.35 m diameter by 3.0 m dehydration column was designed and constructed on the basis of data obtained in a series of bench-scale experiments.

The results demonstrated that grain corn would upgrade 91% ethanol to 99%-plus at a rate of about 0.20 L/min. The capacity of the corn bed in the prototype ranged from7.6 to 10.5 mL/kg of bed, which was lower than expected from the bench-scale experiments. The difference was attributed to the significant thermal effect of the heat of adsorption, which caused higher bed temperatures.

The performance of the prototype was modelled mathematically using a one-dimensional dispersive-convective description of the bed. The model was observed to fit the experimental data well in the regions where heat effects were not pronounced (where C/C₀ < 0.5), and showed a systematic departure in the non-isothermal regions.

The estimated energy consumption for the dehydration and regeneration cycles was observed to be lower than that normally associated with azeotropic distillation. Aside from the energy advantage, an adsorption system is easier and safer to operate than azeotropic distillation.

Energy costs constrain Nepalese agriculture and fertilizer usage in particular. The electric arc process may loosen this constraint. This process produces large quantities of waste heat. Ammonia absorption refrigeration requires high-grade heat input. An energy balance model was developed for the electric arc and ammonia absorption refrigeration systems. Laboratory experimentation combined these two complementary technologies, and the energy balance model was applied in providing an explanation of system performance. Economic analysis examined the feasibility of implementing such a combined technology in Nepal. This analysis concluded that it is more feasible to use waste heat from the electric arc system in traditional Nepalese processes which normally consume large quantities of fuelwood than for refrigeration purposes.

This study was conducted in the Harikot village of Hisar district in Haryana State on a microlevel. The power requirements during the peak months of October, November, April and May were estimated. The requirement of bullock-pairdays of 5861 per year was established on the basis of this study. It was found that the requirement of labour and bullocks for various crops are 7087 mandays and 1007 bullock-pairdays during the month of October, and 7197 mandays and 1384 bullock-pairdays during the peak month of November. It further revealed that tractor and bullock power are more than adequate throughout the year and even during peak seasons. Manpower is adequate on annual basis but in reality it falls short during the months of peak seasons by 38 persons. It has been further established that bullock power and tractor power are under-utilised in this village but seasonal requirements for manpower are higher than that available.