17. Promising Options
Major requirement of a dryer for drying freshly harvested cereals are during adverse weather conditions. To improve the reliability of solar dryers under adverse weather conditions, a subsidiary heat source is essential. Major investment in solar dryer is towards establishment of solar component, which contributes towards little during adverse conditions, when the need felt for the dryer is maximum, also impact of this investment adversely affects the cost of drying. Nor, the solar component can be used for other farm related activities. Thus solar dryers are not likely to be a promising option under present environment.
Out of the options discussed, the following hold
i) Direct utilization of combustion gases: and
ii) Hot air engines
Neither of the above two options have been used for drying freshly harvested cereals on a commercial scale in the environment prevailing in the rural surroundings. In brief, hot air engine have the advantage of producing both hot air and power necessary to dry freshly harvested cereals. In addition, the engine can be used for farming related activities like irrigation, threshing, etc. Direct utilization of the combustion gases system can only provide hot air for drying. To effect controlled drying, the power required for forcing the hot air through the grains has to be obtained either through utility power or by the operation of diesel engine. From above it is apparent that hot air engines hold better promise due to their ability of :
- Simultaneous generation of power and heat: and
- multi-purpose to which they can be put.
However, although these engineers have been available for the past few years, they have not yet been widely used for drying. Similarly, though the technology of direct utilization of combustion gases has been widely used for other applications, its use for drying freshly harvested cereals on commercial scale has not been reported.
A detailed analysis of both the above options shows that hot air engines (stirring engines) show better promise, as they meet nearly all oft the basic requirement desired in the promising option outlined in Section 9 above. However, it will be prudent to test the efficiency of both the systems under rural environment to arrive at a conclusive result.
18. Further Actions Considered Necessary
To improve the acceptability of promising options for drying freshly harvested cereal, following investigations/developments are considered necessary:
i) Identification of suitable methods to obtain controlled combustion of paddy straw at a scale appropriate for rural application.
ii) Ambient air dilution system using combustion gases of paddy straw to obtain drying air with controlled temperature of 50 to 60?C.
iii) Identification of actions necessary to reduce cost of drying and installed capital costs.
iv) Development and availability of cost effective attachments to make the options amenable for use in other applications in the farm to improve the utilization of the capital investment.
